Using high-throughput sequencing,we characterized 20 pairs of polymorphic microsatellite primers from the Crassostrea sikamea genome, and we examined the markers in a wild population. A total of 330 alleles were found in 25 microsatellites.The observed number of alleles (Na) ranged 6-39 in average of 16.500 0,and the effective number of alleles(Ne) ranged 1.352 9-33.361 7. The observed and expected heterozygosity values range 0.200 0-1.000 0 and 0.265 6-0.987 7, respectively.The Shannon Wiener index ranged 0.648 3-3.585 8 and Polymorphic information content (PIC) ranged 0.254 5-0.969 2. 16 microsatellite markers accord with Hardy-Weinberg equilibrium. Using these loci to analyze the genetic diversity of a cultured population, the average number of alleles was 10.25; the average number of Ne was 5.843 4. The observed heterozygosity (Ho) average was 0.639 1; the expected heterozygosity (He) average was 0.763 6; the Shannon-wiener index ( I ) average was 1.791 4; and the polymorphic information content (PIC) average was 0.720 7. It was found that the genetic diversity of the C. sikamea cultured population was lower than that of the wild population, but it maintained a high-genetic diversity. The results of this study indicate that in the artificial breeding process of C. sikamea, the use of a large number of parents for breeding can effectively prevent the genetic diversity of the cultured population, but artificial breeding also has a certain impact on the genetic diversity of the cultured population. The 20 loci were surveyed the cross-species proportions in C. angulate, C. gigas, C. hongkongensis, C. ariakensis, Saccostrea cucullata, Ostrea mordax and Hyotissa hyotis. Locis XB1-6, XB1-39, and XB1-45 can amplify the target band in 8 species, and the loci XB1-41 can only amplify the target band in C. sikamea.
The susceptibility of the Pyropia haitanensis and its bacteria to chloramphenicol, oleandomycin and cefotaxime was studied. They were combined with ampicillin, kanamycin and gentamicin to optimize the sterilization effect of P. haitanensis thalli. The effects were evaluated by plate count, Q-PCR and 16SrRNA sequencing analysis. The results show that when P. haitanensis thalli was treated with ampicillin (300 mg/L), kanamycin (100 mg/L) and gentamicin (100 mg/L) mixture for 18 h, and then treated with chloramphenicol (50 mg/L), cefotaxime (200 mg/L) and oleandomycin (50 mg/L) mixture for 4 days, the health of the thalli is above 96.3%, and the inhibition rate of bacteria reached to 99.9 %. According to the results of Q-PCR and 16SrRNA, the number of bacterial in this antibiotic combination was nearly reduced by one time as compared with the first three antibiotic combination, and the bacteria abundance and diversity index were also significantly decreased. Among them, Pseudoalteromonas, Altererythrobacter, Salinimonas and Marinobacter were specifically inhibited. These results indicated that the optimal combination of multiple antibiotics could significantly affect the community structure of epiphytes on the thalli, which could be inhibited to the minimum, but still could not achieve the absolute sterilization.
VIIRS/DNB satellite nighttime image was used as the data source for studying the dynamics of fishery vessels. A total of 719 nighttime light images were recorded in the Yellow Sea in 2016. We designed a new method to extract the light point information of the nighttime operation vessel for Yellow Sea. Analysis of the lightting points in combination with the China-Korea Fishery Agreement Area and the Yellow Sea area fishery division. The results show that the seasonal distribution of fishery lights is significant, and the number of fishing boats in the four seasons shows the trend of autumn> spring> summer> winter. The number of light points is the most in South Korea's waters, followed by China's side waters, and the waters in China and South Korea are the least. Combined with the light point density map, the Korean side waters have higher intensity and wider distribution range in autumn, while other seasons have moderate intensity, and high-grade agglomeration areas distributed in coastal waters all year round; The Chinese side waters have lower intensity in summer and winter, higher intensity in spring and autumn, and The overall intensity of the year is low but the distribution is broad. The number of light points in both sides has obvious seasonal patterns, and the proportion of light points decreased by 86.9% during the no-fishing period. Therefore, it is inferred that most of the light points identified in this study are fishery vessels, which can be used to provide reference for night fishing activities.
In order to investigate the relationships among the C-Myc expression, glutamine metabolism and replication of NNV. First of all, the C-Myc gene (GF-1-C-Myc) from Epinephelus coioides fin cell (grouper fin cells, GF-1) was cloned. The full length of GF-1-C-Myc gene cDNA was 814 bp with 285 bp ORF, encoding 95 amino acid (aa) with leucine zipper domain and helix-ring-helix (HLH) domain. GF-1-C-Myc protein was expressed and purified, and its polyclonal antibody was generated. The expressions of GF-1-C-Myc gene and the replication of NNV were monitored by real-time quantitative PCR (qRT-PCR) and immunoblotting (WB). The results showed that lack of glutamine could inhibit both the expression of GF-1-C-Myc gene and replication of NNV, while additional glutamine could promote both the expression of GF-1-C-Myc gene and replication of NNV. In addition, the expression of GF-1-C-Myc gene was up-regulated in GF-1 cells infected with NNV, and the glutamine in the medium was significantly consumed. Taken together, GF-1-C-Myc gene was involved in the regulation of glutamine metabolism in the cell, subsequently facilitated the replication of NNV. Our results will shed a new light on the prevention and control of NNV infection.
In order to understand the expression of MITF gene and its association with shell color in Pacific oyster Crassostrea gigas, we verified the four MITF genes in oyster, analyzed the sequence and compared with multiple sequences of other species. And the transcriptome of each stage of oyster development was analyzed. We also studied the mRNA expression in different tissues and mantle of black shell and white shell oyster. We found that three of the four MITF genes are pseudogenes which are confirmed by transcriptome and RT-PCR, and the only real expressed MITF gene in oyster encodes 448 amino acids. MITF protein is a hydrophilic and unstable protein and contains a N-terminal domain (MITF_TFEB_C_3_N superfamily) and HLH domain which is a highly conserved functional domain. Transcriptome analysis found that MITF was expressed at various stages of ontogeny of C. gigas, and the expression reached the highest level at the juvenile stage. The results of mRNA expression in tissues showed that the expression level of MITF in mantle was significantly higher than that in other tissues. The expression level of MITF in the adductor muscle of oysters with black shell was significantly lower than that of oysters with white shell. However, the expression level in the mantle of oysters with black shell was higher than that of oysters with white shell, but not significant. Both in black and white shell oysters, the expression of MITF gene in the outer edge of the mantel is significantly higher than inner edge. The results show that MITF gene of C. gigas might be participate in the regulation of the melanin’s information and the development of oysters at the early stage of oyster shell formation, it also might regulate tyrosinase Tyr2 gene of oyster and participate in the formation of melanin in mantle and shell. This study lays a foundation for further study on the formation mechanism of shell color in oysters.
To better study the structure and function of the growth hormone receptor (GHR) of the topmouth culter, Culter alburnus, the DNA sequences of GHR1 and GHR2 were cloned based on mRNA data from the transcriptome of C. alburnus. Bioinformatics analysis were performed and the polymorphic microsatellite loci in the GHRs were tested in 120 samples which were bred in the same batch and cultured in the same pond. The full length of GHR1 cDNA is 3 498 bp, with an open reading frame (ORF) of 1 818 bp, and a 605 amino acid residue encoded protein. The full length of GHR2 cDNA is 1 743bp, and with an ORF of 1 743 bp, and a 580 amino acid residue encoded protein, the amino acid sequences of GHR1 and GHR2 both comprised a signal peptide, extracellular region, transmembrane region, and intracellular region, and are 37.2% similar. There were marked differences in their structures. GHR1 has seven cysteine residues in its extracellular region of GHR1, but GHR2 has only five. GHR1 has three N-glycosylation sites more than GHR2. In the intracellular domain, there are 10 tyrosine residues in GHR1, but only 5 in GHR2, indicating that the two proteins may have different biological functions. Homologous amino acid sequence alignment showed that the GHRs are highly conserved with GHRs from other Cyprinidae. There were both 9 introns in the GHRs of C. alburnus, the length of intron 1 and 2 is GHR1 is over 10 kb so that they weren't amplified in this experiment. Six microsatellite loci were found in the obtained sequence: the microsatellite locus (CT)6 in the exon 2 of GHR1 was located in the signal sequence coding region, and no polymorphism of the (AC)5 in intron 8 was detected; There were four microsatellite loci in GHR2, including (TG)5 in intron 1, (TATC)5(AT)15(AC)11(AT)14(TG)6 and (TA)15 in intron 7, which belonged to highly polymorphic loci (PIC > 0.5). The (GAAG)5 microsatellite loci in intron 6 was moderately polymorphic (PIC = 0.463). The number of genotypes detected using two microsatellite loci in intron 7 was 50 and 61, respectively, which had good potential for individual identification. Correlation analysis indicated that the four polymorphic microsatellite loci were all closely related to the growth traits. The cloning and the characterization of microsatellites in GHR gene provide a reference for further study of its biological function and molecular marker assisted breeding in C. alburnus.
In order to study the impact of environmental and feeding factors on the distribution of rockfish Sebastes schlegeli in artificial reef areas, this study used environmental and fishery data of three reef areas in Shandong Province from 2017 to 2018. Fish body length was divided into 10 groups by Using the mean of the coefficient of variation, the interval was 33 mm. Using Bray-Curtis similarity index to compare the similarity of the body length composition of rockfish in different regions; Detrended correspondence Analysis (DCA) and canonical correspondence Analysis (CCA) were used to describe the effects of environmental factors on the rockfish distribution of different body length groups; The composition of the food of rockfish was detected by using the stomach contents analyses. The results showed that the body length composition similarity index of Xixiakou and Changdao artificial reef area was 70.66%, Compared with Xixiakou and Changdao, the Qiansandao artificial reef area has a low similarity index with them, which is 54.94% and 59.46% respectively. The distribution of rockfish with larger body type (299-365 mm) is more correlated with depth, WQI and chemical oxygen demand (COD), and it prefers to live in a deep, nutrient-rich environment. Small body type (35-200 mm) rockfish prefers environment with shallow sea areas and good water quality. The older (2-3 years old) small body length (200-365 mm) mainly consumes fish, shrimp and crabs, and the dominant bait is fish (IRI, %=65.94). Younger (0-1 year old) small body length (35-200 mm) individuals mainly feed on shrimp and crab, the dominant bait is shrimps (IRI, %=45.69). Consequently, the application of juvenile-fish-protect artificial reefs in shallow water can provide shelter for juvenile rockfish; Focus on fishing in deep water can reduce the bycatch of juvenile rockfish, then their resources can be proliferated and protected.
Hybridization is the most widely used and effective way of artificial breeding in aquaculture. This study use Epinephelus lanceolatus as female parent, E. moara as male parent by artificial insemination technology has carried on the interspecific cross experiment, and developmental sequence of fertilized egg, growth of larvae, juvenile and young fish was observed and studied, and then with the parent and the hybrid F1 generation “Yunlong grouper” (E. moara ♀× E. lanceolatus) contrasted the phenotypic traits. Results showed that the embryos as oval, transparent, floating, the fertilized eggs size (0.787±0.013)mm, each egg has one oil globule in the center. In sea-water temperature of 24 °C, salinity 30, pH 7.8, embryos can develop normally, according to the data, six period including 25 stages of embryos were recorded,which were fertilized egg, cleavage, blastula, gastrula, organogenesis and hatching period, the length of newly hatched larvae (1.595±0.015)mm and shows the feasibility of the cross;3 days after hatching, the yolk membranes disappeared and became the late larva, with a total length of (2.530±0.023)mm. 52 days after hatching, entering the juvenile stage, the total length (17.500±1.915)mm, the length of the second dorsal fin spine (5.795±0.049) mm, and the length of the first pelvic fin (2.992±0.911) mm. When the dorsal fin spine contracted to the minimum value (4.460±0.600) mm, scales began to appear and body color began to darken. The second dorsal fin spine and the first pelvic fin spine completely degenerated. The body shape was similar to that of the adult fish. The whole body was covered with scales. The growth comparison results showed that the growth rate of the positive and negative cross F1 generation was between that of the parents, which was faster than that of the E. moara, which was slower than that of the E. lanceolatus, and the growth rate of the reverse cross F1 generation was slower than that of the orthogonal F1 generation. The results provide a basis for the formation of hybrid dominant traits and genetic analysis of grouper.
This study was conducted to explore the ecological advantages that occured in the rice-fish co-culture systems in Hani Terrace. High-throughput sequencing technique was used to analysis the bacterial diversity of water, surface soil, root soil and carp intestine (16S rDNA) between rice-carp co-culture (RC) and rice-monoculture (CK) models. The results shown that Proteobacteria, Actinomycetes, Firmicutes, Chlorobacteria, Acidobacteria, Bacteroidetes, Nitrospira, Bacteroidetes were the dominant phyla the rice-fish co-culture systems. Compared with CK group, the relative abundance of Chlorobacteria and Firmicutes in RC surface soil significantly increased, and the significantly increased genera mainly including Anaerolineaceae_norank, Aminicenantes_p_norank, Chloroflexi _p_unclassified, Clostridium_sensu_stricto_1, Clostridium_sensu_stricto_12, Syntrophaceae_f_norank, Gemmatimonadaceae_f_norank. The relative abundance of Chlorobacteria in root soil was significantly increased in RC group compared with CK group, and the significantly increased genera including Anaerolineaceae_norank, Sideroxydans, Aminicenantes_p_norank, Chloroflexi_p_unclassified, Gemmatimonadaceae_f_ norank. The dominant phyla of intestine bacterial communities in RC group were Firmicutes and Proteobacteria, and the relative abundance of Firmicutes was 58.59%. The pH, total nitrogen, ammonia-N, nitrate-N, hydrolysis nitrogen, total phosphorus, available phosphorus and soil organic carbon contents were lower in the surface soil of RC group than the CK group, and the pH, total P and available P were significantly reduced. Sobs and PD indexes of bacteria in surface and root soil of RC group were also increased, and these two indexes were significantly increased in the surface soil of RC group. In brief, the introduction of fish to rice farming ecosystems changed the physico-chemical properties and bacterial community structure of surface soils, and also affected the microbiota community structure of root soil and fish intestine to a certain extent. Our preliminary results provides microbial ecological evidences for the advantages of rice-carp co-culture over rice monoculture system.
In this study, using twelve novel microsatellite markers, we construct a paternity test technology for Acanthopagrus latus basing on a mixed family of Acanthopagrus latus including 112 parent individuals and 393 offspring individuals. Genetic diversity data demonstrated that there were 119 alleles observed and the mean number of alleles (Na), observed heterozygosity (Ho), expected heterozygosity (He) and polymorphism information content (PIC) were 9.91, 0.651, 0.661, 0.621, respectively. Paternity analysis showed that the combined probability of exclusion reached 99.58 % when both parents were unknown (confidence level, 95%) by 12 loci. And, the combined probability of exclusion reached 99.1 % when both parents were unknown (confidence level, 95%) by 8 loci. Consequently, the 8 high polymorphic microsatellite markers (AL49, AL37, AL01, AL20, AL14, AL18, AL15 and AL51) made up the system of paternity test for A. latus. The cumulative exclusion rate of their parents was 99.1% without parents' gender by 8 loci. The rate of assignment success for the real data set was only 89.31 %. in conclusion, the combination of this novel 12 microsatellite markers in our study provided highly effective testing tools for the paternity identification, population breeding and molecular assisted family management in A. Latus.
Seaweed plays an important part in structuring seaweed-associated amphipods population characteristics. However, as for this system progress, most studies have constructed in the benthic seaweed bed. In this study, eleven representative seaweeds were sampled in raft-mussel-culture area, Gouqi Island during the flourishing period of seaweeds. And biological parameters of seaweeds and amphipods associated with each seaweed species were measured. Results showed that the population characteristics of Gammaridea and Caprellidae attached on different seaweed species were significantly different. Both of highest population density and largest body size of Gammaridea appeared on Pachydictyon coriaceum. And highest population density and largest body size of Caprellidae appeared on Ganonema farinosum and Grateloupia constricata, respectively. Moreover, seaweed species with relatively lower biomass tended to support higher population density of Gammaridea and Caprellidae and smaller size of Caprellidae, but had no significant effect on size of Gammaridea. Furthermore, seaweed with higher surface area to biomass ratio tended to support higher density and larger body size of Gammaridea, but had no significant effect on density or body size of Caprellidae. In a word, our investigation indicated that seaweeds community paly different functional role in structuring seaweed-associated amphipods population characteristics in mussel rafts culture area, which were determined by the diverse seaweed biological traits.
In order to understand the structural characteristics of MR and its role in anti-infective immune responses in Leptobarbus hoevenii, we cloned and sequenced the MR of L. hoevenii. Subsequently, real-time polymerase chain reaction (qRT-PCR) assay was used to measure the expression of the MR in the tissues of L. hoevenii with or without F. columnare infection. The results showed that the MR of L. hoevenii (LhMR) open reading frame was 4 296 bp, encoding 1 431 amino acids (aa). The amino acid sequence and molecular structure of LhMR are highly similar to the MRs from other animals, i.e., containing an extracellular ricin-like β-type clover domain (RICIN), a fibronectin type II domain (FNII) and eight tandem C Lectin-like domains (CLECTs), a transmembrane region and a short intracellular region. The mRNA of LhMR was widely expressed in 11 tested tissues, including spleen, kidney, heart, brain, skin, muscle, gills, liver, post intestine, fore intestine and mid intestine, with the highest expression level in the spleen. The mRNA expression of LhMR was significantly increased in the spleen, intestine, kidney and gills of L. hoevenii infected with F. columnare measured by qRT-PCR. Furthermore, the protein expression of LhMR was also increased in the spleen, kidney and gill of L. hoevenii infected with F. columnare revealed by immunochemistry assay. By Hematoxylin eosin staining, there were various pathological changes observed in the trunk kidney, intestine, liver and gills. In the body kidney, there were blood cells infiltrated in the renal tubules with necrosis in epithelial cells. The wall of intestine became thinner with diffused necrosis. Numerous vacuoles were observed in the liver cells. Gill lamella showed swollen, disordered, necrosis and detached. The results revealed that LhMR plays an important role in the immune responses of L. hoevenii infected with F. columnare and will pave a new way for development prevention and therapy strategies against columnaris.
In order to investigate the variations of gene expression of salivary gland in Hirudo nipponia under starvation stress, two libraries of starvation treatment group (D30) and control group (D0) were constructed and sequenced using the Illumina HiSeq 2500 platform (paired-end). After stringent quality control of raw data, 145 981 unigenes were obtained using de novo assembly. The average length of unigenes was 675 bp and N50 lengths was 1 127 bp. And then all of unigenes were annotated via sequence alignment analysis in CDD, KOG, COG, NR, NT, PFAM, Swissprot, TrEMBL, GO and KEGG databases. The amount of gene expression was also estimated according to TPM (Transcripts Per Kilobase Million). By comparing the transcriptome data of D30 sample and D0 sample, the differentially expressed genes (DEGs) were screened out with a threshold criteria Q Value<0.05 and |FoldChange|> 2. Totally 2 650 DEGs were identified under starvation stress, among which 667 genes were up-regulated and 1 983 genes were down-regulated. Four functional DEGs were selected for qRT-PCR analysis, and the results confirmed that the transcriptome analysis was reliable. In addition, 175 pathways were significantly enriched when the DEGs were subject to GO enrichment analysis. The results showed that most of the DEGs were involved in cytoplasmic ribosome pathway and ribosome pathway. The DEGs were almost down-regulated in these pathways. It also was proved in KEGG enrichment analysis that most DEGs were involved in ribosome pathway. The DEGs down-regulated in ribosome pathway can indicate that it reduces protein metabolism under starvation stress. Futhermore, were predicted to be involved in anticoagulatory, antithrombotic, antibacterial, anti-inflammatory and antitumor processes, which might play important roles in the treatment of various diseases. The results above mentioned provide foundation information for further study on the molecular mechanism of starvation tolerance of salivary gland and the discovery of pharmaceutical value genes in Hirudo nipponia, and also provides reference for other medicinal leeches.
Scophthalmus maximus is a commercially valuable flatfish and one of most promising aquaculture species in Europe. Since S. maximus was introduced into China in 1990s, it has been a major maricultured fish in northern coastal areas of China. As a kind of cold-water fish, S. maximus has strict requirements on breeding temperature, which greatly limits the breeding range of this important marine fish. Therefore, it has great research significance to explore the mechanism of heat-resistance in turbot. In this paper, tissue distribution of PPARs and the expression of PPARs in kidney under different temperature were analyzed by qPCR.The results showed that there are significant differences in the tissue distribution of the three subtypes of S. maximus PPARs. PPARα1 and PPARα2 were markedly expressed in the heart, PPARβ was widely distributed in various tissues of S. maximus, while PPARγ was significantly expressed in the gill of S. maximus. What's more, the transcript abundance of PPARs in S. maximus kidney showed different response patterns with the elevated temperature. At 20 ℃, the expression level of PPARα diminished dramatically and then increased with the elevated temperature. The expression of PPARβ was not significantly different at 14, 20, 23 and 25 ℃, however, its transcript abundance increased significantly when the temperature was increased to the lethal temperature of S. maximus at 28 ℃. The expression level of PPARγ showed a tendency to increase with increasing temperature. In summary, our results revealed that there are three subtypes PPARα, PPARβ and PPARγ in S. maximus, which may be involved in the regulation of lipid metabolism in a tissue-specific manner, and more importantly, the expression of three subtypes of PPARs in thermal stress was pointed out for the first time. Collectively, these studies will shed light on the regulation mechanism of PPARs on lipid metabolism in the kidney of S. maximus during heat stress, which will promote the further study of fish lipid metabolism.
As the first pilot site of the Globally Important Agricultural Heritage System (GIAHS), Qingtian rice-fish co-culture system has attracted more and more interests due to its unique advantages. In order to better conserve the first GIAHS project in Asia, We investigated the effects of different rice planting densities on soil fertility of Qingtian rice-fish co-culture systems. The results showed that the pH value of the tested paddy soil was varied between 5.50~6.13, which was weakly acidic. The contents of soil nutrients (such as the soil total nitrogen, soil organic matter, available phosphorus and available potassium) decreased until and reached the lowest values at the booting stage, which were recovered to the similar higher levels with the initial before rice harvesting, indicating that the activity of the field fish and perhaps fish feces could help maintain the soil fertility. According to the results of Grey relational analysis (GRA) between rice yield and soil nutrient, it was found that soil pH and available potassium were most closely related to rice yield. Compared with the richful nitrogen, available phosphorus and soil organic matter, the less suficiently available potassium and low pH value might be responsible for the limited growth and yield of rice. Rice planting densities were not found to significantly affect on soil fertility in Qingtian rice-fish co-culture system in one growing season.
In order to better analyze the possibility that the floating Sargassum horneri in East China Sea originated from benthic S. horneri in Zhoushan sea area, and provide an ecological reference for effective tracking and monitoring of floating Sargassum, morphological characteristics of vesicle of S. horneri and its relationship to environmental factors were investigated. The results showed that algae began to have vesicle in September, and have a highest growth rate from March to May. The number of vesicles in the main side branches increased rapidly from March to April, and reached a maximum in April. The number, average length, average wet weight and average volume of vesicles in each month outnumbered in top main side branch than in middle and bottom main side branch, but the average diameter was relatively uniform. The net effective accumulated temperature needed by S. horneri to complete the life history was 4 434.75 ° C/d. Vesicle germinating net effective accumulated temperature in September was 1 853.47 ° C/d, and development completing net effective accumulated temperature in April was 3 611.25 °C/d. The sea surface temperature change in the study area is mainly affected by the current changes caused by monsoon activity. The warming condition after a low temperature period of sea water may be the factor that induces the rapid growth of S. horneri, and higher sea temperature can limit algae growth.
The purpose of the experiment was to explore the effects of different riboflavin levels on the growth performance, body composition, and immune parameters of Schizothorax prenanti. Six purified diets were formulated to contain 0.67、2.96、5.83、9.05、11.58 and 23.42 mg/kg riboflavin, respectively. S. prenanti with an average initial body weight of (11.21±0.16) g were fed the diets for 8 weeks and each diet had 3 replicates with 30 fish per replicate．The results showed as follows: The weight gain rate (WGR), specific growth rate (SGR) and protein efficiency (PER) of the fish were increased first and then decreased with the increase of riboflavin level, and reached the maximum and significantly higher in the 5.83 mg/kg group and the other groups; the feed coefficient (FCR) decreased first and then increased, the lowest in the 5.83 mg/kg group and significantly lower than the other groups; riboflavin significantly affected the survival rate of the test fish (SR), liver index (HSI) and visceral index (VSI); riboflavin significantly affected the crude fat content of whole fish, but had no significant effect on crude protein, water and ash content. The amount of riboflavin in the liver increased with the increase of the riboflavin level; the liver D-α-amino oxidase (DAAO) activity reached the highest in the 5.83 mg/kg group. The activities of serum lysozyme (LYZ) and catalase (CAT) increased first and then stabilized with the increase of riboflavin. The content of malondialdehyde (MDA) decreased first and then stabilized with the increase of riboflavin level. It is indicated that riboflavin can effectively improve the digestibility of feed with the feed, improve the immunity and antioxidant capacity, and promote its growth. Considering the best growth performance and immune ability of S. prenanti, 5.32-5.89 mg/kg of riboflavin would be enough.
Growth traits of blood clam (Tegillarca granosa) is quantitative traits. In order to acquire some reliable molecular genetic markers for growth-related traits, the correlation analysis of 12 SSR markers and growth-related traits in T. granosa were analyzed using 150 samples with the fourth-generation selected line of blood clam. And the correlation and path analysis method were used to analyze the effect of phenotypic character on body weight. Then results showed that the correlations among the quantitative characters reached extremely significant levels. The shell height showed the greatest correlation coefficients to the body weight (0.930). However, the result of the path coefficient analysis showed that the highest path coefficients were the shell width (0.432). The results of the determinant coefficients were consistent with the results of the path analysis. In addition, a total of 61 alleles for the 12 loci were detected (3-8 alleles for each locus), and the average number of alleles and effective number of alleles were 5.083 and 3.038, respectively. The average observed heterozygosity (Ho), expected heterozygosity (He) and polymorphism information content (PIC) was 0.528, 0.646, and 0.594, respectively, both of which indicated that the population genetic diversity was high. Correlation analysis between genotypes of SSR and growth traits indicated that 3012-2 had a significant impact on shell length, shell width and shell umbo width. Locus 3564 showed a significant influence on shell height and radial rib width. Locus 2692 showed a significant correlation with shell length. Our results could provide an theoretical basis for the study of genetic improvement and selective breeding of T. granosa.
A study was carried out to test the effect of acute ammonia stress on antioxidant enzyme activity and mRNA expression levels of HSP70 and HSP90 genes in tissues of yellow catfish, 360 yellow catfishes (17.25 ± 0.05) g were randomly exposed to ammonia: 0 (control), 5.70, 28.50 and 57.00 mg/L total ammonia concentrations for 96 h, respectively. Experimental fish were sampled on 0, 12, 24, 48 and 96 h. The results showed that the superoxide dismutase (SOD) activity in liver of fish in low and medium concentration groups increased from 0 to 6 h, and then gradually decreased, but high concentration group continued to decrease. Malondialdehyde (MDA) content in liver of fish in low, medium and high concentration group was significantly increased throughout the 96-h period; At hour 3, SOD activity in liver of fish in high concentration group was the lowest, while MDA content was the highest. Liver catalase activity increased significantly at hour 24. In low, medium and high concentration groups, the mRNA expression of HSP70 in liver of fish decreased from 0 to 6 h, and then gradually increased, and in gill of fish continued to increase, but in brain of fish continued to decreased. The mRNA expression of HSP70 in liver and brain of fish was significantly lower than that of control group at hour 3, but in gills is opposite. Compared with HSP70, the mRNA expression of HSP90 in liver and gill of fish in high concentration group reached the highest value at hour 24. The results showed that the antioxidant enzymes activity was inhibited by different concentrations of ammonia, the reason is related to the accumulation of MDA. Compared with HSP90, the mRNA expression of HSP70 in yellow catfish was rapidly up-regulated after the occurrence of ammonia stress, and this physiological regulation mechanism suggests that HSP70 plays a more important role in the response to acute ammonia stress.
Coast of Zhejiang province is one of the important fishery production areas in China. As an important part of the marine ecosystem, cephalopods also play a very important role in the coastal fisheries of Zhejiang Province. Based on the trawl survey data in the coast of East China Sea during 2014-2016 in spring and autumn, all the cephalopods species were selected, we analyzed the species and dominant species composition using statistical methods, studied the spatial-temporal distribution of the dominant species, and also investigated the dynamic of community structure using the ecological methods. The results showed that a total of 22 species were captured and identified in the three-year survey, which belong to 3 orders, 7 families and 10 genus, dominant species were Abralia multihamata, Loliolus beka, Loligo duvauceli, Loligo edulis, Sepiola birostrata and Octopus minor. A spatial and temporal variation of cephalopod community were presented. Octopus minor dominated in the north station in spring, and its biomass density was higher than the south station, which dominated by Loligo edulis, Abralia multihamata and Loliolus beka were the dominant species in autumn, and the biomass density in 2016 is much less than the other two years before. Cluster analysis separated as two groups based on different years, months and stations, significant difference existed among community structures, Octopus minor made the largest contribution to the communities, and also made a decisive effect on the spatial community structure, individual migration may the main factor for the seasonal dynamic of community structures.
To investigate the characteristics of Tc1/Mariner transposons in four catfish genomes (Ictalurus punctatus, Glyptosternum maculatum, Silurus asotus and S. meridionalis) and their role in the evolution, we used de novo and homology methods to predict Tc1/Mariner transposons and explored the role in the evolution of those four catfishes. The results showed that the contents of Tc1/Mariner transposons in the four catfishes were 9.46%, 2.70%, 7.83% and 8.54%, respectively. All the Tc1/Mariner transposons in the four catfishes were classified into 38, 20, 43 and 55 families, respectively. Based on the structural and phylogenetic analysis of the catalytic region of the transposase, the Tc1/Mariner transposons in the four catfishes can be classified into five different subgroups: Tc1 (DD34E), DD35E, DD36E, DD37E and pogo (DD35D). Phylogenetic analysis indicated that the transposons of most of the branches for S. asotus and S. meridionalis were clustered into sister groups. The results indicated that the insertion time of the majority Tc1/Mariner transposons mainly ranges between 0-5 Mya. Many Tc1/Mariner transposons have a burst expansion between 0-1 Mya or 1-2 Mya. In addition, most of the Tc1/Mariner transposons in the four catfishes were inserted into the intron of the gene. In summary, this study provides new insights into the evolution of Tc1/Mariner transposons in the fish genomes.
In order to understand the grain size structure characteristic of fish communities in the Jiaozhou Bay, in this study, we constructed the biomass particle size spectrum of fish in this area based on the data collected from the four submarine trawl surveys performed during 2016 to 2017. The heterogeneities of the characteristic parameters of biomass particle size spectrum of fish in four seasons were analyzed and compared. The results showed that the Sheldon-type biomass particle size spectrum of fish in the Jiaozhou Bay displayed the unimodal pattern, with the fish particle sizes being ranged from -3 to 10, showing a relatively uniform particle size distribution spectrum and the highest peak was on the 5-6 grain size. It is mainly composed of small fish, such as Hexagrammos otakii and Sebastiscus marmoratus. There was a significant difference in the curvature and curvature of the normalized biomass particle size spectrum of each season. Among them, the spring curvature was the largest and the curve was gentle whereas the summer curvature was the smallest and the curve was relatively steep. The curvature and curvature of the curve were mainly related to the presence of a large number of endemic perennial species, such as Liparis tanakae, Ammodytes personatus, and Cryptocentrus filifer as well as the seasonal migratory fish, such as Thrissa kammalensis, and Argyrosomus argentatus. The ABC curve indicated that the spring was in an undisturbed state, the winter was in a moderately disturbing state whereas the summer and autumn were in a state of severe interference. These results represented the fish biomass spectrum in Jiaozhou Bay was unimodal, and the particle size structure was mainly small-sized fish. The number and size of supplementary populations such as local perennial and seasonal migratory fish affected the peak shape and curvature of the biomass particle size spectrum of fish in the Jiaozhou Bay.
The traditional water quality regulations could not destroy thermocline and inhibit macroalgae growth, which result in poor water quality and Apostichopus japonicus growing poorly and even death. Jet water mixing (JWM) can break down thermocline and inhibit the growth of macroalgae. To study the purification efficiency and mechanism of JWM, the primary productivity in the ponds with a jet water mixer (JWM), a submerged aerator (SA) or without any artificial mixing (control) were studied. The results showed that the annual average primary productivity and P/R values of the pond with JWM were the highest, followed by SA pond, and the lowest in the pond without any artificial mixing (control). The mean annual primary productivity in the ponds with JWM, SA and Control pond were 6.22±0.54, 5.37±0.60 and 4.69±0.53 gO2/(m2·d), respectively. The primary productivity in the ponds decreased with the depth of water. There was no significant difference in primary productivity between 30~50 cm water layer and 50~100 cm water layer in JWM pond, while there was significant difference between the SA pond and Control pond (p<0.05). In addition, the primary productivity of the water layer of 50~150 cm in JWM pond was significantly higher than that of the SA and Control pond (p<0.05) from June to September. Conclusion: compared with SA facility, JWA can improve significantly the primary productivity of the lower water layer, which can significantly improve the total primary productivity of the pond and facilitate the rapid circulation of the pond substances.
Oxygen is the most important critical factor on animal’s life activities. When the animals was exposed to hypoxia environment, the biochemical reaction and physiological function of the animals will correspondingly change, which can finally cause a series of metabolic disorders and damage in organisms or even death. Hypoxia stress mechanisms is complex physiological regulation process involving multiple genes and regulated by fine-tuning, hypoxia stress and molecular adaptation mechanism of crustaceans is unclear compared with mammal. In this paper, the causes of hypoxia stress were analyzed, and stress reacting process and physiological adaptation strategies of crustaceans in response to hypoxia, as well as the effects of hypoxia on behavior, survival, antioxidant ability metabolic reaction, and molecular mechanisms of hypoxia-stress of crustacean were described and reviewed. In addition, the molecular mechanism responded to hypoxia was discussed from HIF-1 (hypoxia-inducible factor 1) signaling pathway, AMPK (adenosine 5'-monophosphate (AMP)-activated protein kinase) signaling pathway and apoptosis pathway. On this basis, the multiple measures are necessary to prevent and regulate negative effects of hypoxia stress, including the breeding hypoxia-resistant variety, and nutritional regulation, which provide a theoretical reference for people to deeper understand the mechanism of hypoxia stress and molecular adaptation in crustaceans.
Based on the data from fishery resources survey carried out in southern coastal waters in Taizhou in October 2016 (autumn) and April 2017 (spring), this study defined the dominant species and main species that appeared in the two surveys as the dominant fish, and analyzed the niche and interspecific associations of dominant fish by the methods of index of relative importance, niche breadth, niche overlap, the variance ratio, Chi-square test, Pearson correlation test and Spearman rank correlation test. The results showed that there were 8 and 11 dominant fish species in autumn and spring respectively, and 5 common dominant fish species were in these two seasons. The index of niche breadth and overlap of dominant fish in autumn were slightly higher than those in spring. There were 4 wild niche species, 3 middle niche species and 1 narrow niche species in autumn, while 4 wild niche species, 5 middle niche species and 2 narrow niche species were in spring. The number of pairs with significant niche overlap in autumn accounted for 32.14% of the total pairs, while only 12.73% in spring. In autumn, overall interspecific associations indicated that significantly negative association existed among dominant fish species. Chi-square test, Pearson correlation test and Spearman rank correlation test showed that the positive and negative correlation ratios in the community were 1.50, 1.33 and 2.11 respectively, and the test significant rates were about 0%, 17.86% and 10.71% respectively. In spring, overall interspecific associations indicated that insignificantly negative association existed among dominant fish species. Chi-square test, Pearson correlation test and Spearman rank correlation test showed that the positive and negative correlation ratios in the community were 0.93, 0.90 and 1 respectively, and the test significant rates were about 9.1%, 18.18% and 21.82% respectively.
To provide a basis for the application of Lactobacillus in the healthy aquaculture of tilapia, the effect of mixed culture of Lactobacillus as water additive on the environment of pond, and the health of intestine and gill of tilapia were studied. Mixed culture of Lactobacillus were added to the water of tilapia (Oreochromis niloticus) pond (control group: 0; experimental group: with a final concentration of 1.0×104cfu/mL) for ten weeks. The components of mixed culture of Lactobacillus were Lactobacillus casei and Lactobacillus acidophilus, with a 1:2.2 ratio. The water quality of pond, immune and antioxidant indexes of the intestine and gill of tilapia were monitored. High throughput sequencing technique (Illumina Miq) was used to compare the community structure of microbiota in water, sediment, intestine and gill mucosa of tilapia between the control and the experimental group. The results showed that the nitrate content in the water samples of the experimental group was lower than that of the control group. From the seventh week, and the nitrate content in the water samples of the experimental group was 72.68% (P< 0.05), 72.00% (P>0.05), 26.27% (P>0.05) and 21.46% (P>0.05) lower than that of the control group, respectively. The total nitrogen content in the water samples of the experimental group was 43.39% (P>0.05), 44.64% (P>0.05), 15.64% (P>0.05), 37.57% (P>0.05) and 34.49% (P>0.05) lower than that of the control group from the sixth week, respectively. The total phosphorus content in the water samples of the experimental group was 40.91% (P>0.05), 33.33% (P>0.05), 50.00% (P>0.05), 33.33% (P>0.05), 17.39% (P>0.05), 39.29% (P< 0.05) and 25.71% (P>0.05) lower than that of the control group from the fourth week, respectively. Compared with the control group, the activity of alkaline phosphatase (AKP) in the intestine of tilapia in the experimental group increased by 45.04% (P< 0.05), and the total superoxide dismutase (SOD) and AKP in the gill of tilapia in the experimental group increased by 58.26% (P< 0.05) and 60.99% (P< 0.05), respectively. Mixed culture of Lactobacillus influenced the community structure of microbiota of pond water, but did not affect that of sediment. Microbiota of intestine and gill of tilapia were affected by the probiotic, among which, the conditional pathogens, Acinetobacter and Pantoea were decreased, while the beneficial bacteria, Cetobacterium was increased. Using mixed culture of Lactobacillus as water additive could improve water quality, the immunity and antioxidant capacity of intestine and gill of tilapia, and regulate the community structure of microbiota of intestine and gill of tilapia.
Suppressor of cytokine signaling (SOCS) is a class of intracellular proteins that inhibited cytokine signaling in. We cloned the sequence of SOCS1 gene from yellow catfish Pelteobagrus fulvidraco, whose length was 561 bp. We constructed the recombinant expression plasmid [pET32a (+)-SOCS1] carrying PfSOCS1 protein. The recombinant PfSOCS1 protein was optimally expressed by transformation into Escherichia coli BL21 (DE3) and then highly purified under inclusion body conditions. The polyclonal anti-PfSOCS1 antibodies were prepared by immunizing Balb/C mouse with recombinant PfSOCS1 protein, which could be used to recognize recombinant PfSOCS1 protein by Western blotting. The protein expression of PfSOCS1 was detected in kidney, intestine, liver and ovary, with relatively predominant level in the liver in P. fulvidraco.
In this research, the biological characteristics and life cycle of Sargassum fusiformis, including the sexual reproduction of its mature sporophytes, asexual reproductions of its rhizoids and lateral branches were comprehensively studied. The meiosis and mitosis of the eggs, sperm and fertilized eggs of maricultural and natural S. fusiformis in Dongtou coastal waters were recorded in detail. In addition, the growth, development and differentiation of organs such as rhizoids, stems (main stem and lateral stem), leaves (air-bladders) and receptacles (female and male), as well as the morphology and structure features of embryos, young and mature sporophytes of S. fusiformis were described. On this basis, the existing reproductive biology and life cycle of S. fusiformis were partially supplemented and revised, the contents about asexual reproduction of S. fusiforme lateral branches and sexual reproduction of young S. fusiforme sporophytes were supplemented, and the life cycle diagrams of sexual and asexual reproduction of S. fusiforme were redrawn. The results established a foundation in the study of the maricultural ecology and the reproductive rhythm of S. fusiformis, as well as the population reproduction and its relationship to environmental factors.
The origin of teleost skin color is from chromatophores. Different chromatophores synthesize distinct pigments, including melanin, carotenoid, pteridine and purine. Sepiapterin is a yellow pteridines, which could be transformed into tetrahydrobiopterin (BH4) and yellow/red pteridines pigments together with sepiapterin reductase (SPR), dihydrofolate reductase (DHFR) and other enzymes. SPR is the last enzyme in the process of de novo BH4 synthesis. In order to explore the function of spr in koi carp color formation, this study amplified the whole cDNA of spr and analyzed the spatio-temporal profile. Furthermore, we also detected the expression and distribution of SPR in the skin, fins and scales of koi carp with different colors by western blot and immunochemistry methods. The results showed that the size of spr cDNA was 879 bp, including 132 bp and 134 bp 5′ and 3′ untranslated regions, and a 510 bp open reading frame encoding 170 amino acids. Sequences alignment and phylogenetic analysis revealed the spr gene of koi carp contained a adh_short_C2 conserved domain and had 97.65% similarity with gold fish. spr was expressed in every tissues, especially highest expressed in skin. In the four ontogenetic stages, the expressive level of spr firstly decreased then rose. The expression level of spr mRNA and protein in skins, fins and scales displayed the same condition among three colors (whole red koi carp, whole white koi carp and kohaku koi carp). The highest expressive level was detected in whole red koi carp and rarely in white skin, fins and scales of kohaku koi carp. The immunohistochemical positive signals were detected in both skins of whole red and whole white koi carp, and intensively exhibited in red skin comparing with white skin. All the results might inferred the spr gene has relationship with the xanthophores/erythrophores differentiation and formation, involving in koi carp color formation.
Pyropia species were the most popular algae cultivated in China with great commercial importance. Yellow spot disease (YSD) was a high-incidence infectious disease in the conchocelis filament sporing stage of Pyropia, which seriously affects the production. In this paper, the free living conchocelis filament of Pyropia haitanensis were infected by Vibrio mediterranei 117-T6, a YSD pathogen. The effects of environmental factors on the growth of the strain and its infectious ability were studied. The activities of SOD, POD and the contents of phycobiliprotein, chlorophyll a (Chl. a), soluble protein, free proline (Pro) and malondialdehyde (MDA) in the algae were measured under susceptible infectious condition. The results showed that the optimum growth conditions of V. mediterranei 117-T6 were 30 °C, pH 7.0 and salinity 20, while the most susceptible infectious conditions were temperature 30 °C, pH 6.0 and salinity 20. After it was infected by V. mediterranei 117-T6 under the susceptible infectious conditions for 12 hours, the activity of SOD, POD, the content of phycobiliprotein, soluble protein and free Proline in P. haitanensis conchocelis filaments were significantly higher than those in the control group (P<0.05). The content of MDA reached the highest value at 6 hours and was significantly higher than that in the control (P<0.05). After infected for 24 hours, the content of Chl a in the infectious group achieved the highest, which was significantly higher than that in the control group (P<0.05). The study showed that in a short period, V. mediterranei 117-T6 could stimulate the algae to produce stress-response reactions. However, with the continues of the infection, the reactive oxygen species and osmotic pressure in the algae caused by pathogen increased and finally lead to the death of Pyropia. Adverse environmental factors such as high temperature and acidification can exacerbate the infectious ability of V. mediterranei 117-T6, the influence degree of which were temperature, pH and salinity. The results suggested that the comprehensive treatment of Pyropia YSD should be carried out from the two aspects of the environment and the pathogenic bacteria.
Conger myriaster is a commercially important specie in China. The population structure of C. myriaster remains a mystery and the spawning activities of C. myriaster are not well known because larvae and adults of this species have separate habitats and its spawning grounds have not been discovered. Several hypotheses on the population structure and spawning grounds of C. myriaster have been proposed. Takai described that this species have a singer population with a singer spawning site. On the other hand, there are also some indications of the possibility of multiple spawning populations. So it is important to clarify the population structure of C. myriaster to provide basics for future detailed examination on its life history. If this species have multiple populations, there may be some morphological and genetic differences in the samples collected from different sea areas at the same time. In the present study, we combined morphological and genetic methods to understand the morphological and genetic differences of C. myriaster in the two different localities of Zhoushan (East China Sea) and Qingdao (Yellow Sea). The morphological studies were conducted by using one-way ANOVA, discriminant analysis and principal component analysis. Genetic analysis of the mitochondrial DNA (mtDNA) sequence was carried out. Results from morphological studies indicated that there were intermuscular bones of “I” type in the muscle of the C. myriaster from Zhoushan group but not in Qingdao group. The results of multivariate statistical analysis showed that there were significant differences in seven morphological measurements (preanal length, head width, snout length, rictus length, eye diameter, predorsal length) of C. myriaster from different groups, and these measurements were all over the body. In principal component analysis, the C. myriaster from different groups could be distinguished by a scatter plot based on the first two principal components. Discriminant analysis results showed that the correct classification ratios of Qingdao and Zhoushan groups were 100% and 94.7%, respectively. The results of multivariate statistical analysis methods showed that there were significant differences in morphology between the two groups. But according to the Mayr’s 75 % rule, most differences in morphology between the two groups were characterized under-subspecies. Genetic results suggested that there was no significant difference in genetic diversity between samples collected from different locations on the level of mtDNA. The neighbor-joining tree showed no genealogical clade. The pairwise fixation index FST revealed no significant genetic difference between the two groups. The present study provides morphological and genetic basis for the taxonomic status of the C. myriaster population in China. It also provides useful information for the population assessment, management and conservation of C. myriaster.
Developing modern aquaculture seed industry, leading the green development of aquaculture, will secure the sustainable aquaculture industry in the future. New aquaculture varieties with high quality, high efficiency, multi-resistance and safety advantages should be encouraged to breed and popularize in aquaculture seed industry, and shift from pure high-production yield to high quality, high efficiency, feed saving, drug saving, stress resistant and wide adaptability varieties suitable for ecological and intensive aquaculture mode. In this paper, some problems existing in aquaculture seed industry were analyzed, and indicated that the foundation of high quality, high efficiency and multi-resistance aquaculture varieties is stress resistance. Arrange of topics related to stress resistance select breeding technology, including stress response, stress recovery, stress coping style and the case studies of stress coping style in animal and poultry seed industry were discussed, the concept of environmental restricted breeding and the future direction of comprehensive stress resistance breeding technology were introduced, it will lay the foundation and leading forward to promote sustainable aquaculture in China.
Aiming to improve the growth and survival performance of “Pingyou No. 2” flounder in different aquaculture areas, in this study, broodstocks which were selected based on the results of genetic parameter estimation and genome selection for growth and resistance traits, are used to produce “Pingyou No. 2” families. In total, 28 families were produced. Then these families were cultured in different sites (Site 1: Hebei; Site 2: Shandong). Genotype by environment interactions for growth and survival traits were estimated based on mixed linear models. The average daily gain was 1.5 g/d and 1.2 g/d in Site 1 and Site 2 respectively, and the survival rate was 81.4% and 82.2% in Site 1 and Site 2 respectively. Both traits showed a superior performance in the 2 sites. The genetic correlations for harvest body weight and survival traits between both environments were 0.57 and 0.82 respectively, which indicating that there was a significant genetic by environment interaction effect for harvest body weight but not for survival. These results suggest that “Pingyou No. 2” flounder showed a good growth and resistance performance in different sites. The harvest body weight and survival traits still have certain selective potential. Hence, to ensure a good demonstration and extension results, it is needed to improve and optimize the seed production techniques (e.g., seeds with a well environmental adaptability) for achieving the dominance of fast growth and high survival rate of olive flounder in different aquaculture environments.
Based on the trawl data of fishery resources collected from comprehensive surveys from May 2016 to February 2017 in Yueqing bay. Species composition, biodiversity index, community structure and its relationship with environmental factors were examined by cluster analysis, multivariate statistical analysis and redundancy analysis. The results showed that a total of 43 species of crustacean were identified, which belonged to 28 genera, 18 families and 2 orders. Portunus trituberculatus, Charybdis japonica and Parapenaeopsis hardwickii were annual dominant species. The species number of crustacean was greatest in summer and the least in winter which varied significantly in four seasons, while the composition of dominant species changed slightly. The research about crustacean species in different depth indicated that the richest crustacean were in depth of 5~10 m while less in depth of less than 5 m and more than 10 m. The results of one-way ANOVA showed that the richness index (D) of crustacean community in different depth were distributed significantly (P<0.05), and no significant differences in evenness index (J') and diversity index (H')(P>0.05). Redundancy analysis suggested that temperature, depth and turbidity were the most important environmental factors affecting the crustacean species composition and community structure characteristics. In particular, the depth has a great influence on the community structure of crustacean.
The changes in the spermatozoa number in spermatangia and seminal receptacles at different times after copulation, and the structure of the seminal receptacle were examined by using experimental ecology and tissue section techniques to reveal the mechanism of sperm storage in seminal receptacle and sperm utilization during oviposition. The results showed that paired seminal receptacles were located in the raised ventral portion of the buccal membrane, and opened inside the buccal membrane. The entire seminal receptacle was connected by a central duct, which had many folds and cilia on its inner surface. Each seminal receptacle had 12-20 sperm storage bulbs surrounded by circular muscles. A large number of spermatozoa were stored in sperm storage bulbs, and the heads of most spermatozoa faced toward the inner surface of sperm storage bulbs. After one copulation, the utilization of spermatozoa in spermatangia and seminal receptacles could be divided into three stages: ① the utilization of spermatozoa mainly from spermatangia (1-2 d after copulation); ② the transition from the utilization of spermatozoa in spermatangia to spermatozoa in seminal receptacles (2-3 d after copulation); ③ the utilization of spermatozoa mainly from seminal receptacles (more than 3 d after copulation). These results suggest that spermatozoa released from the spermatangia reached the seminal receptacles through the folds on the surface of the female buccal membrane. Spermatozoa entered the sperm storage bulbs through self-movement and cilia fluttering on the inner surface of the central duct. The distribution of spermatozoa inside the sperm storage bulbs was highly ordered, and the head of most spermatozoa faced toward the inner surface of the sperm storage bulbs. During spawning, females preferred to use spermatozoa from spermatangia to fertilize their eggs. When spermatozoa in spermatangia were insufficient, spermatozoa in seminal receptacles were released gradually by muscle contraction and cilia fluttering, and ova were fertilized externally near the female buccal membrane.
Cynoglossus semilaevis Günther is an important economic aquaculture species in China, but the nowadays, C. semilaevis disease occurs frequently in factory culture, especially ulcer disease is the most serious.. In this experiment, 40 bacterial strains were isolated from the intestinal tract and surface lesions of the diseased C. semilaevis with 2216E and TCBS medium. The hemolytic activity of the strains was tested, and three strains with the strongest hemolysis activity were selected as the three potential pathogenic strains were screened and identified in vitro, Vibrio harveyi, V. alginolyticus and V. parahaemolyticus. Secondly, by co-culturing the three kinds of potential pathogenic bacteria with the intestinal epithelial cells of the healthy C. semilaevis Günther, the relative expression of the immune genes and the apoptosis rate of the intestinal epithelial cells after co-culture were detected separately to evaluate the pathogenicity of these strains at the cellular level. The results showed that the expression of interleukin-10 (IL-10) in intestinal epithelial cells was significantly up-regulated after stimulated with V. harveyi, suggesting that the V. harveyi elicited the most intense immune response after co-culturing; and the apoptosis rate of the intestinal epithelial cells after co-cultured with V. harveyi, V. alginolyticus and V. parahaemolyticus was 48.3%, 36% and 34.5%, respectively. It is speculated that the Vibrio harveyi is a highly pathogenic strain of the C. semilaevis Günther ulcer disease. Finally, the results of the artificial infected showed that The mortality rates of V. harveyi, V. alginolyticus and V. parahaemolyticus were 100% and 95% and 75% respectively on the sixth day after artificial anaesthesia of C. semilaevis, which is consistent with the results of the cellular level test. Indicated that the three Vibrio strains screened in this experiment had strong toxicity and pathogenPicity, especially the pathogenicity of V. harveyi was the strongest, and it is speculated that the C. semilaevis ulcer disease may be caused by co-infection of various pathogenic bacteria.
The ichthyoplankton net was used to carry out the survey of fish eggs and larvae of Daiquyang during May 2010 and February 2012. According to the investigation results, 1042 fish eggs and 2055 fish larvae were identified as 26 species of fishes belonging to 26 genera, 15 families and 9 orders (not including twelve unidentified species). The dominant species of fish eggs were Auxis thazard and Eupleurogrammus muticus while fish larvae were Liza haematocheilus, Engraulis japonicas and Stolephorus chinensis. The average density of fish eggs in the surveyed areas was 8.40ind./100m3 while fish larvae was 14.85 ind./100 m3. The results of one-way ANOVA showed that there were highly significant differences among the diversity index (H′) in 4 seasons of spring and summer from 2010 to 2011, so did the evenness index (J′) and richness index (D).The CPUE of fish eggs and larvae were uneven distribution, it was higher in spring and summer, but lowest in winter, which revealed that fish eggs and larvae resource density demonstrated a tendency of higher in the south stations and lower in the north stations. Pearson Correlation Analysis proved that the environmental factors most closely related to fish eggs and larvae were temperature, salinity and suspended matter. The results suggested that spring and summer were important seasons for fish spawning and Daiquyang areas were important spawning and nursery grounds for pelagic fishes such as Engraulis japonicas, Auxis thazard and Stolephorus chinensis.
Cephalopod beaks, a major feeding structure, is characterized by special formation of pigment. In this study, we analyzed the main chemical composition and carbon-nitrogen stable isotope ratio of whole beaks of three species and beaks different parts of Dosidicus gigas with different pigment formation. The results showed that the protein and catechol content in different parts of the beaks were observably different with rostrum>lateral wall>wing, and the C/N ratio is wing>lateral wall>rostrum. The protein and catechol content of three cephalopods were observably different (P<0.001) with Sepiella maindroni>Dosidicus gigas>Uroteuthis edulis, and the C/N ratio is U. edulis>D. gigas>S. maindroni. There was a significant positive correlation between chitosan content and the C/N value in different parts of D. gigas’s beaks. There was a significant negative correlation between protein content and C/N value. The C/N of three cephalopods increased with the increasing of chitosan content and the C/N decreased with the increasing of protein content. When the C/N increased, the chitin content was high, the protein content was low and the corresponding pigment became shallow, while when the C/N decreased, the chitin content was low, the protein content was high and the pigment is deep. Consequently, the degree of pigmentation results from the proportion of protein and chitin, which provides an important basis for investigating specific foraging strategy and individual ontogenetic feeding variation.
In order to find out the influence of different entrance orientations and positions on fish attractive effect, a generalized model of fishway entrance was established and three environmental velocity conditions were designed in this paper. Tests were carried out at fishway entrance of different orientations and positions. The results showed that the fishway entrance in the direction perpendicular to the river flow had better attractive effect than the one in the direction parallel to the river flow at the same fishway entrance; When the fishway is located in the middle of the river, the closer the fishway entrance is to the tail water of the power station, the better the fish luring effect will be; In all conditions, when the environmental velocity is 0.3 m/s, there is the best attractive effect for the fishway entrance. The research results will have important reference significance for the layout of fishway entrance in hydraulic engineering and guide the engineering practice.
The changes in the marine environment and overfishing have caused imbalances in the ecological environment, making the various diseases of shellfish increasingly prominent, and the diseases caused by pathogenic Vibrio have become more common. In this context, the number of wild resources of Scapharca broughtonii has been sharply reduced, and its breeding industry is in urgent need of germplasm improvement. In order to effectively prevent the damage of bacteria and other pathogenic microorganisms to S. broughtonii, we observed the response process of the lysozyme activity in different tissues of S. broughtonii infected by Vibrio anguillarum, and explored the immune function of the lysozyme in the body of S. broughtonii. In this experiment, 20-month-old S. broughtonii. individuals were infected by injecting live bacteria, and 16 individuals were randomly selected. And 1 mL (about 1×109 bacteria) V. anguillarum suspension was injected into the axe foot of each individual as the infection group. 16 randomly selected individuals were not injected with V. anguillarum as the control group. The two groups were cultivated in clean seawater for 4, 12, 24 and 48 h. In each group, randomly selected 4 S. broughtonii individuals were dissected for the blood, mantle, gill, axe foot, hepatopancrea and adductor muscle tissues. The concentration of lysozyme was determined by ELISA kit. The results showed that for the invasion of V. anguillarum, the lysozyme content in the blood of the S. broughtonii rapidly increased from the normal low value and maintained a high level, indicating that the blood is one of the main immune tissues of S. broughtonii body defensing against pathogen. In the case of no infection, S. broughtonii mantle always maintained a high lysozyme concentration to prevent the interference of the external water environment. The concentration of lysozyme in infected gills and axe foot are significantly higher than the normal values after the injection for 24 hours, indicating that the mantle, gills and axe foot were the first barrier as S. broughtonii body to contact with the outside world which can also respond to the invasion of pathogenic bacteria, but the response was delayed compared with the blood. The lysozyme content of hepatopancrea and adductor muscle did not change significantly. And it was speculated that hepatopancrea and adductor muscle were not important immune tissues or organs of S. broughtonii. The results of this study can provide relevant parameters for the study of disease resistance and immune mechanism of S. broughtonii.
Since the outbreak of white spot syndrome virus (WSSV) in prawns in 1990s, WSSV has attracted extensive attention and research due to its wide outbreak range and high mortality. VP19 and VP28 are main envelope proteins of WSSV, which play important roles in the early stage of the prawn WSSV infection. These studies focused on using envelope proteinsVP28 and VP19 to prepare submit vaccines to protect the host, which currently made significant protective effect. This paper reviews the protein structure of VP28 and VP19 and their role in WSSV invasion, and the immune application of VP19 and VP28 vaccines in WSSV invasion, including protein subunit vaccine, DNA vaccine, RNA vaccine, and corresponding antibody. The protective efficiency of different types of vaccines is summarized, and the protective rate of VP19 + VP28 dual-potency vaccine is relatively high, which provides a reference for formulating effective methods of WSSV control.
In our study, a complete open reading frame of PyMFG was obtained by RT-PCR based on the sequence of differentially expressed genes (Contig-21827) screened by transcriptome sequencing of Pyropia yezoensis. Sequence analysis showed that the ORF of the PyMFG was 1224 bp in length and encoded a polypeptide fragment of 407 amino acids with a molecular weight of 46.24 ku, and theoretical pI of 9.08. Domain analysis revealed that the protein contains a conserved TEA domain and a YAP domain, which belongs to the TEA-ATTS superfamily domain. We found that the protein and fungal conidia forming proteins clustered into one large branch with close genetic relationship through multiple sequence alignment and phylogenetic analysis. In addition, the comparison of the ability of releasing monospores and qRT-PCR analysis between different strains indicated that the expression trend of PyMFG in PY26W and PY26W' was highly consistent with macroscopic statistical results, while the trend in PY26R and PY26R' were exactly existed difference. By inference, the gene type and molecular mechanism regulating the formation and release of monospores in the parental (PY26W) and partial parental strain (PY26W') and the female parental (PY26R) as well as partial female strain (PY26R') existed certain difference, leading to the divergence between the macroscopic statistical results of monospores and the qRT-PCR results.
The molting process is an essential physiological process in crustaceans that is closely related to the synthesis of ecdysteriods. Cytochrome P450(CYP)302a1 is the key enzyme which plays a critical role in the synthesis of ecdysteriods. Here we present the cloning and characterization of CYP302a1 gene from Macrobrachium rosenbergii (Mr-CYP302a1). The acquired gene was 1859 bp in full-length with the open reading frame (ORF) of 1629 bp that encodes 543 amino acids (aa) with a molecular weight of 61.09 ku and an isoelectric point of 8.42. The aa sequence analysis revealed that there were five P450 characteristic conserved regions, i.e., heme-binding, helix-K, helix-C, helix-I, and PERF. Phylogenetic analysis demonstrated that Mr-CYP302a1 was closely related to the CYP302a1 of Neocaridina denticulata, and then clustered with the CYP302a1 from Decapoda crustaceans such as Litopenaeus vannamei and Portunus trituberculatus. Real-time quantitative PCR (qRT-PCR) results showed that Mr-CYP302a1 was expressed in almost all the tissues tested with significantly higher expression levels in the Y-organ. On the other hand, the expression of Mr-CYP302a1 was significantly lower at the postmolt stage (stages A and B), and it was increased gradually at the intermolt (stage C), significantly enhanced and reached the maximal level at the D1 stage. Mr-CYP302a1 was expressed and its polyclonal antibody was generated. Western Blot (WB) showed that the expression of Mr-CYP302a1 protein was the highest in Y- organs of M. rosenbergii. The expression level of Mr-CYP302a1 protein also reached a peak at D1 stage during the molting process. In summary, our results indicate that Mr-CYP302a1 may play an important role in molting of M. rosenbergii.
JAK/STAT signaling pathway plays an important role in innate immune response. Bacillus thuringiensis is one of the main pathogens of shrimp hepatopancreatic necrosis. In order to understand the expression profile of JAK (Lv-JAK) and STAT (Lv-STAT) gene in Litopenaeus vannamei during the infection of pathogenic bacteria, relative expression of Lv-JAK and Lv-STAT gene were analyzed in this study. Relative expression profile of Lv-JAK and Lv-STAT in different tissues and during the infection of Bacillus thuringiensis were analyzed by semi-quantitative PCR and quantitative real-time PCR (qRT-PCR), respectively. The results showed that transcript of Lv-JAK and Lv-STAT was mainly detected in gill, intestine and heart. The relative expression of Lv-JAK and Lv-STAT were significantly up-regulated in gill tissues at the middle and late stages of B. thuringiensis infection (24 hpi~72 hpi). In intestine, the relative expression of Lv-JAK was significantly up-regulated at 6 hpi and 24 hpi, while that of Lv-STAT was significantly up-regulated at 24 hpi and 72 hpi. These studies indicated that JAK and STAT participated in the innate immune response induced by B. thuringiensis in L. vannamei. Understand the expression profile of JAK and STAT in response to B. thuringiensis infection will be helpful to study the function and regulatory mechanism of shrimp JAK/STAT signaling pathway in response to bacterial infection.
Pseudorasbora Parva is originally distributed in Jinshajiang and Nanpanjiang in Yunnan. However, it has been widely distributed in all major river systems and become an invasive fish in other four river systems in Yunnan. In order to reveal the difference of genetic diversity and genetic differentiation of P. parva between Yunnan after the invasion and the native region, we collected 220 samples distributed in 13 different sites of Lancang River, Nujiang, Honghe and Irrawaddy River in Yunnan, and 6 native populations in Yellow, Yangtze, and Pearl River. Here we analyses a 1 072 base pair fragment of the mitochondrial cytochrome b gene to examine the genetic diversity and genetic structure. A total of 72 mutation sites and 25 Cyt b haplotypes were identified. The haplotype diversity and nucleotide diversity of the four river systems in Yunnan were 0.828±0.014 and 0.005 44±0.001 18, respectively. Haplotype diversity of the introduced populations from the four river systems in Yunnan was higher than that of the native populations. The haplotype maximum likelihood tree and haplotype network map show that the haplotypes of the Yellow River population are special, while haplotype in the invasive populations in Yunnan were mixed with that in Yangtze and Pearl River. It is speculated that P. parva in Yunnan were mainly came from the Yangtze River and the Pearl River, which was consistent with the history of introduction of economic fish in Yunnan Province. Analysis of molecular variance (AMOVA) revealed significant genetic subdivision among individuals within populations and among populations within rivers but not among rivers, indicating distribution of genetic diversity was inconsistent with contemporary hydrological structure. That may be the human effect who introduced them from many native regions. The results of Fu’s Fs neutral test showed that there was no expansion of the invasive population of P. parva in Yunnan. In the subsequent management of the invasive population of P. parva in Yunnan, it is necessary to avoid the exchange of special haplotype groups with other regional groups, and to reduce the introduction of fish from different river systems. In addition, the development of new ways to utilize P. parva may be a useful way to control their population and reduce the damage to indigenous species and fishery culture in Yunnan.
The ectopic biofloc reactor was used to compare the simulated carbon sources (NaHCO3) concentration of 0.0 g/L (control group), 0.5 g/L, 1.0 g/L and 1.5 g/L of simulated aquaculture wastewater which effect the nitrogen reduction and sedimentation performance of the bioflocs in two stages: organic carbon source exist (stage I for 21 d) and organic carbon source loss (stage II for 21 d). The results showed that the effluent ammonia nitrogen concentration in the first-stage control group was significantly higher than that in the other treatment groups (P < 0.05), but generally decreased first and then stabilized. The nitrite nitrogen and nitrate nitrogen in each group accumulated a small amount; the biofloc biomass and sedimentation rate of the control group were significantly lower than the treatment groups (P < 0.05), and the difference between the treatment groups was not significant. There was no significant difference in the concentration of ammonia nitrogen and nitrite nitrogen in the effluent of each group in stage II (P > 0.05). The concentration of nitrate nitrogen in the control group was higher than that in treatment groups, and the concentration of ammonia nitrogen decreased rapidly. At this stage, the biomass and sedimentation rate of the bioflocs decreased, and the 1.0 g/L NaHCO3 treatment group showed better sedimentation effect; the particle size distribution also tends to be uniform. During the whole experimental period, the removal efficiency of ammonia nitrogen reached 97.8% and the nitrite nitrogen did not accumulate significantly under different concentrations of inorganic carbon source. The sedimentation rate and biomass of bioflocs in the treatment groups were significantly higher than those in the control group (P < 0.05). The results show that the addition of inorganic carbon source can improve the nitrogen reduction performance of bioflocs and enhance its sedimentation rate. After removing the organic carbon source, the biofloc reactor can maintain the ammonia nitrogen removal capacity, but caused nitrate nitrogen accumulation, biofloc organisms. The amount is reduced when the organic carbon source was missing, the inorganic carbon source (≥0.5 g/L) helps the biofloc reactor to maintain its ammonia nitrogen removal capacity.
To evaluate the differences of spoilage potential of Shewanella and Aeromonas in refrigerated seafood. [Methods] Growth curves, trimethylamine (TMA), biogenic amines and total volatile basic nitrogen (TVB-N) of S. baltica and A. salmonicida isolated from Larimichthys crocea were measured at 28 °C and 4 °C. And trimethylamine reductase (torA) gene in two kinds of spoilage bacteria were amplified, and similarity, physicochemical properties and protein spatial structure of TorA protein were compared by bioinformatics. A.salmonicida grew faster at 28 °C, while S. baltica grew faster at 4 °C. Compared with A.salmonicida, S.baltica produced the higher levels of TMA, biogenic amines, and TVB-N in refrigerated fish juice, which indicated that S.baltica had stronger ability to produce amine metabolites. The torA genes of 2490 bp and 1959 bp were amplified from S.baltica and A.salmonicida respectively. Bioinformatics analysis showed that the similarity between the two TorA proteins and the same genus was higher than 97%, and the similarity between the two was only 36.90%. The molecular weight and isoelectric point of TorA protein in S.baltica were about 92.3 k and 6.52, with highest content of glycine, while those of A.salmonicida were about 90.6 k and 6.74, with alanine as the highest amino acid. The spatial structure of TorA protein in two isolates were significantly different, the results of RT-PCR showed that the expression of genes related to corruption in S.baltica was much higher than that of A.salmonicida. S.baltica and A.salmonicida are psychrophilic spoilage bacteria in marine products, of which S.baltica is more capable of amine metabolism, and is closely related to its high expression level and specific physicochemical and structural characteristics. The study provides theoretical support for revealing the spoilage mechanism involving in psychrophilic spoilage bacteria.
An 10 weeks feeding trial was to investigate the effects of dietary arginine levels on the growth performance and immunity of Epinephelus coioides. Seven isonitrogenous and isolipid diets were formulated with arginine contents of 2.13%, 2.42%, 2.71%, 2.95%, 3.20%, 3.48% and 3.74% (dry matter). Randomly selected healthy groupers [initial weight (80.11±0.03) g] were divided into 7 groups, with 3 replicates in each group and 25 fish per replicate. It was found that the weight gain rate (WGR) and specific growth rate (SGR) of 2.71% group were significantly higher than 2.13% and 2.42%, and the feed coefficient (FCR) was significantly lower than that 2.13% group. The protein efficiency rate of the 2.71% group was significantly higher than that 2.13% and 3.48% group, and the protein deposition rate of the 2.71% group was not significantly different from that 2.95% group, which were significantly higher than that other groups. Broken-line model analysis of weight growth rate against dietary arginine levels indicated that the optimum requirement of arginine for maximum growth of subadult grouper was 2.73%, corresponding to 5.40% of dietary protein on a dry weight basis. There was no significant difference between 3.20% serum insulin (INS) and 3.48% group, which were significantly higher than other groups. The level of TOR gene in muscle of 3.48% group was significantly higher than that of 2.13%, 2.42% and 2.71% group. The expression of b0,+ AT gene in the hindgut of 2.42% group was the highest, which was significantly higher than that of other groups. There was no significant difference in the expression of b0,+ gene of kidney between 2.95% and 3.28% groups, which was significantly higher than that of other groups. In conclusion, the appropriate level of feed arginine can stimulate the secretion of IGF-I of E. coioides to promote the synthesis of protein and improve the expression of immune genes of the intestine, kidney and liver of fish to improve the body immunity., and ultimately promote the growth of fish.
Transferrin (TF) and Transferrin Receptor (Tfr) play vital roles in iron homeostasis. In order to explore the transcriptional regulation mechanism of the tf and tfr1a genes in Megalobrama amblycephala, the genomic sequences of tf and tfr1a were obtained from whole genome sequence database. Transcription factor binding sites and CpG islands in the promoter regions of tf and tfr1a genes were predicted by using bioinformatics methods. Fragments of different length of the predicted promoter region of tf and tfr1a were cloned by PCR amplification. The amplified different fragments were ligated to the pGL3-Basic/pEGFP-1 vector. Subsequently, the recombinant plasmids were transiently transfected into Hela cells for fluorescence detection by the Dual-Luciferase Reporter System. Bioinformatics analysis showed that there was no CpG island site in the tf promoter, and there were two CpG island sites in the tfr1a promoter. A total of 9 tf and 10 tfr1a recombinant plasmids containing promoter fragments of different lengths were successfully constructed. The detection of Dual-Luciferase Reporter System showed that the core region of the tf promoter was −268~+56 bp, and the −1 308~−1 102 bp fragment may have a transcription factor binding site that positively regulates the gene expression. The core region of the tfr1a promoter was −224~+48 bp, and the +48~+92 bp region may contain negative regulatory elements that inhibit the transcription of this gene, while the −1 229~−1 219 bp region might contain positive regulatory transcription factor binding sites that promote the tfr1a gene expression.
The suppressor of cytokine signaling 1 (SOCS1) is an essential feedback regulator extensive involved in many different cytokine signaling pathways,regulating immune and growth of organism. In this study, the obtained genes of Megalobrama amblycephala, socs1a and socs1b, were used as genetic editing objects, and we screened for appropriate target synthetic gRNA (guide RNA) by online analysis. According to the mixture injection (gRNA and Cas9 protein) in the 1-2 cell stage embryos, the results of identifications of socs1 expression level by qRT-PCR and gene mountions by sequencing show that we successfully established socs1 koock-out mutant. Compared with wildtype, the growth performance and body mass of SOCS1a+/- and SOCS1b+/− were significantly increased, Meanwhile, the expression levels of inflammatory cytokines TNF-α and IL-6 were significantly increased, while the expression levels of IL-1β were not changed. After aeromonas hydrophila injection,In contrast to the wild type, significant increases in levels of IL-6 and TNF-α mRNA were observed in both socs1a and socs1b heterozygous mutants. The dupliacated socs1 knockout blunt snout bream have been successfully obtained by the CRISPR/Cas9 gene editing system, which provides a basis for further study of the socs1 gene. Meanwhile, our experimental results provide a basis and reference for the study of CRISPR/Cas9 gene editing techniques in other aquaculture species.
In this study, the growth and physiological parameters were compared between tilapia (GIFT Oreochromis niloticus) cultured in a traditional pond and in an in-pond raceway system (IPRS) for 120 days. For the traditional way, 5 tails/m2 (stocking densities 1, SD1) were reared, while 180 tails/m2 (SD2) and 270 tails/m2 (SD3) were cultured in an IPRS. The main objective of this study was to find the appropriate density of tilapia to be cultured in an IPRS. The results showed that after 120 days of culture, the body weight, specific growth rate and absolute growth rate of the SD2 fish were significantly higher than those of the SD1 and SD3 fish. The survival rate, coefficient of variation of weight and feed coefficient rate of SD2 and SD3 tilapia were lower than those of the SD1 tilapia. Compared with SD1 fish at 30 days, the relative expressions of serum cortisol, serum alanine aminotransferase, lysozymal aspartate aminotransferase and hepatic hsp70 mRNA were significantly increased in the SD2 fish. After The levels of serum cortisol and glucose in the SD3 fish were significantly higher after 120 days of culture than those in the SD1 fish. Compared with SD1, the levels of SAA, LAA and hepatic hsp70 mRNA expressions of the SD2 fish were significantly higher after 60 and 90 days, while the level of triglyceride was significantly lower during the whole experimental period. The results implied that tilapia in the SD2 were stressed in the early stage of cultivation but gradually acclimated to the environment, while tilapia in the SD3 were stressed for a relatively longer time. Taken together, this study demonstrated that the appropriate stocking density of tilapia cultured in the IPRS might be 180tails /m2 or less in order for a better growth performance than in the traditional culturing mode.
A 56-d feeding trial with 480 yellow catfish (Pelteobagrus fulvidraco) juveniles [(1.67±0.01) g initial body weight] was carried out to estimate the effect of replacing fish meal with defatted black soldier fly larvae meal (DBSFLM) on growth performance, nutrient retention, serum biochemical parameters and digestive enzymes activity of juvenile P. fulvidraco. Fish were randomly allocated into four isolipidic and isoprotein dietary treatments which were formulated by replacing 0 (T0), 20% (T20), 40% (T40) and 60% (T60) of fish meal (FM) protein with DBSFLM. Each treatment was randomly assigned to triplicate groups of 40 fish per aquarium. Fish were fed twice daily to apparent satiation. With increasing content of DBSFLM, the final body weight (FBW), weight gain rate (WGR) and specific growth rate (SGR) of yellow catfish was increased at first and then decreased. Gowth performance of FBW, WGR and SGR in T20 were highest and higher than T60, whereas the feed conversion rate was the lowest. The feed intake in T20 and T60 was higher than that in control and T40 groups. With the increasing content of DBSFLM, the intraperitoneal fat index (IFI) was declining with T60 group was lower than control, ash, calcium retention declining with T40 and T60 group lower than control.There was no difference of condition factor, viscera index, hepatosomatic index, intestine index and gastric index among treatments. Nutrient retention such as protein,lipid and phosphorus, moisture, crude protein, lipid and ash in whole body were not affected by dietary treatments. Compared with control, the serum cholesterol and triglyceride were reduced and the high density/low density lipoprotein cholesterol were increased in T20, T40 and T60 groups and pepsase and intestinal trypsin increase in T40 group. Results suggested that the growth performance and body composition of yellow catfish juveniles was not affected by dietary DBSFLM and the optimal alternative ratio was 20%,which was better than control. The replacement of fish meal with DBSFLM may reduce IFI, serum triglyceride, cholesterol and ash, calcium retention and increase protease.
This study aimed to investigate the effect of soybean meal on the growth, intestinal microbiota composition and metabolic enzymatic activities of microbial amino acid of Channa argus. Four isonitrogenous and isoenergetic diets were formulated with soybean meal by replacing 0, 25%, 50% and 75% fish meal (G1, G2, G3 and G4, respectively). The fish of (8.65±0.25)g was hand-fed daily to satiation twice in cylindrical fiberglass tanks for 21 days. Results showed that no significant difference in survival rate was found among four groups. The growth performance of C. argus in G4 was significantly lower than those in G1 and G2, while the difference was not statistically significant between G3 and other three groups. The proportion of Firmicutes in the intestine of fish in G1 and G2 was significantly higher than that in G3, and the lowest was found in G4. The proportion of Proteobacteria in G1 and G2 was significantly lower than those in G3 and G4. The proportion of Lactococcus, Bacillus, Pseudomonas, Streptococcus, Laseczka and Acinetobacter in G4 was significantly lower than those in the other three groups. Additionally, the activities of glutamic-pyruvic transaminase and adenosine deaminase were highest in G4, while the activity of lactic dehydrogenase was highest in G1. All results indicated that, except for the effect on the growth of C. argus, dietary soybean meal significantly induced the changes in the intestinal microbiota composition and the activity of the microbial amino acid metabolic enzymes, which may provide theoretical basis for further considering the application of soybean meal in the formulated diets of C. argus.
The previous studies found that KK-42 treatment can significantly shorten the duration of molting cycle in juvenile prawn Macrobrachium nipponense, and increase the thickness of the carapace endocuticle in late premolt (D3 stage). In order to further investigate the effect of KK-42 on cuticle structure, the juvenile prawns in postmolt stage during which the formation of exocuticle gradually ends but that of endocuticle starts, were employed to study the structures of carapace exocuticle and endocuticle using the observation of paraffin section by scanning electron microscopy (SEM). Healthy intermolt juvenile prawns with body length of 3.5±0.1 cm were randomly divided into two groups. The prawns were soaked for 1 min in KK-42 solution at a concentration of 1.95×10−4 mol/L (treatment group) or 0 mol /L (control group), respectively. The carapaces of juvenile prawns at 1.5, 3, 6 and 12 h after molting were obtained to be used for ultrastructural observation. To observe directly the surface structure of endocuticle, the carapace obtained at 6 h after molting was scraped gently with an anatomical knife to remove tissues on the inner surface of carapace, and then examined using SEM. The results showed that the carapace was only composed of the epicuticle and exocuticle at 1.5 and 3 h after molting. The number of exocuticle lamellae derived from KK-42 treatment group rised significantly at 1.5 and 3 h after molting, and the thickness of exocuticle increased by 72.07% and 38.67%, respectively, compared with the corresponding control group. At 6 and 12 h after molting, the loose lamellaes in exocuticle tended to be dense, and there was no significant difference in thickness to be found between two groups. The number of endocuticle lamellar with a loose structure, being only one at 6 h, separately increased to two in control group and three in treatment group at 12 h after molting. In addition, pore canals within the endocuticle presented different sizes and head-tail orientation. No significant structural change was observed in the endocuticle after KK-42 treatment. The results reveal that KK-42 treatment has a significant effect on the carapace ultrastructure of juvenile M. nipponense during postmolt, and accelerate the formation rate of the exocuticle as well as endocuticle.
A plenty of non-coding RNAs (ncRNAs) have been identified through the application of high-throughput analysis of the transcriptome, and this has led to an intensive search for possible biological functions attributable to these transcripts. In this study, the gonad tissue of the two-year-age Crassostrea gigas of same family cultured in Rizhao Huanghai area were used to identify a large number of miRNA, lncRNA and circRNA by small RNA-seq and RNA-seq, and their biological characteristics were analyzed. The results showed that, with Danio rerio as a reference, 25-30 known miRNA matures and 51-63 known miRNA hairpin was obtained, 53-71 new miRNA matures and 53-77 new miRNA hairpin were predicted. The length of miRNA in C. gigas ranged from 18-26 nt, where the largest number was in the 20-22 nt and the first nucleotide position was tent to U. 2302-2349 known lncRNA transcripts were obtained, and 20083-24114 new lncRNA were predicted. Among them, the percentage of the intergenic lncRNA, intronic lncRNA and antisense lncRNA was 29.0%, 62.1%, and 8.9%, respectively. The data showed that genomic characteristics of lncRNA in C. gigas were similar to those of other eukaryotes. Compared with mRNA, the transcript and open reading frame of lncRNA was much shorter at length and much lower at expression level. 383 circRNA transcripts were obtained, among which the average percentage of 88.54% came from exon, 4.51% came from intronic and 6.95% came from intergenic. The data showed that the endogenous circRNA have a lot miRNA target sites. This study showed that the basic biological characteristics of miRNA, lncRNA and circRNA in C. gigas. The results set the foundation for the subsequent research on the expression and biological function of regulatory non-coding RNA in C. gigas.
Length distribution data provide insight into the dynamics of fish populations. However, it is hard to determine the sample size required to describe size structure. In order to compare the relation between the precision of frequency distributions and sample size for several commercial fish species in the Wentai fishing ground, a resampling approach was used to calculate the mean square difference of length distributions based on actual sampling size and various simulated sampling sizes. The results showed that: ①Factors such as biology difference and seasonal variation would affect the relation of the precision of frequency distributions and sample size. ②The accuracy for estimating the precision of length frequency distributions would be impacted by the numbers of length intervals in iteration calculation. ③The precision of length frequency distributions could be considered as a theoretical basis to optimize sample size. For the reason of lacking domestic researches on sampling design and optimization, the results of this study could provide certain technical reference.
The paper studied the occurrence time and physiological characteristics of slow growth seahorse. Comparisons of the growth, the ratio of RNA/DNA, digestive enzymes and related immune enzymes activities in normal growth seahorses[(8.57±0.61) cm, (1.51±0.38) g] and slow growth seahorse [(6.68±0.35) cm, (0.81±0.14) g]Hippocampus erectuswere studied in a cultural experiment for 110 d. The results showed that the average daily gain, specific growth rate, condition factor and viscera index in the normal growth seahorses were significantly higher than those of the slow growth seahorse, respectively. The normal growth seahorses grew faster than that of the slow growth seahorses after the body length was5.026 cm. The amylase, protease and lipase activities in normal growth seahorses were as the same tendency as those of the slow growth seahorses under different reaction temperatures (5 °C, 15 °C, 25 °C, 30 °C, 35 °C, 45 °C and 55 °C) and pH (2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0 and 9.0). However, the digestive enzymes activities of the former were higher than those of the latter, except amylase activity at 35-55 °C and protease activity at 5–25 °C. The activities of ACP、AKP、T-AOC and SOD in normal growth seahorses were 12.83%, 48.21%, 44.71%and 65.75% more than those of the slow growth seahorses, respectively. The MDA of the normal growth seahorse was only 61.09% of that in the slow growth seahorse, and the ratio of RNA/DNA in the normal growth seahorse was higher 23.75% than that of the slow growth seahorse. The growth, digestion and immunity of he normal growth seahorses were obviously better than those of the slow growing hippocampus when their body length were more 5.026 cm.
With the aim to explore the molecular mechanism of vitellogenin (Vtg) in Scatophagus argus, we cloned the full-length cDNA sequence of three types of vtg by using reverse transcription-polymerase chain reaction (RT-PCR) and rapid amplification of cDNA ends (RACE) procedures. The length of the vtgAa cDNA is 5360 bp (GenBank No. KY676847), and it encodes a protein consist of 1696 amino acids. The length of the vtgAb cDNA is 5346 bp (KY654346), and it encodes a protein consist of 1699 amino acids. The length of the vtgC cDNA is 4244 bp (KY676848), and it encodes a protein consist of 1275 amino acids. Sequence analysis showed that three vitellogenin homologs of Scatophagus argus have highest homology with Morone americana (83%, 85% and 85%). VtgAa and VtgAb contain all the three major portions, but VtgC lacks phosvitin (PV). Quantitative real-time PCR (qPCR) assay were employed to determine the mRNA expression of vtgAb in the liver after 17 α-ethynylestradiol (EE2) injection in vivo and hepatocytes after exposure EE2 in vitro. Results of qPCR showed that the hepatic expression of vtgAb was higher than vtgAa and vtgC. 48 h after injection, mRNA expression of vtgAb was extremely increased and obviously decreased after 72 h. The expression of vtgAb mRNA was elevated after EE2 exposure to hepatic cells. Based on our results, expressions of vtgAb could be induced by EE2.