Female Yellow Catfish Research Articles

Dietary carbohydrate to lipid ratio affects growth, reproductive performance and health of female yellow catfish (Pelteobagrus fulvidragrus): a lipidomics analysis

This study aimed to examine the impact of dietary carbohydrate to lipid (CHO/L) ratio on the growth, reproductive, and offspring performance of broodstock yellow catfish, and to elucidate the metabolic differences between mothers and offspring using lipidomics. Five isonitrogenous and isoenergetic diets with varying CHO/L ratios (0.65, 1.44, 2.11, 3.13, and 5.36) were fed to three groups of 35 female broodfish in a pond-cage culture system. After an eight-week feeding trial, the dietary CHO/L ratio had a significant impact on the growth and reproductive performance of female yellow catfish. The weight gain ratio (WGR) and specific growth rate (SGR) in the CHO/L0.65 and CHO/L2.11 groups were significantly higher than those in the CHO/L5.36 group (P < 0.05). The fertilization and hatching rates were the highest when the dietary CHO/L ratio was 0.65 and 2.11, respectively. When the dietary CHO/L ratio was 3.13 and 5.36, the plasma contents of testosterone (T) was significantly lower than those of other groups (P = 0.013), and the plasma vitellogenin (VTG) content was the lowest when the CHO/L ratio was 5.36. The plasma contents of estradiol (E2) significantly decreased with increasing dietary CHO/L ratio (PL = 0.012). Lipidomic analysis revealed that the ovary primarily consisted of five subclasses in terms of lipid composition, namely triglyceride, fatty acyl, sterol, glycerophospholipid, and sphingolipid; however, sphingolipids were not detected in the larvae. The relative expression levels of the ovarian lipid metabolism-related genes sterol regulatory element binding protein 1 (srebp1), acetyl-coa carboxylase (acc), delta (12)-oleate desaturase (fad2), and elongation of very long chain fatty acids protein 5 (elvol5) significantly increased with increasing dietary CHO/L ratio (P < 0.05). The relative expression levels of lipid metabolism-related genes srebp 1, peroxisome proliferator activated receptor α (pparα), carnitine palmitoyl transferase 1 isoform (cpt), adipose triglyceride lipase (atgl), fad2, and elvol5 in offspring larvae were initially increased and then decreased with increasing dietary CHO/L ratios until reaching a maximum at a ratio of 2.11 (P < 0.05). In conclusion, based on the broken-line regression of the dietary CHO/L ratio and egg diameter, the optimal dietary CHO/L ratio was 1.91 for broodfish yellow catfish. A high-CHO/L ratio diet results in increased lipogenesis and hepatic lipid accumulation in maternal organisms, leading to impaired reproductive performance and reduced offspring quality.

Administration of Arginine Vasotocin and modified Isotocin improve artificial propagation and post-spawning survival of female yellow catfish

Low rate of spawning and high percentage of death after artificial propagation are frequently observed in catfish, which do harms to the long-term population stability and genetic breeding programs in aquaculture. In this study, yellow catfish (Pelteobagrus fulvidraco), an important freshwater species in China was used as a research model, since the farmed female yellow catfish had poor reproduction performance and a high death rate after treatment with the traditional exogenous hormones, luteinizing hormone releasing hormone analogues2 (LHRH-A2) and human chorionic gonadotropin (HCG). We tried to investigate the roles of the Arginine Vasotocin (AVT)/ Isotocin (IT) neuropeptide family in reproduction and design an optimal strategy for inducing artificial propagation in yellow catfish. Two copies of pro-avt and pro-it were detected in hypothalamus and ovaries of yellow catfish, and their mRNA levels gradually increased during spring-summer season. Furthermore, the transcript levels of pro-avt and pro-it in hypothalamus significantly increased after injection of LHRH-A2 and HCG. Although AVT could not induce germinal vesicle breakdown (GVBD) in female yellow catfish, administration of AVT significantly stimulated premature ovulation in a dose-dependent manner and induced the expression of ovulation-related genes, ptgs2a and acvr1. Furthermore, there is a significant up-regulation of serum prostaglandin E2 (PGE2) and luteinizing hormone (LH) in female fish after AVT treatment, whereas no difference was observed in follicle stimulating hormone (FSH). Since IT of yellow catfish was insoluble in saline, a rigid peptide segment was added at the end of IT (the modified IT was named IT-M), which could greatly improve its solubility and induce ovulation in female yellow catfish. Subsequently, we demonstrated that adding carp pituitary extraction (CPE) to the second injection of traditional methods could efficiently improve the spawned fish, eggs production, fertilization rate, hatching rate and post-spawning survival of female yellow catfish, despite at a relatively high cost in hormones. We further discovered that IT-M + AVT could substitute for HCG + CPE in the second injection and had high efficiency in artificial propagation, reducing the hormone costs to less than one-third. Altogether, we provide an effective and affordable combination of exogenous hormones to improve reproduction performances and post-spawning survival rate in yellow catfish.

Compared to Fishmeal, Dietary Soybean Meal Improves the Reproductive Performance of Female Yellow Catfish (Pelteobagrus fulvidraco) Broodstock.

To investigate the effects of different dietary protein sources on the reproductive performance of female broodstock, yellow catfish (Pelteobagrus fulvidraco) were fed with three experimental diets using fishmeal (FM), soybean meal (SBM), and rapeseed meal (RSM) as main protein sources, respectively. Females (initial weight: 64.56 ± 0.45 g) were distributed into 9 net cages for feeding trial. Results indicated that 30% dietary SBM improved the reproductive performance for higher gonadosomatic index (GSI), relative fecundity, total egg production, egg diameter, and hatching rate. In addition, SBM and RSM diets resulted in higher estradiol (E2), vitellogenin (VTG), luteinizing hormones (LH), and lower follicle-stimulating hormone (FSH) and testosterone (T) in plasma (P < 0.05) of female broodstock. Dietary SBM and RSM also resulted in lower mesenteric fat index (MFI), plasma total cholesterol (TC), plasma total bilirubin (T-Bil) contents, and gonadal cortisol concentrations, while dietary SBM downregulated the transcription levels of steroidogenesis-related proteins by negative feedback (P < 0.05). The results demonstrated that dietary SBM and RSM could promote sex steroid hormone and VTG biosynthesis and showed hypocholesterolemic effects. Besides, 30% dietary SBM inclusion could improve the reproductive performance of female yellow catfish broodstock.

A time-course transcriptome analysis of gonads from yellow catfish (Pelteobagrus fulvidraco) reveals genes associated with gonad development

BackgroundThe yellow catfish, Pelteobagrus fulvidraco, is a commercially important fish species. It is widely distributed in the fresh water areas of China, including rivers, lakes, and reservoirs. Like many other aquaculture fish species, people have observed significant size dimorphism between male and female yellow catfish and it shows a growth advantage in males.ResultsHere, at the first time, the time-course transcriptome was used to explore the various expression profiles of genes in different gonad developmental stages and genders. A total of 2696 different expression genes (DEGs) were identified from different stages. Based on these DEGs, 13 gonad development related genes were identified which showed time-specific or sex biased expression patterns.ConclusionThis study will provide the crucial information on the molecular mechanism of gonad development of female and male yellow catfish. Especially, during the different gonad development stages, these 13 gonad development related genes exhibit various expression patterns in female and male individual respectively. These results could inspire and facilitate us to understanding the various roles of these genes play in different gonad development stages and genders.

Genome-wide association study reveals the genetic basis of growth trait in yellow catfish with sexual size dimorphism

Sexual size dimorphism has been widely observed in a large number of animals including fish species. Genome-wide association study (GWAS) is a powerful tool to dissect the genetic basis of complex traits, whereas the sex-differences in the genomics of animal complex traits have been ignored in the GWAS analysis. Yellow catfish (Pelteobagrus fulvidraco) is an important aquaculture fish in China with significant sexual size dimorphism. In this study, GWAS was conducted to identify candidate SNPs and genes related to body length (BL) and body weight (BW) in 125 female yellow catfish from a breeding population. In total, one BL-related SNP and three BW-related SNPs were identified to be significantly associated with the traits. Besides, one of these SNPs (Chr15:19195072) was shared in both the BW and BL traits in female yellow catfish, which was further validated in 185 male individuals and located on the exon of stat5b gene. Transgenic yellow catfish and zebrafish that expressed yellow catfish stat5b showed increased growth rate and reduction of sexual size dimorphism. These results not only reveal the genetic basis of growth trait and sexual size dimorphism in fish species, but also provide useful information for the marker-assisted breeding in yellow catfish.

Effects of dietary protein level on the growth, reproductive performance, and larval quality of female yellow catfish (Pelteobagrus fulvidraco) broodstock

This study was conducted to evaluate the effects of dietary protein levels on the growth, spawning, and larval quality of female yellow catfish (Pelteobagrus fulvidraco) broodstock through a six-week feeding trial. Five isoenergetic diets were formulated, and the crude protein levels were 34.4 (DP34), 38.8 (DP39), 44.2 (DP44), 49.3 (DP49), and 52.7% (DP53). The results showed that the growth and reproductive performance, including the specific growth rate (SGR), feed efficiency (FE), gonadosomatic index (GSI), and hatching rate of yellow catfish broodstock in the DP44, DP49, and DP53 groups were significantly higher than those of other groups (P < 0.05). The optimal dietary protein levels for yellow catfish broodstock were 45.8% and 44.1% based on SGR and GSI. The lowest condition factor (CF), GSI, and smallest egg size were found in the DP34 group, while the total egg production was the highest in the DP53 group. Vitellogenin (VTG) contents in eggs and plasma were enhanced significantly with the increasing dietary protein levels from 34% to 49%, but decreased precipitously in the DP53 group (P < 0.05). The optical densities of androgen receptor (AR) and estrogen receptor (ER) in the DP34 group were significantly lower than those in other groups. The mRNA expression levels of CYP19a, AR, and ERβ were significantly increased in the DP49 group (P < 0.05). For larval quality, the deformity rate decreased significantly with the increasing dietary protein levels (P < 0.05). The larval survival rate at 9 DPH (days post-hatching) as a function of dietary protein level was analyzed by second-order polynomial regression. The results showed that a level of 47.7% was optimal for improving larval quality. Thus, a suitable range of dietary protein of yellow catfish broodstock for growth and reproduction is 44.1–47.7%.

Effects of feeding rate and dietary protein levels on the breeding performance of female yellow catfish ( Pelteobagrus fulvidraco )

Nutritional components and feeding strategies are multifarious amongst different producers, whereas they are just designed for fish farming but not suitable for improving the reproductive performance of broodfish. Yellow catfish (Pelteobagrus fulvidraco), an omnivorous species, is one of the important aquaculture fish in China. In order to improve the reproductive performance of female yellow catfish (119.86—134.54 g), four feeding strategies (0.5%, 0.75%, 1% and 1.5% BW/d) and three dietary protein levels (34%, 40% and 46%) were examined, respectively, in the two separate trials. The females with moderate feed restriction (1%) showed significant lower mesenteric fat index (MFI) and higher gonadosomatic index (GSI) than the satiation group (1.5%) and excessive feeding restriction groups (0.5% and 0.75%). Females with high MFI were difficult to be artificially propagated and showed a high mortality rate, whilst the fish at 1.0% feeding rate displayed low mortality rate and high ratios of spawned fish, as well as high percentages of fertilization and hatching. Meanwhile, the offspring of 1.0% feeding rate group showed a low malformation rate and high survival rate. Multiple spawning in the same breeding season are applied in yellow catfish to reduce the number of parent fish and increase the fry production, and gonadal recrudescence after spawning might be affected by different nutrient values including dietary protein levels. In the second trail, female yellow catfish were fed with 34%, 40% and 46% crude protein diet at 1% feeding rate for the second spawning, and the best reproductive and breeding performances were observed in the fish group with 46% crude protein diet. These results demonstrate that 1% feeding rate is optimum for the spawning and reproductive performance of female yellow catfish for the first artificial spawning, and 46% dietary protein group had the best reproductive performances in the second spawning.

Intraperitoneal injection of genistein affects the distribution and metabolism of cholesterol in female yellow catfish Tachysurus fulvidraco.

Genistein is an abundant phytoestrogen in soybean. This study aimed to determine the effects of genistein on cholesterol distribution and metabolism in female yellow catfish. Three hundred fish (49.2 ± 1.4g) were randomly divided into five treatments and received intraperitoneal injections as follows: (1) blank, no injection; (2) control, vehicle only; (3) E2, 17β-estradiol at 10μg·g-1 body weight; (4) low genistein doses, genistein at 10μg·g-1 body weight; (5) high genistein doses, genistein at 100μg·g-1 body weight. Both high and low genistein doses significantly reduced (p < 0.05) serum TC and LDL-C 24h after injection. Moreover, the high genistein doses significantly reduced (p < 0.05) serum HDL-C. Both high and low doses of genistein significantly increased (p < 0.05) hepatic TC. Only high genistein doses significantly increased (p < 0.05) ovary TC. In the liver, both high and low genistein doses significantly increased (p < 0.05) protein and mRNA expression of ldlr. Meanwhile, high genistein doses significantly decreased (p < 0.05) mRNA expression of hmgcr. In ovary tissue, high genistein doses significantly decreased (p < 0.05) mRNA expression of cyp11a1. These results suggested that genistein affected the cholesterol distribution in female yellow catfish. Both high and low doses of genistein reduced cholesterol content in blood and increased its content in the liver by increasing the uptake of blood cholesterol. Meanwhile, high genistein doses may inhibit hepatic cholesterol synthesis. Additionally, high genistein doses could increase cholesterol transfer from serum into the ovary and disturb cholesterol conversion to pregnenolone.

Effects of dietary arachidonic acid on reproduction performance, tissue fatty acid profile and gonadal steroidogenesis in female yellow catfish Pelteobagrus fulvidraco

Effects of dietary arachidonic acid on reproduction performance, tissue fatty acid profile and gonadal steroidogenesis in female yellow catfish <i>Pelteobagrus fulvidraco</i>

Synergistic Combination of Exogenous Hormones to Improve the Spawning and Post-spawning Survival of Female Yellow Catfish.

Multiple repeat spawners make large contributions to long-term population stability and aquaculture breeding programs. A high percentage of female yellow catfish (Pelteobagrus fulvidraco) died for spawning failure or incomplete spawning after artificial spawning by traditional synthetic hormones including human chorionic gonadotropin (hCG), luteinizing hormone releasing hormone (LHRH), and domperidone (DOM). The present study was designed to compare the efficacy of different combinations of exogenous hormones for inducing ovulation in yellow catfish using hCG, LHRH, DOM, and carp pituitary extraction (CPE). We found a optimal strategy for exogenous hormones administration, the mixture of LHRH/CPE for the first injection and LHRH/CPE/DOM for the second injection, could greatly improve the rates of spawning success, weight of ovulated eggs and survival rate after spawning. Interestingly, a population of female yellow catfish with defective reproductive duct could not spawn and showed high mortality after induced by a combination of hCG/LHRH/DOM, whereas a synergistic combination of hCG, LHRH, DOM, and CPE could efficiently induce spawning and reduce mortality in the defective yellow catfish, in which a significant decrease of Vitellin and E2 levels. Altogether, our findings provide an effective combination of exogenous hormones to improve spawning and post-spawning survival of female yellow catfish.

Sex-related differences in disposition of sulfamethoxazole, N-acetyl-sulfamethoxazole and trimethoprim in yellow catfish (Pelteobagrus fulvidraco) following a single oral administration

The aim of this present study was to explore the sex-related differences in disposition regularities of sulfamethoxazole (SMZ), N-acetyl-sulfamethoxazole (N-ac-SMZ) and trimethoprim (TMP) in male and female yellow catfish. Concentrations of target compounds were determined using a reliable HPLC-MS/MS approach, which was validated according to the guidelines defined by FDA. The results showed that there are significant sex-associated differences in SMZ concentrations of muscle with skin and liver, in N-ac-SMZ levels of muscle with skin and kidney, and in TMP concentrations of muscle with skin, liver and kidney. Whereas, no significant sex differences were also observed in SMZ, N-ac-SMZ and TMP levels of plasma, in SMZ concentrations of kidney and in N-ac-SMZ concentrations of liver. Longer residue time of N-ac-SMZ than SMZ was observed in male and female yellow catfish. Withdrawal time (WT) of SMZ (N-ac-SMZ as the marker residue) calculated by the WT 1.4 software, was 11 days (male) and 9 days (female), respectively. By contrast, WT of SMZ (SMZ as the marker residue) was 9 days (male) and 7 days (female), respectively. These results could serve as reference data for establishing disparate use regimen and drug withdrawal time of SMZ and TMP in male and female yellow catfish.

The effects of dietary linolenic acid to linoleic acid ratio on growth performance, tissues fatty acid profile and sex steroid hormone synthesis of yellow catfish Pelteobagrus fulvidraco

The effects of different linolenic acid (LNA)/linoleic acid (LA) on tissues fatty acid composition and steroid hormone secretion of the female yellow catfish Pelteobagrus fulvidraco were evaluated after an 8-week feeding trial. Four isonitrogenous and isolipidic formulated diets were designed to contain different LNA/LA ratios of D0.27, D0.82, D1.71 and D2.63, respectively. The result showed that there were no significant effects on the weight gain (WG), gonadosomatic index (GSI), condition factor (CF) of yellow catfish among different diet treatments (P > 0.05). The relative fecundity was greatest in the D2.63 group (P < 0.05). The muscle and hepatic fatty acids profiles reflected corresponding dietary fatty acid profiles treatments, but not ovary. Eicosapentaenoic acid (EPA), arachidonic acid (ARA) and n–3 polyunsaturated fatty acid (PUFA) concentrations were significantly increased with increasing dietary LNA/LA ratios, in both muscle and liver (P < 0.05). ARA and highly unsaturated fatty acid (HUFA) concentrations in the egg were higher than that in liver and muscle, ARA was preferentially accumulated in yellow catfish gonad, which was not influenced by the dietary LNA/LA ratios. The levels of serum testosterone (T) decreased with increasing diet ratios of LNA to LA (P < 0.05), and the mRNA levels of steroidogenesis-related genes (CYP17a1, CYP19a and erβ) were significantly down-regulated with increasing dietary LNA/LA ratios in ovary of female (P < 0.05). In parallel with the changes of plasma follicle-stimulating hormone (FSH) and luteinizing hormone (LH), the mRNA levels of 20 β-hydroxysteroid dehydrogenase (20β-HSD) upregulated with increasing LNA/LA ratios (P < 0.05). In conclusion, the present results suggest that dietary LNA/LA ratios regulated steroid hormone synthesis during ovarian development of yellow catfish. Higher-level dietary LNA/LA ratios are beneficial for HUFA -rich gonadal development and steroid synthesis of yellow catfish.

Endoplasmic Reticulum Stress–Mediated Autophagy and Apoptosis Alleviate Dietary Fat–Induced Triglyceride Accumulation in the Intestine and in Isolated Intestinal Epithelial Cells of Yellow Catfish

BackgroundThe intestine is the main organ for absorbing dietary fat. High dietary lipid intake leads to fat deposition in the intestine and adversely influences fat absorption and health, but the underlying mechanism is unknown. ObjectiveWe used yellow catfish and their isolated intestinal epithelial cells to test the hypothesis that endoplasmic reticulum (ER) stress, autophagy, and apoptosis mediate fat-induced changes in lipid metabolism. MethodsMale and female yellow catfish (weight: 3.79 ± 0.16 g; age: 3 mo) were fed diets containing lipid at 6.98% (low-fat diet; LFD), 11.3% (middle-fat diet; MFD), or 15.4% (high-fat diet; HFD) (by weight) for 8 wk. Each dietary group had 3 replicates, 30 fish per replicate. Their intestinal epithelial cells were isolated and incubated for 24 h in control solution or various concentrations of fatty acids (FAs) with or without 2-h pretreatment with an inhibitor [3-methyladenine (3-MA), 4-phenyl butyric acid (4-PBA), or Ac-DVED-CHO (AC)]. Triglyceride (TG) contents, genes, and enzymes involved in lipid metabolism, ER stress, autophagy, and apoptosis were determined in intestinal tissue and cells; immunoblotting, BODIPY 493/503 staining, ultrastructural observation, and the detection of autophagic and apoptotic vesicles were performed on intestinal cells. ResultsCompared with the LFD and MFD, the HFD increased intestinal TG content by 120–226%, activities of lipogenic enzymes by 19.0–245%, expression of genes related to lipogenesis (0.77–8.4-fold), lipolysis (0.36–6.0-fold), FA transport proteins (0.79–1.7-fold), ER stress (0.55–7.5-fold), autophagy (0.56–4.2-fold), and apoptosis (0.80–5.2-fold). Using isolated intestinal epithelial cells and inhibitors (4-PBA, 3-MA, and AC), we found that ER stress mediated FA-induced activation of autophagy (11.0–50.1%) and apoptosis (10.4–32.0%), and lipophagy and apoptosis mediated FA-induced lipolysis (3.40–41.6%). ConclusionsAn HFD upregulated lipogenesis, lipolysis, and FA transport, induced ER stress, and activated autophagy and apoptosis. ER stress, autophagy, and apoptosis play important regulatory roles in fat-induced changes in lipid metabolism in the intestine and intestinal epithelial cells of yellow catfish.

Comparative Study of Growth, Feed Utilization, and Immunity of Hybrid Catfish and All‐Male Yellow Catfish

AbstractHybridization is an alternative approach in aquaculture that can improve performance via heterosis. In this study, the growth performance, feed utilization, and immunity of hybrid catfish (female Yellow Catfish Pelteobagrus fulvidraco × male Darkbarbel Catfish P. vachelli) were compared with that of all‐male Yellow Catfish. After a 45‐d feeding trial, the final weight, weight gain, and specific growth rate in hybrid catfish were significantly higher than these values in all‐male Yellow Catfish. For feed utilization, a significantly higher protein efficiency ratio and lower feed conversion ratio and energy efficiency ratio were found in hybrid catfish. At the end of the experiment, the analyzed lysozyme activity in hybrid catfish was significantly higher than it was in all‐male Yellow Catfish. Our results suggest that hybrid catfish display higher growth performance, feed utilization, and lysozyme activity than all‐male Yellow Catfish under equal conditions. In conclusion, the hybrid catfish shows potential as an aquaculture species with fine production characteristics.

Delayed elimination of paternal mtDNA in the interspecific hybrid of Pelteobagrus fulvidraco and Pelteobagrus vachelli during early embryogenesis

Mitochondrial homoplasmy is essential for normal development, as its heteroplasmy usually leads to abnormal or diseased phenotypes in mammals. So far, diverse mechanisms have been proposed to play roles in ensuring uniparental inheritance of mitochondria in many organisms. In recent years, hybrid yellow catfish from mating female yellow catfish (Pelteobagrus fulvidraco) with male darkbarbel catfish (Pelteobagrus vachelli) has been widely cultured in China due to its fast-growing. However, a high rate of abnormal and defective embryos was observed in the offsprings of hybrid yellow catfish. In this study, we systematically investigated the elimination process of paternal mitochondrial DNA (mtDNA) in yellow catfish and hybrid yellow catfish. The mtDNA contents significantly decreased in the isolated mature sperm compared with the semen. Different from the elimination of paternal mtDNA after fertilization in yellow catfish, paternal mtDNA was retained in the developmental embryos of hybrid yellow catfish as later as gastrula stage, indicating a delay of elimination for paternal mtDNA and mitochondrial heteroplasmy during embryogenesis in hybrid yellow catfish. Altogether, the present study suggests that mitochondrial heteroplasmy may affect embryonic development of hybrid progeny between catfish species.

Differential effects of acute and chronic zinc exposure on lipid metabolism in three extrahepatic tissues of juvenile yellow catfish Pelteobagrus fulvidraco

The aim of this study was to determine the potential mechanisms of exposure to waterborne zinc (Zn) on lipid metabolism in three extrahepatic tissues (ovary, muscle and mesenteric adipose tissue) of female yellow catfish Pelteobagrus fulvidraco. Female yellow catfish were chronically exposed to Zn (0.05, 0.35 or 0.86 mg Zn/l; duration of treatment 8 weeks) or acutely exposed to a high level of Zn (4.71 mg Zn/l for 96 h). Following the respective treatment, lipid deposition and mRNA levels of 11 genes (CPT IA, CPT IB, PPARα, PPARγ, SREBP-1, G6PD, 6PGD, FAS, ACCa, ACCb and LPL) involved in lipid metabolism were determined. Waterborne Zn exposure significantly reduced growth performance and lipid content in muscle but had no significant effect on lipid content in ovary and mesenteric adipose tissue. The change in the levels of the mRNA genes under study was Zn concentration-dependent and tissue-dependent. Pearson correlations between the mRNA levels of three transcriptional factors and enzymes in these tissues revealed that variations in gene expression as a result of the different Zn treatments underlay the patterns of lipid metabolism, which in turn affected fat storage and mobilization. To our knowledge, this is the first study to demonstrate the effect of waterborne Zn exposure on lipid metabolism in extrahepatic tissues at the molecular level. These results therefore contribute to our understanding of Zn-induced toxicity in fish.

Genetic Manipulation of Sex Ratio for the Large-Scale Breeding of YY Super-Male and XY All-Male Yellow Catfish (Pelteobagrus fulvidraco (Richardson))

Yellow catfish has become one of the most important freshwater aquaculture species in China. The mono-sex male yellow catfish has important application value in aquaculture because the male grows generally faster than the sibling females under the same conditions. This study has screened YY super-male and YY physiological female yellow catfish by sex reversal, gynogenesis, and progeny testing, which can help to achieve the large-scale production of YY super-male and XY all-male. From 2008 to 2010, about 123,000 YY super-male were produced, and about 81 million XY all-male fry were produced with 100% male rate by random sampling. Therefore, these results indicate that YY super-male and YY physiological female yellow catfish can be viable and fertile. We conclude that the mono-sex breeding technique by YY super-male yellow catfish is stable and reliable, which has great potential for application in yellow catfish aquaculture.

Polymorphism of &lt;I&gt;MSTN&lt;/I&gt; gene and its association with growth traits in yellow catfish (&lt;I&gt;Pelteobagruse fulvidraco&lt;/I&gt;)

Myostatin (MSTN) gene has negative influence on the growth of muscle, which belongs to transforming growth factor-β family. Using single-strand conformation polymorphism (SSCP), single nucleotide polymorphisms (SNPs) of MSTN gene were detected in yellow catfish. Correlation analysis between MSTN polymorphisms and growth traits was also carried out. Results indicated that five genotypes (AA, BB, CC, CD and DD) were found in the first intron with one deletion site and two mutant sites (T1003del, G1022A and T1063G), two genotypes (EE and EF) were found in the third exon with one mutant site (T132C). The individuals with genotypes AA had a lager value than the individuals with the genotype CD and DD in total length, body length, body height, body width, head length and body weight (Plt;0.05). The female individuals with genotypes AA also had a lager value than the female individuals with genotypes DD in total length, body length, body height, body width, caudal peduncle height, caudal peduncle width and body weight (Plt;0.05). This implies that genotype AA has a positive influence on the growth traits of female yellow catfish, and genotype DD is opposite. Genotypes AA and DD can be used in marker assisted selection of female yellow catfish breeding in the future.

Molecular cloning of follicle-stimulating hormone receptor(FSHR) and expression analysis during the reproductive cycle in female yellow catfish(Pelteobagrus fulvidraco)

Follicle-stimulating hormone(FSH)controls gonadal function in mammalian and many non-mammalian vertebrates through the interaction with their receptors(FSHR).Molecular cloning of the yellow catfish FSH receptor is reported together with changes in the gene expression throughout a reproductive cycle.This work describes the molecular cloning of the cDNA encoding the follicle-stimulating hormone receptor(FSHR)of yellow catfish(Pelteobagrus fulvidraco)by means of reverse transcriptase polymerase chain reaction(RT-PCR),degenerate primers PCR amplification and 5′ and 3′ rapid amplification of cDNA ends(RACE)analyses.We cloned the complete cDNA sequence of FSHR gene and the length is 2 340 bp,encoding a protein of 661 amino acids.This gene belongs to G protein-coupled receptor(GPCR)family,which contains the seven conserved transmembrane helix(TM helix)domains.We found that the amino acids sequence contains nine Leucine-rich repeats(LRRs),five potential N-linked glycosylation sites and that only one protein kinase C phosphorylation site is 403Y in ELⅠ(extracellular loop,ELⅠ)and three protein kinase C phosphorylation sites are 634S,643S,632T in C-terminal domain.The areas played the important role in the function of FSHR gene.The tissue distribution pattern showed high expression of FSHR gene in ovary and brain,and trace amount was detected weakly in other tissues.We also analyzed the mRNA expression level of FSHR gene in ovary at different stages of reproductive cycle.Result showed that the transcript level of FSHR gene was high from Ⅲ to Ⅳ phases then followed by a substantial decline.These changes in expression profiles may imply differences in the functionality of the enzyme gene between different stages,suggesting an important role of FSHR gene in yellow catfish development.We inferred that the gene of FSHR in ovary might also be involved in the processes which regulate ovulation maturation and ovulation,and preferentially promote vitellogenin accumulation.The result has provided an improtant theoretical basis for the function of FSHR gene and the breeding of yellow catfish.

Expression patterns of cytochrome P450 aromatase genes during ovary development and their responses to temperature stress in female yellow catfish (Pelteobagrus fulvidraco)

Cytochrome P450 aromatase (P450arom) plays a pivotal role in ovary development. In this study, we used semi-quantitative reverse transcription PCR (RT-PCR) to analyze spatiotemporal expressions of two P450arom genes (CYP19A and CYP19B) and their responses to temperature stress in female yellow catfish (Pelteobagrus fulvidraco). Tissue distribution pattern of CYP19 showed that CYP19B was abundantly expressed in fish brain and ovary (brain > ovary), but weakly in intestines, whereas CYP19A was exclusively expressed in ovary. Semi-quantitative RT-PCR analyses showed high transcript abundance of both CYP19A and CYP19B in the ovarian reproductive cycle, corresponding with serum estradiol-17β (E2) levels. Increases in aromatases, serum E2 and testosterone (T) levels in fish exposed to higher temperature indicated stimulation of ovarian maturation and recrudescence by heat stress in stages II and V during the ovarian cycle, whereas associated decreases in stage III suggested vitellogenesis inhibition by heat stress. Gene expression of CYP19 was closely related to levels of serum E2. Results demonstrated CYP19 played a crucial role in the reproductive cycle of female yellow catfish. Different temperature stress affected CYP19 gene expression in the fish ovarian reproductive cycle. Associated P450arom genes could be useful for studying physiological aspects of yellow catfish.