Pengze Crucian Carp Research Articles

Effects of three different protein levels on the growth, gonad development, and physiological biochemistry of female Pengze crucian carp (Carassius auratus var. Pengze) broodstock

A 56-days feeding experiment was conducted to evaluate the effect of dietary protein levels on fish growth, gonad development, and physiological biochemistry of female Pengze crucian carp (Carassius auratus var. Pengze) broodstock. Three isoenergetic diets were formulated, and the crude protein levels were 26.85%, 35.73% and 44.38%, the lipid levels were 7.39%, 7.92% and 7.91%, respectively. The results showed that the weight gain rate (WGR), the specific growth rate (SGR) and the protein efficiency ratio (PER) of the female Pengze crucian carp broodstock increased significantly and the feed conversion ratio (FCR) decreased significantly when the dietary protein level was 35.73% (P < 0.05). The WGR, the SGR and the PER were significantly higher in the 35.73% and 44.38% protein groups than in the 26.85% protein group (P<0.05). Increasing dietary protein levels led to a significant increase in the gonad index and the egg menstrual length of the female Pengze crucian carp broodstock (P<0.05). The higher protein levels resulted in a significant increase in total amino acids, total essential amino acids, and total nonessential amino acids (P<0.05). The varying ovaries of each group of total saturated fatty acids, total highly unsaturated fatty acids, and total polyunsaturated fatty acids all increased significantly with increasing protein levels (P<0.05). Furthermore, the aspartate transaminase (AST), low-density lipoprotein cholesterol (LDLC), and malondialdehyde (MDA) contents in plasma were significantly lower in the 35.73% and 44.38% groups than in the 26.85% group (P < 0.05). The 35.73% group exhibited the highest plasma superoxide dismutase (SOD) activity,. The plasma vitellogenin (VTG), estradiol 2 (E2), and progesterone (PROG) in plasma of female Pengze crucian carp broodstock were significantly higher in the 35.73% and 44.38% protein groups than in the 26.85% protein group (P<0.05). The results showed that the addition of an appropriate amount of protein to the feed can significantly improve the growth, gonadal development, and health of female Pengze crucian carp. In this study, the effect of 35.73% protein concentration was better than in the other two groups.

Deciphering male influence in gynogenetic Pengze crucian carp (Carassius auratus var. pengsenensis): insights from Nanopore sequencing of structural variations.

In this study, we investigate gynogenetic reproduction in Pengze Crucian Carp (Carassius auratus var. pengsenensis) using third-generation Nanopore sequencing to uncover structural variations (SVs) in offspring. Our objective was to understand the role of male genetic material in gynogenesis by examining the genomes of both parents and their offspring. We discovered a notable number of male-specific structural variations (MSSVs): 1,195 to 1,709 MSSVs in homologous offspring, accounting for approximately 0.52%-0.60% of their detected SVs, and 236 to 350 MSSVs in heterologous offspring, making up about 0.10%-0.13%. These results highlight the significant influence of male genetic material on the genetic composition of offspring, particularly in homologous pairs, challenging the traditional view of asexual reproduction. The gene annotation of MSSVs revealed their presence in critical gene regions, indicating potential functional impacts. Specifically, we found 5 MSSVs in the exonic regions of protein-coding genes in homologous offspring, suggesting possible direct effects on protein structure and function. Validation of an MSSV in the exonic region of the polyunsaturated fatty acid 5-lipoxygenase gene confirmed male genetic material transmission in some offspring. This study underscores the importance of further research on the genetic diversity and gynogenesis mechanisms, providing valuable insights for reproductive biology, aquaculture, and fostering innovation in biological research and aquaculture practices.

Probiotics Bacillus cereus and B. subtilis reshape the intestinal microbiota of Pengze crucian carp (Carassius auratus var. Pengze) fed with high plant protein diets.

The intestinal dysfunction induced by high plant protein diets is frequently observed in farmed fish, and probiotics of Bacillus genus were documented to benefit the intestinal health through the modulation of intestinal microbiota without clearness in its underlying mechanism yet. Fusobacteria, Proteobacteria, and Firmicutes were observed to be the dominate phyla, but their proportion differentiated in the intestinal bacterial community of Pengze crucian carp (Carassius auratus var. Pengze) fed different diets in this study. Dietary supplementation of B. cereus and B. subtilis could reshape the intestinal bacterial community altered by high plant protein diets through a notable reduction in opportunistic pathogen Aeromonas together with an increase in Romboutsia and/or Clostridium_sensu_stricto from Firmicutes. Due to the alteration in the composition of bacterial community, Pengze crucian carp exhibited characteristic ecological networks dominated by cooperative interactions. Nevertheless, the increase in Aeromonas intensified the competition within bacterial communities and reduced the number of specialists within ecological network, contributing to the microbial dysbiosis induced by high plant protein diets. Two probiotics diets promoted the cooperation within the intestinal bacterial community and increased the number of specialists preferred to module hubs, and then further improved the homeostasis of the intestinal microbiota. Microbial dysbiosis lead to microbial dysfunction, and microbial lipopolysaccharide biosynthesis was observed to be elevated in high plant protein diets due to the increase in Aeromonas, gram-negative microbe. Probiotics B. cereus and B. subtilis restored the microbial function by elevating their amino acid and carbohydrate metabolism together with the promotion in the synthesis of primary and secondary bile acids. These results suggested that dietary supplementation of probiotics B. cereus and B. subtilis could restore the homeostasis and functions of intestinal microbiota in Pengze crucian carp fed high plant protein diets.

Dietary Antimicrobial Peptides Improve Intestinal Function, Microbial Composition and Oxidative Stress Induced by Aeromonas hydrophila in Pengze Crucian Carp (Carassius auratus var. Pengze).

There is increasing evidence for the potential use of antimicrobial peptides as dietary supplements and antibiotic substitutes. In this study, we analyzed the differential effects of varying levels of antimicrobial peptides on the intestinal function and intestinal microbial and disease resistance of Pengze crucian carp. Approximately 630 experimental fishes were randomized in the control group (G0: 0 mg/kg) and in five groups supplemented with different doses of AMPs (G1: 100 mg/kg, G2: 200 mg/kg, G3: 400 mg/kg, G4: 800 mg/kg, and G5: 1600 mg/kg) and were fed for ten weeks. Three replicates per group of 35 fish were performed. The results showed that AMPs promoted intestinal villus development and increased intestinal muscular thickness (p < 0.05) and goblet cell abundance. The enzymatic activities of all groups supplemented with AMPs were effectively improved. AMP supplementation significantly enhanced the activities of antioxidant enzymes and digestive enzymes in the intestines of G3 animals (p < 0.05). Compared with G0 animals, AMP-supplemented animals regulated the expression of intestinal immune-related genes and exhibited significant differences in the G3 animal group (p < 0.05). The abundance of intestinal Firmicutes and Bacteroidetes increased in the AMP-supplemented groups, but the Firmicutes/Bacteroidetes ratio was lower than that in the G0 group. AMP supplementation also decreased the abundance of Fusobacterium while increasing the proportion of Actinobacteria (p < 0.05). After Aeromonas hydrophila infection, the expression levels of anti-inflammatory factors in the intestinal tract of G3 animals were significantly upregulated, and the level of the proinflammatory factor was decreased (p < 0.05). The intestinal Cetobacterium levels of G3 animals were significantly increased (p < 0.01), while the Proteobacteria levels were decreased, and the intestinal goblet cell proliferation was significantly lower than that of G0 animals (p < 0.05). This indicates that groups supplemented with AMPs have better disease resistance than the G0 group and can rapidly reduce the adverse effects caused by inflammatory response. Taken together, the present results suggest that AMP supplementation can improve intestinal function and intestinal microbial and pathogen resistance in Pengze crucian carp.

Blood-brain barrier permeability to enrofloxacin in Pengze crucian carp (Carassius auratus var. Pengze).

Enrofloxacin (ENR) is a kind of quinolone antibiotic that is most widely used antimicrobials in veterinary practice, and possesses both a broad spectrum antimicrobial activity against a range of bacteria and adverse effects towards plants and animals. This study was conducted to explore the permeability of blood-brain barrier (BBB) to ENR and brain injury based on crucian carp orally administrated with high dose of ENR. Juvenile Pengze crucian carp were treated with halflethal dose (LD50 ) or safe dose (SD50 ) of ENR. BBB permeability was determined by evaluating ENR contents detected by HPLC and evens blue contents estimated by confocal laser scanning microscope. Brain damage was evaluated by measuring protein and mRNA contents of related molecules with western blotting and qPCR. Data indicated that ENR destroyed BBB structure of crucian carp and enhanced permeability of the biological barrier, resulting in more ENR crossed BBB and induced brain damage of crucian carp. This data indicated that ENR can induce brain damage of crucian carp through destroying BBB structure and enhancing permeability.

Effects of dietary sodium butyrate on growth performance, antioxidant capacity, intestinal histomorphology and immune response in juvenile Pengze crucian carp (Carassius auratus Pengze)

The current study was done to assess the effects of dietary sodium butyrate (SB) on growth performance, antioxidative capacities, intestinal microvilli morphology and intestinal immune response in juvenile Pengze crucian carp (Carassius auratus Pengze). Three treated diets and a control containing 0, 1,000, 2,000, 4,000 mg/kg SB (CON, SB1, SB2, SB3) were fed for juvenile Pengze crucian carp (5.49 ± 0.41 g) for 8 weeks. The results revealed that fish in SB2 and SB3 groups showed significantly higher growth performance compared to the control (P < 0.05). The body lipid was significantly decreased in SB-containing groups compared with that of the control (P < 0.05). Trypsin and lipase activities of fish fed SB2 and SB3 diets were both significantly higher than those of fish fed CON and SB1 diets (P < 0.05). However, no significant difference was found in α-amylase activity among all groups (P > 0.05). The intestinal total antioxidant capacity, catalase and superoxide dismutase activities were significantly enhanced in SB groups compared to the control (P < 0.05). The activities of brush border enzymes such as alkaline phosphatase, γ-glutamyl transpeptidase and Na+/K+-ATPase of fish fed SB2 and SB3 diets were both significantly higher than those of fish fed CON and SB1 diets (P < 0.05). However, the malondialdehyde contents of intestines in fish fed SB diets were remarkably reduced (P < 0.05). In addition, the serum total antioxidant capacity, superoxide dismutase, lysozyme activities and complement C3 content of fish fed SB2 and SB3 diets were significantly increased than those of fish in the CON (P < 0.05). The analysis of scanning electron microscopy and transmission electron microscopy demonstrated that density and length of microvilli were increased in the SB2 and SB3 groups (P < 0.05). The mRNA expression levels of pro-inflammatory gene IL-1β was significantly down-regulated in the SB2 and SB3 groups (P < 0.05). Moreover, the mRNA expression levels of anti-inflammatory gene TGFβ and IL-10 were significantly up-regulated in SB groups (P < 0.05). The mRNA expression levels of TNFα were not significantly different among all the groups (P > 0.05). Conclusively, our results showed the positive effects of the SB in Pengze crucian carp diets to improve the growth, intestinal microvilli morphology and intestinal immune response.

Effects of mixed antimicrobial peptide on the growth performance, antioxidant and immune responses and disease resistance of Pengze crucian carp (Carassius auratus var. Pengze)

Antimicrobial peptides have broad-spectrum antibacterial properties and low drug resistance, and they demonstrate great potential as antibiotic substitutes. In this study, five dietary mixed antimicrobial peptide supplement groups were set and fed to Pengze crucian carp for 10 weeks. The 6 groups were G0 (control group) and 5 additional groups: G1 (100 mg/kg), G2 (200 mg/kg), G3 (400 mg/kg), G4 (800 mg/kg) and G5 (1600 mg/kg). The results showed that the final body weight (FBW), weight gain rate (WGR) and specific growth rate (SGR) of fish in G1 and G2 were higher than those of fish in the control group, and G1 was significantly higher than G0 (P < 0.05). In addition, the FBW, WGR, and SGR of the G3 group were significantly lower than those of the G0 group. The chymotrypsin, lipase and amylase activities of G1 and G2 were significantly upregulated compared with G0 and reached peak values in G1. The activity of T-AOC and SOD in the addition group was higher (except G2 and G4) than that in the control groups, and significantly increased in G3 compared to the control group. The activity of MDA in the addition group was lower than that in the control group (p > 0.05). The expression levels of TLR-4, MYD88 and TNF-α in the three organs of the addition group were higher than those in G0 and reached the peak value in G3 (p < 0.05). Furthermore, the expression levels of TLR-4, MYD88 and TNF-α in the three organs of G3 were significantly lower than those in G0 and lower than those in the other supplemented groups. The expression levels of IL-10 and IL-11 tended to be upregulated after A. hydrophila challenge, and G3 in different organs was significantly higher than that in other supplemented groups and G0. The results of this study show that an appropriate amount of mixed antimicrobial peptides can improve the growth performance and antioxidant and immune capabilities of Pengze crucian carp and can also play a positive role in the treatment of A. hydrophila infection.

Effects of pre‐freezing methods and storage temperatures on the qualities of crucian carp ( Carassius auratus var. pengze) during frozen storage

Pengze crucian carp was pre-frozen by liquid nitrogen and freezer, and then stored at −20/−40°C and −20°C, respectively, for 15–60 days. Effects of pre-freezing methods and storage temperatures on the qualities of fish were investigated. The pH showed a “V” trend. The soluble myofibrillar protein content, hardness, springiness, cohesiveness, gumminess, chewiness, and resilience decreased. Thiobarbituric acid value, total volatile basic-nitrogen value, thawing and cooking loss rates increased with the extending of storage period. LF-NMR analysis indicated that the water-protein connection became less tight. Moreover the qualities decline degrees were higher for freezer pre-frozen than liquid nitrogen pre-frozen, and higher for −20°C storage than −40°C storage. Accordingly, compared with conventional freezer pre-freezing and storage, liquid nitrogen pre-freezing and low temperature storage could inhibit the oxidation and degradation, and keep better water holding and textural properties of muscle. The present study showed a great potential application in aquatic products processing industry. Practical applications In aquatic product enterprise, liquid nitrogen can be used to pre-freeze fishes in seconds. And combined with low temperature storage, the oxidation and degradation of fish can be significantly inhibited. In addition, water holding capacity and textural properties of fish muscle can be better kept, and the shelf-life of fish can be extended by several weekends in comparison with those of fishes pre-frozen and stored in freezer.

Beneficial effects of emodin and curcumin supplementation on antioxidant defence response, inflammatory response and intestinal barrier of Pengze crucian carp ( Carassius auratus var. Pengze)

The object of this work is to investigate the effects of emodin and curcumin on Pengze crucian carp. Fish was, respectively, fed Control diet and supplementation of 50 mg/kg emodin (EM group) and curcumin (CU group) with 4 repetitions each group (20 fish per cage). Our results indicated that the growth was unaffected by diets, whilst whole‐body lipid content was detected to remarkably decrease in EM group. Two additives exerted positive impacts on antioxidant system through elevation of antioxidant enzymes activities and antioxidants content. The improvement of intestinal antioxidant property appeared to be associated with up‐regulating expression of antioxidant genes through nuclear factor erythroid 2‐related factor 2 (Nrf2) activation. Moreover, intestinal inflammatory response was suppressed in EM and CU groups through inhibition of Toll‐like 4 receptor (TLR4) signalling pathway and pro‐inflammatory cytokine genes expression, and it may be related to the regulation of antioxidant system and overexpression of interleukin‐10. Afterwards, intestinal barrier function was enhanced in EM and CU groups by inducing the expression of tight junction protein genes. These results revealed that emodin and curcumin exerted positive benefits on the health of Pengze crucian carp by enhancing antioxidant capacity, suppressing inflammatory response and improving intestinal barrier function.

Probiotic (Bacillus cereus) enhanced growth of Pengze crucian carp concurrent with modulating the antioxidant defense response and exerting beneficial impacts on inflammatory response via Nrf2 activation

The purpose of this research was to explore the mechanism of action of B. cereus on Pengze crucian carp (Carassius auratus var. Pengze). Fish fed basal diet with supplementation of living (LBC group) and heated-inactivated (HIBC group) B. cereus at the dose of 1 × 109 CFU kg−1, and basal diet served as Control group. Our results indicated that both additives remarkably promoted the growth of fish (P < .05). Compared to Control group, living B. cereus significantly improved serum antioxidant status through an elevation in the activities of total superoxide dismutase, catalase and glutathione peroxidase and the concentration of reduce glutathione (P < .05), whereas only a significantly higher catalase activity was detected in fish fed heated-inactivated B. cereus (P < .05), concurrent with a significant decrease in malondialdehyde concentration in two additive groups (P < .05). Meanwhile, the intestinal antioxidant property was improved in two additive groups through the increase in catalase and glutathione peroxidase activities and reduce glutathione content together with a significantly lower malondialdehyde content (P < .05). The gene expression analysis indicated that the improvement of intestinal antioxidant property appeared to be associated with Nrf2 signaling pathway via up-regulating the mRNA levels of target genes like catalase, glutathione peroxidase 1, or copper/zinc superoxide dismutase. Besides, living and heated-inactivated B. cereus supplementation could inhibit intestinal inflammatory responses by suppressing the transcription of pro-inflammatory cytokine due to the regulation of antioxidant system by Nrf2 activation and inducing the overexpression of anti-inflammatory cytokine interleukin-10 (P < .05). Then, the intestinal barrier function in two B. cereus groups was improved by up-regulating expression of tight junction protein genes like Claudin12, zonula occludens 1, and/or Occludin-like (P < .05). These results revealed that probiotics B. cereus supplementation could promote the growth and further improve intestinal health by enhancing antioxidant capacity, suppressing inflammatory response, and improving intestinal barrier function of Pengze crucian carp through Nrf2 signaling pathway.

Carvacrol promotes intestinal health in Pengze crucian carp, enhancing resistance to Aeromonas hydrophila

This study was performed to determine the effects of dietary microencapsulated carvacrol (MC) on growth, resistance to A. hydrophila, and intestinal health parameters including intestinal bacteria, intestinal morphology and intestinal cytokines, in Pengze crucian carp (Carassius auratus var. Pengze). Fish were divided into four groups. Each group was fed a different diet for 56 days (a control diet or diets supplemented with 200, 400, or 600 mg/kg of MC). Our results indicate that MC had no effect on growth but significantly decreased A. hydrophila infection-associated mortality rates at 400 and 600 mg/kg and the lowest mortality was present at 600 mg/kg. The intestinal health of fish receiving the control diet was compared with that of the group receiving 600 mg/kg MC. High-throughput sequencing showed that MC increased the abundance of phylum Fusobacteria. It also increased the abundance of the genus Cetobacterium and decreased those of Flavobacterium and Pseudomonas. Light microscopy and transmission electron microscopy images support the ability of MC to improve the integrity of the lamina propria, increase microvilli height, and strengthen tight junctions, especially in the foregut. An ELISA assay indicated that levels of intestinal pro-inflammatory cytokines, including tumor necrosis factor-α and interleukins-1β, were reduced, whereas the level of the anti-inflammatory cytokine interleukins-10 was increased of fish administered dietary MC. We conclude that carvacrol promotes intestinal bacteria composition, intestinal morphology status and reduces intestinal inflammatory, which enhances resistance to A. hydrophila in Pengze crucian carp.

The effects of partial replacement of fishmeal protein by hydrolysed feather meal protein in the diet with high inclusion of plant protein on growth performance, fillet quality and physiological parameters of Pengze crucian carp ( Carassius auratus var. Pengze)

Goal of this research is to explore the effects of graded dietary levels of hydrolysed feather meal (HFM) protein as an alternative of fishmeal protein on Pengze crucian carp (Carassius auratus var. Pengze). Five isonitrogenous (35% crude protein) diets were formulated as Control diet and four other diets F15, F30, F45 and F60 wherein 15%, 30%, 45% and 60% fishmeal protein replaced by HFM protein fed for 70 days. The results showed that fish growth was unaffected up to 45% fishmeal protein replacement. Dietary HFM protein could reduce the crude protein composition of body and further affect fillet quality through a significant increase in springiness, gumminess, chewiness and/or resilience. Activity of digestive enzymes (amylase, lipase and tryptase) increased as the fishmeal protein replacement increased, whereas a higher replacement level had negative impacts on absorptive capacity of intestine by decreasing its absorptive area, following by a reduction in concentration of lactate dehydrogenase, total cholesterol, high‐density lipoprotein, low‐density lipoprotein and ammonia in serum. Although intestinal antioxidant parameters were elevated by dietary HFM protein, the content of malondialdehyde in intestine was also positively associated with the protein replacement level. Overall, our results indicate that up to 45% of fishmeal protein could be replaced by HFM protein in diet without significant impact on the growth of Pengze crucian carp, whereas the crude protein content of whole body, fillet quality and oxidative status would significantly be affected when the replacement level of fishmeal protein reaches 30% together with a negative effect on the intestinal histology.

Dietary supplementation of Bacillus cereus as probiotics in Pengze crucian carp ( Carassius auratus var. Pengze): Effects on growth performance, fillet quality, serum biochemical parameters and intestinal histology

This study was aimed to evaluate the effects of dietary supplementation of Bacillus cereus as probiotics on growth, fillet quality, serum biochemical parameters and intestinal histology of Pengze crucian carp (Carassius auratus var. Pengze). Fish were fed basic diet (Control group) and three diets such as CD7, CD9 and CD11 supplemented with B. cereus at dose of 107, 109 and 1011 CFU/kg for 70 days. The results showed that supplementation of 109 CFU/kg B. cereus significantly improved the growth performance compared to that in the Control group. The textures of muscle were improved by dietary supplementation of probiotics, and the hardness, gumminess, chewiness and the resilience of fish fillet increased with increasing dose of B. cereus. Total cholesterol including high-density lipoprotein and low-density lipoprotein level in serum decreased correspondingly with increasing level of probiotics whereas, acid phosphatase and catalase activities increased in serum. B. cereus supplementation enhanced the immunity and antioxidant capacity via an increase in acid phosphatase, alkaline phosphatase, glutathione peroxidase, reduce glutathione, and catalase, accompanied by a significant reduction in malondialdehyde. Higher intestinal fold height was observed in CD9 group than other groups. The lowest enterocyte height was exhibited in the Control group, HE values increased with increasing dose of probiotics. Moreover, dietary inclusion of B. cereus significantly affected the digestive enzymes activities in terms of higher lipase and trypase activities. In conclusion, dietary supplementation of B. cereus could promote the growth, elevate the immunity and antioxidant status of carp, and importantly improve the texture of fish fillet.

Effects of dietary supplementation with β-glucan and Bacillus subtilis on growth, fillet quality, immune capacity, and antioxidant status of Pengze crucian carp (Carassius auratus var. Pengze)

A 70-day feeding trial was conducted to investigate the effects of dietary supplementation with prebiotics β-glucan (BG group) and probiotics Bacillus subtilis (BS group) on growth performance, fillet quality, immune response, and antioxidant status of Pengze crucian carp (Carassius auratus var. Pengze). The results showed that supplementation of B. subtilis significantly improved the growth performance than other groups whereas feed efficiency was unaffected by dietary treatments. The textures of muscle in terms of hardness, springiness, cohesiveness, gumminess, chewiness, and resilience were higher in BG and BS groups than Control group. Supplementation of β-glucan and B. subtilis acted as an hypolipidemic in terms of decreasing the total cholesterol, high-density lipoprotein, and low-density lipoprotein whereas, increased the immune responses in serum measured by acid phosphatase, alkaline phosphatase, and catalase activities. Dietary supplementation of β-glucan and B. subtilis significantly improved the fold height and microvillus height in contrast to basal diet. Moreover, β-glucan could significantly increase digestive capacity observed in terms of an increase in amylase and trypsase activities, and B. subtilis significantly increased amylase and lipase activities in intestine. β-glucan and B. subtilis supplementation enhanced the immunity and antioxidant capacity via an increase in acid phosphatase, alkaline phosphatase, glutathione peroxidase, reduce glutathione, catalase, and total superoxide dismutase activities, accompanied by a significant reduction in malondialdehyde. Overall, the results indicated that B. subtilis improved the growth performance by increasing the digestive enzymes activities and improving the intestinal morphology. β-glucan and B. subtilis supplementation significantly improved the fillet quality, immune responses and antioxidant status of Pengze crucian carp.

Molecular mechanism of endocrine system impairment by 17α-methyltestosterone in gynogenic Pengze crucian carp offspring

The effects of synthetic androgen 17α-methyltestosterone (MT) on endocrine impairment were examined in crucian carp. Immature 7-month old mono-female Pengze crucian carp (Pcc) F2 offspring were exposed to 50 and 100μg/L of MT (week 2, 4, and 8). Gonadosomatic index, hepatosomatic index and intestine weight altered considerably and oocyte development was repressed. In the treatment groups, ovarian 11-ketotestosterone decreased, whereas 17β-estradiol and testosterone increased, and ovarian aromatase activities increased at week 4. However, in the brain tissue, those values significantly decreased. Quantitative RT-PCR analysis demonstrated changes in steroid receptor genes and upregulation of steroidogenic genes (Pcc-3bhsd, Pcc-11bhsd2 Pcc-cyp11a1), while the other three steroidogenic genes (Pcc-cyp17a1, Pcc-cyp19a1a and Pcc-star) decreased from week 4 to week 8. Ovarian, hepatic Pcc-vtg B and vitellogenin concentration increased in both 50 and 100μg/L of MT exposure groups. This study adds further information regarding the effects of androgens on the development of previtellogenic oocytes, which suggests that MT could directly target estrogen signaling pathway, or indirectly affect steroidogenesis and vitellogenesis.

Large-scale tissue-specific and temporal gene expression profiles in Pengze crucian carp.

In the present study, the tissue-specific and temporal gene expression profiles of four catalogues of gonadal development-related genes (sex differentiation-related, steroid receptor, steroidogenic, and structural genes) were detected in nine tissues and during 11 successive developmental stages in the Pengze crucian carp (Pcc) (a triploid mono-female gynogenic fish). The results showed that these target genes exhibited overlapping distributions in various tissues, with the exception of Pcc-vasa and Pcc-cyp17a1. Gene expression profiling of the developmental stages showed that all of the target genes simultaneously reached peak expression levels at 40 and 48 days post hatching (dph). Both 40 and 48 dph appeared to be two key time points associated with the process of Pcc gonadal development. These data will provide a clear understanding of gene expression patterns associated with the gonadal development-related genes of this gynogenic teleost.

Gender-specific differences in gene expression profiles in gynogenetic Pengze crucian carp

Gynogenesis is a form of asexual reproduction that is used to obtain all-female fish stocks. In this study, we were interested in studying gender-specific differences in gene expression profiles in gynogenetic teleosts, using a carp species. The four-month old gynogenetic Pengze crucian carp F1 (Carassius auratus var. pengzensis, Pcc) showed a high ratio of males under laboratory culture condition. The present study aimed to investigate the differences between males and females. The gonadosomatic index of the females was significantly higher than that of the males. Moreover, the hepatosomatic index of the females was significantly lower than that of the males. Vitellogenin B mRNA was abnormally highly expressed in male hepatopancreas and testes compared to females. Similarly, zona pellucida 2 expressed at a significantly high level in the testes. For the sex related genes, dosage-sensitive sex reversal, adrenal hypoplasia congenital critical region on the X-chromosome gene 1, doublesex and mab-3 related transcription factor 1a, nuclear receptor subfamily 5, group A, member 1b and SRY-box containing gene 9a had significantly higher expression levels in the males than in the females, whereas there was no difference in expression of anti-Müllerian hormone, cytochrome P450 family 19 subfamily A member 1A and forkhead box L2 transcripts between the two genders. The females showed higher levels of estrogen but no significant difference in testosterone compared to the males. The data suggest remarkable differences between the two genders of the Pengze crucian carp.

Complete mitochondrial DNA genome of triploid pengze crucian carp (Carassius auratus)

The complete mitochondrial genome sequence of triploid pengze crucian carp was 16,580 bp in length. The mitochondrial genome contains 22 transfer RNAs, 13 protein-coding genes, 2 ribosomal RNAs and 2 non-coding regions (control region and origin of light-strand replication). All genes were encoded on the heavy strain except for ND6 and eight tRNA genes. The overall base composition is A 31.53%, T 26.23%, G 16.15%, C 26.09%, with an A + T bias of 57.76%. The complete mtDNA sequence of the geographic triploid pengze crucian carp was reported in this study for the first time.

Molecular cloning of Pcc-dmrt1s and their specific expression patterns in Pengze crucian carp (Carassius auratus var. Pengze) affected by 17α-methyltestosterone

Dmrt1, an important transcription factor associated with testicular differentiation, is conserved among teleost, which could also be detected in ovaries. In the present study, three isoforms of Pcc-dmrt1s (Pcc-dmrt1a, Pcc-dmrt1b and Pcc-dmrt1c) resulting from alternative splicing of the dmrt1 gene were cloned and characterized in the triploid gynogenetic fish, the Pengze crucian carp. Their mRNA expression profiling was investigated in juvenile developmental stages, tissues of the adult fish, and the juveniles under 84.2ng/L 17α-methyltestosterone (MT) treatments. Results showed that their putative proteins shared high identities to Dmrt1 in cyprinid fish species. Gene expression profiling in the developmental stages showed that all the three target genes had a highest/lowest expression at 56/40days post-hatching (dph), respectively. The period of 40 dph appeared to be a key time during the process of the ovary development of Pengze crucian carp. The tissue distribution results indicated that Pcc-dmrt1s were predominantly expressed in hepatopancreas, brain, spleen and ovary of the female fish. MT significantly increased the mRNA expression of Pcc-dmrt1a (all 4-week exposures) and Pcc-dmrt1b (except for week 2), while repressed Pcc-dmrt1c transcripts at all exposure period except for week 2. MT extremely significant repressed cyp19a1a transcripts for 1week. The present study indicated that MT could influence the ovary development of Pengze crucian carp by disturbing gene expressions of Pcc-dmrt1s and cyp19a1a. Furthermore, the present study will be of great significance to broaden the understanding of masculinizing pathway during ovary development in gynogenetic teleost.

Molecular characterization of five steroid receptors from pengze crucian carp and their expression profiles of juveniles in response to 17α-ethinylestradiol and 17α-methyltestosterone

Pengze crucian carp (Carassius auratus var. pengze, Pcc), a triploid gynogenetic fish, was used in this study to investigate the cross-talk between EDCs and steroid receptors. The full-length cDNAs of five steroid receptors (esr1, er alpha2, esr2a, esr2b, ar) and partial cDNA of vtg B were isolated. The tissue distributions of these genes were analyzed in adult fish by qRT-PCR. Then the expression profiles of five steroid receptors (esrs and ar) and vtg B were detected in the juveniles exposed to 17α-ethinylestradiol (EE2, 0.1, 1 and 10ng/L) and 17α-methyltestosterone (MT, 50μg/L) for 4weeks. The results demonstrated that esrs, ar, and vtg B were predominantly expressed in liver of adult fish. However, among these detected genes, esr1 and er alpha2 mRNAs are sensitive biomarkers in response to EE2 at 0.1, 1, and 10ng/L for 1 and 2weeks compared to esr2a, esr2b, ar, and vtg B in the juveniles of mono-female gynogenetic fish. Totally, the subtypes of esrs show biphasic responses to EE2 exposures for 4weeks, and most of the EE2 exposures at 0.1, 1, and 10ng/L for 1, 2, 3 and 4weeks did not induce the mRNA expressions of vtg B. However, 1-, 2-, and 4-week 50μg/L MT all significantly stimulated vtg B transcripts. Further investigations are needed to elucidate the mechanism underlying the insensitivity or down-regulation of vtg B mRNA in response to EE2 in juvenile Pcc.