Reproduction and breeding最新文献

The present study used hybrid fish (Megalobrama amblycephala ♀ × Culter alburnus ♂, abbreviated as BT) and topmouth culter (Culter alburnus, abbreviated as TC) as research subjects to assess and compare the effects of carbohydrate on the growth, oxidative stress and glucolipid metabolism of the two fish. The TC (initial weight, 13.10 ± 0.10 g) and BT (initial weight, 12.85 ± 0.13 g) were fed isonitrogenous (43% crude protein) and isolipidic (6.5% crude lipid) diets with carbohydrate levels of 10% (LC diet) and 30% (HC diet) for 11 weeks, respectively. The results showed that the HC diet resulted in a significant decrease in specific growth rate (SGR) of both fish. However, the SGR in BT was significantly higher than in TC, regardless of diet. Furthermore, HC diet significantly increased serum alanine transaminase (GPT) and hepatic malondialdehyde (MDA) content, decreased hepatic catalase (CAT) activity and resulted in increased hepatocyte volume, nucleus deficiency and nucleus deviation from the center of cytoplasm in both fish. However, BT had significantly higher glutathione peroxidase (GPx) activity and lower serum GPT and aspartate transaminase (GOT) content compared to TC. The HC diet induced significant increases in hepatosomatic index (HSI), liver lipid droplet area, liver glycogen, serum glucose (GLU) and triglyceride (TG) content in both fish. However, HSI and lipid droplet area were significantly higher in BT than in TC, while serum GLU and TG content were significantly lower in BT than in TC. Both fish can adapt to the HC diet by up-regulating the expression of glycolysis-related gene (glucokinase (gk)) and lipogenesis-related genes (acetyl-CoA carboxylase a (acca), fatty acid synthase (fas)). However, the expression levels of glucose transporter 2 (glut2), glycolysis-related gene (phosphofructokinase liver b (pfklb)) and lipogenesis-related genes (sterol regulatory element-binding protein 1 (srebp1), ATP citrate lyase a (aclya)) were increased only in BT fed HC diet. In summary, the BT liver has stronger glucose transport, glycolysis, and lipid tolerance compared to TC, thus exhibiting better glucose homeostasis and growth performance. It indicates that hybridization may help to produce new strain of fish with high carbohydrate utilization capacity.

MnSOD is a ubiquitous metalloenzyme that constitutes the first line of antioxidant defense against oxidative stress. In this study, full length sequence of MnSOD was identified from hybrid crucian carp (WR, Carassius cuvieri ♀ × Carassius auratus red var ♂). Tissue-specific analysis revealed that the highest expression of WR-MnSOD was detected in kidney. Aeromonas hydrophila challenge could dramatically enhance WR-MnSOD mRNA expression in tissues. In vivo administration of purified WR-MnSOD peptide could maintain gut mucosal barrier function, rescue redox balance as well as decrease apoptotic cell death in midgut upon bacterial infection, suggesting that WR-MnSOD is playing a crucial role in gut mucosal barrier function and could be used as feed additive to improve gut immunity in fish.

Gene editing technique has been widely applied for gene function characterization. However, such an approach is often time-consuming to obtain homozygous mutant. In this article, through timing the earlier injection of embryos, the gene editing efficiency is significantly improved, and together with the technique of the UV inactivated sperm and heat shock treatment for blocking the first cleavage, the gene-edited homozygous zebrafish are successfully obtained in F0 generation, rather than in the third or more generations as reported in the existing results. It is concluded that genetic purification of artificial gynogenesis can play critical role in more efficiently preparing the gene-edited homozygous individuals in fish.

Tetraploid is a very important experimental material, whether in scientific research or breeding practice. However, tetraploid strains are relatively rare. It was reported that chromosomes allocation disorder during cell division may lead to high embryonic mortality and low fertility in tetraploid fish. In this paper, tetraploid zebrafish is prepared by ploidy operation. And successfully establishes a tetraploid zebrafish cell line in vitro. To tracing status of microtubules, the tetraploid zebrafish cells are transfected with two plasmids of pBLK-α-tubulin-mCherry and pBLK-γ-tubulin-EGFP by electroporation in vitro. Observation shows that these transfected cells can be traced the changes of spindle and centrosomes during cell division in tetraploid cells. The results provide important material platform in vitro for studying the chromosome behavior in tetraploid cell proliferation, especially the formation mechanism of aneuploidy.

The IL-20 cytokine family, which includes only IL-20, IL-22 and IL-26 in teleost, has a wide range of biological functions and is essential for epithelial integrity and innate host defense. IL-22 and IL-26 are the most intensively studied cytokine within this family; however, the immunological function of IL-20 in fish is essentially unknown. In this study, we examined the expression and function of an IL-20 homologue (WR-IL20) from White crucian carp (Carassius cuvieri, WCC, female) × Red crucian carp (Carassius auratus red var., RCC, male). WR-IL20 and its parents, WCC-IL20 and RCC-IL20, were both composed of 177 residues with high identities among them. Additionally, gene structure, functional domain, tertiary structure, multiple sequence alignment, and phylogeny analysis showed a conserved status between WR-IL20, WCC-IL20 and RCC-IL20. WR-IL20, WCC-IL20 and RCC-IL20 were mainly expressed in the head kidney and were upregulated by Aeromonas hydrophila infection in vivo. Furthermore, recombinant WR-IL20 protein (rWR-IL20) induced increased transcript levels of c-Myc, cyclin D, Bcl-2, JAK1, TYK2 and STAT3 in head kidney lymphocytes in vitro. These results provide a new perspective for understanding the origin, evolution and function of IL-20 in teleost.

Stimulator of interferon gene (STING) functions importantly as antiviral adaptor protein during the innate immune activation. The role of the dimerization domain (DD) of STING remains obscure although other domains of this molecule have been studied extensively. To clarify the mechanism of black carp STING (bcSTING) in the innate immunity, bcSTING-ΔDD (bcSTING without DD) and bcSTING-ΔCTT (bcSTING without CTT domain) were constructed and analyzed in this manuscript. The reporter assays revealed that the induced transcription of IFN promoters mediated by bcSTING-ΔDD were much higher than that of the wild type bcSTING; however, bcSTING-ΔCTT almost lost the activities to trigger the interferon (IFN) promoters transcription. The mRNA transcriptional levels of IFN and interferon stimulated genes (ISGs) in EPC cells expressing bcSTING-ΔDD were obviously higher than those of EPC cells expressing wild type bcSTING; however, the transcriptional levels of the above cytokines of EPC cells expressing bcSTING-ΔCTT were basically the same as those of control cells. EPC cells overexpressing bcSTING-DD showed stronger antiviral activity than those overexpressing wild-type bcSTING. Furthermore, the co-immunoprecipitation assay identified the self-interaction between bcSTING-ΔDD molecules. And it was interesting that the affinity between bcSTING-ΔDD and bcTBK1 was obviously stronger than that between bcTBK1 and wild-type bcSTING. Thus, our data suggests that DD of black carp STING plays a negative regulatory role in STING-mediated antiviral immunity, which provides a new perspective for further researching the function of fish STING in the innate immunity.

With the gradually upgrade of formulated feeds, the largemouth bass Micropterus salmoides has been domesticated to adapt to formulated diets to reduce the use of bait fish and cut cost. However, whether the formulated diets influence the nutritional content and muscle quality of largemouth bass and related mechanisms remains unclear. In this study, we evaluated the effects of forage fish and formulated diets on growth performance, proximate compositions, muscle histology and fiber character. Largemouth bass with initial weights of 39.37 ± 1.37g and 39.45 ± 1.40g were fed with formulated diets and forage fish for 8 months, respectively. The results showed that formulated diets group (FDG) exhibited higher levels of protein content and free amino acids compared with forage fish group (FFG). Interestingly, the diameter of muscle fiber was larger in FDG than in FFG through microsection observation. A comparative analysis of transcriptome was constructed for muscle tissues of FDG and FFG, respectively. Compared with FFG, 2186 differentially expressed genes (DEGs) were identified in FDG, including 1915 upregulated genes and 271 downregulated genes. Gene ontology (GO) analyses revealed that DEGs were significantly enriched in GO terms regarding mitochondrial metabolism, muscle growth and development. KEGG enrichment indicated that DEGs were involved in the amino acid metabolism. Our results indicated that replacing forage fish with formulated diets affected the muscle quality and fiber character of largemouth bass, which could provide a basis for the regulation of nutrition and accurate selection for meat traits in largemouth bass.

Distant hybridization refers to the combination of different genomes from different species and further leads to genetic structure changes in hybrids. For next-generation sequencing limitations, the genetic changes with respect to hybrids or polyploids cannot be fully explained. Here, we obtained 117,526 full-length isoforms from a triploid hybrid grass carp (3nGT, 3n = 72) by the crossing of female grass carp (GC, 2n = 48) and male topmouth culter (TC, 2n = 48) using single-molecule long reads sequencing technology. Further, the gene fusion, alternative splicing (AS), transcription of homologous genes, and novel genes were analyzed. The results showed that 1563 fusion genes were detected in 3nGT including 872 heterogenous fusion genes derived from GC and TC genomes. Meanwhile, 175,644 AS events were identified and divided into five models, of which IntronR was the dominant model. In addition, 8964 novel genes were discovered, of which 2802 novel genes were annotated. Finally, scans results of Hox gene family revealed that both GC and TC Hox genes were transcribed in 3nGT, but presented asymmetric transcription patterns with a bias towards the maternal parent GC genome. This study not only provides a rich resource of transcript isoforms for the superior triploid grass carp, but also provides an important insight into rapid genetic changes in hybrid fish.

The litter size and litter weight are the most important indicators of growth production system in goats as they are directly related to the survival and growth of the kids. The present attempt was made to estimate genetic parameters of litter traits such as litter size at birth (LSB), litter size at weaning (LSW), litter weight at birth (LWB) and litter weight at weaning (LWW) of Jakhrana breed of Indian goat. These traits were subjected to study variation due to direct additive genetic effects by adjusting non-genetic factors under linear mixed model. The data of litter records of 101 Jakhrana goats including pedigree information were processed and the results showed that the least-square means for LSB, LSW, LWB and LWW were 1.20 ± 0.05, 1.19 ± 0.05, 3.08 ± 0.11 and 12.11 ± 0.49, respectively. The direct heritability estimates for LSB, LSW, LWB and LWW were 0.17, 0.01, 0.001 and 0.10, respectively. The genetic (0.70–0.97) and phenotypic (0.61–0.92) correlation estimates among litter traits were high and positive. This study indicated that the additive variation among the early reproductive traits was low in range which does not provide a warrant for the improvement through selection. However, the evaluation of these traits has provided the current state of litter performance of Jakhrana goat which may be upgraded by managerial practices specially care and feeding of pregnant goats.

Artificial gynogenesis is an important method for accelerating the selective breeding of varieties and populations. In this study, ultraviolet-irradiated sperm of Common carp (Cyprinus carpio) was used to activate the mature eggs of mrigal carp (Cirrhinus mrigala, MC), after cold shock at 4–8 °C for 16 min to double the chromosomes, a population of gynogenetic mrigal carp (GMC) was obtained. The fertilization rate, hatching rate and survival rate of GMC exceeded 62.2%, 6.3% and 2.9%, respectively. Comparative analyses of morphological traits, DNA content, chromosome numbers and 5S rDNA sequences showed no significant differences between MC and GMC. However, microsatellite (MFW1, CCA15) analysis revealed that paternal DNA fragments were inserted and a parent DNA fragment was deleted in the GMC. The GMC population survived the natural winter for more than 50 days with a temperature below 10 °C, while all the normal MC individuals perished. In addition, lower critical thermal minimum (CTMin) and lethal temperature (T_LD50) values were detected in GMC than that in MC. Our results indicated that the artificial gynogenesis method improved the cold tolerance of mrigal carp. The results of this study are of great significance for fish breeding and application.