Genetic improvement and genomic resources of important cyprinid species: status and future perspectives for sustainable production

Cyprinid species are the most cultured aquatic species around the world in terms of quantity and total value. They account for 25% of global aquaculture production and significantly contribute to fulfilling the demand for fish food. The aquaculture of these species is facing severe concerns in terms of seed quality, rising feed costs, disease outbreaks, introgression of exotic species, environmental impacts, and anthropogenic activities. Numerous researchers have explored biological issues and potential methods to enhance cyprinid aquaculture. Selective breeding is extensively employed in cyprinid species to enhance specific traits like growth and disease resistance. In this context, we have discussed the efforts made to improve important cyprinid aquaculture practices through genetic and genomic approaches. The recent advances in DNA sequencing technologies and genomic tools have revolutionized the understanding of biological research. The generation of a complete genome and other genomic resources in cyprinid species has significantly strengthened molecular-level investigations into disease resistance, growth, reproduction, and adaptation to changing environments. We conducted a comprehensive review of genomic research in important cyprinid species, encompassing genome, transcriptome, proteome, metagenome, epigenome, etc. This review reveals that considerable data has been generated for cyprinid species. However, the seamless integration of this valuable data into genetic selection programs has yet to be achieved. In the upcoming years, genomic techniques, gene transfer, genome editing tools are expected to bring a paradigm shift in sustainable cyprinid aquaculture production. The comprehensive information presented here will offer insights for the cyprinid aquaculture research community

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Not AvailableSeveral options have been proposed for eradication of germ cells (GCs) in mammals such as treatment with cytotoxic drugs, irradiation, cold ischemia and hyperthermic treatment. Some of these methods have been also tried in fish but conditions for complete sterilisation of gonads have not been established. Here, we report the production of sterile adult common carp Cyprinus carpio in 10 weeks by the heat and chemical treatments. The cytotoxic drug busulfan (40 mg/kg) was intraperitoneally injected into the animals at 2-week intervals (5 doses in total), and they were maintained in water at 38 °C between Weeks 1 and 10. The effectiveness of the treatments was assessed using gonadal index, histology, and vasa gene expression. At the end of Week 10, very severe gonadal degeneration was observed in fish treated with the heat–chemical combination, and 100% of male and female fish were devoid of endogenous GCs. The average levels of vasa transcript were 0.01 ± 0.005 and 0.02 ± 0.016 for males and females, respectively. By contrast, high temperature alone caused minor gonadal degeneration and the gene transcript were 0.59 ± 0.131 for male and 0.62 ± 0.13 for female. In Week 20, after the recovery period of 10 weeks at 25 °C, the gonadal germ cell did not recover from the sterile condition in any of the sampled individuals. The change in colouration of gonads was an additional useful index of the degree of gonadal sterility.Not Availabl

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Not AvailableHere we report the full-length cDNA cloning and nutritional regulation of a putative Δ6 fatty acyl desaturase (Δ6 fads) gene from striped catfish, Pangasianodon hypophthalmus. The 5′ and 3′ RACE analysis revealed a cDNA sequence of 1896 base pairs (bp) comprising a 5′ UTR of 49 bp, 3′ UTR of 509 bp and an open reading frame (ORF) of 1338 bp specifying a protein of 445 amino acids. Bioinformatics analysis showed that the deduced peptide sequence included all the characteristic features of microsomal fatty acyl desaturases, including N-terminal cytochrome b5 domain containing the haem binding motif H-P-G-G, fatty acyl (FA) desaturase domain, three histidine boxes and transmembrane regions. P. hypophthalmus ∆6 desaturase peptide sequence shares high similarity with Pangasius larnaudii (95%) and Clarias macrocephalus (90%). The predicted secondary and tertiary protein structures revealed that desaturase protein contains mostly α-helix followed by random coils and strands. Tissue distribution analysis showed that Δ6 fads is mainly expressed in brain followed by liver, heart, gill and muscle. Since α-linolenic acid is a substrate for the Δ6 FADS enzyme, various concentrations of this fatty acid (0.5, 1, 1.5 and 2 g kg− 1) were administered to experimental fish through feed to find out its effect on the expression of Δ6 fads. Results showed that the liver Δ6 fads gene expression is up-regulated in fish fed with experimental diets (p < 0.05).Not Availabl

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Not AvailableHere we report the full-length cDNA cloning and nutritional regulation of a putative Δ6 fatty acyl desaturase (Δ6 fads) gene from striped catfish, Pangasianodon hypophthalmus. The 5′ and 3′ RACE analysis revealed a cDNA sequence of 1896 base pairs (bp) comprising a 5′ UTR of 49 bp, 3′ UTR of 509 bp and an open reading frame (ORF) of 1338 bp specifying a protein of 445 amino acids. Bioinformatics analysis showed that the deduced peptide sequence included all the characteristic features of microsomal fatty acyl desaturases, including N-terminal cytochrome b5 domain containing the haem binding motif H-P-G-G, fatty acyl (FA) desaturase domain, three histidine boxes and transmembrane regions. P. hypophthalmus ∆6 desaturase peptide sequence shares high similarity with Pangasius larnaudii (95%) and Clarias macrocephalus (90%). The predicted secondary and tertiary protein structures revealed that desaturase protein contains mostly α-helix followed by random coils and strands. Tissue distribution analysis showed that Δ6 fads is mainly expressed in brain followed by liver, heart, gill and muscle. Since α-linolenic acid is a substrate for the Δ6 FADS enzyme, various concentrations of this fatty acid (0.5, 1, 1.5 and 2 g kg− 1) were administered to experimental fish through feed to find out its effect on the expression of Δ6 fads. Results showed that the liver Δ6 fads gene expression is up-regulated in fish fed with experimental diets (p < 0.05).Not Availabl

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Not AvailableAlthough feed cost is the greatest concern in aquaculture, the inclusion of carbohydrates in the fish diet, and their assimilation, are still not well understood in aquaculture species. We identified molecular events that occur due to the inclusion of high carbohydrate levels in the diets of genetically improved ‘Jayanti rohu’ Labeo rohita. To reveal transcriptional changes in the liver of rohu, a feeding experiment was conducted with three doses of gelatinized starch (20% (control), 40%, and 60%). Transcriptome sequencing revealed totals of 15,232 (4464 up- and 4343 down-regulated) and 15,360 (4478 up- and 4171 down-regulated) di erentially expressed genes. Up-regulated transcripts associated with glucose metabolisms, such as hexokinase, PHK, glycogen synthase and PGK, were found in fish fed diets with high starch levels. Interestingly, a de novo lipogenesis mechanism was found to be enriched in the livers of treated fish due to up-regulated transcripts such as FAS, ACC , and PPAR . The insulin signaling pathways with enriched PPAR and mTOR were identified by Kyoto Encyclopedia of Genes and Genome (KEGG) as a result of high carbohydrates. This work revealed for the first time the atypical regulation transcripts associated with glucose metabolism and lipogenesis in the livers of Jayanti rohu due to the inclusion of high carbohydrate levels in the diet. This study also encourages the exploration of early nutritional programming for enhancing glucose e ciency in carp species, for sustainable and cost-e ective aquaculture production.Not Availabl