Revealing Alteration in the Hepatic Glucose Metabolism of Genetically Improved Carp, Jayanti Rohu Labeo rohita Fed a High Carbohydrate Diet Using Transcriptome Sequencing.

Although 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) differentially 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, ACCα, and PPARγ. 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 efficiency in carp species, for sustainable and cost-effective aquaculture production.

Establishment of base population for selective breeding of catla (Catla catla) depending on phenotypic and microsatellite marker information.

The phenotypic and microsatellite marker information of nine strains of catla (Catla catla) for growth trait was used to infer relationship within and between strains. This information helped in optimizing the proportion of individuals to be used from each strain while creating a base population for selective breeding. For this purpose, nine strains were collected from different sources and places of India namely West Bengal, Bihar, Odisha, Andhra Pradesh and Uttar Pradesh. Two riverine sources i.e. Ganga and Subarnarekha were also represented among the nine strains collected for base population. They were brought to Indian Council of Agricultural Research-Central Institute of Freshwater Aquaculture (ICAR-CIFA) at fry stage and reared separately till fingerlings. After passive integrated transponder tagging fingerlings were stocked in three communal ponds for one year culture. Live body weights were then measured and least square means were obtained after pond effect correction. A wide range of variation was observed among and between strains. Microsatellite markers were used to estimate genetic differences of different strains of catla using pair wise F ST estimates. Overall multi locus F ST, including all loci was estimated to be 0.4137 (P < 0.05), indicating genetic heterogeneity among them. Analysis of molecular variance revealed that, 58.63% of variation was due to within individual variation, 3.45% of variation was due to among individuals within strain and 37.92% was due to among strain variations. Both phenotypic as well as microsatellite data will be used to form a base population of catla with individuals from the stock having broad genetic variation for selective breeding programme.

Heat and chemical treatments in adult Cyprinus carpio (Pisces cypriniformes) rapidly produce sterile gonads.

Several 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 (40mg/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.