How The Grass Carp Went Vegetarian

The draft genome suggests that differences in the mevalonate pathway and steroid biosynthesis in liver aided the grass carp’s transition from a carnivorous to a herbivorous diet.

AsianScientist (May 13, 2015) – As one of the most important freshwater aquaculture species in the world, grass carp make up 16 percent of the world’s cultured fish. China is the world’s largest grass carp culturing country; in fact, the majority of the freshwater species cultivated in China fall under the Cyprinidae family to which grass carp belong.

Now, three teams led by Professors Zhu Zuoyan, Wang Yapping and Han Bin from the Chinese Academy of Sciences, as well as Professor Lin HaoRan at the Sun Yat-sen University report the draft genome of the grass carp (Ctenopharyngodon idellus). Their work has been published in the journal Nature Genetics.

Using a whole-genome shotgun sequencing strategy and improved de novo Phusion-meta assembly methods, Wang and his colleagues generated a 0.9 gigabyte (GB) draft genome of a gynogenetic female adult and a 1.07 GB genome of a wild male adult.

Gene annotation identified 27,263 protein-coding genes in the female genome. Comparative genomics analyses demonstrated that zebrafish and grass carp share a similar genomic evolutionary history. The divergence between grass carp and zebrafish is estimated to have occurred 49-54 million years ago.

More interestingly, Wang and his colleagues reveal that transcriptional activation of the mevalonate pathway and steroid biosynthesis in liver is likely associated with the grass carp’s adaptation from a carnivorous to an herbivorous diet.

“The genome sequence of Cyprinidae fish species will provide key technical support to understanding of important developmental characters and genetic improvement of breeding varieties,” says Han.

Meanwhile, it will also benefit the studies of genome evolution, sex determination and differentiation mechanism in fishes.

The article can be found at: Wang et al. (2015) The Draft Genome Of The Grass Carp (Ctenopharyngodon idellus) Provides Insights Into Its Evolution And Vegetarian Adaptation.

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Source: Shanghai Institutes for Biological Sciences.
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