Transcriptome analysis of grass carp (Ctenopharyngodon idella) fed with animal and plant diets

• Grass carp fed with plant diet had significantly higher relative length of gut.
• 4435 differentially expressed genes were identified by transcriptome sequencing.
• The most representative pathway was digestion and metabolism.
• 71 differentially expressed genes with alternative splicing sites were identified.

Numerous studies have been focused on the replacement of fish meal by other alternative protein sources. However, little is currently known about the molecular mechanism of utilization of diets with different protein sources in fish. Grass carp is a typical herbivorous fish. To elucidate the relationship between gene expression and utilization of animal and plant diets, transcriptome sequencing was performed in grass carp fed with chironomid larvae and duckweed. Grass carp fed with duckweed had significantly higher relative length of gut than those fed with chironomid larvae. 4435 differentially expressed genes were identified between grass carp fed with chironomid larvae and duckweed in brain, liver and gut, involved in cell proliferation and differentiation, appetite control, circadian rhythm, digestion and metabolism pathways. These pathways might play important roles in utilization of diets with different protein sources in grass carp. And the findings could provide a new insight into the replacement of fish meal in artificial diets.