Metabolism response of fasting in Octopus sinensis paralarvae revealed by RNA-seq

Abstract

The limited knowledge regarding the nutritional physiology in East Asian common octopus (Octopus sinensis) during the early stages of their life has been hampering their large-scale industrial farming. Especially, inadequate nutrition is considered the primary cause for low paralarvae survival and growth. In order to study the metabolic molecular mechanism in the early stages of larval, transcriptomes of O. sinensis paralarvae in the fasting group were profiled by RNA-seq. A total of 42,824,129 clean reads were generated through Illumina sequencing and assembled into 72,379 unigenes. 10,415 unigenes were matched to the KEGG database significantly and 160 unigenes of them were assigned to the glycolysis/gluconeogenesis, fat digestion and absorption, protein processing in the endoplasmic reticulum, and citrate cycle (TCA cycle) signaling pathway, which was related to metabolism function. The results of the expression of 37 unigenes, which were measured by qRT-PCR proved that the transcriptome data were accurate. The responses of the metabolic-related genes demonstrated that there were sequential transition stages to metabolic in response to fasting in cephalopods that resemble the responses of fasting in vertebrate animals, in which a mix of fuels (amino acids, carbohydrates, lipids) was used at the early phase, then heavy reliance upon lipid-based fuels and carbohydrates are conserved, and protein fuels become the primary fuel as a last resort following starvation extends. The findings of this study can provide a deeper insight into the molecular mechanism of fasting in the O. sinensis hatchlings, which may be helpful for the East Asian common octopus aquaculture to overcome the obstacles of high mortality due to inadequate nutrition. Meanwhile, the transcriptome data obtained in this study provide valuable genetic resources for the study of metabolic function genes of cephalopods.