Effect of dietary carbohydrate on glycometabolism of juvenile golden pompano (Trachinotus ovatus) related to growth performance, hepatic histopathology, transcriptome profiles and identification of differentially expressed genes

A hepatic transcriptome was produced through the technology of RNA sequencing and short-read assembly in golden pompano Trachinotus ovatus fed with three experimental diets respectively containing low carbohydrate diet (LCD), intermediate carbohydrate diet (MCD), and high carbohydrate diet (HCD). In total, 57,217 unigenes were acquired in the current study, with average length 1182.24 bp. 21,920, 22,514 and 24,680 unigenes were acquired from LCD, MCD and HCD groups, respectively. There were 1513 differential expressed genes in LCD and MCD groups, with 676 up-and 837 down-regulated genes in LCD group; 2369 genes were differentially expressed between HCD vs MCD, containing 1397 up and 972 down-regulated genes in HCD group. 1686 differential expressed genes were observed in the comparison of HCD and LCD, containing 1044 up-and 642 down-regulated genes in HCD group. Some differential expressed genes, such as hexokinase-1-like isoform X3, pancreatic alpha -amylase-like, hexokinase-1-like isoform X1, ADP-dependent glucokinase isoform X2, fructose-bisphosphate aldolase A-like, and acetyl-CoA carboxylase isoform X8, were related to carbohydrate metabolism, indicating these genes in the golden pompano were in response to dietary carbohydrate. In this study, long-chain-fatty-acid-CoA ligase 5 was up-regulated in comparison of HCD_vs_MCD and HCD_vs_LCD, which indicated that FACL5 may be sensitive to high dietary carbohydrate. This result coincides with the pathological changes of hepatocyte morphology in the present study. The results of transcriptome analysis in this study were confirmed by RT-PCR in 14 randomly selected unigenes. This study may provide novel data and theoretical support on hepatic tran-scriptome information of the golden pompano, which is a vital resource for studies of bioinformatics in golden pompano. Besides, the present study identifies some pivotal genes related to dietary carbohydrate and lipid deposition, which will accumulate data on carbohydrate and/or lipid metabolism in marine fish species to support related research.