Abstract:Foundamental Courses of Aquatic Products Science. Molecular cloning of hepatic glucose-6-phosphatase catalytic subunit from Erythroculter ilishaeformis: response of its expression to refeeding and carbohydrate in diet. Liver glucose-6-phosphatase(G6Pase, EC 3.1.3.9)，one of the key enzymes in the glycolysis and glyconeogenesis，plays a key role in blood glucose homeostasis by catalyzing the dephosphorylation of glucose-6-phosphate(Glu-6P) to glucose. RT-PCR and RACE(rapid amplification cDNA ends ) was used for the isolation of the full length cDNA of G6Pase gene from liver of Erythroculter ilishaeformis. The cDNA was 1913 bp containing the 49 bp 5′-untranslated region, 778 bp 3′-untranslated region and 1068 bp open reading frame, which encoded 355 amino acid with a predicted molecular weight of 39.89 ku. We compared the E.ilishaeformis alignment of deduced amino acid sequences of G6Pase cDNA with Danio rerio, Mus musculu, Canis familiaris, Homo sapiens, Xenopus laevis, Sparus aurata and Tetraodon nigroviridis. The score was 95%, 63%, 63%, 63%, 63%, 69 %, 55% and 76% respectively. E.ilishaeformi G6Pase also contained three conserved domains. To examine the relationship between dietary carbohydrate and G6Pase gene expression, we compared the G6Pase mRNA levels in different dietary with or without carbohydrate. Two groups of Erythroculter ilishaeformis were pair-fed for 8 weeks either a high protein without carbohydrate(63.38% protein,0 carbohydrate)or a low protein with carbohydrate (40.53%protein, 23.98%carbohydrate) diet. Real time RT-PCR was used to examine the levels of G6Pase mRNA in fasted and 3, 6, 12, 24 h after feeding in contrast to the different dietary. There was some increase in the level of G6Pase mRNA in dietary with and without carbohydrates at 12 h after feeding, which showed that refeeding affected the gene expression of G6Pase. Levels of G6Pase mRNA were 2-4 times in dietary with carbohydrate than those without carbohydrate at fasted and 3, 6, 12 h after feeding. These results showed that dietary carbohydrate can enhance the liver G6Pase gene expression. 21 Refs.In Chinese. Key words:RACE; G6Pase; carbohydrate; Erythroculter ilishaeformis; real time PCR TANG Yong-kai(Freshwater Fisheries Research Center, Chinese Academy of Fishery Sciences，Wuxi 214081, China) , YU Ju-hua, LIU Bo, GE Xian-ping //J Fish China,2007,31(1).45-53