Glycogen content relative to expression of glycogen phosphorylase (GPH) and hexokinase (HK) during the reproductive cycle in the Fujian Oyster, Crassostrea angulata

Abstract

Glycogen, a polymer of glucose, is an important means of storing energy. It is degraded by glycogen phosphorylase (GPH) and hexokinase (HK), glycogen phosphorylase, and hexokinase cDNAs (Ca-GPH and Ca-HK, respectively), which encode the primary enzymes involved in glycogen use, cloned and characterized and used to investigate the regulation of glycogen metabolism at the mRNA level in Crassostrea angulata. Their expression profiles were examined in different tissues and during different reproductive stages. Full-length cDNA of GPH was 3 078 bp in length with a 2 607 bp open reading frame (ORF) predicted to encode a protein of 868 amino acids (aa). The full-length HK cDNA was 3 088 bp long, with an ORF of 1 433 bp, predicted to encode a protein of 505 aa. Expression levels of both genes were found to be significantly higher in the gonads and adductor muscle than in the mantle, gill, and visceral mass. They were especially high in the adductor muscle, which suggested that these oysters can use glycogen to produce a readily available supply of glucose to support adductor muscle activity. The regulation of both genes was also found to be correlated with glycogen content via qRT-PCR and in situ hybridization and was dependent upon the stage of the reproductive cycle (initiation, maturation, ripeness). In this way, it appears that the expression of Ca-GPH and Ca-HK is driven by the reproductive cycle of the oyster, reflecting the central role played by glycogen in energy use and gametogenic development in C. angulata. It is here suggested that Ca-GPH and Ca-HK can be used as useful molecular markers for identifying the stages of glycogen metabolism and reproduction in C. angulata.Citation: Zeng Zhen, Ni Jianbin, Ke Caihuan. 2015. Glycogen content relative to expression of glycogen phosphorylase (GPH) and hexokinase (HK) during the reproductive cycle in the Fujian Oyster, Crassostrea angulata. Acta Oceanologica Sinica, 34(6): 66-76,

Characterization, fluctuation and tissue differences in nutrient content in the Pacific oyster ( Crassostrea gigas ) in Qingdao, northern China

“…GSK and PBK expression patterns were nearly the same as those for GP and GDE, which may reflect their regulatory function of glycogen metabolism. Hexokinase and GLUT expression was consistent with that of GS, which provides glycogen synthesis precursors (Martínez‐Quintana & Yepiz‐Plascencia, ; Zeng, Ni, & Ke, ). Pyruvate kinase, PFK and PGK in the glycolysis pathway had similar expression patterns as those for GP and GDE, which may reflect their whereabouts after glycogen decomposition.…”

Comparison of the Biochemical Composition and Nutritional Quality Between Diploid and Triploid Hong Kong Oysters, Crassostrea hongkongensis

“…Gametogenesis in triploids is retarded in the reproductive season, since triploid oysters have poorly developed gonads compared to diploids. According to previous studies on diploid Tapes philippinarum (Shpigel and Spencer, 1996 ), Crassostrea gigas (Soudant et al, 1999 ; Dridi et al, 2007 ; Pogoda et al, 2013 ), Ostrea edulis (Houcke et al, 2016 ), and Crassostrea virginica (Zeng et al, 2015 ), large changes in biochemical composition occur in response to gonad development.…”

“…Glycogen is the main molecular contributor to flavor quality in bivalves (Berthelin et al, 2000b ; Racotta et al, 2008 ; Zhang et al, 2015 ). Glycogen content decreased is strongly linked with gonad development and gametogenesis in C. gigas (Berthelin et al, 2000b ; Zeng et al, 2015 ). Various studies have confirmed glycogen synthesis and glycogen degradation can be altered by changes of the glycogen synthesis gene ( Ch GS) and glycogen phosphorylase gene ( Ch GP) (Greiwe et al, 1999 ; Bacca et al, 2005 ; Dridi et al, 2007 ).…”

A proteomic insight into vitellogenesis during tick ovary maturation

“…This is consistent with the dynamic of the final stages of oocyte maturation, which requires different compounds such as fatty acids, amino acids, electrolytes, purines and pyrimidines, and other metabolites 49 . Regarding metabolites, glucose, glycogen, lipids, and pyruvate were also observed by many authors in different arthropods 51 – 53 . Furthermore, carbohydrates facilitate oocyte maturation and developmental competence after fertilisation in mammals 49 , 54 , and are important for embryonic development in arthropods 55 , suggesting a highly conserved link between carbohydrate metabolism and oocyte development.…”