| Sinonovacula constricta is one of the large-scale seafood economic shellfish in China,it has important nutritional value.In recent years,S.constricta culture industry has developed rapidly with the goal of pursuing high yields,but less consideration has been given to nutritional quality,which has failed to meet market demand.Glycogen,protein and fat are the important nutrients of the razor clam,among which glycogen affects the growth,development and taste.Studying the genes related to glycogen metabolism of the razor clam is of great significance to carry out genetic improvement genetic breeding and promote the sustainable and healthy development of its breeding industry.In this study,the annual variation of glycogen content of the razor clam was detected.The full-length c DNA sequences of glycogen synthase gene(Sc-GYS)and glycogen phosphorylase gene(Sc-GPH)of the razor clam were cloned by race technology,and the expression differences in different tissues and months were analyzed.The SNP loci related to glycogen content and growth traits were further screened.This experiment can provide a candidate marker for genetic improvement in glycogen content of this species.The main results are as follows:(1)The change of glycogen content of different tissues showed that the glycogen content in foot and mantle was significantly higher than that in other tissues(P<0.05).The change of glycogen content in soft part,foot and mantle of S.constricta showed that the glycogen content was higher from February to June,reached the maximum in April,decreased gradually after June,and reached the minimum in October.The total length of the Sc-GYS gene are 2 402 bp,ORF is 2 136 bp,encoding 711 amino acids.The results of fluorescence quantitative PCR showed that the expression of Sc-GYS gene was mainly expressed in the mantle and foot tissues.The expression level in different months was consistent with the annual change of glycogen content.The expression level in April was significantly higher than that in other months(P<0.01),Indicating that the gene was closely related to glycogen synthesis.Two SNP locirelated to glycogen content were screened for the exons of Sc-GYS gene.(2)(2)The total length of Sc-GPH gene are 3 963 bp,ORF is 2 541 bp,encoding846 amino acids.The results of q PCR showed that the expression of Sc-GPH gene was found in all tissues,of which the expression content in mantle and foot tissues was the highest,which was related to the ability to store and use glycogen;in different months,the expression level of Sc-GPH in mantles and foot gradually increased from February to August,when the glycogen content decreased,indicating that the expression of Sc-GPH was caused by S.constricta The driving force of reproductive cycle.Four SNP loci related to glycogen content were screened for the cod region of Sc-GPH gene of YL1 strain.Among them,c.930T>C was verified in TZ population,which provided a candidate marker for genetic improvement in glycogen content of S.constricta.(3)The correlation analysis of glycogen content and growth characters(shell height,shell length,shell width,total weight and soft part weight)of YL1 and TZ population of S.constricta showed that glycogen content of two populations was significantly correlated with shell length,soft weight and shell weight(P<0.05).The results showed that c.248C>T locus was significantly related to the total weight,soft weight and shell weight of the clam(P<0.05);c.260C>G locus was significantly related to the growth(P<0.05);c.839T>C locus was significantly related to the shell length,total weight,soft weight and shell weight.The homozygous of S.constricta was significantly lower than that of heterozygous individuals(P<0.05).The correlation analysis of Sc-GPH gene polymorphism and growth traits in two populations showed that the total weight of GG at c.420 G >A locus was significantly lower than that of GA(P<0.05);the soft weight of TT at c.867T>A and c.1284T>A locus was significantly higher than that of TA(P <0.05). |
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