| Tapes conspersus is one of the most important bottom mariculture mollusks for economic aquaculture in Southern China,and the aquaculture and consumption market is very broad.In this study,path analysis,correlation analysis,multiple regression analysis and other methods were used to explore the factors that affect the body weight of the different sizes of the T.conspersus.The ovary development,germ cell occurrence and ultrastructure were observed and studied by electron microscope technique and histological section in Beibu Gulf,Guangxi.RNA-Seq sequencing technology was used to sequence and analyze the male and female glands of T.conspersus,and some genes involved in sex determination and reproductive development were screened.The purpose of this study is to provide basic information on artificial seedlings and selection,reproductive biology,germ cell occurrence and sex determination mechanisms of T.conspersus.The results are as follows:1.Main factors affecting the body weight of T.conspersus with different sizes.In order to determine the relationship between the morphological traits and quality traits of different sizes of T.conspersus,this study aimed at the growth population of T.conspersus indoor medium cultivation stage,medium culture stage in the sea area,and sea area development stage.Shell length,shell width,shell height,and body weight were measured and analyzed.The results of correlation analysis showed that there were extremely significant correlations between the quantitative traits of different sizes of T.conspersus(P < 0.01).The results of path analysis showed that the influence of each morphological trait on body weight was different at each stage.The order of juvenile indoor medium culture stage was shell length > shell height > shell width.The order of juvenile sea area medium culture stage was shell length > shell width > shell height.In the sea area development stage is shell height > shell width > shell length.The changes of the quantitative traits of different sizes of T.conspersus on the path analysis results of body weight were consistent with the results of the coefficient of determination.2.Gonadal development,reproductive law and characteristics of T.conspersus.In order to understand the sperm ovary development,germ cell occurrence and ultrastructure of T.conspersus in the Beibu Gulf of Guangxi,the growth population of T.conspersus was observed by histology and electron microscope.Studies have shown that the development of the gonads of T.conspersus is a reproductive cycle,which is divided into proliferation stage,growth stage,maturity stage,discharge stage and rest stage.The peak breeding season is from November to the end of April of the following year.The male to female ratio is 1.22 : 1.The development of oocytes in T.conspersus can be divided into oogonia,primary oocytes,secondary oocytes,and mature eggs.Vitellogenesis of T.conspersus can be divided into the early stage of yolk synthesis,the stage of yolk synthesis,and the late stage of yolk synthesis.Sperm cell development of T.conspersus can be divided into spermatogonia stage,primary spermatocyte stage,secondary spermatocyte stage,spermatocyte stage and mature sperm stage.Mature sperm is composed of 3 parts,head,middle and tail.The head of sperm is conical,composed of nucleus and acrosome,and the acrosome is inverted "V" shape.The middle part is mainly composed of 5 circularly arranged mitochondria and 1 centriole complex.The 2 parts of the axoneme and the plasma membrane together constitute the tail.The cross-section of the doublet microtubule structure of the axoneme shows a "9+2" type,and a double-tailed structure can be observed in some sperm tails.3.Transcriptome analysis of sex determination and differentiation in the T.conspersus.In order to obtain genes related to sex determination and differentiation in T.conspersus,this study used RNA-Seq technology to analyze the testis and ovary.The results showed that the sex determination of T.conspersus was co-regulated by multiple genes and multiple pathways.In addition,this study also preliminary screened a number of genes related to sex determination and differentiation in T.conspersus,such as zglp1,foxl2,tssk1,spag6.In conclusion,this study explored the relationship between morphological traits and quality traits of the growth population,the development of gonads and germ cells,reproductive laws,sex determination and differentiation genes,which laid the foundation for large-scale artificial breeding and aquaculture of T.conspersus. |
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