Reproduction Characteristics And Genetic Difference Of Black And Yellow Shell Color Of Clam Honze Lake River

Corbicula fluminea(C.fluminea)is one of the important benthic resources in Hongze Lake.In recent years,as the economic value of river clams improved continuously,the exploitation intensity of Corbicula fluminea in Hongze Lake has also increased year by year.There are serious problems in natural Corbicula fluminea in lakes,such as miniaturization of individuals,limitation of distribution area and exhaustion of resources.This study aims to provide theoretical support and guidance for resource conservation,sustainable development and utilization and genetic research of C.fluminea by analyzing the biological characteristics of Hongze Lake C.fluminea.and the genetic differences between black river clams and yellow river clams.1.The main results are as follows: C.fluminea in Hongze Lake is mainly hermaphrodite and a few are dioecious.The annual gonadal development can be divided into six periods: increment period,growth period,maturity stage,discharge period,recovery period and resting period.There are two main reproductive periods in a year for Corbicula fluminea,and the peak reproductive period is concentrated in SeptemberOctober.2.The full-length mitochondrial sequencing of two species of Corbicula fluminea were completed.Among them,C.fluminea B is 17,293 BP in length.It contains 13 coding protein genes(nd2,cox3,cox1,cox 2,cob,atp8,nd4,atp6,nd4,nd3,nd1,nd5,nd6,nd4l).The initial codons used by cox3,nd4,nd3 and nd4 l are ATA,atp6,nd6,nd2 and cytb are ATG.And the rest are ATT.It also contains 22 transporting RNAs and 2 ribosomal RNAs—rrnS(868 bp)and rrnL(1011 bp).C.fluminea Y is 17,068 BP in length.It contains 13 coding protein genes(cox1,cox1,cox2,cob,atp8,nad4,atp6,nad3,nad1,nad5,nad6,nad4 l,nad2,cox3).The initial codons used by cob,nad4 and nad4 l are ATA,atp6,nad6,nad2 and cox3 are ATG.And the rest are ATT.It also contains 22 transporting RNAs and 2 ribosomal RNAs(12rRNA and 16srRNA).12 S rRNA(rrnS)gene length is 869 bp,located between trnT and trnM genes,16 S rRNA(rrnL)gene length is 1,238 bp,located between cob and atp8 genes.The COI gene of C.fluminea B has a specific extension at the 5'end,which leads to the increase of amino acid polymorphism,while the COII gene polymorphism is low and the evolution is conservative.NJ evolutionary tree showed that there were some genetic differences between C.fluminea B and C.fluminea Y.The genetic distance between C.fluminea B and C.fluminea Y based on COI gene is 0.005,and that based on COII gene is 0.046,which is greater than that between C.fluminea B and other two Corbicula families.According to the available data,it can be inferred that C.fluminea B and C.fluminea Y may belong to different species of corbicidae.3.Six transcriptional libraries of C.fluminea were constructed and sequenced at a depth of 6G.A total of 461248698 transcripts and 184740303 unigene transcripts were obtained.The function annotation of unigene was carried out,and a total of 50191 unigene with functional annotation were obtained based on NR library.In the species comparison,the Pacific oyster had the highest homology,and the other invertebrates had the highest homology.The most enriched items in GO analysis were 758 cell processes,614 single organisms and 556 genes involved in metabolic processes.In addition,the top 10 functional groups with high enrichment level were stimulation response,cell localization,cell component tissue or origin,cell signal,multicellular biological process and development process.A total of 7730 genes have been enriched in KEGG database,mainly involving the first level—metabolism: the specific metabolic processes involved include sugar metabolism,energy metabolism,lipid metabolism,nucleic acid metabolism and amino acid metabolism.The analysis of differential gene expression showed that 941 unigenes were upregulated and 626 down-regulated in C.fluminea B.GO and KEGG analysis of differentially expressed genes showed that the most abundant pathway in GO enrichment was cell metabolism function in cell process,and in KEGG analysis,the most enriched pathway was cell metabolism.It contained amino acid metabolism(maximum),lipid metabolism,sugar metabolism,and the expression of unigene enriched in these pathways was up-regulated in C.fluminea B.In BP,cell processes(GO: 0009987),cell membranes(GO: 0016020)and catalytic activities(GO: 0003824)were the most abundant in CC and MF.The most obvious enrichment level was metabolic pathway,including amino acid metabolism,lipid metabolism and sugar metabolism.In these metabolic pathways,the enriched gene expression level was upregulated;in exogenous substance degradation metabolism,the enriched gene expression level was down-regulated.