The Molecule And Genetic Analysis Of Inbreeding Depression In Bay Scallop (Argopecten Irradians)

The bay scallop(Argopecten irradians) is a simultaneous hermaphroditic marine bivalve with distinct male and female gonads, and external fertilization. Outbred, inbred and selfed-families standing for the different inbreeding level could be produced. In this study,10 microsatellites were used to check the segregating distortion in two outbred, two inbred and four selfed-families (3 selfed-families for one generation and 1 for two generation).The outbred families were found to have the most segregated markers, then were the selfed-families for one generation and the selfed-families for two generations, and the inbred families were found to have the least segregated markers. The homozygote deficiency was only found in the selfed-families and the three markers might be linked to the lethal genes.we also found that the homozygous rate of the two growth related loci is lower, it will provide some references for the genetic basis of inbreeding expression.Through the Gene expression profiles analysis of inbred and outcross families, we concluded that compared with inbred families, there are 1175 genes up-regulated and 1390 genes down-regulated respectively. From the component gene ontology terms points of view, the differentially expressed gene ontology are mainly concentrate on sarcomere, contractile filaments, cell periphery, cell membrane and cell junction, especially on cell membrane and cytoskeleton. From the function points of view, the GO are transferase, phosphotransferase, peptidase and so on.The most differentially expressed genes lie in muscle component, resistance and detoxification, oxidative phosphorylation, protein synthesis,sphingolipid metabolize and purine synthesis.The differentially expressed pathways are focus on the oxidative phosphorylation pathway and cell apoptosis pathway and which related to thermal resistance. Genes involved in the oxidative phosphorylation pathway are down-regulated such as NADH oxidation-reduction system, iron-sulfur protein, ubiquinone Q,cytochrome oxidation-reduction system, ATP synthetase;yet genes related to apoptosis pathway are all up-regulated except HSP90.These genes mainly are IKK, complement component C3,IAP,Caspase 9,Caspase 3 like protein,JNK,Fas,TNFR,TRAF, Caspase recruitment domain,hsp70,NF-kappaB,P53 et al. The third part of genes aremetastasis-associated protein, cystatin A, cathepsin L, Ras family GTP-binding protein non-selenium peroxidase, D-LDH, eIF-2B and so on. The DEGs were all verified by FQ-PCR in highly-inbred and outcross families and reached same result. In sum, the inbred bay scallop adapt himself to environment through up-regulating genes relate to resistance and down-regulating genes involve in metabolize.