| The Bohai Sea is the orgin of the whole northern marine fishery resources. With an area of about seventy-eight thousands square kilometers, the Bohai Sea is the primary spawning ground, nursing ground and also feeding ground of various economic fish species which inhabit the Yellow Sea and The Bohai Sea. There are more than 300 species of fish and the maximum annual catch accounted for almost 10 percent of the national total in history. Fishery resources of the Bohai Sea is of great significance for the development of Chinese marine fishery.However, since the 1980s, because of over-fishing, environment-deterioration and coastal sea-related project, the catching fishery of the Bohai Sea declines severely, ecological structure suffers serious damage and the biodiversity decreases dramatically. In order to better protect and make maximum use of fishery resources, molecular genetic analyses in some fishes with economic or ecological importance are necessary, which are also basic to studies on fish ecology, fishery resources and genetic breeding.This dissertation consists of three sections:The first one is construction of partly enriched-genomic libraries of Cynoglossus semilaevis, Paralichthys olivaceus, Navodon septentrionalis, Scomberomorus niphonius, Pseudosciaena polyactis, Hyporhamphus sajori and Sparus macrocephalus based on magnetic beads method. 131,202,121,33,23,60 and 35 microsatellite sequences is obtained separately through screening and sequencing. The perfect, imperfect and compound microsatellite sequences take up 76.80%,13.66% and 9.54% separately. The method of FIASCO modified in the present study is efficient and low-cost choice for the isolation of microsatellite in marine fish species. The second section is to analyze population genetic structure of three natural catched fish including Navodon septentrionalis, Johnius belengerii and Mugil soiuy. The microsatellite squences are selected from both enriched-genomic librarie and Genbank. The polymorphisms of markers are assessed with at least 21 individuals and the result showes the number ofallele ranges from 2 to 18. The values of He and Ho ranged from 0.1463 to 0.9449 and 0.1562 to 1.0000 with the average of 0.6437 and 0.5774, respectively. Among them, the average Ho of Johnius belengerii is the highest(0.8052) indicating a high level of heterozygosity.The last section is the application of the Half-Smooth Tongue Sole microsatellite markers in construction of genetic linkage map, male and female pupolation and the genotyping of progenies from gynogenetic technique:1. A full-sib family of tongue sole was constructed and used for the development of a genetic linkage. Parents and 84 Fl progeny are used as mapping population.306 pairs of SSR primers are used to detect the polymorphisms between parents. Checking the segregation profile of the mapping population,100 loci are found to be polymorphic among the parents and segregating in the progeny. However, Only more polymorphic markers and the high-density linkage map are obtained, can the molecular marker-assisted selection and quantitative trait loci(QTL) mapping be genuinely achieved.2. Eight polymorphic microsatellite makers are used to investigate 24 meio-gynogenetic progenies in Half-Smooth Tongue Sole. The result shows that 4 out of 8 loci are all heterozygous. Loci Newcyse105 has the lowest heterozygote proportion (0.5833). The average heterozygote proportion is 0.8665.The high proportion of heterozygotes for 8 loci demonstrates that it is not a practical method for producing homozygous inbred lines in the gynogenetic fish produced by retention the seeond polar body.3. Twenty-five polymorphic microsatellite markers are used for genetic analysis in female and male population, and female-special DNA fragment is detected in loci CSf1. |
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