| Spotted scat, Scatophagus argus, is a commercially important marine fish, which hashigh ornamental and edible value. Because the growth rate in female S.argus is significa--ntly faster than that in males, the isolation of sex-specific molecular marker, as well as subsequently all-female culture is particularly important in study. Recently, germplasm resources of S.argus degenerated continually with the worsening of environm-ent, and the evaluation of genetic diversity in S.argus would provide theoretical reference for scientific protection policy.In this study, S.argus is selected as our experiental animal. Methods of SSR, AFLP,and SRAP were selected to screen the sex-specific molecular marker, and to analysis the male and female population genetic diversity. The main results are as follows:1. The isolation of sex-specific SSR marker and the analysis of genetic structure between males and females S.argusSixty-five microsatellite sequences were obtained by the magnetic-bead enrichment method, and 45 pairs of primers based on the microsatellite sequences were designed to screen the gene pools of male and female S.argus. Results showed that distinctive sex-specific bands could be amplified by primer SAS21 and SAS23, respectively. More samples of 30 males and 30 females were used to screen by these two pair primers. The percentage of sex-specific band occurred by primer SAS21 was 30% in female S.argus, but10% in males, while that by primer SAS23 was 10% in females, and 60% in males. Base on the 6 pairs SSR primers, the male and female population of S.argus’ s Nei’s gene diversity index H was 0.5342 and 0.5408, Shannon’s Information index was 0.962 and0.996, Polymorphism information content is 0.4708 and 0.4853, the Effective number of alleles was2.5954 and 2.6973, respectively in female and male S.argus.2. The isolation of sex-specific AFLP marker and the analysis of genetic structure between males and females S.argus144 primer-combinations were used to screen the gene pools of male and female of S.argus’ s, and obtained 5780 bands, showed that distinctive sex-specific bands could be amplified by primer E7M8、E1M3 and E2M8, respectively. More samples of 30 males and30 females were used to screen by these three pair primers. The percentage of sex-specific band occurred by primer E7M8 was 83.3% in female S.argus, but 40% in males, while thatby primer E1M3 was 100% in females, and 44% in males, by E2M2 was 41.1% in females,and 0 in males. Base on the 6 pairs AFLP primers-combination, the results show that the female was detected 51 polymorphic loci, the proportion of polymorphic loci was 29.48%,the male was detected 68 polymorphic loci, a higher percentage of polymorphic loci, was39.31%. The male and female population of S.argus’ s Nei’s gene diversity index H was0.1149 and 0.1465, Shannon’s Information index was 0.1682 and 0.2169, Polymorphism information content is 1.2034 and 1.252, the Effective number of alleles was 1.2034 and1.252.Besides The male and female individuals of S.argus’ similarity coefficient was0.8927-0.8927, the genetic distance was 0.1069-0.1069, shows that there is little differen-tiation between the male and female S.argus.3. The isolation of sex-specific SRAP marker and the analysis of genetic structure between males and females S.argus64 primer-combinations were used to screen the gene pools of male and female of S.argus’ s, and obtained 461 bands, and distinctive sex-specific bands could be amplified by primer Me4Em5.More samples of 30 males and 30 females were used to screen by the primer. The percentage of sex-specific band occurred by primer E7M8 was 96.7% in female S.argus, but 30% in males. Base on the 3 pairs AFLP primers-combination,The male and female population of S.argus’ s Nei’s gene diversity index H was 0.3585 and0.3984, Shannon’s Information index was 0.5269 and 0.5757, Polymorphism information content is 0.28482 and 0.30935, the Effective number of alleles was 1.616 and 1.703. The male and female population of S.argus’ s genetic distance and similarity coefficient was0.1329 and 0.8756.4. Methods of SSR, AFLP, and SRAP were selected to screen the sex-specific molecular marker.Methods of SSR, AFLP, and SRAP were selected to screen the S.argus’ s sex-specific molecular marker, not found gender marker, but found the 85.7 percentage of sex-specific band occurred by SSR primer SAS23 maybe male of S.argus, the 100 percentage of sex-specific band occurred by AFLP primer E2M8 maybe male of S.argus. Another with the same three kinds of molecular markers analysised the male and female population of S.argus’ s genetic diversity, the results show that three kinds of molecular markers SSR、AFLP 、 SRAP technology results had consistency, the S.argus population have a low genetic diversity, and there is little genetic variation between male and female, But the male’s genetic diversity is higher than the female of S.argus, and the S.argus’ s breeding potential is smaller. |
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