Isolation Of Microsatellite Molecular Markers And Correlationanalysis With Growth Trait Of Silurus Lanzhouensis

Silurus lanzhouensis, known as the Yellow Catfish, which is the unique large-scale commercial fish in the upper reaches of the Yellow River. In recent decades, because of the water pollution, overfishing, water conservancy construction and other factors, the wild populations for Silurus lanzhouensis have recessed dramatically and attracted a lot of attentions of sociologist, conservation scientists and other conservative organizations in the world. Therefore, it’s necessary to seek an appropriate protective measure using molecular genetic markers to analysis genetic diversity, construct microsatellite genetic linkage mapping and analysis, solid foundation for resources conservation and give marker-assisted selection and quantitative trait loci location for Silurus lanzhouensis.The object of current study contains isolated microsatellites and analyzed the correlation growth in S. lanzhouensis, which can be summarized as the following:1. Isolation and characterization of genomic microsatellites library from S. lanzhouensis were carried out using a FIASCO(Fast Isolation by AFLP of Sequences Containing Repeats) method, which contained(AC)n,(AG)n,(ATC)n,(CAG)n,(AAAC)n,(AGAT)n and(GATA)n repeat units, respectively, and 326 of them contained microsatellites(Gen Bank Accession Number: KJ008462-KJ008582, KJ545973-KJ545998, KJ598088-KJ598120, KP280324-KP280469), the rates of positive colonies were 40.75%. According to Weber’s classification rules, perfect type 170(52.15%), imperfect repeat type 72(22.09%), and compound repeat type 84(25.76%). Most of the repeat numbers were ranged from 10 to 20, the proportion of below 30 times were 80.16%. The results indicated that magnetic beads enriched method was a good method for enhancing the efficiency of development of S. lanzhouensis genomic microsatellite markers library.2. Based on the public database Gen Bank, there were total 2002 ESTs(Expressed Sequence Tags)from Clariidae and Siluridea in Siluriformes screened for Silurus lanzhouensis microsatellites, 209 SSRs were mined from all ESTs with a frequency of 10.94%. Trinucleotide repeats EST-SSRs were dominant, accounting for 76(36.36%) in all SSRs, dinucleotide,tetranucleotide, pentanucleotide and hexanucleode accounting for 59(28.22%), 52(24.88%), 17(8.13%) and 5(2.41%), respectively. As well dinucleotide, trinucleotide and tetranucleotide repeat mainly on TG/CA, AAT/ATT/TAA/TTA/ATA/TAT and AAAC/GTTT and accounting for 32.79%, 47.37% and 24.53, respectively. The results indicated that isolate S.lanzhouensis EST-SSR markers screening from Clariidae and Siluridea ESTs sequences is a good method for enhancing the efficiency of isolating microsatellite DNAs.3. According to unique sequences flanking each motif, we designed 200 pairs of G-SSR and E-SSR primers, 57 polymorphic microsatellite markers were screened out. Using 57 pairs of these microsatellite markers, we analyzed genetic structures of 30 units from one population of Silurus lanzhouensis; the alleles were ranged from 2 to 9(average 3.965). The ranges of observed and expected heterozygosity were 0.097 to 0.7326(average 0.4601) and 0.0881 to 0.7298(average 0.4963), respectively and the polymorphic information content were ranged from 0.1148 to 0.7945(average 0.4426). The verification showed that perfect type of microsatellite polymorphism was significantly higher than imperfect repeat type and compound repeat type(P<0.01). This result suggested that S. lanzhouensis had rich genetic diversity and these 57 microsatellite markers will be benefit for the evaluation of genetic resource from S. lanzhouensis populations.4. Correlations of 57 microsatellite markers to analyzed on genotypic differences from an artificial breeding progenies in maximal weight group and minimal weight group of S. lanzhouensis with the SPSS 18.0 χ2-test, and 10 of these microsatellites were effect on body weight, length and height. Results uncovered SLsis10, SLsis26, SLsis46, SLsis76, SLsis89, SLsis112 and SLsis120 had significant impacts on body weight; SLsis2, SLsis3 and SLsis249 had a significant impact on body length(P<0.05, P<0.01), SLsis89 had significant on body weight and length(P<0.05, P<0.01), and the SLsis46, SLsis26 and SLsis120 had a significant on body weight, body length and body depth(P<0.05).