Development Of The Microsatellite And Genetic Structure Of Scylla Paramamosain Population

Scylla paramamosain, which is of great commercial importance, is a valuable crab alongthe coast of China. However, the natural resource of S. paramamosain has been destroyed due todifferent reasons (e.g. over exploitation and pollution to its living environment).8polymorphismmicrosatellite loci have been developed in our study using magnetic bead hybridization method.And the genetic diversity and differentiation of S. paramamosain population have been analyzedby the eight microsatellite loci. The aim of our study is to provide scientific basis for thesustainable utilization and protection of S. paramamosain resource as well as its selectivebreeding.1. We used magnetic bead hybridization method to develop the microsatellite loci of S.paramamosain. The genomic DNA of S. paramamosain was extracted and digested withrestriction enzyme Mse1I. Fragments from500bp to1200bp were isolated and then washybridized with a biotin-labeled microsatellite probes (GT)15and (CT)15.The hybrid mixture wasincubated with magnetic beads coated with streptavidin. After washing to remove the non-SRSfragments, the eluted single-stranded DNA contains the selected microsatellite DNA. Theselected DNAs are then cloned into the pMD18-T vector. Positive clones in the enrichedgenomic DNA bank were screened out through PCR method and sequenced．In our study, weisolated350clones and selected130sequences, which length was above500bp, to design48pairs of primers. The analysis of the genetic diversity by8primer pairs indicated that number ofalleles per locus ranged from2to8, polymorphism information content ranged from0.239to0.841, the observed and expected heterozygosities ranged from0.3333to0.667and from0.2778to0.8589, respectively. The study also indicated that the polymorphism information content of8primer pairs were high and these primer pairs can be used in the population analysis.2. The genetic diversity and differentiation of ten wild S. paramamosain populations inChina were detected using eight pairs of microsatellite primers. High level of genetic diversitywas detected among the S. paramamosain populations. The mean number of alleles per locus (A)ranged from3.6250to4.5000, with an average of4.1111. And the mean effective number ofalleles per locus (Ae) ranged from2.3550to2.9611, with an average of2.6818. The average ofthe observed heterozygosities (Ho) was0.4215, ranging from0.3228to0.4859, and the averageof the expected heterozygosities (He) was0.5492, ranging from0.5042to0.6092. In general, thegenetic diversity among the ten populations was moderate. And the genetic differentiation among the ten populations was low. The genetic distance among the ten populations ranged from0.011to0.1983, the FSTvalues (FST) was0.0411. Based on the FSTvalues and the genetic distance, tenwild S. paramamosain populations clustered into two major groups, the hainan、fujian、guangdong and zhejiang populations belonged to one group, and the rest belonged to anothergroup.