| Widely spread in the tropical and subtropical regions of the Indian and westernPacific oceans, Atrina pectinata, is a kind of large fan-shaped bivalve. It is aneconomically important shellfish, belonged to Mollusca, Lamellibranchia, Pterimorphia,Mytiloida, Pinnidae. In this paper, the effects of weight traits on morphometrical traitswere first studied, then microsatellite markers were enriched by magnetic beads, at lastgenetic diversity in five groups of A. pectinata was studied.1. Seven morphometric traits and weight traits including shell length （SL）, width（SW）, height （SH）, live body weight （WG）, tissue weight （WT）, adductor muscle weight（WM） and Shell dip Angle （AG） were measured in101wild A. pectinata. Therelationships between these morphological traits （SL, SW, SH, SA） and weight traits（WG, WT and WM） were evaluated by correlation analysis at first. Path of traits ofA.pectinata were analyzed. SL, SW, SH and SA were used as independent variablesand WG, WT and WM were used as a dependent variable. The results showed thatcorrelation coefficients between morphometrical traits SL, SW, SH and WG, WT, WMwere very significant difference （P<0.01）. Shell height as a key effective factor hadpredominant direct effect and indirect effect on weight traits; Shell length and width hadsignificant indirect effect through shell height and slightly direct effect and on weighttraits, which is the secondary factor. The morphometric traits which have significantimpact on weight traits were used to establish the multiple regression equations of WG（Y=69.112SH+52.823SW-751.36）, WT （Y=38.485SW-472.912） and WM（Y=4.275SH-18.610）. The results provide a theoretical tool to measure the A.pectinata in aquaculture.2. With the characteristics of codominant, conservative, abundant polymorphism and rich information, microsatellite markers were widely used in animal genetics andbreeding, protection and utilization of genetic resources, etc. Through the effectiveanalysis of genetic diversity, however, its application in A. pectinata was less.3. As a simple and efficient method, isolation of microsatellite markers with theenrichment of magnetic beads is carried out for A. pectinata. The genomic DNA wasextracted and digested with restriction enzyme Mspâ… , and the reaction products wasligated with short linkers with enzyme T4. This genomic DNA was hybridized with abiotin-labeled microsatellite probe （AC）15, the hybrid mixture was incubated withmagnetic beads coated with streptavidin. After washing to remove the non-SSRfragments, the obtained single-stranded DNA contains the selected microsatellite loci.The selected DNAs were then amplified using primers designed complementary to thelinkers, cloned into the pMD18-T vector and transformed into competent E.coli TOP10.In this experiment,93positive clones were obtained, and contained66microsatelliteloci. In these microsatellite sequences,51were perfect repeat motifs （77.3%）,11wereimperfect （16.7%） and4were compound （about6.1%）. Except the biotin-labeled SSRprobes AC, there were microsatellites of TG, TC and GA repeats. In addition,32pairsof primers were composed and26of them screened the microsatellites, and21werepolymorphism within species.According to the above results,8microsatellite loci were used to analyze5groupsand a total of150individuals from the Penglai Bay, Wendeng Bay, Rizhao Bay,Zhanjiang Bay and Sanya Bay. We mainly analyzed effective number of alleles,heterozygosity and the polymorphism information. A total of41alleles were detectedand observed, effective number of alleles varied from1.6590to6.1205, PIC of eachgroup varied from0.4162to0.5017, expected and observed heterozygosity varied from0.4162to0.5817and from0.2512to0.4195. The Fst value between groups variedfrom0.0292to0.2805, the genetic distance is minimum between Zhanjiang Bay andSanya Bay and maximum between Penglai Bay and Zhanjiang Bay. UPGMA clusteron the basis of genetic distance was developed at last. |
