MICROSATELLITE ANALYSIS OF ARTIFICIAL GYNOGENESIS IN THE SCALLOP, CHLAM YS FARRER I

Zhikong scallop, Chlamys farreri,which is widely distributed along the coasts of North China, Korea, Japan andEastern Russia, is one of the commercially important fishery and aquaculture species in China.Compared with classical genetic methods, artificial gynogenesis has proved to be avaluable genetic tool for the rapid production of inbred lines, development of all female populations as well as for gene mapping.Microsatellite recently has become an extremely popularmarker in a wide variety of its genetic investigation1We used the genotyp ing data of five microsatellite loci to check the absence of any paternal contribution to the gynogenetic offsp ring genome, to estimate the MC recombination rate and to analyze the homozygous ratio in the induced gynogenetic dip loids.In this research, gynogenetic dip loid Chlamys farreriwere induced by inhibiting exclusion of the second polar bodywith 62DMAP in eggs fertilized with UV irradiated sperm1Five poly morphism microsatellite markerswere used to detect the genetic variations of 30 larvae in the gynogenetic familiesA,B andC, 40 larvae in their control group s and their parents1Two of the five microsatellite loci showed the existence of null allelesin two control group s1 In the 15 genotyp ic ratios observed (3 families ? loci), 13 genotyp ic ratioswere in accordance withMendelian expectations(p>01122).The remaining two genotypic ratios in family B at CFMSM020 and family C atCFMSM009 conformed to Mendelian expectations when null alleles were considered1The presence of null alleles was themajor problem ofmicrosatellite markers for population genetics studies in the Chlamys farreri1The results of the five micro2satellite analyses revealed the presence of male DNA in the three gynogenetic families, indicating they all derived from normal fertilization162DMAP treatment produced 7012% gynogenetic dip loids1Recombination was observed at the five polymorphicloci and the recombination rates between microsatellite locus and centromere ranged from 2617% to 5510%(4818% mean).The observed Recombination rates were often lower than the theoretical maximum 6710%.These resultsindicated that there was higher heterozygosity in the first meiogynogenetic generation of scallop, Chlamys farreri1The production of gynogenetic diploids provided a new way for genetic improvement of scallop culture and to get well2bred spe2cies1The homozygosity ratio of the offsp ring from the three familieswere 6410% , 5613% , 5711% , respectively and the average homozygous ratio was 5911% while that of the control group s were 215% 1The homozygous ratio was increased5616% by gynogenesis1This study shows that gynogenesis is an effective method to p romote gene purification1 Induced diploid gynogenesis has been recognized as apotential method to produce inbred line of Chlamys farreri rap idly.In addition,microsatellite analysis is an effective method for the verification of gynogenesis because of their codominant and highlypolymorphic nature.