牙鲆连续两代减数分裂雌核发育家系的遗传特征

对牙鲆(Paralichthys olivaceus)减数分裂雌核发育二倍体(Meio-G1)再次诱导减数分裂雌核发育,获得连续两代雌核发育二倍体家系(Meio-G2),以Meio-G1亲本与1尾普通牙鲆雄鱼人工授精获得的家系作为对照组(control)。利用15个微卫星标记对3个家系进行遗传特征分析。结果显示,15个微卫星位点在Meio-G1、Meio-G2和对照组3个家系中,分别扩增到30、28、50个等位基因,平均等位基因数为2.0、1.9、3.3,平均观测杂合度(Ho)分别为0.875 3、0.774 2、0.908 3,平均纯合度分别为0.124 7、0.221 5、0.091 7。3个家系个体间的平均遗传相似系数分别为0.891 7、0.923 8、0.520 2,亲代与子代之间的平均相似系数分别为0.916 6、0.930 4、0.560 3。高重组率的Poli9-8tuf、Poli18tuf、Poli107tuf 3个位点在Meio-G1和Meio-G2中观测杂合度均为1.0,低重组率的Poli33tuf、Poli24MHFS两个位点在Meio-G1和Meio-G2中均全部纯合,观测杂合度为0。结果表明,Meio-G2的纯合度、个体间平均相似系数以及亲子之间的平均相似度均略高于Meio-G1,显著高于对照组家系,证明连续两代诱导减数分裂雌核发育,能提高鱼类纯合度和遗传相似度,具有固定母本遗传性状的作用。

Analysis of homozygosity and genetic similarity between two successive generations in a meiogynogenetic Japanese flounder family

The artificial induction of gynogenesis is a form of chromosome manipulation that has several applica-tions,including the rapid establishment of inbred lines or strains.The technique offers a high degree of homozy-gosity,sex-control,and accelerated elimination of recessive deleterious genes from a cultured population.We produced two meiotic gynogenetic Japanese flounder(Paralichthys olivaceus) family lines: meio-G1(the first generation) and meio-G2(the second generation).We evaluated the efficacy of artificial meiotic gynogenesis for producing pure inbred lines by quantifying the homozygosity and genetic similarity of meio-G1 and meio-G2 us-ing microsatellite markers The average homozygosity among 15 loci was 0.124 7 for meio-G1 and 0.221 5 for meio-G2,which was higher than that in the natural mating family(0.091 7).The average similarity indices among individuals within meio-G1 and meio-G2 were 0.891 7 and 0.923 8,which were higher than within the natural mating family(0.5603).The average similarity in meio-G2 was slightly higher than in meio-G1.The observed heterozygosity in meio-G1 and meio-G2 was 1 at the Poli9-8tuf,Poli18tuf,Poli107tuf loci,all of which were lo-cated at some distance from the centromere(i.e.,had high recombination frequencies).The loci(Poli33tuf,Po-li24MHFS) closest to the centromere(i.e.,with a low recombination frequency) were homozygous in meio-G1 and meio-G2.Our results suggest that artificially induced meiotic gynogenesis is an efficient method for inbreeding to purify the genome,increase genetic similarity,and fix maternal genetic traits in the Japanese flounder.The mei-ogynogenetic families cultured in our study may be used in further selective breeding research.