合浦珠母贝二倍体、三倍体和非整倍体群体的基因杂合度与生长比较

COMPARISON OF HETEROZYGOSITY AND GROWTH BETWEEN DIPLOID,TRIPLOID AND ANEUPLOID PEARL OYSTER PINCTADA MARTENSI (D.)

采用淀粉凝胶电泳方法对合浦珠母贝Pinctadamartensi(D.)雌性三倍体与雄性二倍体交配,细胞松弛素B抑制其受精卵第一极体释放产生的二倍体、三倍体及非整倍体3个群体进行了同工酶研究。二倍体、三倍体及非整倍体群体在6个多态位点的平均基因杂合度分别为0.255±0.087,0.286±0.097,0.275±0.089,三倍体的杂合度高出二倍体约12%,表明多倍体诱导能增加诱导群体的杂合度。但在单个位点上,三倍体的杂合度不一定高于二倍体;在各自群体内,平均杂合位点数与生长间无明显的相关性,单个位点上的杂合子也未完全表现出其生长大于纯合子,且差异不明显(p>0.05)。因此,合浦珠母贝三倍体的快速生长难以完全用杂合度增高假说解释,只能说明诱导处理能使三倍体的杂合度增高,而能量再分配和"巨型性"可能对其快速生长起着不可忽视的作用。非整倍体群体的杂合度高于二倍体群体,但其生长却小于二倍体,其原因可能是染色体的增减对机体的生长有一定的影响。

Eleven loci,such as Lap,Got,Pgm,Pgi,To,Xrd,Est1,Est2,Pt1,Pt2 and Pt3 in diploid (2n),triploid (3n) and aneuploid populations resulting from the group of 3ncrossing 2nby inhibiting the first polar body,were encoded by starch electrophoresis.The mean heterozygosities of 6 polymorphic loci in diploids,triploids and aneuploids were 0.255±0.087,0.286±0.097 and 0.275±0.089 respectively.The heterzygosity of triploid group was 12% higher than that of diploid group,which supported the statement that polyploid induction increases the heterozygosity in the polyploid group.But the heterozygosity of triploids was not always higher than that of diploids in all loci,it might be even lower than that of diploids in some loci,and no significant correlation was found evident between the growth and the number of heterozygosity loci.Also there was no significant difference of growth between homozygotes and heterozygotes at single locus.Therefore,the hypothesis of heterozygosity could not completely explain the phenomenon of the faster growth of triploid pearl oysters.The research results only demonstrated that polyploid induction could increase the heterozygosity in the polyploid individuals.Energy reallocation and polyploid gigantism may play an important role in leading to faster growth in triploid group.The heterozygosity of aneuploids was higher than that of diploids,but the body size and weight of aneuploids was smaller than that of diploids.The main reason was probably that the gain or loss of chromosomes had certain effects on the growth.