Whitt G S, Childers W F, Shaklee J B, Matsumoto J
Genetics. 1976 Jan;82(1):35-42. doi: 10.1093/genetics/82.1.35.
The purpose of the present investigation is to determine whether the two duplicated glucosephosphate isomerase (EC 5.3.1.9) loci Gpi-A and Gpi-B reside on the same chromosome in teleostean fishes. Interspecific sunfish hybrids were employed for the cross because of the different species-specific electrophoretic mobilities of the allelic isozymes at each GPI locus and because of their genomic compatibility. F1 sunfish hybrids, formed from a male warmouth (Lepomis gulosus) X female green sunfish (L. cyanellus) cross, were mated to form the F2 generation. The number of each of the nine different isozyme phenotypes, revealed by starch gel electrophoresis, was determined using 256 F2 individuals. The high frequency of recombinant phenotypes in the F2 generation indicated that the two GPI loci are not linked. An excess of F2 individuals heterozygous at both loci was observed and is interpreted as being caused by heterosis. The absence of linkage for the homologous loci encoding GPI subunits and for other multilocus isozyme systems is consistent with the postulate that the genomes of present-day vertebrates arose through one or more polyploidization events early in vertebrate evolution.
本研究的目的是确定在硬骨鱼类中,两个重复的葡萄糖磷酸异构酶(EC 5.3.1.9)基因座Gpi - A和Gpi - B是否位于同一条染色体上。由于每个GPI基因座上等位基因同工酶具有不同的物种特异性电泳迁移率,且它们的基因组具有兼容性,因此采用种间太阳鱼杂交种进行杂交。由雄性暖口太阳鱼(Lepomis gulosus)与雌性绿太阳鱼(L. cyanellus)杂交形成的F1代太阳鱼杂交种相互交配,产生F2代。利用256个F2个体,通过淀粉凝胶电泳确定了九种不同同工酶表型各自的数量。F2代中重组表型的高频率表明这两个GPI基因座没有连锁。观察到F2代中两个基因座均为杂合的个体过量,这被解释为杂种优势所致。编码GPI亚基的同源基因座以及其他多基因座同工酶系统不存在连锁,这与当今脊椎动物的基因组是在脊椎动物进化早期通过一次或多次多倍体化事件产生的假设相一致。