酶的基因剂量效应及其对鱼类远缘杂交的影响

亲缘关系较远的杂种二倍体，酶的表达出现父本基因受抑制，双亲基因表达迟缓和母本基因提前表达三种类型的紊乱。由于双亲等位基因不亲和，各等位基因只调控产生1／2的基因产物，从而致使胚胎出现“双单倍体综合症”而在孵化期全部死亡。远缘杂交三倍体由于母本基因剂量加倍，一方面抑制了父本基因的表达，消除了不协调基因活动的干扰，另一方面母本基因产物趋于正常，代谢得以正常进行，杂种后代能成活并正常生长。

EFFECT OF ENZYMIC GENE DOSAGE ON THE DISTANT HYBRIDIZATION OF FISHES

Three kinds of abnormal isozymic expression, paternal allele being inhibited,delay in parental gene activations and preferential gene expression of the maternal allele, occur in diploid hybrids between distant parents. Since the incompatibility between two parental alleles, and every allele only controls the half amount of product of gene, the hybrid embryos all appear "double haploid" syndrome and die in the hatching period. In the triploid distant hybrids which obtained two maternal genomes, the insufficient dosage of gene was compensated by the maternal double alleles and the disturbances of spatial and temperal expressions of paternal heterogenetic alleles are possibly inhibited by double maternal alleles. As a results, the normal metabolism and development occur and the triploid hybrid embryos can pass hatching period and grow into adults.