远缘杂交形成的二倍体鱼和多倍体鱼生殖细胞染色体研究

CHROMOSOMAL STUDIES OF GERM CELLS IN DIPLOID AND POLYPLOID FISH PRODUCED BY DISTANT CROSSING

本文采用性腺染色体制片及组织学切片方法,系统地研究了不同发育时期的鲫鲤杂交第二代(F2)(2n=100)、异源四倍体鲫鲤(4n=200)、三倍体鲫鱼(3n=150))、雌核发育二倍体鲫鲤第二代(G2)(2n=100)及鲤鱼(CyprinuscarpioL)(2n=100)(对照组)生殖细胞的染色体特征。研究结果表明,对照组中鲤鱼精原细胞染色体数与体细胞染色体数一致,为二倍体精原细胞(2n=100),而远缘杂交形成的二倍体鱼和多倍体鱼的生殖细胞中则观察到明显的染色体数加倍现象,其中,鲫鲤杂交第二代(F2)精巢生殖细胞染色体数加倍现象特别丰富,占检测的染色体分裂相的21.6%,为其产生不减半的二倍体配子提供了直接的细胞学证据,同时也说明远缘杂交是导致生殖细胞染色体数加倍的一个重要因素。该研究在探讨多倍体鱼的发生及鱼类遗传育种方面具有重要意义。

By observing the chromosomal spreads of germ cells and tissue sections, we studied the chromosomal spreads of germ cells in diploid and polyploid fish produced by distant crossing. The samples covered the second generation of hybrids of red crucian carp （Carassius auratus red var.）（ ♀ ） × common carp （Cyprinus carpio） （ ♂ ）（2n=100）（F2）, allotetraploid hybrids of red crucian carp（ ♀ ） × common carp（ ♂ ）（4n=200）, triploid hybrids of gold fish（ ♀ ）× allotetraploid（ ♂ ）（3n=150）, the second generation of the gynogenetic progeny of allotetraploid hybrids（G2）（2n=100）, and the common carp（2n= 100） used as a control. The results demonstrated that chromosomal number of spermotogonia in common carp was equal to that of their somatic cell （2n=100）, while the chromosomal number of germ cells in diploid hybrid fish and polyploid hybrid fish had doubled obviously, and the frequent of chromosomal doubling in spermotogonia of F2 appeared especially high, accounting for 21.6% of all examined chromosomal spreads, which provided directly cytological evidence for the production of unreduced diploid gametes in F2 and also indicated that distant crossing was an important factor to lead to chromosomal doubling in germ cell. This research had important significance in studies on the formation of polyploidy fish and fish breeding.