Breeuwer J A, Werren J H
Department of Biology, University of Rochester, New York 14627.
Nature. 1990 Aug 9;346(6284):558-60. doi: 10.1038/346558a0.
Microorganisms have been implicated in causing cytoplasmic incompatibility in a variety of insect species, including mosquitoes, fruitflies, beetles and wasps. The effect is typically unidirectional: incompatible crosses produce no progeny or sterile males, whereas the reciprocal crosses produce normal progeny. The parasitic wasp Nasonia vitripennis is one of the few species in which the cytogenetic mechanism of incompatibility is known. In this species the paternal chromosome set forms a tangled mass in a fertilized egg and is eventually lost. Here we report that cytoplasmic microorganisms are associated with complete bidirectional incompatibility between N. vitripennis and a closely related sympatric species, N. giraulti. Microorganisms can be seen in the eggs of both species. Hybrid offspring are normally not produced in crosses between the two species, but do occur after elimination of the microorganisms by antibiotic treatment. A cytogenetic and genetic study shows that bidirectional interspecific incompatibility is due to improper condensation of the paternal chromosomes. Microorganism-mediated reproductive isolation is of interest because it could provide a rapid mode of speciation. The mechanism of incompatibility in Nasonia is also of interest as a potential tool for studying chromosome imprinting and chromosome condensation.
微生物已被认为会在包括蚊子、果蝇、甲虫和黄蜂在内的多种昆虫物种中引发细胞质不亲和。这种效应通常是单向的：不亲和的杂交组合不会产生后代或产生不育雄性，而反交则会产生正常后代。寄生黄蜂丽蝇蛹集金小蜂是少数几种已知不亲和细胞遗传学机制的物种之一。在这个物种中，父本染色体组在受精卵中形成一团纠结物，最终丢失。我们在此报告，细胞质微生物与丽蝇蛹集金小蜂和一个密切相关的同域物种吉氏金小蜂之间的完全双向不亲和有关。在这两个物种的卵中都能看到微生物。这两个物种之间的杂交通常不会产生杂交后代，但在通过抗生素处理消除微生物后会产生。一项细胞遗传学和遗传学研究表明，双向种间不亲和是由于父本染色体的异常凝聚。微生物介导的生殖隔离很有意思，因为它可能提供一种快速的物种形成模式。丽蝇蛹集金小蜂中的不亲和机制作为研究染色体印记和染色体凝聚的潜在工具也很有意思。
