Mochizuki Atsushi, Yahara Koji, Kobayashi Ichizo, Iwasa Yoh
National Institute for Basic Biology, Okazaki, Japan.
Genetics. 2006 Feb;172(2):1309-23. doi: 10.1534/genetics.105.042895. Epub 2005 Nov 19.
The evolution and maintenance of the phenomenon of postsegregational host killing or genetic addiction are paradoxical. In this phenomenon, a gene complex, once established in a genome, programs death of a host cell that has eliminated it. The intact form of the gene complex would survive in other members of the host population. It is controversial as to why these genetic elements are maintained, due to the lethal effects of host killing, or perhaps some other properties are beneficial to the host. We analyzed their population dynamics by analytical methods and computer simulations. Genetic addiction turned out to be advantageous to the gene complex in the presence of a competitor genetic element. The advantage is, however, limited in a population without spatial structure, such as that in a well-mixed liquid culture. In contrast, in a structured habitat, such as the surface of a solid medium, the addiction gene complex can increase in frequency, irrespective of its initial density. Our demonstration that genomes can evolve through acquisition of addiction genes has implications for the general question of how a genome can evolve as a community of potentially selfish genes.
分离后宿主杀伤或遗传成瘾现象的进化与维持是自相矛盾的。在这种现象中，一个基因复合体一旦在基因组中确立，就会致使已经清除它的宿主细胞死亡。该基因复合体的完整形式会在宿主群体的其他成员中存活下来。关于为何这些遗传元件得以维持存在争议，因为宿主杀伤具有致死效应，或者也许是某些其他特性对宿主有益。我们通过分析方法和计算机模拟对它们的种群动态进行了分析。结果表明，在存在竞争遗传元件的情况下，遗传成瘾对基因复合体是有利的。然而，在没有空间结构的种群中，比如在充分混合的液体培养物中，这种优势是有限的。相比之下，在结构化的栖息地中，比如固体培养基表面，成瘾基因复合体的频率可以增加，而与它的初始密度无关。我们证明基因组可以通过获得成瘾基因而进化，这对于基因组如何作为一个潜在自私基因的群落而进化这一普遍问题具有启示意义。
