Skulachev V P
Department of Bioenergetics, Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, 119899, Russia.
Biochemistry (Mosc). 1998 Nov;63(11):1335-43.
The concept formulated here presumes the existence of specific mechanisms of evolution that save intermediate (and therefore imperfect) forms of organisms from elimination by natural selection. A change in the life strategy made in situations when the appearance of a new trait worsens, rather than improves, adaptation of the organism to the changing environment can be one of these mechanisms. The concept postulates that, in such cases, K-strategy (relatively low rates of reproduction and activity in general but long life span) is replaced by r-strategy (high activity and reproduction but short life span). A decrease in the life span upon the K --> r transition is suggested to be an unavoidable consequence of an elevation of formation of toxic reactive oxygen species under conditions of increased rates of aerobic metabolism required for the increased life activity. The phenomenon of giantism of transgenic tobacco plants that overproduce a mitochondrial heat shock protein (experiments done by A. Moore) is assumed to be explained by an r --> K transition. On the other hand, a decrease in the life activity and a considerable increase in life span occurring in a nematode upon mutations inhibiting the CoQ biosynthesis (S. Hekimi) might serve as an example of a K --> r transition.
这里阐述的概念假定存在特定的进化机制，这些机制能使生物的中间（因而并不完美）形式免遭自然选择的淘汰。当新性状的出现恶化而非改善生物体对变化环境的适应时，在这种情况下做出的生活策略改变可能就是其中一种机制。该概念假定，在这种情况下，K策略（总体繁殖和活动速率相对较低，但寿命长）会被r策略（高活动和繁殖速率，但寿命短）所取代。K向r转变时寿命缩短被认为是在增加生命活动所需的有氧代谢速率提高的条件下，有毒活性氧生成增加的必然结果。过量产生线粒体热休克蛋白的转基因烟草植株出现巨型化现象（由A. 摩尔进行的实验）被认为可用r向K转变来解释。另一方面，线虫中抑制辅酶Q生物合成的突变导致生命活动减少和寿命大幅增加（S. 赫基米）可能是K向r转变的一个例子。
