筛选机制与细胞衰老的DNA损伤假说

生理界存在一类筛选机制，它将DNA损伤较小的细胞筛选出来，产生后代。主要有两类模式－机制1和机制2，分别以细菌和人的成纤维细胞为代表，那些具有筛选机制1的细胞（如：细菌、生殖细胞、癌细胞）能无限传代，而体细胞则不能。这两类筛选机制背后有更深刻的原因，而细胞2的癌变正是林合同制2退化为机制1的过程。

Selective Mechanisms and the DNA Injury Hypothesis of Cell Senescence

Selective mechanisms exist in organism and biosphere,which select the cells with less DNA injury and reproduces them . There are two models :Mechanisms 1 and Mechanisms 2,represented respectively by bacteria and mechanolytes of human beings.Cells with Mechanisms 1(e.g. bacteria, generative cells, cancer cells)can reproduce infinitely,while somatic cells can not.There are deep-going reasons behind the two categories of selective mechanisms.The canceration of the cells is a degenerating process from Mechanisms 2 to Mechanisms 1.