Programmed Death of Escherichia coli after UV Radiation
It is known that unicellular organisms are able to perpetuate themselves indefinitely. Under unfavorable conditions, however, they can meet their biological end-point. This end-point, i.e. cell death, is usually thought to be the result of passive “wearing out” processes. Senescence and death of human fibroblasts in vitro 1‚2 and even biological aging of higher organisms are also ascribed to such processes. It is assumed that errors in protein and DNA synthesis passively accumulate to the point where, due to impaired cell functions, death ensues 3‚4. In marked contrast to this,our recent results 5‚6 indicate that death of Escherichia coli cells after UV radiation might be an active “self-destruct” program.
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