Tuyển tập các báo cáo nghiên cứu về sinh học được đăng trên tạp chí sinh học Journal of Biology đề tài: Environmental stresses can alleviate the average deleterious effect of mutationsi. | J. Biol. Journal of Biology BioMed Central Research article Open Access Environmental stresses can alleviate the average deleterious effect of mutations Roy Kishony and Stanislas Leibler Address Laboratory of Living Matter Rockefeller University 1230 York Avenue New York NY 10021 USA. Correspondence Stanislas Leibler. Published 29 May 2003 Received 13 December 2002 Revised 17 April 2003 Journal of Biology 2003 2 14 J Igy Accepted 2 May 2003 The electronic version of this article is the complete one and can be found online at http content 2 2 14 2003 Kishony and Leibler licensee BioMed Central Ltd. This is an Open Access article verbatim copying and redistribution of this article are permitted in all media for any purpose provided this notice is preserved along with the article s original URL. Abstract Background Fundamental questions in evolutionary genetics including the possible advantage of sexual reproduction depend critically on the effects of deleterious mutations on fitness. Limited existing experimental evidence suggests that on average such effects tend to be aggravated under environmental stresses consistent with the perception that stress diminishes the organism s ability to tolerate deleterious mutations. Here we ask whether there are also stresses with the opposite influence under which the organism becomes more tolerant to mutations. Results We developed a technique based on bioluminescence which allows accurate automated measurements of bacterial growth rates at very low cell densities. Using this system we measured growth rates of Escherichia coli mutants under a diverse set of environmental stresses. In contrast to the perception that stress always reduces the organism s ability to tolerate mutations our measurements identified stresses that do the opposite - that is despite decreasing wild-type growth they alleviate on average the effect of deleterious mutations. Conclusions Our results show a qualitative difference between various .
