Mutation is a primary source of genetic variation that is used to power evolution.Many studies,however,have shown that most mutations are deleterious and,as a result,extremely low mutation rates might be benefcial for...Mutation is a primary source of genetic variation that is used to power evolution.Many studies,however,have shown that most mutations are deleterious and,as a result,extremely low mutation rates might be benefcial for survival.Using a mutation accumulation experiment,an unbiased method for mutation study,we found an extremely low base-substitution mutation rate of 5.94×10^(-11) per nucleotide site per cell division(95%Poisson confdence intervals:4.65×10^(-11),7.48×10^(-11))and indel mutation rate of 8.25×10^(-12) per site per cell division(95%confdence intervals:3.96×10^(-12),1.52×10^(-11))in the bacterium Photorhabdus luminescens ATCC29999.The mutations are strongly A/T-biased with a mutation bias of 10.28 in the A/T direction.It has been hypothesized that the ability for selection to lower mutation rates is inversely proportional to the efective population size(drift-barrier hypothesis)and we found that the efective population size of this bacterium is signifcantly greater than most other bacteria.This fnding further decreases the lower-bounds of bacterial mutation rates and provides evidence that extreme levels of replication fdelity can evolve within organisms that maintain large efective population sizes.展开更多
基金This work is supported by the Young Taishan Scholars Program of Shandong Province(tsqn201812024)the Fundamental Research Funds for the Central Universities of China(201822020)to H.L.+1 种基金the Multidisciplinary University Research Initiative Award from the US Army Research Ofce(W911NF-09-1-0444 and W911NF-09-1-0411)National Institutes of Health award(R35-GM122566)to M.L.
文摘Mutation is a primary source of genetic variation that is used to power evolution.Many studies,however,have shown that most mutations are deleterious and,as a result,extremely low mutation rates might be benefcial for survival.Using a mutation accumulation experiment,an unbiased method for mutation study,we found an extremely low base-substitution mutation rate of 5.94×10^(-11) per nucleotide site per cell division(95%Poisson confdence intervals:4.65×10^(-11),7.48×10^(-11))and indel mutation rate of 8.25×10^(-12) per site per cell division(95%confdence intervals:3.96×10^(-12),1.52×10^(-11))in the bacterium Photorhabdus luminescens ATCC29999.The mutations are strongly A/T-biased with a mutation bias of 10.28 in the A/T direction.It has been hypothesized that the ability for selection to lower mutation rates is inversely proportional to the efective population size(drift-barrier hypothesis)and we found that the efective population size of this bacterium is signifcantly greater than most other bacteria.This fnding further decreases the lower-bounds of bacterial mutation rates and provides evidence that extreme levels of replication fdelity can evolve within organisms that maintain large efective population sizes.
