Whether youre baking bread or building an organism, the key to success is consistently adding ingredients in the correct order and in the right amounts, according to a new genetic2 study by University of Michigan researchers. Using the bakers yeast3 Saccharomyces cerevisiae, Patricia Wittkopp and her colleagues developed a novel way to disentangle the effects of random4 genetic mutations and natural selection on the evolution of gene1 expression. Their findings are scheduled for online publication in the journal Nature on March 16.These results tell us that the effects of mutations available for natural selection to act on can play a large role in how an organism evolves. The approach we developed allows us to test what those influences are and to better understand how evolution works, said Wittkopp, an associate professor in the U-M Department of Ecology and Evolutionary6 Biology and in the Department of Molecular7, Cellular8 and Developmental Biology.The first authors of the Nature paper are EEB graduate student Brian Metzger and former MCDB graduate student David Yuan.In their study, the U-M researchers used the TDH3 gene, which helps bakers yeast cells convert sugar into energy used for growth. To understand how different genetic mutations impact TDH3 expression, they systematically9 changed each of the DNA10 base pairs in a region of the gene known as the promoter, which controls the amount of the gene that is expressed.They created all of the different possible genetic mutations in this region and measured the change in gene expression caused by each mutation5.Surprisingly, we found that most mutations didnt change the average expression of TDH3 but instead changed how variable TDH3 expression was among genetically11 identical cells, Wittkopp said.It would be as if you changed the recipe for a loaf of bread in a way that didnt change the average quality of the bread but instead caused individual loaves to be unpredictably good or bad, Metzger said.
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1 gene n.遗传因子，基因 参考例句： A single gene may have many effects.单一基因可能具备非常多种效应。 The targeting of gene therapy has been paid close attention.其中基因治疗的靶向性是值得密切关注的问题之一。
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