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Life in the fast path of evolution



<div data-thumb = "https://3c1703fe8d.site.internapcdn.net/newman/csz/news/tmb/2019/5ce3bc144b7be.jpg" data-src = "https: //3c1703fe8d.site.internetcdn .net / newman / gfx / news / hires / 2019 / 5ce3bc144b7be.jpg "data-sub-html =" Hanseniaspora uvarum one of the budding yeast species that live without many genes is otherwise considered to be essential for Life. Credit: UC Davis, Department of Wine Growth and Enology ">

<img src = "https://3c1703fe8d.site.internapcdn.net/newman/csz/news/800/2019/5ce3bc144b7be.jpg" alt = "Life in the fast path of evolution" title = " Hanseniaspora uvarum one of the budding yeasts that live without many genes is otherwise considered essential for life. Credit: UC Davis, Ministry of Science and Enology "/>
Hanseniaspora uvarum one of the budding yeast species that live without many genes are otherwise considered to be crucial for life. Credit: UC Davis, Science and Enology

Most living things have a number of genes dedicated to repairing their DNA, limiting the rate at which their genomes change over time. But scientists at Vanderbilt and the University of Wisconsin-Madison have discovered an ancient genus of budding yeast that apparently has accumulated a remarkably high burden of mutations due to the unprecedented loss of dozens of genes involved in repairing DNA defects. and cell division, earlier thought to be crucial.


In a new study published May 21

in open access journal PLOS Biology graduate student Jacob L. Steenwyk, who works in the laboratory of Professor Antonis Rokas at the Department of Life Sciences at Vanderbilt University in Nashville, Tennessee, discovered that a group of budding yeasts in the genus Hanseniaspora closely related to baker's yeast Saccharomyces cerevisiae has lost a large number of genes related to cell cycle and DNA repair processes. These losses are particularly surprising not only because these genes are widely conserved across living organisms, but also because mutations in the human versions of many of these genes dramatically increase the frequencies of different types of mutations and lead to cancer. Steenwyk's analyzes show that the genomes of [Hansen] spore budding yeast have lost hundreds of genes, including dozens involved in DNA repair, cell cycle, and metabolism. "It seems that Hanseniaspora is at least the yeast," Steenwyk said, adding: "They have very small genomes and among the smallest number of genes of any kind in the genus. Dramatic loss of so many genes is reflected in "The rate at which the genomes of these yeasts have mutated is hitherto unseen, and their cell division seems to be extremely rapid, but also somewhat irregular – a quantum over-quality approach, so to speak," said Rokas (see video illustrating the smaller cell size and faster cell division of a Hanseniaspora species compared to the baker's yeast). Due to the loss of these genes, Hanseriaspora yeasts have experienced many more changes in their DNA than their relatives and carry many "genomic scars" from natural mutagens from the inside (eg, oxidative damage) and from outside (eg UV radiation).

"We are happy to continue studying Hanseniaspora yesterday," said Steenwyk. "There is much we can learn about the basic processes of life from these humble gamers."


Losses are more: Today's budding yeasts distinguish features from their 400 million year old ancestor


More Information:
Stone JL, Opulent DA, Kominek J, Shen X-X, Zhou X, Labella AL, et al. (2019) Extensive loss of cell cycle and DNA repair genes in an old genus of bipolar budding yeast. PLoS Biol 17 (5): e3000255. doi.org/10.1371/journal.pbio.3000255

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Life in the Fast Course of Evolution (2019, May 21)
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