01928nas a2200169   4500008004100000245010300041210006900144260001200213300001400225490000700239520131500246100001901561700002001580700002101600700002701621856011001648       2010                        eng d00aViable microbes in ice: application of molecular assays to McMurdo Dry Valley lake ice communities0 aViable microbes in ice application of molecular assays to McMurd  c10/2010  a470 - 4760 v223 a<p>The permanent ice covers of the McMurdo Dry Valley lakes, Antarctica, are colonized by a diverse microbial assemblage. We collected ice cores from Lakes Fryxell, Hoare and Bonney. Propidium monoazide (PMA) was used in combination with quantitative PCR (qPCR) and denaturing gradient gel electrophoresis (DGGE) to examine membrane integrity of prokaryotes in these extreme environments. PMA selectively penetrates cells with compromised membranes and modifies their DNA resulting in the suppression of PCR amplification. Our results based on analysis of 16S rRNA genes demonstrate that despite the hostile conditions of the Dry Valleys, the permanent ice covers of the lakes support a &lsquo;potentially viable&rsquo; microbial community. The level of membrane integrity, as well as diversity, was higher in samples where sediment was entrapped in the ice cover. Pronounced differences in the fraction of cells with intact and compromised cell membranes were found for Lake Fryxell and east lobe of Lake Bonney, both expressed in differences in DGGE banding patterns and qPCR signal reductions. Limitations in the ability to distinguish between intact or compromised cells occurred in samples from Lake Hoare and west lobe of Lake Bonney due to low DNA template concentrations recovered from the samples.</p>1 aDieser, Markus1 aNocker, Andreas1 aPriscu, John, C.1 aForeman, Christine, M.  uhttp://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=7909836&fileId=S0954102010000404