MedWorm provides a medical RSS filtering service. Over 6000 RSS medical sources are combined and output via different filters. This feed contains the latest medical blog items that have been tagged with 'genetic variation'. Sat, 03 Sep 2011 02:49:58 +0100 http://www.medworm.com/index.php?rid=3420672&cid=t_131877_131_f&fid=34995&url=http%3A%2F%2Ffeedproxy.google.com%2F%7Er%2Fscienceblogs%2Fgnxp%2F%7E3%2FsdoVPlbMcgM%2F A follow up to the post below, see John Hawks, Selection’s genome-wide effect on population differentiation and p-ter’s Natural selection and recombination. As I said, it’s a dense paper, and I didn’t touch on many issues. (Source: Gene Expression) Gene Expression blogs http://www.medworm.com/rss/comments.php?id=3420672 Sun, 28 Mar 2010 18:31:46 +0100 3420672 http://www.medworm.com/index.php?rid=3420674&cid=t_131877_131_f&fid=34995&url=http%3A%2F%2Ffeedproxy.google.com%2F%7Er%2Fscienceblogs%2Fgnxp%2F%7E3%2F0-5hB0p-XtA%2F The following passage is from the epilogue of The Real Eve: Modern Man’s Journey Out of Africa by Stephen Oppenheimer: In this book I have offered a synthesis of genetic and other evidence. Everything points to a single southern exodus from Eritrea to the Yemen, and to all the non-African male and female gene lines having arisen from their respective single out-of-Africa founder lines in South Asian (or at least near the southern exit). I regard the genetic logic for this synthesis as a solid foundation, and I have based the rest of my reconstruction of the human diaspora upon it. Obviously, the ‘choice’ of starting point (mine or theirs) determined all the subsequent routes our ancestors and cousins took. Tracing the onward trails is only possible as a result of marked s... Gene Expression blogs http://www.medworm.com/rss/comments.php?id=3420674 Sun, 28 Mar 2010 07:15:38 +0100 3420674 http://www.medworm.com/index.php?rid=3420678&cid=t_131877_131_f&fid=34995&url=http%3A%2F%2Ffeedproxy.google.com%2F%7Er%2Fscienceblogs%2Fgnxp%2F%7E3%2FJr_qmaJW7go%2F In conclusion, we have shown that genome-wide human population differentiation in allele frequencies is significantly correlated with recombination rate on a megabase scale, demonstrating that natural selection has had a profound effect on allele frequency distributions averaged over the last hundred thousand years. While these results likely reflect the effects of hitchhiking and background selection, disentangling the strengths of these two forces will require extending the analyses presented in this paper. One important direction is to use genetic maps that have fine spatial resolution, which may shed light on the detailed distribution of selective coefficients that have shaped allele frequency differentiation. A second direction in which these results can be extended is to compare more... Gene Expression blogs http://www.medworm.com/rss/comments.php?id=3420678 Fri, 26 Mar 2010 16:28:15 +0100 3420678 http://www.medworm.com/index.php?rid=966606&cid=t_131877_107_f&fid=36585&url=http%3A%2F%2Ffeeds.feedburner.com%2F%7Er%2FHighlightHealth%2F%7E3%2F162040249%2F This article was published on Highlight HEALTH. (Source: Highlight HEALTH) Highlight HEALTH blogs http://www.medworm.com/rss/comments.php?id=966606 Thu, 27 Sep 2007 15:47:26 +0100 966606 http://www.medworm.com/index.php?rid=738945&cid=t_131877_107_f&fid=35025&url=http%3A%2F%2Frrresearch.blogspot.com%2F2007%2F07%2Fmore-about-reduced-variation-at-usss.html The analysis I showed in my last post deserves more discussion. First, it could be improved in a couple of ways. Second, is this an expected result for sequences subject to a molecular drive resulting form biased DNA uptake and unbiased homologous recombination?Improvement one: better controls. As it stands, the comparisons of variation at USS positions is compared to adjacent positions that are not part of the USS motif. This is a bit weak, because some of these positions may contribute to DNA uptake but not show up as 'motif'. A better control comparison would be with random segments of the genome. This is easy to do, as I already have a set of 3500 segments of 39bp (like the USS-centered segments) that I used as a control for the analysis of covariation. Well, 'easy' to see how to do (c... RRResearch blogs http://www.medworm.com/rss/comments.php?id=738945 Tue, 17 Jul 2007 00:07:00 +0100 738945 http://www.medworm.com/index.php?rid=735104&cid=t_131877_107_f&fid=35025&url=http%3A%2F%2Frrresearch.blogspot.com%2F2007%2F07%2Fblast-success-analysis-success.html Everything is working. I still can't get BLAST to attend to matches close to the ends of the 39 nt fragments, but I'm treating these as mismatches at the innermost position and 'no information' at positions closer to the end. For example, if a sequence matches at positions 4-39, I assume there's a mismatch at position 3 and that I have no information about positions 1 and 2.I'm searching for the two USS orientations separately (searching the forward and reverse strands of the query genome separately). I'm analyzing the data separately. So far I've analyzed only the forward searches, but I'll need to flip the results I'll get from analyzing the reverse searches.I'm collecting the output as pairwise comparisons between query and USSs, because this makes it easiest to pull out the positions o... RRResearch blogs http://www.medworm.com/rss/comments.php?id=735104 Sun, 15 Jul 2007 05:59:00 +0100 735104