Tuyển tập các báo cáo nghiên cứu về y học được đăng trên tạp chí y học Wertheim cung cấp cho các bạn kiến thức về ngành y đề tài: DNA transposons and the role of recombination in mutation accumulation in Daphnia pulex. | Schaack et al. Genome Biology 2010 11 R46 http 2010 11 4 R46 Daphnia Genomics Consortium w Genome Biology RESEARCH Open Access DNA transposons and the role of recombination in mutation accumulation in Daphnia pulex Sarah Schaack1 Eunjin Choi2 Michael Lynch2 Ellen J Pritham1 Abstract Background We identify DNA transposons from the completed draft genome sequence of Daphnia pulex a cyclically parthenogenetic aquatic microcrustacean of the class Branchiopoda. In addition we experimentally quantify the abundance of six DNA transposon families in mutation-accumulation lines in which sex is either promoted or prohibited in order to better understand the role of recombination in transposon proliferation. Results We identified 55 families belonging to 10 of the known superfamilies of DNA transposons in the genome of D. pulex. DNA transposons constitute approximately of the genome. We characterized each family and in many cases identified elements capable of activity in the genome. Based on assays of six putatively active element families in mutation-accumulation lines we compared DNA transposon abundance in lines where sex was either promoted or prohibited. We find the major difference in abundance in sexuals relative to asexuals in lab-reared lines is explained by independent assortment of heterozygotes in lineages where sex has occurred. Conclusions Our examination of the duality of sex as a mechanism for both the spread and elimination of DNA transposons in the genome reveals that independent assortment of chromosomes leads to significant copy loss in lineages undergoing sex. Although this advantage may offset the so-called two fold cost of sex in the short-term if insertions become homozygous at specific loci due to recombination the advantage of sex may be decreased over long time periods. Given these results we discuss the potential effects of sex on the dynamics of DNA transposons in natural populations of D. pulex. Background The role of .
