tailieunhanh - Báo cáo y học: "Origin of nascent lineages and the mechanisms used to prime second-strand DNA synthesis in the R1 and R2 retrotransposons of Drosophila"

Tuyển tập các báo cáo nghiên cứu về y học được đăng trên tạp chí y học Minireview cung cấp cho các bạn kiến thức về ngành y đề tài: Origin of nascent lineages and the mechanisms used to prime second-strand DNA synthesis in the R1 and R2 retrotransposons of Drosophila | Open Access Origin of nascent lineages and the mechanisms used to prime second-strand DNA synthesis in the Rl and R2 retrotransposons of Drosophila Deborah E Stage and Thomas H Eickbush Address Biology Department University of Rochester 213 Hutchison Rochester NY 14627-0211 USA. Correspondence Thomas H Eickbush. Email eick@ Published 5 May 2009 Genome Biology 2009 10 R49 doi gb-2009- l0-5-r49 The electronic version of this article is the complete one and can be found online at http 2009 l0 5 R49 Received 27 January 2009 Revised 27 March 2009 Accepted 5 May 2009 2009 Stage and Eickbush licensee BioMed Central Ltd. This is an open access article distributed under the terms of the Creative Commons Attribution License http licenses by which permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited. Abstract Background Most arthropods contain Rl and R2 retrotransposons that specifically insert into the 28S rRNA genes. Here the sequencing reads from l2 Drosophila genomes have been used to address two questions concerning these elements. First to what extent is the evolution of these elements subject to the concerted evolution process that is responsible for sequence homogeneity among the different copies of rRNA genes Second how precise are the target DNA cleavages and priming of DNA synthesis used by these elements Results Most copies of Rl and R2 in each species were found to exhibit less than sequence divergence. However in many species evidence was obtained for the formation of distinct sublineages of elements particularly in the case of Rl. Analysis of the hundreds of Rl and R2 junctions with the 28S gene revealed that cleavage of the first DNA strand was precise both in location and the priming of reverse transcription. Cleavage of the second DNA strand was less precise within a species differed between species and gave rise to variable .