02108nas a2200241   4500008004100000020001400041245010600055210006900161260005900230300001300289490000700302520131600309100002101625700002101646700001901667700002201686700002301708700001901731700002301750700002001773700001601793856005701809       2015                        eng d  a1932-620300aUnusually Large Number of Mutations in Asexually Reproducing Clonal Planarian <i>Dugesia japonica</i>0 aUnusually Large Number of Mutations in Asexually Reproducing Clo  aSan Francisco, CA USAbPublic Library of Sciencec2015  ae01435250 v103 a<p>We established a laboratory clonal strain of freshwater planarian (Dugesia japonica) that was derived from a single individual and that continued to undergo autotomous asexual reproduction for more than 20 years, and we performed large-scale genome sequencing and transcriptome analysis on it. Despite the fact that a completely clonal strain of the planarian was used, an unusually large number of mutations were detected. To enable quantitative genetic analysis of such a unique organism, we developed a new model called the Reference Gene Model, and used it to conduct large-scale transcriptome analysis. The results revealed large numbers of mutations not only outside but also inside gene-coding regions. Non-synonymous SNPs were detected in 74% of the genes for which valid ORFs were predicted. Interestingly, the high-mutation genes, such as metabolism- and defense-related genes, were correlated with genes that were previously identified as diverse genes among different planarian species. Although a large number of amino acid substitutions were apparently accumulated during asexual reproduction over this long period of time, the planarian maintained normal body-shape, behaviors, and physiological functions. The results of the present study reveal a unique aspect of asexual reproduction.</p>
1 aNishimura, Osamu1 aHosoda, Kazutaka1 aKawaguchi, Eri1 aYazawa, Shigenobu1 aHayashi, Tetsutaro1 aInoue, Takeshi1 aUmesono, Yoshihiko1 aAgata, Kiyokazu1 aFu, Binying  uhttp://www.ncbi.nlm.nih.gov/pmc/articles/PMC4654569/