Unusually Large Number of Mutations in Asexually Reproducing Clonal Planarian Dugesia japonica

Publication Type:Journal Article
Year of Publication:2015
Authors:O. Nishimura, Hosoda, K., Kawaguchi, E., Yazawa, S., Hayashi, T., Inoue, T., Umesono, Y., Agata, K.
Secondary Authors:B. Fu
Journal:PLoS ONE
Volume:10
Issue:11
Pagination:e0143525
Date Published:2015
ISBN Number:1932-6203
Abstract:

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.

URL:http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4654569/
Short Title:PLoS One
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