02108nas a2200241 4500008004100000020001400041245010600055210006900161260005900230300001300289490000700302520131600309100002101625700002101646700001901667700002201686700002301708700001901731700002301750700002001773700001601793856005701809 2015 eng d a1932-620300aUnusually Large Number of Mutations in Asexually Reproducing Clonal Planarian Dugesia japonica0 aUnusually Large Number of Mutations in Asexually Reproducing Clo aSan Francisco, CA USAbPublic Library of Sciencec2015 ae01435250 v103 a

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.

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/PMC4654569/02497nas a2200229 4500008004100000020001400041245010200055210006900157260001500226300001600241490000700257520177600264100002202040700002202062700002502084700002202109700001902131700002002150700002702170700002602197856004402223 2015 eng d a1552-578300aControl of Maintenance and Regeneration of Planarian Eyes by ovoPlanarian Eye Regeneration by ovo0 aControl of Maintenance and Regeneration of Planarian Eyes by ovo c2015/11/30 a7604 - 76100 v563 a

Abstract Purpose: Following decapitation, the planarian Schmidtea mediterranea regenerates its head and eyes. The gene ovo is required for eye maintenance and regeneration in response to wounding. In this study, we investigated whether eye regeneration in S. mediterranea could occur absent a wound healing response. Methods: One hundred twenty S. mediterranea were treated with ovo RNA interference (RNAi) or control (unc-22) RNAi by feeding double-stranded RNA (dsRNA). Following eye loss, ovo RNAi treatment was halted and replaced with control RNAi treatment. Quantitative real-time PCR (qPCR) was used to monitor ovo expression. Eye functionality was monitored via a phototaxis assay. Photoreceptor neurons were visualized via immunofluorescence staining of arrestin. Results: Treatment with ovo RNAi caused eyes to gradually shrink until they were completely absent. One hundred percent of ovo RNAi-treated planarians lost both eyes within 137 days of treatment onset. ovo RNAi-treated planarians were unable to regenerate eyes in response to decapitation. Upon removal of ovo RNAi, eyes became visible as small pigmented spots in the head within 28 days. The eyes slowly developed, appearing to gain pigmented cells first and then nonpigmented photoreceptors. Phototaxis assays demonstrated functional eye loss and eye restoration. ovo mRNA was significantly decreased following treatment with ovo RNAi and significantly increased following removal of ovo RNAi. Arrestin staining was present in the eyes, optic nerves, and optic chiasm of worms with regenerated eyes but not in eyeless worms. Conclusions: S. mediterranea have the ability to generate functional eyes in the absence of a wound healing response. This ability requires the expression of ovo.

1 aCross, Samuel, D.1 aJohnson, Adiv, A.1 aGilles, Benjamin, J.1 aBachman, Lori, A.1 aInoue, Takeshi1 aAgata, Kiyokazu1 aMarmorstein, Lihua, Y.1 aMarmorstein, Alan, D. uhttp://dx.doi.org/10.1167/iovs.15-17458