@article {1538, title = {Unusually Large Number of Mutations in Asexually Reproducing Clonal Planarian Dugesia japonica}, journal = {PLoS ONE}, volume = {10}, year = {2015}, month = {2015}, pages = {e0143525}, publisher = {Public Library of Science}, address = {San Francisco, CA USA}, 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.

}, isbn = {1932-6203}, url = {http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4654569/}, author = {Nishimura, Osamu and Hosoda, Kazutaka and Kawaguchi, Eri and Yazawa, Shigenobu and Hayashi, Tetsutaro and Inoue, Takeshi and Umesono, Yoshihiko and Agata, Kiyokazu}, editor = {Fu, Binying} } @booklet {1500, title = {Planarian shows decision-making behavior in response to multiple stimuli by integrative brain function}, volume = {1}, year = {2015}, month = {2015//}, pages = {1 - 15}, abstract = {Planarians belong to an evolutionarily early group of organisms that possess a central nervous system including a well-organized brain with a simple architecture but many types of neurons. Planarians display a number of behaviors, such as phototaxis and thermotaxis, in response to external stimuli, and it has been shown that various molecules and neural pathways in the brain are involved in controlling these behaviors. However, due to the lack of combinatorial assay methods, it remains obscure whether planarians possess higher brain functions, including integration in the brain, in which multiple signals coming from outside are coordinated and used in determining behavioral strategies.}, isbn = {2056-306X}, url = {http://dx.doi.org/10.1186/s40851-014-0010-z}, author = {Inoue, Takeshi and Hoshino, Hajime and Yamashita, Taiga and Shimoyama, Seira and Agata, Kiyokazu} } @article {1499, title = {Control of Maintenance and Regeneration of Planarian Eyes by ovoPlanarian Eye Regeneration by ovo}, volume = {56}, year = {2015}, note = {10.1167/iovs.15-17458}, month = {2015/11/30}, pages = {7604 - 7610}, abstract = {

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.

}, isbn = {1552-5783}, url = {http://dx.doi.org/10.1167/iovs.15-17458}, author = {Cross, Samuel D. and Johnson, Adiv A. and Gilles, Benjamin J. and Bachman, Lori A. and Inoue, Takeshi and Agata, Kiyokazu and Marmorstein, Lihua Y. and Marmorstein, Alan D.} }