若尾氏の講演要旨(11月12日@ Berkeley)

Singlet oxygen (1O2*) is a highly reactive oxygen species that is generated under excess light in the PSII reaction center. Using Rose Bengal (RB) as a photosensitizer of 1O2* formation, we have found that Chlamydomonas reinhardtii, a model photosynthetic eukaryote, exhibits an acclimation response to 1O2* stress. Acclimation was defined as the activation of defense responses upon a sublethal pretreatment that enhances survival to a subsequent higher dose of 1O2* stress that would otherwise be lethal. To dissect the signal transduction pathway involved in sensing and responding to 1O2*, we have identified singlet-oxygen-sensitive (sos) insertional mutants that are unable to acclimate to 1O2*. In contrast to the wild type, the sos1 mutant exhibited altered mRNA expression of a large number of genes. The expression pattern of a putative 7,8-didemethyl-8-hydroxy-5-deazariboflavin synthase (FOS) gene proximal to the sos1 lesion was altered during acclimation to RB as compared to wild type. The 1O2* hypersensitivity and acclimation defect of sos1 were partially rescued by the introduction of an antisense construct of the putative FOS gene. Similar complementation was also observed by introduction of two endogenous transcripts that overlap with the 3’-UTR of the putative FOS gene in the antisense orientation. These results suggest the involvement of the putative FOS gene, possibly regulated by endogenous antisense transcripts, in 1O2* signaling of Chlamydomonas reinhardtii. (Supported by the National Institutes of Health)
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Japanese San Francisco Bay Area Seminar は生物学・医学に関するセミナー開催を中心的な活動として研究者支援を行っている非営利団体です。

 
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