@misc{SaitoKoizumiSakaietal., author = {Saito, Ryota and Koizumi, Ryota and Sakai, Tatsuya and Shimizu, Taiga and Ono, Taiki and Wanner, Manfred and Takyu, Toshio and Tanaka, Toshihiko and Sogame, Yoichiro}, title = {Recovery of proliferative capability in gamma irradiated Colpoda cucullus (ciliated protist) resting cysts and its radiation hormesis}, series = {Protistology}, volume = {14}, journal = {Protistology}, number = {3}, issn = {1680-0826}, doi = {10.4467/16890027AP.19.006.10837}, pages = {160 -- 171}, abstract = {The resting cyst is one of the quietest life stages (i.e. cryptobiosis) with hardly measurable or even ceased metabolic activity. However, are the resting cysts just resting? Here, to our knowledge, we report for the first time radiation hormesis in resting cysts. In the present study, we focused on the proliferative capability of excysted cells from 500-4000 Gy-gamma-irradiated Colpoda cucullus resting cysts by a bioassay method. Generally, excysted cells from irradiated cysts lose their proliferative capability. However, we observed an increased proliferative capability promoted by low doses of irradiation. Cells, which had excysted from 500-Gy-irradiated cysts, restored their proliferation capability with a recovery period of 12 h and 24 h before excysting. Additionally, cells, which had excysted from 500-4000-Gy irradiated cysts, recovered proliferative capability by re-forming resting cysts. Here, the proliferative capability of excysted cells from 500-Gy-irradiated cysts was even higher than that of non-irradiated.}, language = {en} } @misc{SaitoYamanobeYabukietal., author = {Saito, Ryota and Yamanobe, Hiroki and Yabuki, Kazuma and Suzuki, Tomohiro and Saito, Takeru and Hakozaki, Shuntaro and Wanner, Manfred}, title = {Salinity tolerance in resting cysts of colpodid ciliates : comparative transcriptomics analysis and chemical analysis of cyst walls to investigate their tolerance capability.}, series = {Current research in microbial sciences}, volume = {8}, journal = {Current research in microbial sciences}, publisher = {Elsevier}, address = {Amsterdam}, issn = {2666-5174}, doi = {10.1016/j.crmicr.2025.100371}, pages = {1 -- 15}, abstract = {The formation of resting cysts is a strategy for survival in unfavorable environments by single cell organisms such as protists. Here, we show that Colpoda resting cysts have high salinity tolerance and investigate the changes in gene expression that underpin this effect. Colpoda resting cysts can tolerate saline conditions up to 3.5 \% NaCl. A comparative transcriptome analysis of vegetative cells and resting cysts showed that the relative levels of expression of genes associated with membrane function increased in resting cysts. These changes in gene expression suggest that reconstruction of the plasma membrane is associated with salinity tolerance. The resting cyst forms cyst-specific cellular structure known as the cyst wall. The outer shell-like layer, called the ectocyst, while the inner multiple layers, known as the endocyst. The chemical analysis showed ectocyst contains chitin and endocyst contains several proteins. These structures can protect cells by acting as a biological armor or protective materials. The results of this study offer a possible scenario in which salinity tolerance enables the widespread dispersal of protists.}, language = {en} }