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The World of Protozoa, Rotifera, Nematoda and Oligochaeta

Ref ID : 4113

Juan C. Gutierrez and Julio Perez-Silva; Effects of UV-Radiation on Kinetics of Encystment and on Morphology of Resting Cysts of the Ciliate Laurentiella acuminata. J.Protozool. 30(4):715-718, 1983

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The effects of ultraviolet radiation (lambda=254 nm) on the kinetics of encystment of the hypotrichous ciliate Laurentiella acuminata and the structure of resting cysts obtained from irradiated precystic cells are reported. High doses of UV-radiation caused a delay of encystment with a linear increase in the average time for obtaining 50% of encystment (EN50). Resting cysts with abnormal cyst walls were obtained when precystic cells were irradiated in the exposure range 720 to 960 J/m2. The cystic layer (mesocyst) was approximately twice as thick (6.5 µm) as normal (3.7 µm). Microscopical observations of abnormal cysts revealed the presence of two complete mesocysts, and the absence of the spines characteristic of the ectocyst. The UV-dependent effects on the cyst wall were gradually corrected in successive generations of the irradiated cells.