A novel phenomenon of pseudoencystment in free living ciliate Pseudourostyla levis (Ciliophora, Hypotrichia) from River Yamuna, Delhi

Free living ciliates are exposed to environmental challenges such as starvation, temperature fluctuations, high population density and salinity variations. Ciliates lower their metabolic activity form cysts, an adaptive strategy evolved in response stress. In the present study on Pseudourostyla levis, a novel phenomenon of pseudoencystment had been noticed which cells entered state dormancy but did not secrete cyst wall. The process pseudoencystment, physiologically resembled true encystment, was functionally unrelated it thus designated pseudoencystment. Unlike pseudocysts remained dormant for about 12 hours then reverted active trophic without any change conditions. Another unique feature synchronized induction formation, achieved by brief spell starvation provide long-term protection ciliate appeared be short term adaptation environment. aimed analyze parameters pseudocyst cortical topological changes possible significance this process. However, occasionally cysts were also obtained prolonged lasting 3-4 days required either food or fresh culture medium excystation.