Effects of irradiation on the peritrich ciliates Vorticella and Telotrochidium

Vorticella microstoma and Telotrochidium henneguyi were exposed to doses of x- and gamma-radiation ranging from 46 r to 120 Kr. Irradiation was applied to freshly excysted motile organisms. Doses below 2 Kr did not induce noticeable morphological effects in either peritrich. Doses between 2 and 5 Kr induced Pellicular blisters in Vorticella but to a very limited extent; the blisters were more prevalent 12 hr post-irradiation. Pellicular blisters were not induced in Telotrochidium, regardless of the dose. A 30 Kr dose caused both peritrichs to become more rounded than the control animals. Doses above 2 Kr altered the normal life cycle of both peritrichs as follows. The post-excystment binary fission stage was extended beyond the normal 18 yr. Post-excystment conjugation occurred later than the usual 18 to 36 hr period. A 38 Kr dose depressed Vorticella's population growth curve during the first 24 hr after irradiation, but recovery and growth was almost complete between 24 to 48 hr post-irradiation. A 57 Kr dose also depressed the population growth curve during the 24 hr following irradiation, but recovery to near normal did not occur until 60 hr post-irradiation. Telotrochidium's response was different and inconsistent in comparison with Vorticella's response. In some experiments only 10% of the Telotrochidium population survived a single 38 Kr dose and growth occurred. Likewise, 57 Kr gave inconsistent results in that it was lethal to the total population in some experiments but merely retarded growth and recovery of the total population in other experiments