Effect of acute gamma radiation on some physiological features of lichens

The influence of acute gamma radiation on four physiological characteristics of lichens was investigated. Membrane permeability in irradiated thalli of Cladonia arbuscula, Cetraria islandica and Hypogymnia physodes increased considerably compared to controls. The nitrogen content in Peltigera aphthosa appeared to be stable to acute gamma radiation. Up to 1000 Gy there was no essential decrease in respiration intensity in H. physodes and P. aphthosa or of peroxidase activity in P. aphthosa.     

Effect of physiological age on radiation resistance of some bacteria that are highly radiation resistant

Physiological age-dependent variation in radiation resistance was studied for three bacteria that are highly radiation resistant: Micrococcus radiodurans, Micrococcus sp. isolate C-3, and Moraxella sp. isolate 4. Stationary-phase cultures of M. radiodurans and isolate C-3 were much more resistant to gamma radiation than were log-phase cultures. This pattern of relative resistance was reversed for isolate 4. Resistance of isolate 4 to UV light was also greater during log phase, although heat resistance and NaCl tolerance after heat stress were greater during stationary phase. Radiation-induced injury of isolate 4 compared with injury of Escherichia coli B suggested that the injury process, as well as the lethal process, was affected by growth phase. The hypothesis that growth rate affects radiation resistance was tested, and results were interpreted in light of the probable confounding effect of methods used to alter growth rates of bacteria. These results indicate that dose-response experiments should be designed to measure survival during the most resistant growth phase of the organism under study. This timing is particularly important when extrapolations of survival results might be made to potential irradiation processes for foods.     

Effect of physiological age on radiation resistance of some bacteria that are highly radiation resistant.

Physiological age-dependent variation in radiation resistance was studied for three bacteria that are highly radiation resistant: Micrococcus radiodurans, Micrococcus sp. isolate C-3, and Moraxella sp. isolate 4. Stationary-phase cultures of M. radiodurans and isolate C-3 were much more resistant to gamma radiation than were log-phase cultures. This pattern of relative resistance was reversed for isolate 4. Resistance of isolate 4 to UV light was also greater during log phase, although heat resistance and NaCl tolerance after heat stress were greater during stationary phase. Radiation-induced injury of isolate 4 compared with injury of Escherichia coli B suggested that the injury process, as well as the lethal process, was affected by growth phase. The hypothesis that growth rate affects radiation resistance was tested, and results were interpreted in light of the probable confounding effect of methods used to alter growth rates of bacteria. These results indicate that dose-response experiments should be designed to measure survival during the most resistant growth phase of the organism under study. This timing is particularly important when extrapolations of survival results might be made to potential irradiation processes for foods.     

Effect of ionizing radiation on large bodies ofProteus vulgaris

Proteus vulgaris (Штамм P₂) весьма устойчив к облучению. Средней летальной дозой оказалось облучение 10 000 r. Крупнье круглые тельца, образующиеся под действием, пенициллина, так зе чувствительны к рентгеновскому облучению, как палочки. После облучения, уже начиная с дозы в 5–10 тысяч r, набльдалось слияние нуклеоидов (ядерных эквивалентов) подобно тому, как под действием охлаждения до 6° C. В среде без солей это явление не наблюдалось.     

Effect of ionizing radiation on the aggressive behavior of mice

Changes in the aggressiveness of mice were studied after exposure thereof to 5, 10, 30, 60 and 100 Gy radiation. With doses of 5, 10 and 30 Gy no stable effect on the aggressive behaviour of mice was observed, while doses of 60 and 100 Gy suppressed it drastically. Stress at the time of exposure can enhance the antiaggressive effect of radiation.