On the issue of the thermal adaptation of the larvae caucasian brown frog Rаna macrocnemis Boulenger, 1885 (Amphibia, Ranidae) to low-temperature environmental conditions

The results of the study of hematological parameters of the blood of the larvae caucasian brown frog Rana macrocnemis and the total activity of catalase compared with adults and at different temperature conditions: at 23°C and after five days of hypothermia at 5°C. Differences in the blood formula were revealed in different periods of ontogenesis and under the influence of artificial hypothermia. The number of erythrocytes in tadpoles at the 28–30 stage of development according to Gosner is 2 times less than in adult frogs, a lymphocytic profile is noted in the blood of larvae and adults. The content of lymphocytes is slightly higher at the larval stage, and eosinophils, basophils and monocytes – in adults. With hypothermia in the blood of tadpoles, a decrease in eosinophils and neutrophils was noted against the background of an increase in the level of immunocompetent cells. With low-temperature exposure, catalase activity in the body of tadpoles decreased by 2 times at the 34th stage, and by 1.3 times at the 40th stage, that is, before metamorphosis, antioxidant protection decreases. The dependence of catalase activity on temperature in adult frogs with hypothermia has not been noted, which allows us to conclude that the enzyme's tolerance to temperature changes increases as it develops in ontogenesis. The revealed changes in the studied parameters are adaptive in nature.