Ecological and physiological parameters of Myotis dasycneme (Mammalia: Chiroptera: Vespertilionidae) in the Urals

Abstract

Understanding the evolution of bat homeostasis and the formation of an adaptive strategy of animals to climatic fluctuations and pathogens determine the need for further laboratory and modelling studies devoted to the ecology and physiology of bats. This study was aimed to assess the hematological and biochemical parameters of homeostasis of Myotis dasycneme, a protected endemic bat species of the Urals. Animals (n = 65) were caught in the zone of mass habitation of bats in the Southern Urals (Chelyabinsk Region) and the Middle Urals (Sverdlovsk Region). We used samples from M. dasycneme populations in the Ilmensky State Nature Reserve (Russia). Multivariate non-parametric analysis of variance has shown no significant sex differences in red blood parameters in bats (p > 0.05). The blood of bats was characterised by high levels of hemoglobin (167.9–187.2 g/L), hematocrit (47.2–51.5%), erythrocytes (9.6–11.5 × 1012/L), platelets (136.8–271.3 × 109/L). In the autumn-winter period of hibernation, under hypoxic load on the body and prolonged exposure to low positive and near-zero temperatures, an increased content of agranulocytes (50.6–53.6%) was noted in the blood of females and males. The spring process of awakening and exit from deep hypothermia is accompanied by the reactivity of the innate immune system in males and females (granulocytes: 53.2–54.2%). During the winter period of hypobiosis in bats, the basal metabolism increases and the concentration of glucose in the blood increases to 4.7 ± 0.5 mmol/L (p < 0.05). The absence of statistically significant sex differences in the content of glucose and triglycerides (p > 0.05) in the blood plasma of animals has been noted. This ensures metabolic processes (carbohydrate and lipid metabolism) in all seasonal periods of their annual life cycle. The amino acid fund of blood plasma of bats is represented by 22 amino acids. In the blood plasma of males and females, the fund of free amino acids decreases during the year in the following direction: summer ≥ autumn ≥ winter > spring (p < 0.05). There were no sex differences (p > 0.05) in the content of amino acid metabolic groups, namely glycogenic (GGAA), non-essential (NEAA), branched carbon chain (BCCA). A significant accumulation of metabolically active glucoplastic alanine in autumn (3.1 times) and winter (2.3 times) in the blood of females, and in autumn and winter (2.0 and 1.9 times) in males indicates its role as a low-temperature adaptogen. Under conditions of low positive temperatures, in the blood plasma of M. dasycneme, the disappearance of the essential amino acid tryptophan was observed (p < 0.05). This suggests a high demand for serotonin synthesis as one of triggers actively involved in maintaining hypothermia and hypometabolism in bats. Thus, the biochemical and immunohematological parameters, obtained in the course of the study, make it possible to expand and systematise the available information on the mechanisms of participation of the blood system in the regulatory processes in bats. They can be used for long-term monitoring in solving problems of conservation and abundance of healthy populations of bats that adapt both to seasonal modulations and biotic factors, and to stressors of zoonotic significance.