Limits of Temperature Adaptation and Thermopreferendum

Abstract

Background Managing the limits of temperature adaptation is relevant both in medicine and in biotechnology. There are numerous scattered publications on the identification of the temperature limits of existence for various organisms and using different methods. It was shown earlier that each cycle of synaptic exocytosis includes reversible phase transitions of lipids of the presynaptic membrane due to the entry and subsequent removal of calcium ions from the synaptic terminal. Violation of cyclic changes in membrane fluidity caused by a sharp increase or decrease in ambient temperatures will lead to the termination of synaptic transmission, which can be recorded by the loss of righting reflex.Results The viability polygon for Danio rerio was determined by the minimum temperature of cold shock (about 6 o C), maximum temperature of heat shock (about 43 o C), and thermopreferendum temperature (about 27 o C). The ratio of the temperature range of cold shock to the temperature range of heat shock was about 1.3. Conclusions The experimental values of the temperatures of cold shock and heat shock and the temperature of the thermal preferendum correspond to the temperatures of phase transitions of the lipid-protein composition of the synaptic membrane between the liquid and solid states. The viability range for zebrafish coincides with the temperature range, over which enzymes function effectively and also coincides with the viability polygons for the vast majority of organisms. The boundaries of the viability polygon are characteristic biological constants. The viability polygon of a particular organism is determined not only by the genome, but also by the physicochemical properties of lipids that make up the membrane structures of synaptic endings. The limits of temperature adaptation of any biological species are determined by the temperature range of the functioning of its nervous system.