Limits of temperature adaptation and thermopreferendum

Area of Science:

• Physiology
• Biophysics
• Neuroscience

Background:

• Temperature adaptation limits are crucial in medicine and biotechnology.
• Previous research identified temperature limits for various organisms using different methods.
• D.P. Kharakoz hypothesized that synaptic exocytosis involves reversible lipid phase transitions in the presynaptic membrane due to calcium ions.

Purpose of the Study:

• To test D.P. Kharakoz's hypothesis in vivo.
• To investigate the influence of long-term acclimatization temperature on heat and cold shock responses and adaptation kinetics in zebrafish.
• To compare experimental results with data from other organisms.

Main Methods:

• Determining the viability polygon for zebrafish (Danio rerio).
• Measuring minimum cold shock temperature, maximum heat shock temperature, and thermopreferendum temperature.
• Comparing zebrafish data with published data from other species.

Main Results:

• The viability polygon for zebrafish was defined: cold shock ~6°C, heat shock ~43°C, thermopreferendum ~27°C.
• The ratio of cold shock to heat shock temperature ranges was approximately 1.3.
• These parameters accurately described the viability polygons of other species, including humans.

Conclusions:

• Experimental temperatures for shock and preferendum align with lipid-protein phase transitions in synaptic membranes.
• Zebrafish viability range matches optimal enzyme function and the viability polygons of most organisms.
• Organismal temperature adaptation limits are dictated by the functional temperature range of the nervous system, influenced by membrane lipid properties.