Cell thermoregulation and origin of homeothermic animals

Abstract

Temperature has a fundamental influence in all chemical and biochemical reactions. It influences reaction rates, equilibrium amounts, viscosity, solubility, molecular arrangements and numeric other parameters. Temperature is important for all physiological processes. Maintaining the relative constancy of the internal temperature (temperature homeostasis) is a necessary condition for normal life. Some living beings maintain temperature homeostasis in the body due to external sources of energy (poikilothermy), others due to the energy of food consumption (homeothermy). However, it is unknown the origin of homeothermic organisms. Despite the fundamental similarity of the mechanisms of the central organ-based physiological thermoregulation, even among the higher vertebrates exists poikilothermy and homeothermy animals. It is assumed that homeothermy is not the result of the evolution of physiological mechanisms of thermoregulation. Homeothermy is the result of the evolution of non-coding DNAs in the genome, some of which formed the so-called chromosomal heterochromatin regions (HRs). Chromosomal HRs constitutes the material basis of cell thermoregulation, which is responsible for the removal of excess thermal energy from the nucleus into the cytoplasm. Homeothermic organisms, unlike poikilotherms capable of faster and more efficient leveling of temperature difference between the nucleus and the cytoplasm with all the ensuing consequences.