Thermally Dependent Behaviour of Cold-Blooded Animals: Overcoming Two Temperature Barriers on the Way to Warm-Blooded

Background: The temperature preferences of cold-blooded animals are different for different groups of animals and are closely related to their evolutionary status and level of adaptive capabilities. The range of preferred temperatures for reptiles (28°C - 32°C) coincides with the zone of temperature-dependent increase in the rate of the M-cholinergic reaction in the brain, which was previously found in warm-blooded neurons. The growth of the M-cholinergic process contributes to the transition of adaptive behavior to a higher level. Of the cold-blooded, only reptiles actively use thermoregulatory behavior as a tool to achieve a temperature optimum. This paper is devoted to the study of the behavior of red-eared turtles aimed at reaching the range of preferred temperatures. Temperature conditions necessary for the survival of different groups of cold-blooded animals are compared and the reason for temperature preferences is discussed. Methods: The behavior of turtles was studied under conditions of variable solar radiation and in a 3-section terrarium with gradual temperature ranges: 23°C - 24°C;28°C - 31°C and 45°C - 50°C. Results: It was found that prolonged (up to 1.5 hours) heating at a temperature of 45°C - 50°C was the best way to achieve the preferred temperatures. This method of heating results in increasing the temperature of the shell to an average of 37°C, followed by a very slow decrease during 4 - 6 hours within the limits that closely coincided with the preferred level. Conclusion: The results obtained demonstrate that the main function of the turtle shell is to accumulate heat and keep it for a long time in a variable climate. The preferred temperature achieved in this case is necessary for the temperature-dependent transition of the rate of the M-cholinergic reaction in the brain to a higher level, which creates more significant adaptive capabilities. The temperature range of the M-cholinergic process has two inflection points at 27°C - 29°C and 34°C - 36°C. In accordance with these values, the temperature preferences of cold-blooded animals are divided into three groups: 0°C - 28°C (fish and amphibians);28°C - 32°C (reptiles) and 34°C - 36°C (dinosaurs). Different ranges of preferred temperatures correspond to three stages of adaptive development.

Physiological and molecular biochemical mechanisms of bile formation

This review considers the physiological and molecular biochemical mechanisms of bile formation.The composition of bile and structure of a bile canaliculus,biosynthesis and conjugation of bile acids,bile phospholipids,formation of bile micellar structures,and enterohepatic circulation of bile acids are described.In general,the review focuses on the molecular physiology of the transporting systems of the hepatocyte sinusoidal and apical membranes.Knowledge of physiological and biochemical basis of bile formation has implications for understanding the mechanisms of development of pathological processes,associated with diseases of the liver and biliary tract.

Primary biliary cirrhosis: Clinical and laboratory criteria for its diagnosis

Primary biliary cirrhosis(PBC) is a chronic progressive cholestatic granulomatous, and destructive inflammatory lesion of small intralobular and septal bile ducts, which is likely to be caused by an autoimmune mechanism with a the presence of serum antimitochondrial antibodies and a potential tendency to progress to cirrhosis. Despite the fact that the etiology of this disease has beenunknown so far, there has been a considerable body of scientific evidence that can reveal the clinical and laboratory signs of PBC and the individual components of its pathogenesis and elaborate diagnostic criteria for the disease and its symptomatic therapy. Deficiencies in autoimmune tolerance are critical factors for the initiation and perpetuation of the disease. The purpose of this review is to summarize the data available in the literature and the author's findings on clinical and laboratory criteria for the diagnosis of PBC. This review describes the major clinical manifestations of the disease and the mechanisms of its development. It presents the immunological, biochemical, and morphological signs of PBC and their significance for its diagnosis. A great deal of novel scientific evidence for the problem of PBC has been accumulated. However, the inadequate efficiency of therapy for the disease lends impetus to the quest for its etiological factors and to further investigations of its pathogenetic mechanisms and, on this basis, to searches for new methods for its early diagnosis.