Electrophysiological Mechanisms of Adaptation Processes

A systemic analysis of the relationships between electrophysiological parameters of the cardiovascular and respiratory systems during adaptation processes has been performed in order to study some electrophysiological mechanisms of stress. Studies were performed in subjects with various circulatory disorders and in healthy subjects at rest and during exercise; in skilled and apprentice workers at an electronics plant; and in students under examination stress. It is demonstrated that determining the set of parameters of the integrated cardiac–respiratory–hemodynamic system is necessary but not sufficient for diagnosing stress and its individual stages. The main characteristic is the degree of harmony in the ratios between these parameters, i.e., the balance of relationships between subsystems; the ratios thereby serve as new diagnostic signs of the functional state of the body. A resonance–wave model of stress is proposed. This model forms a basis for the assessment of stress during its development, with the stages of strain and overstrain being regarded as stages of the positive dynamics of adaptation syndrome provided that self-regulation is preserved during the progress of these stages, i.e., resonance is formed. In the case of disharmonic ratios between electrophysiological parameters and imbalance of their relationships, the stages of adaptation processes differ in the degree of deviation from invariant ratios between parameters.     

Assessment of female gamete quality in the Pacific oyster Crassostrea gigas

Summary

The possible relationship between certain oocyte and embryo characteristics and larvae viability was investigated with reference to the following aspects: (1) morphological—oocyte diameter and shape; (2) cytological—overall ultrastructure and membrane integrity; (3) biochemical—content of lipids, proteins and carbohydrates; and (4) physiological—respiration. The rate of survival and incidence of abnormality were estimated 24 h after fertilization. The first results showed that 80–90% of oocytes were cytologically viable before fertilization. Eighty to 90% of oocytes are apparently viable before fertilization on the basis of staining with Trypan blue, but this parameter shows little correlation with larval viability. However, Trypan blue staining is of value in allowing the recognition of oocytes with damaged membranes. Respiration was measured for unfertilized oocytes 5 min after stripping, after 6 h, and for 3-h embryos. Positive correlations were found between the O₂-consumption of embryos and both the rate of fertilization and the hatching rate of 24-h larvae. In contrast, no correlation was found between hatching parameters and the O₂-consumption of unfertilized oocytes. These results suggest that embryos possess quality indicators, relating to metabolic characteristics, which can be quantified more easily than those of oocytes.