The Intra-Annual Variability of Immune System Organs and Lysozyme Content in Male Pike <i>Esox lucius</i> L.

Abstract

The effect of the physiological state on the lysozyme concentration in the liver, kidney, spleen and serum, as well as the total amount of the enzyme in the organs, was studied in male pike Esox lucius L., 1758 under different conditions of the annual cycle. Multidirectional intra-annual dynamics of organ somatic indices and quantitative parameters of lysozyme in fish tissues and organs, depending on the temperature regime of the water body, was found. Despite significant changes in liver size and lysozyme concentration, the total amount of the enzyme in the organ, the lysozymic index, remained constant. A similar result was found in the spleen. When the influence of the temperature factor at low temperatures was minimized, the liver parameters changed to the opposite ones, while those in the kidney remained unchanged. Such a temperature regime did not affect the spleen parameters and the concentration of the enzyme in the serum. With significant differences between the liver and spleen in the enzyme concentration and size, their lysozymic indices were indicators of the same level. Stages of gonad maturity affected the liver index and the amount of lysozyme in the kidney, but the correlation of the kidney enzyme with maturity was not significant. The kidney lysozyme and the spleen parameters correlated with body mass without organs, although fish weight and length were not influencing factors. The size of the kidney, unlike the spleen, did not affect the enzyme in fish tissues. The liver and kidney enzyme concentrations and kidney lysozymic index were inversely correlated with liver size. A complex nature of the enzyme relationships in organs was revealed, at which the amount of lysozyme in one organ could affect the amount of the enzyme in the other. The relationship between the concentration of serum lysozyme and the morphophysiological parameters of fish under stable low temperature conditions in the water body was not found.