The Effect of Gonads Maturation on Lysozyme of Pike Females <i>Esox lucius</i> (Esocidae)

Abstract

The effect of the gonad development in the pike Esox lucius females on the quantitative parameters of the lysozyme, a component of nonspecific resistance, and the size of some the immune system organs was studied from September to April. The variability of the lysozyme concentration as an indicator of the amount of enzyme in a fixed dimension, as well as the total amount of lysozyme in the whole organ was evaluated. It is established that during the period of female maturation and gonad development the concentration of lysozyme in the serum and spleen significantly decreases. At this time, the size of the liver increases, and the spleen decreases, the kidney index remains unchanged. The concentration of lysozyme in the liver and serum is inversely correlated with the increase of the gonads, but the dependence on the gonads size is weak. The growth of the gonads and a significant increase in the size of the liver do not affect the lysozyme index of the liver, which reflects the total amount of the enzyme in this organ. It was found that the decrease in the enzyme concentration in the liver is proportional to the increase in the size of the organ. A direct relationship was found between the quantitative parameters of the lysozyme in the kidney and the total amount of the enzyme and the size of the spleen, therefore, a decrease in the concentration and total amount of lysozyme in the kidney may be a manifestation of the indirect effect of gonad maturation. The concentration of lysozyme in the serum showed a direct relationship with the water temperature of the water body, but such a relationship was not manifested in the organs. In the studied period, the quantitative parameters of the enzyme in the spleen and the relative size of the organ turned out to be more related to the water temperature than to the gonadosomatic index. The maturation of the gonads in females, combined with the external influence of temperature, has both a direct and indirect effect on the concentration of lysozyme in tissues. The concentration of tissue lysozyme as an indicator with a fixed dimension can be determined not only by the state of immunity, but also by changes in the size of organs. Determination of the total amount of lysozyme in the immune system organs increases the objectivity of assessing the influence of the physiological state of the organism on the nonspecific immunity of fish.