Circadian Rhythmic Changes in the Lipid Composition of Muscles in Kilka Clupeonella cultriventris (Clupeidae, Clupeiformes) during Natural Periodicity of Feeding in the Feeding and Spawning Periods in the Rybinsk Reservoir

摘要

According to data of observations in 2002—2004, differences in the pattern of diurnal fluctuations in the total content and fractional composition of hpids in muscles of mature specimens of kilka Clupeonella cultriventris from the Rybinsk Reservoir in the feeding and spawning periods were revealed. It was estabMshed that the feeding intensity in Mlka considerably changes throughout 24 h in both periods of the annual cycle, while diurnal fluctuations in the fatness of muscles are distinctly manifested only in the reproductive period and have a dissimilar pattern in specimens of different sexes. In females and males, they are determined mainly by the change in the content of the fraction of reserve hpids—triacylglycerols, as a rule, by its increasein the light hours of the day, several hours after an increase in the feeding activity offish. The pattern of diurnal fluctuations of the level of lipid fractions (phospholipids, triacylglycerols, cholesterol, and its ethers) in kilka's muscles differs from that in the feeding period. Possible causes of the change of diurnal variations of the considered indices of lipid metabolism in kilka at an increase in the endocrine activity of its body in the reproductive period is discussed.