Influence of dehydration on cytoplasmic RNA in the neurocytes of the preoptic nucleus of Rana temporaria L. in the annual cycle.

Sexually mature male and female Rana temporaria L. of similar body length were captured in their natural habitat in seven stages of the annual cycle. Each stage included one control and two experimental groups of frogs exposed to dehydration. Measurements of cytoplasmic RNA in the neurocytes of the preoptic nucleus (PON) were done by a microspectrophotometer. Analysis of the obtained results based on the cosinor procedure revealed that the dehydration caused a decrease in mean annual content of cytoplasmic RNA in the PON neurocytes in females and an insignificant increase in males. At the same time, amplitudes were markedly lowered, whereas rhythm acrophase in dehydrated animals were shifted to earlier months, as compared with findings in both sexes of the control group. The only exception were females of the second experimental group where the dehydration stress induced a disappearance of rhythmic variations of cytoplasmic RNA in the annual cycle.