ABSTRACT
DNA and RNA were measured from February 1992 to March 1993 to investigate mechanisms of nutrient storage in digestive tissues during the annual reproductive cycle. Pyloric caeca indices of Asterias forbesi markedly decreased from March until spawning ceased in July. Gut indices of Strongylocentrotus droehachiensis decreased after spawning ceased in April. Prior to spawning there was a decrease in total DNA content and an increase in DNA concentration of the pyloric caeca, suggesting that A. forbesi depletes cytoplasmic reserves and catabolizes whole cells to mobilize nutrients for reproduction. After spawning, total DNA content increased and DNA concentration decreased, indicating that nutrients are being stored by increasing the number and the average size of the cells of the pyloric caeca. There were no substantial changes in total DNA content of the gut of S. droehachiensis during the reproductive cycle, suggesting that cell number does not change. DNA concentrations of the gut fluctuated in a manner not readily related to the annual reproductive cycle. For both the pyloric caeca of A. forhesi and the gut of S. droehachiensis, RNA:DNA ratio varied independently of the gonadal cycle.
