Ecdysteroid titers and Y-organ activity during late anecdysis and proecdysis in the fiddler crab, Uca pugilator.

The titer of ecdysone in hemolymph and the ratio of ecdysone to other radioimmunoassay(RIA)-active hemolymph ecdysteroids were compared to in vitro secretion of ecdysone in Y-organs removed from eyestalkless fiddler crabs at various times following eyestalk ablation. Using high-pressure liquid chromatography (HPLC) and RIA it was established that ecdysone, 20-hydroxyecdysone, and RIA-active metabolites are present in the hemolymph at the end of anecdysis and throughout proecdysis. There was little correlation between in vitro secretory activity and total ecdysone in circulation. Ratios of ecdysone and 20-hydroxyecdysone changed during proecdysis as did the percentage of total RIA activity attributable to both. Positive correlations were observed between in vitro Y-organ secretion rates and amounts of ecdysteroids extracted from hemolymph and added to incubation media.