Patterns of serum ecdysteroids during induced and uninduced proecdysis in the fiddler crab, Uca pugilator

Abstract

Eyestalk-intact and eyestalkless fidller crabs, Uca pugilator, have similar temporal patterns of circulating serum ecdysteroids during proecdysis. Both groups of animals showed two distinct transient peaks of radioimmunoassay (RIA)-active ecdysteroids. Peak 1 occurred 3 weeks prior to ecdysis and preceded the onset of rapid proecdysial limb bud growth. Peak 2 was a larger peak that occurred a few days prior to ecdysis. Thin-layer chromatography profiles of the two peaks showed at least seven RIA-active compounds common to both peaks. The relative abundance of these compounds differed between the two peaks. The role of the eyestalks in control of circulating ecdysteroids was limited to maintenance of intermolt conditions. During proecdysis, the control of circulating ecdysteroid levels was located outside of the eyestalks. There was no correlation between limb bud growth rates and serum ecdysteroid levels during proecdysis.