Partial Characterization of Eyestalk Hormones Controlling Molt and Gonadal Development in the Spiny Lobster Panulirus Argus

The eyestalk neurosecretory system of Crustacea contains several peptide factors affecting various important physiological processes. Gonad inhibiting hormone (GIH) and a molt inhibiting hormone (MIH) have been separated and partially characterized using Sephadex gel chromatography and polyacrylamide gel electrophoresis. The eyestalks of the spiny lobster Panulirus argus were the source for these isolations, and activity was bioassayed in the fiddler crab Uca pugilator. Gonad inhibiting hormone has an apparent molecular weight near 5,000 daltons. Molt inhibiting hormone does not induce gonadal inhibition in fiddler crabs, but it does delay the onset of the molt cycle in eyestalkless crabs. Melanin dispersion in intact Uca pugilator was inversely correlated with gonadal growth.