Meeting Abstract

P1.29  Tuesday, Jan. 4  Regulation of Ecdysteroid Biosynthesis in the fiddler crab, Uca pugilator KHAMBADAKONE, D*; DURICA, D.S.; HOPKINS, P. M.; Univ. of Oklahoma, Norman; Univ. of Oklahoma, Norman; Univ. of Oklahoma, Norman deepak.p.khambadakone-1@ou.edu

Ecdysteroid biosynthesis in crustaceans occurs in the Y-organs. In the fiddler crab, Uca pugilator, ecdysone (E), 25 deoxyecdysone (25dE) are the two ecdysteroids secreted from the Y-organs and finally converted into 20-hydroxyecdysone (20E) and ponasterone A (PA) respectively, in the peripheral tissues . The regulation of ecdysteroidogenesis in the Y-organs is under the inhibitory control of neuropeptides such as molt inhibiting hormone (MIH) and crustacean hyperglycemic hormone (CHH) released from neurosecretory cells in the eyestalks and central nervous system. The concentration and composition of hemolymph ecdysteroids fluctuate during the molt cycle in Uca pugilator. Hemolymph ecdysteroids remain low throughout intermolt (C_1-4), rise during premolt (D₀) and reach peak during late premolt (D_1-D4). This peak drops sharply just before ecdysis. These fluctuations are also found in eyestalk ablated animals that removes the neuropeptides from the eyestalk source indicating involvement of other signals in regulation of ecdysteroid biosynthesis. In this study we are investigating the feedback role of 20E and PA on regulation of ecdysteroid biosynthesis. Furthermore we are investigating the effect of PA and 20E on the composition of ecdysteroids produced in the Y-organs during different molting stages.