Meeting Abstract

P3.33  Monday, Jan. 6 15:30  The Effect of Eyestalk-Ablation on Ecdysteroids and Vitellogenins in Three Sexual Stages of the Spot Prawn (Pandalus platyceros) MILLER, B.D.*; TAMONE, S.L.; Georgia Southern University; University of Alaska Southeast bm03548@georgiasouthern.edu

The objective of this project was to investigate the role of eyestalk neurohormones in the regulation of molting and reproductive physiology of the spot prawn Pandalus platyceros. The molting hormone, ecdysone and the egg yolk precursor protein vitellogenin were measured using an ELISA and SDS-PAGE respectively. Hemolymph concentrations were compared between male, female, and transitional shrimp. Hemolymph from 9 transitional, 19 male, and 14 female prawns was sampled to determine baseline ecdysone and vitellogenin concentrations. Transitional shrimp had significantly higher ecdysone concentrations (172.2 ± 49.9 ng/ml) than males (10.7 ± 4.25 ng/ml) and females (39.8 ± 19.8 ng/ml). Protein bands associated with vitellogenin in female and transitional shrimp hemolymph were significantly denser (indicating higher concentrations) than those measured in male hemolymph. Concentrations of ecdysone and vitellogenin in male and female spot prawns in response to eyestalk-ablation (EA) were also examined. Hemolymph was sampled one day before and one week after EA and analyzed for ecdysteroids and vitellogenin. All transitional shrimp molted prior to the EA experiment so there were no transitional shrimp for the EA experiment. Eyestalk-ablation resulted in significantly higher circulating ecdysteroids in males (n=5; P<0.003) when compared to sham-operated controls demonstrating that the molt-inhibiting hormone regulates secretion of ecdysteroids from the y-organ. Females did not respond to EA (n=4; P=0.08). Eyestalk-ablation did not result in significant changes in male and female vitellogenin levels. This research provides further information concerning molting biology of these shrimp.