PT09 Emerging Pollutants / Receptors
Exhibit Hall
8:00 AM - Tuesday
(PT137) The morphological basis for olfactory perception of steroids during agonistic behavior in lobsters: preliminary experiments.
Borsay Horowitz, D.1, Kass-Simon, G.2, Coglianese, D.2, Martin, L.2, Boseman, M.2, Cromarty, S.3, Randall, K.3, Fini, A.2, 1 US EPA, NHEERL, ORD, Atlantic Ecology Division, Narragansett, RI, USA2 University of Rhode Island, Kingston, RI, USA3 Assumption College, Worcester, MA, USA
ABSTRACT- During fighting, American lobsters urinate on each other with antennules flicking highest during this period. Blocking excretion of urine obliterates established dominance relationships, suggesting individual recognition requires urine. Hemolymph and urine concentrations change over molt cycles; the highest ecdysteroid concentrations found in aggressive premolt. This coincides with differences in agonistic behavior over molt cycles and with differential effects of hemolymph. Our preliminary studies suggest that steroids alter not only internal states, but are also used by lobsters as signaling tools with which to orchestrate agonistic strategies. Perfusion of 20-HE over lateral antennule filaments causes large-scale excitation of individual olfactory receptor neurons (ORNs) in lobsters. Inactive forms of steroids or controls have significantly lower levels of excitation. In order to determine where receptors for 20-HE perception are, we have begun an extensive study of the morphology of receptor neurons. This study is preparatory to the immunohistochemical localization of the receptors on the ORNs. Microscopic sections of antennular filaments, nerve cords, and eyestalks of American lobsters have been prepared and routinely stained to reveal structural morphology. Initial interpretations of these tissues have shown arrangements of emerging aesthetascs and guard hairs on lateral antennular filaments and revealed an increased concentration of aesthetascs in anterior portions of these filaments. This suggests that this technique will yield suitable materials for immunohistochemistry to localize and characterize 20-HE and its precursor, alpha-ecdysone. Antibodies for ecdysteroid receptors from both insect and lobster will be used in locating ORN receptors immunohistochemically. (NSF Grant# IBN0234569 to Kass-Simon & Cromarty.)
Key words: lobster, steroid, behavior, morphology