title: Methoprene and 20-OH-ecdysone affect male production in Daphnia pulex.
abstract: Exposure of Daphnia pulex to the insecticide and juvenile hormone-mimic methoprene resulted in a decrease in the incidence of all-male broods and an increase in the incidence of all-female broods compared with controls. These effects were observed at nominal concentrations of 10 and 100 microg/L, within the upper range of concentrations at which methoprene is applied in the environment. Because methoprene has been found to bind to the mammalian retinoid X receptor, we also tested the effects of retinoic acid on Daphnia reproduction. Neither 9-cis-retinoic acid nor all-trans-retinoic acid had any observable effect. Because juvenile hormone and ecdysteroids interact in many insect systems, we also exposed Daphnia to 20-OH-ecdysone. Exposure to the crustacean hormone 20-OH-ecdysone at levels of 1 and 10 microg/L resulted in an increase in all-male broods and a decrease in all-female broods, but 100 microg/L 20-OH-ecdysone resulted in a decrease in all-male broods and an increase in all-female broods. Our results suggest that juvenile hormone and ecdysteroids might play a role in the Daphnia sex determination system.
authors.affiliation: Department of Zoology, University of Wisconsin, Madison 53706-1381, USA.
authors.forename: J K
authors.initials: JK
authors.lastname: Peterson
authors.forename: D R
authors.initials: DR
authors.lastname: Kashian
authors.forename: S I
authors.initials: SI
authors.lastname: Dodson
mesh_terms: D000077556:Alitretinoin; D000818:Animals; D003621:Daphnia / Q000187:drug effects* / Q000254:growth & development; D004441:Ecdysterone / Q000494:pharmacology*; D005260:Female; D008297:Male; D008726:Methoprene / Q000494:pharmacology*; D011897:Random Allocation; D012744:Sex Ratio; D014212:Tretinoin / Q000494:pharmacology
chemical_list: D000077556:Alitretinoin; D004441:Ecdysterone; D014212:Tretinoin; D008726:Methoprene