| Abstract: | The properties of the high-affinity low molecular weight juvenile hormone (JH) binding protein present in the hemolymph of larvae of five species of pyralid moths, a noctuid moth, and a sphingid moth were compared. The pyralid moths exhibit a facultative diapause as last-instar larvae. The species employed were the southwestern corn borer, Diatraea grandiosella, the southern cornstalk borer, Diatraea crambidoides, the sugarcane borer, Diatraea saccharalis, the European corn borer, Ostrinia nubilalis, the sunflower moth, Homoeosoma electellum, the cabbage looper, Trichoplusia ni, and the tobacco hornworm, Manduca sexta. The binding characteristics of the proteins were determined using saturation binding assays and competitive binding assays. The dissociation constants of JH I, JH II, and JH III for the binding protein of all the species varied from 0.8 x 10?7 M to 2.8 x 10?7 M. Calibrated gel filtration showed that the binding protein of all the species had apparent molecular weights ranging from 29,000 to 31,000. Electrophoresis in 7% acrylamide gels revealed that the relative mobilities of the binding proteins ranged from 0.33 to 0.43. Isoelectric focusing showed that the binding proteins had isoelectric points between 4.4 and 5.0. |
