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A novel low molecular weight ecdysiotropin in post-diapause, pre-hatch eggs of the gypsy moth, Lymantria dispar L. (Lepidoptera" Lymantriidae)

Kelly, T.J., Thyagaraja, B.S., Bell, R.A., Masler, E.P.
Regulatory peptides 1995 v.57 no.3 pp. 253
Lymantria dispar, ova, hormonal regulation, prothoracicotropic hormone, prothoracic glands, ecdysteroids, biosynthesis, molecular weight, dose response, embryo (animal), larvae, brain, hatching
Extracts of post-diapause, pre-hatch eggs of the gypsy moth, Lymantria dispar L. were examined for prothoracicotropic hormone (PTTH)-like activity using an in vitro assay involving last-instar prothoracic glands (PGs). The eggs were extracted in water, eluted from a low-pressure C18-silica cartridge in 60% acetonitrile, and fractionated on a high-performance, size-exclusion column. The primary ecdysiotropic activity eluted with an estimated molecular weight of 2.1 kDa far below the 4-7 kDa size determined for the low molecular weight PTTHs (bombyxins). Dose-response analysis revealed that the maximum activation was reduced by 75% by organic solvent extraction, but the remaining activity retained the ability to maximally activate the PGs 10-fold in vitro. At least some of the ecdysiotropic activity in the post-diapause, pre-hatch egg is localized in the brain of the pharate larva, and this activity increases dramatically prior to hatch when eggs are incubated at 25°C.