Fast induction of vitellogenin gene expression by juvenile hormone III in the cockroach Blattella germanica (L.) (Dictyoptera, Blattellidae)

The present paper describes the effect of juvenile hormone III (JH III) upon vitellogenin (Vg) gene expression in cardioallatectomized females of Blattella germanica. Northern blot analyses of time course studies showed that Vg mRNA can be detected 2 h after the treatment with 1 mu g of JH III. Western blot analyses revealed that Vg protein is detectable 4 h after the same treatment. The study of the influence of the age showed that 48-h-old females seem more sensitive than 24-h-old females, whereas differences were less apparent between 48- and 72-h-old females. Dose-response studies indicated that 0.01 mu g of JH III is ineffective, whereas the doses of 0.1, 1 and 10 mu g induced the synthesis of Vg in a dose-dependent fashion. Finally, the administration of three successive doses, of 0.01 mu g of JH III each, did not result in detectable Vg production, whereas two doses of 0.01 mu g followed by one of 1 mu g of JH III induced a greater response than that resulting from a sole dose of 1 mu g of JH III, which suggests that sub-effective doses of JH III elicit a priming effect on Vg production. (C) 1999 Published by Elsevier Science Ltd. All rights reserved.