Details

Autor(en) / Beteiligte

• Stoltzman, Carrie Ann

Titel

The effect of the ovary on juvenile hormone during the gonadotrophic cycle in the viviparous cockroach Diploptera punctata

Ort / Verlag

ProQuest Dissertations & Theses

Erscheinungsjahr

1998

Quelle

ProQuest Dissertations & Theses A&I

Beschreibungen/Notizen

• In females of the viviparous cockroach, Diploptera punctata, mating on day 0 (the day of adult emergence) initiates a cycle of juvenile hormone (JH) production by the corpora allata (CA) that supports oocyte maturation. Rates of JH synthesis begin to increase on day 3 and continue increasing to day 4-5, promoting vitellogenesis, and then drop dramatically on days 5-6 as oocytes complete maturation. Ovary presence is required for both stimulation and inhibition of JH synthesis. Results presented here provide insight into the stimulation, inhibition, and degradation of JH by activities of the ovary during the gonadotrophic cycle. Adult or larval ovaries induced to grow in last instar larval males and females, respectively, by JH analog treatment did not induce a significant increase in measured rates of TH synthesis by CA of these larvae. However, these animals had generally higher JH titers, as they produced a greater number of supernumerary larval molts than did animals treated with analog in the absence of an ovary. This suggests that male and female larval CA can respond to stimulatory effects of vitellogenic adult or larval ovaries. No active direct inhibition occurred in CA cultured in medium conditioned by ovaries from females in which TH synthesis was sharply declining. Allatostatins, neuropeptides that inhibit JH synthesis, increased in the hemolymph of mated females after JH synthesis had declined, excluding the possibility that the ovary triggers this release and thus indirectly inhibits the CA. Allatostatins may help maintain an established inhibition of the CA. As rates of JH synthesis declined following release of the spermatophore in mated females, their still-vitellogenic ovaries released JH esterase (JHE) in vitro. JHE released from the basal follicles of the ovary is nearly specific to this gonadotrophic stage and is not dependent upon protein in the medium. Ovarian JHE appeared to be different in molecular weight from hemolymph and fat body JHE, and had no direct effect on rates of JH synthesis by CA in vitro. Ovarian JHE may act locally, degrading JH around and in maturing oocytes.