Juvenile hormone activation of gene transcription in locust fat body

Transcription of a vitellogenin gene (VgB) was measured in nuclei isolated from fat body of adult female locusts, to study its relations to juvenile hormone (JH). During the first ovarian cycle, there was a correlation between the rise and fall in the hemolymph titer of JH and the rate of Vg gene transcription, At the oviposition stage, when the JH titer fell sharply, Vg transcription fell almost to zero; both JH titer and Vg transcription then rose again in the subsequent cycle, Administration of the JH analog, pyriproxyfen, to ethoxyprecocene-pretreated locusts was followed, after a lag of about 12 h, by initiation and rapid rise in Vg transcription, Data on transcription of the 21K and apoLpIII genes, although imprecise because of short probe sequences, are consistent with the induction of 21K protein and lack of effect on apoLpIII protein by JH. Total transcription in fat body nuclei was also elevated after pyriproxyfen administration to precocene-treated locusts but declined during the vitellogenic cycle, suggesting that rRNA synthesis is regulated by both JH and other cellular factors.