JUVENILE-HORMONE ACTIVATION OF GENE-TRANSCRIPTION IN LOCUST FAT-BODY

Transcription of a vitellogenin gene (VgB) was measured in nuclei isol ated from fat body of adult female locusts, to study its relations to juvenile hormone (JH). During the first ovarian cycle, there was a cor relation between the rise and fall in the hemolymph titer of JH and th e rate of Vg gene transcription, At the oviposition stage, when the JH titer fell sharply, Vg transcription fell almost to zero; both JH tit er and Vg transcription then rose again in the subsequent cycle, Admin istration of the JH analog, pyriproxyfen, to ethoxyprecocene-pretreate d locusts was followed, after a lag of about 12 h, by initiation and r apid rise in Vg transcription, Data on transcription of the 21K and ap oLpIII genes, although imprecise because of short probe sequences, are consistent with the induction of 21K protein and lack of effect on ap oLpIII protein by JH. Total transcription in fat body nuclei was also elevated after pyriproxyfen administration to precocene-treated locust s but declined during the vitellogenic cycle, suggesting that rRNA syn thesis is regulated by both JH and other cellular factors.