THE ROLE OF JUVENILE-HORMONE AND A BRAIN FACTOR IN THE REGULATION OF VITELLOGENIN BIOSYNTHESIS IN THE LOCUST (LOCUSTA-MIGRATORIA)

In the female locust, Locusta migratoria, at the time of egg laying the biosynthesis of the major storage protein of the egg - vitellogenin - ceases in the fat body; moreover, the corresponding mRNA is stored in a nontranslatable state. It was shown that juvenile hormone alone is insufficient for repeated triggering of vitellogenin synthesis; a factor present in the brain of well-fed insects and absent in starving ones is necessary. In the presence of an analog of juvenile hormone, this factor selectively stimulates vitellogenin synthesis and has no effect on lipophorin synthesis. In an experiment in vivo it was shown that injection of females with methoprene S two days before laying in the presence of feeding prevents the turnoff of vitellogenin synthesis by the time of egg laying. It is suggested that two factors - juvenile hormone and a brain factor - are necessary for repeated activation of vitellogenin biosynthesis after egg laying.