JUVENILE-HORMONE REGULATION OF HEMOLYMPH JUVENILE-HORMONE BINDING-PROTEIN IN THE BLACK STRAIN OF THE TOBACCO HORNWORM, MANDUCA-SEXTA

Numerous studies have demonstrated regulation of specific lepidopteran proteins by pharmacological doses of insect juvenile hormone (JH). In this study, topical application of a 1 pg dose of JH I to fourth stad ium larvae of the black (bl) mutant strain of the tobacco hornworm, Ma nduca sexta, induced a 50% increase in the titer of hemolymph juvenile hormone binding protein (hjHBP). Radioimmunoassay confirmed that JH t iters were lower in bl larvae than in wild-type larvae at the time of JH treatment. Enzyme immunoassay analysis of hJHBP titers demonstrated that regulation by JH I was dose-dependent at doses up to 10 pg and t hat the response was saturated above 100 pg. Western blotting and equi librium dialysis confirmed these results and demonstrated that hjHBP f rom bl larvae had the same molecular mass and displayed the same affin ity for JH I as hJHBP isolated from wild-type larvae. Time course stud ies showed that regulation was complex: 12 h after JH I treatment, hJH BP titers were twofold lower in treated than in control bl larvae, whi te 44 h after treatment they were twofold higher. JH I regulation of h JHBP titers in bl larvae was independent of changes in total hemolymph protein. (C) 1995 Wiley-Liss, Inc.