HIDDEN FACE OF JUVENILE-HORMONE METABOLISM IN THE AFRICAN LOCUST

In the African locust, Locusta migratoria, we have investigated new pa thways for JH metabolism. The JH biosynthetic pathway was studied by i ncubating corpora allata in vitro. Corpora allata released JH-III and JH-III diol as well as 3 unknown methylated isoprenoids. All are parti ally separated using reverse-phase HPLC (RP-HPLC) and are completely r esolved using normal phase HPLC (NP-HPLC). The biosynthetic pathways o f these unknown molecules are not entirely defined, but they could be formed in part from JH-III. Their production is completely suppressed when corpora allata are incubated with mono-oxygenase inhibitors (carb on monoxide and piperonyl butoxide). The JH degradative pathway was in vestigated using labeled JH-III and changing the pH of the mobile phas e of the RP-HPLC procedure. We found 2 unknown catabolites of JH-III p roduced in situ. One of these molecules seems to be the major end prod uct of JH-III catabolism in vivo. In vitro these new catabolites are e ssentially produced by the fat body. Their biosynthesis is inhibited b y piperonyl butoxide. Our data suggest that JH metabolism in the locus t is more complex than previously thought. It seems that monooxygenase s may play an important role in JH metabolism pathway. Possible physio logical relevance of these additional JH-related molecules is discusse d. (C) 1996 Wiley-Liss, Inc.