Juvenile hormone esterase activity from Manduca sexta corpora allata in vitro

✍ Scribed by Thomas C. Sparks; L. Gregory Allen; Frank Schneider; Noelle A. Granger

• Publisher: John Wiley and Sons
• Year: 1989
• Tongue: English
• Weight: 999 KB
• Volume: 11
• Category: Article
• ISSN: 0739-4462
• DOI: 10.1002/arch.940110204

✦ Synopsis

Juvenile hormone esterase (JHE) activity released by the corpora allata (CA) into incubation media (CA-JHE) was titered daily during the course of the last (fifth [V]) larval stadium of Manduca sexta. This CA-JHE activity was relatively low during the early last stadium up to the time of commitment (V4), then rose rapidly to a peak on V6. Activity declined sharply almost to precommitment levels by V8, before rising to a second peak o n the first day of the pupal phase (PO). This pattern of activity i s distinct from that of hemolymph JHE activity, which peaks just prior to wandering o n V4 and again just prior to pupation (V9). Although the CA-JHE and hemolymph-JHE possess different temporal patterns of activity, isoelectric focusing, gel electrophoresis, and initial studies with selected inhibitors suggest that the enzymes responsible for the CA-JHE and hemolymph-JHE activities are similar, but not identical, in nature.

Exposure of the V6 CA in vitro to JH II (0.1 pM) or fluoromevalonolactone (FMev; 0.1 mM) produced an approximate fivefold increase and 60% decrease in JH acid synthesis, respectively. Conversely, the same treatments resulted in an inhibition (JH II) and stimulation (FMev) of CA-JHE activity. These observations suggest that JH may be involved in the direct positive feedback regulation of postwandering larval CA and that the CA-JHE may also be integrally related to this positive feedback mechanism.