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DEPENDENCE OF ECDYSTEROID METABOLISM AND DEVELOPMENT IN HOST LARVAE ON THE TIME OF BACULOVIRUS INFECTION AND THE ACTIVITY OF THE UDP-GLUCOSYL TRANSFERASE GENE.
Citation:
Burand, J. P., J. E. Park, AND T. J. Kelly. DEPENDENCE OF ECDYSTEROID METABOLISM AND DEVELOPMENT IN HOST LARVAE ON THE TIME OF BACULOVIRUS INFECTION AND THE ACTIVITY OF THE UDP-GLUCOSYL TRANSFERASE GENE. BIOCHEMISTRY AND MOLECULAR BIOLOGY INTERNATIONAL 26(8-9):845-852, (1996).
Description:
Infection of fourth-instar gypsy moth (Lymantria dispar, Lepidoptera: Lymantriidae) larvae with the wild-type (Wt) gypsy moth baculovirus, LdNPV on the first day post-molt, or infection of fifth instars on the fifth day post-molt, results in elevated ecdysteroid levels in both hemolymph and the media of cultured prothoracic glands, when examined by radioimmunoassay and compared to mock-infected controls. In contrast, insects infected with an ecdysteroid UDP-glucosyl transferase minus [egt(-)] mutant virus show ecdysteroid levels and gland activity similar to that found in controls. UDP-glucosyl transferase causes sugar-conjugation of ecdysteroids containing a hydroxyl group at the C-22 position, and our ecdysteroid antiserum recognizes these conjugated ecdysteroids. Since we found that 20-hydroxyecdysone inhibits gland activity in culture and glucose-conjugated ecdysone, the major form of ecdysteroid in the hemolymph of Wt baculovirus-infected animals does not, the elevated level of hemolymph ecdysteroids and heightened gland activity in Wt virus-infected animals are most likely due to low levels of 20-hydroxyecdysone resulting from sugar conjugation of ecdysone by EGT. Interstingly, hemolymph ecdysteroid titer and gland activity of fifth-instar larvae infected with either the Wt or [egt(-)] virus on the first day post-molt remain at basal levels throughout the instar, with death occurring prior to pupation, suggesting that LdNPV may have a second egt-independent mechanism for regulation of host ecdysteroid levels.