Ecdysteroid sexta

Vogt R. G., Rybczynski R., Cruz M. and Lerner M. R. (1993) Ecdysteroid regulation of olfactory protein expression in the developing antenna of the tobacco hawk moth, Manduca sexta. J. Neurobiolol. 22, 581-597. 

Expression of PBPs starts 3 days before adult eclosion in L. dispar (Vogt et al., 1989) and 35 10 h before adult emergence in M. sexta (Vogt et al., 1993), with the expression being induced by the decline in ecdysteroid levels. It has been estimated that in L. dispar PBPs undergo a combined steady-state turnover of 8 x 107 molecules per hour per sensillum (Vogt et al., 1989). 

To verify in vitro results, we have also developed an in vivo assay for L. dispar PTTH (52, Thyagaraja et al, in preparation). This assay is comparable to larval assays develop for Af. sexta (56 and B. mori (58) and uses last instar female larvae. Neck ligation prior to day 7, the day when a small pre-peak in hemolymph ecdysteroid titer appears, blocks further development. Injection of PTTH-containing extracts posterior to the ligation, including post-embryonic egg extract, reinitiates development and subsequent pupation. Attempts to develop an in vivo assay comparable to the pupal-adult B. mori assay (5B were unsuccessful, since brain removal as close as 15 min post-pupal ecdysis failed to block L. dispar female adult development (Thyagaraja et a/., unpublished results). 

Free and Conjugated Ecdysteroids in the Tobacco Hornworm, Manduca sexta, at Various Developmental Stages... 

The molting hormones (MHs) and ecdysteroids of the tobacco hornworm (Manduca sexta L.) at different developmental stages are discussed. From this insect nine ecdysteroids have been identified and each has varying degrees of MH activity. There are also qualitative and quantitative differences at the various stages. 20-Hydroxyecdysone is the major ecdysteroid of Manduca during pupal-adult development at peak titer of Mh activity. Five days later, 20,26-dihydroxyecdysone is the major ecdysteroid. 

Studies on the pre-adult ecdysteroidogenins are extensive but include few species. Much of the work was recently reviewed, including studies on the biosynthesis and secretion of ecdysteroids by the PGs (796). More specific reviews on B. mori have dealt primarily with peptide and gene isolation, cellular localization and titer 197-201), specific reviews on M. sexta have dealt primarily with cellular localization, mode of action and titer 202-205), and those on the gypsy moth, Lymantria dispar primarily with isolation and titer 206,207),... 

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