Basso, L.R., Vasconcelos, C., Fontes, A.M., Hartfelder, K., Silva, J.A., Coelho, P.S.R., Monesi, N., Paco-Larson, M.L. (2002). The induction of DNA puff BhC4-1 gene is a late response to the increase in 20-hydroxyecdysone titers in last instar dipteran larvae.  Mech. Dev. 110(1-2): 15--26.

FBrf0141640

Research paper

The characterization of DNA puff BhC4-1 expression was extended and its response to 20-hydroxyecdysone investigated in Bradysia hygida and in transgenic Drosophila carrying the BhC4-1 gene. In both organisms the activation of BhC4-1 in salivary glands occurs at the end of the larval stage coinciding with the peak in ecdysone titers which induces metamorphosis. Injections of 20-hydroxyecdysone into mid-fourth instar larvae of B. hygida show that the induction of BhC4-1 expression, as well as amplification and puff C4 expansion, are late events induced by the hormone. This late response of BhC4-1 expression was also observed in transgenic salivary glands cultivated in the presence of 20-hydroxyecdysone. In vitro studies using transgenic Drosophila indicate that both repressor and activator factors regulate the timing of BhC4-1 expression in salivary glands.