Larval Manduca prothoracic gland cells in vitro responded to prothoracicotropic hormone (PTTH) from neurosecretory cells of the brain with an increase of intracellular free calcium. This effect is reversible and dose-dependent. Preincubation of the glands with TMB-8 and dantrolene, which inhibit the release of calcium from intracellular stores, did not decrease the PTTH-stimulated increase in calcium, indicating that intracellular calcium stores are not involved in the control of ecdysteroidogenesis. Pharmacological studies of the PTTH effect with calcium channel blockers revealed that the increase in calcium was totally blocked by cadmium, partially inhibited by nickel and lanthanum and by amiloride, an antagonist of T-type calcium channels. All other inhibitors tested were ineffective, suggesting that the increase in cytosolic calcium is induced by opening of calcium channels, presumably of the T-type, in response to PTTH. The action of PTTH on these channels may be mediated by a G-protein as shown by the effect of mastoparan, a G-protein activator, which increased the concentration of cytosolic calcium comparable to that evoked by PTTH., Heiner Birkenbeil, and Lit
Despite the state borders, and the different socioeconomical and cultural contexts, productions of Italian opera in Prague and Dresden become considerably interconnected due the activity of the impresario Giuseppe Bustelli. During his directorship (1764-1777 in Prague, 1765-1777 in Dresden) and even in the next decade, more than 50% of the repertoire was shared. Furthermore, some of the artists performed in both cities, and the same or similar adaptations of operas were used. The main difference in repertoire consisted in opera seria productions in Prague until 1777, whereas in Dresden only opera buffa was staged since 1765. Analyses of selected works reveal some of both similar and different performing strategies and their aesthetical, practical as well as political connections., Marc Niubo., and Obsahuje bibliografické odkazy