Different Ca2+ signalling cascades manifested by mastoparan in the prothoracic glands of the tobacco hornworm, Manduca sexta, and the silkworm, Bombyx mori
✍ Scribed by Skarlatos G. Dedos; Dieter Wicher; Sabine Kaltofen; Heiner Birkenbeil
- Publisher
- John Wiley and Sons
- Year
- 2007
- Tongue
- English
- Weight
- 346 KB
- Volume
- 65
- Category
- Article
- ISSN
- 0739-4462
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✦ Synopsis
Abstract
Application of the tetradecapeptide mastoparan to the prothoracic glands (PGs) of the tobacco hornworm, Manduca sexta, and the silkworm, Bombyx mori, resulted in increases in intracellular Ca^2+^ ([Ca^2+^]~i~). In M. sexta, Gi proteins are involved in the mastoparan‐stimulated increase in [Ca^2+^]~i~. However, there is no involvement of Gi proteins in the mastoparan‐stimulated increase in [Ca^2+^]~i~ in prothoracic gland cells from B. mori. Unlike in M. sexta prothoracic glands, in B. mori prothoracic glands mastoparan increases [Ca^2+^]~i~ even in the absence of extracellular Ca^2+^. Pharmacological manipulation of the Ca^2+^ signalling cascades in the prothoracic glands of both insect species suggests that in M. sexta prothoracic glands, mastoparan's first site of action is influx of Ca^2+^ through plasma membrane Ca^2+^ channels while in B. mori prothoracic glands, mastoparan's first site of action is mobilization of Ca^2+^ from intracellular stores. In M. sexta, the combined results indicate the presence of mastoparan‐sensitive plasma membrane Ca^2+^ channels, distinct from those activated by prothoracicotropic hormone or the IP~3~ signalling cascade, that coordinate spatial increases in [Ca^2+^]~i~ in prothoracic gland cells. We propose that in B. mori, mastoparan stimulates Ca^2+^ mobilization from ryanodine‐sensitive intracellular Ca^2+^ stores in prothoracic gland cells. Arch. Insect Biochem. Physiol. 65:52–64, 2007. © 2007 Wiley‐Liss, Inc.