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Journal of Experimental Biology 162,331-338 (1992)
Published by Company of Biologists 1992

Effect of Manduca Sexta Diuretic Hormone and related Peptides on isolated Malpigfflan Tubules of the House Cricket Acheta Domesticus (L.)

GEOFFREY M. COAST ¹, TIMOTHY K. HAYES ², IAIN KAY ¹, and JUM-SOOK CHUNG ¹

¹ Department of Biology, Blrkbeck College, London WC1E 7HX, UK
² Department of Entomology, Texas A & M University, Accepted College Station, TX 77843, USA

Previously, a corticotropin releasing factor (CRF)-like diuretic peptide (Manduca-DH) has been isolated from Manduca sexta and shown to stimulate fluid excretion in vivo in post-eclosion Pieris rapae adults and in pre-wandering postfeeding Manduca sexta larvae. However, Manduca- DH was reported to have no effect on Malpighian tubules in vitro.

Manduca-DH and [Nle_2,11]-Manduca-DH were synthesized in Texas and assayed in London on isolated Malpighian tubules of Acheta domesticus. Manduca- DH stimulated fluid secretion by about 60% of the maximum response achievable with extracts of corpora cardiaca and increased the production of cyclic AMP. In combination with 10^-4 mol l^-1 3-isobutyl-l-methyl xanthine (IBMX), Manduca-DH stimulated maximal secretion. A number of CRF-related peptides also stimulated fluid secretion and cyclic AMP production in cricket tubules, and the CRF antagonist -helical-CRF[_9-14] blocked the stimulation of fluid secretion by Manduca-DH. [Nle_2,11]-Manduca-DH was more active than Manduca-DH in both assays, suggesting that methionine residues in the natural peptide may become oxidized.

Taken in conjunction with previous in vivo studies, the present findings suggest that a Manduca-DH-Mke diuretic peptide is the hormone controlling post-eclosion diuresis in butterflies, and Manduca-DH was shown to stimulate both fluid secretion and cyclic AMP production in Malpighian tubules from 1-12 h posteclosion Pieris rapae adults. The function of the peptide in Manduca sexta is discussed.

Key words: diuretic hormone, Malpighian tubules, fluid secretion, cyclic AMP, Manduca sexta, Pieris rapae, Acheta domesticus

Accepted on September 5, 1991

This article has been cited by other articles:

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