Identification of a potent antidiuretic factor acting on beetle Malpighian tubules

doi:10.1073/pnas.012436199

Identification of a potent antidiuretic factor acting on beetle Malpighian tubules

^*Department of Biochemistry, University of Nevada, Reno, NV 89557-0014; and ^†Department of Zoology and Entomology, University of Pretoria, Pretoria 0002, South Africa

Edited by John H. Law, University of Arizona, Tucson, AZ, and approved October 23, 2001 (received for review August 18, 2001)

Abstract

Beetles, like other insects, depend on diuretic and antidiuretic hormones to control water balance. We have isolated, using head extracts from the beetle Tenebrio molitor, a peptide that strongly inhibits fluid secretion by the Malpighian tubules of this insect. This antidiuretic factor (ADF) appears to elicit its effect via cGMP as a second messenger but does not stimulate NO production. It has primary structure: Val-Val-Asn-Thr-Pro-Gly-His-Ala-Val-Ser-Tyr-His-Val-Tyr-OH. The ADF inhibits tubule secretion with high potency: the EC₅₀ is around 10 fM. It bears no significant resemblance to other biologically active neuropeptides. To our knowledge this is the only endogenous insect ADF acting on Malpighian tubules to be sequenced, and the first coleopteran (beetle) antidiuretic factor fully characterized to date.

cGMP‖water balance‖Tenebrio molitor‖Rhodnius prolixus‖Drosophila melanogaster

Footnotes

↵ ‡ To whom reprint requests should be addressed at: Department of Biochemistry/330, University of Nevada, Reno, NV 89557-0014. E-mail: schooley{at}unr.edu.
This paper was submitted directly (Track II) to the PNAS office.
Data deposition: The sequence reported in this paper has been deposited in the Swiss-Prot Database (accession no. P82965).
Abbreviations:

ADF,

antidiuretic factor;

EIA,

enzyme immunoassay;

RPLC,

reversed-phase liquid chromatography;

TFA,

trifluoroacetic acid