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Please use this identifier to cite or link to this item: http://hdl.handle.net/1942/3704

Title: STIMULATORY AND INHIBITORY EFFECTS OF ENDOGENOUS FACTORS IN HEAD EXTRACTS OF FORMICA-POLYCTENA (HYMENOPTERA) ON THE FLUID SECRETION OF MALPIGHIAN TUBULES
Authors: DE DECKER, Nadine
HAYES, TK
VAN KERKHOVE, Emmy
STEELS, Paul
Issue Date: 1994
Publisher: PERGAMON-ELSEVIER SCIENCE LTD
Citation: JOURNAL OF INSECT PHYSIOLOGY, 40(12). p. 1025-1036
Abstract: This study was designed to investigate the regulation of fluid secretion by the Malpighian tubules of the worker ant Formica polyctena (Hymenoptera). Different solvent systems were used to make crude head extracts and to determine the solubility of the diuretic factors. Surprisingly, when distilled water, acid acetone, methanol and 15% trifluoroacetic acid (TFA) were used as solvents, two consecutive significant stimulations of fluid secretion were obtained: the first, when adding the extract to the tubule and the second, when washing it out. Extract obtained with a fifth solvent, Ringer solution, gave an almost complete but reversible inhibition of fluid secretion. Extracts were prepurified by means of a disposable C-18 column by elution with 20, 40, 60 and 80% acetonitrile. When the fractions were kept apart the 40% acetonitrile fraction caused an inhibition of fluid secretion. The 20, 60 and 80% acetonitrile fractions on the other hand resulted in two consecutive stimulations as described above. The dose-response curve for 15% TFA extract was bell-shaped with a threshold concentration of 1 x 10(-3) heads/mu l Ringer. A maximum response (stimulation of fluid secretion by a factor of 3.3 +/- 0.72, n = 10) was observed with a concentration of 5 x 10(-2) heads/mu l Ringer. Higher concentrations resulted in small increases of fluid secretion rates and in the appearance of the second stimulation when the extract was washed out. The activity present in the heads of Formica was not destroyed by boiling or by proteolytic enzymes (trypsin, chymotrypsin, pronase E and proteinase K). Only immobilized aminopeptidase M, which destroys the activity of peptides with a free N-terminus, had a significant effect on the activity of a 15% TFA head extract. Various biogenic amines were tested for their ability to mimic the effect of the head extracts. Only octopamine and dopamine evoked a small and transient increase in secretion rate. Thus biogenic amines probably do not contribute to a large extent to the response of Formica tubules to the crude head extract. The possibility that both diuretic and antidiuretic factors are present in the extract is discussed.
Notes: LIMBURGS UNIV CENTRUM,PHYSIOL LAB,B-3590 DIEPENBEEK,BELGIUM. TEXAS A&M UNIV,INST BIOSCI & TECHNOL,DEPT ENTOMOL,TEXAS AGR EXPT STN,COLLEGE STN,TX 77843.
URI: http://hdl.handle.net/1942/3704
ISI #: A1994QB34700003
ISSN: 0022-1910
Type: Journal Contribution
Appears in Collections: Research publications

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