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Toxicon. 2002 Oct;40(10):1399-406.

Intersexual variations in the venom of the Brazilian 'armed' spider Phoneutria nigriventer (Keyserling, 1891).

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Department of Neuropharmacology, Eberhard-Karls Universität Tübingen, Germany.


Venom from male and female specimens of the medically most important Brazilian Ctenidae spider Phoneutria nigriventer (Keyserling, 1891) has been compared. Males showed a slightly higher venom yield (386 microg) than equal sized females (296 microg), while adult females showed nearly a three times higher venom yield (1079 microg). High-pressure liquid-chromatography analyses revealed differences in the venom composition between males and females. A single peak in HPLC (peak 11) was only detected in venom from females carrying egg-sacs, and sodium dodecyl sulfate-gel electrophoresis showed a series of high molecular weight proteins only in the male venom pool. The median lethal dose (LD(50)) in mice for female venom was 0.63 microg kg(-1) (95% confidence interval [0.54; 0.71] and 0.61 [0.56; 0.73] microg kg(-1)) for females with egg-sacs, when compared to the male venom which showed a LD(50) of 1.57 [1.46; 1.88] microg kg(-1). The venom of both sexes was also tested in insects using a termite bioassay with doses of 2, 3, 4, and 5 microg per termite. No effect was detected for the lowest dose of female venom, whereas all the other venom doses from both sexes caused a decreased paralysis time and death of the termites. Comparing the venom of both sexes, it was observed that female venom provoked a faster reaction than male venom. The results indicate that males and females of P.nigriventer have differing venom composition which lead to different effects in biological assays.

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