, Intraspecific Diversity of Scorpions' ••• ••••Venom and Its Implications on the Pathophysiological Effects

Abstract

Invertebrate and vertebrate venoms have provided a rich suite of pharmacologically important neurotoxins; many of them are directed at ion channels with a high degree of specificity. It is also established that toxins evolve at high rates by gene duplication and point substitution (Duda and Lalumbi, 1999; Smertenko et al., 2001), so the venomous animals often employ a large battery of toxins. It had been evident that, at least among snakes, high mutation rates permit significant intraspecific toxin variation (Chippaux et al., 1991; Daltry et al., 1996&1997). This kind of variation had been proved in the Egyptian scorpion species, Leiurus quinquestriatus and Scorpio maurus palmatus collected from different geographical regions (Omran and McVean, 2000; Abdel Rahman et al., 2006). It is not clear whether intraspecific venom variation is a response to changes in diet (Daltry et al., 1996), an arms race between prey and predator (Duda and Lalumbi, 1999) or is merely a product of natural molecular evolution (Sasa, 1999). There is some evidence that in pit vipers, variation is related to diet (Daltry et al., 1996). There is also indication that social factors play a part, since male and female pit vipers contain different toxin peptides (Daltry et al., 1996) as do male and female spiders of the genus Loxoscleles intermedia. In the fire ant Solenopis invicta toxin components change with body size (Deslippe and Guo, 2000).