Ontwikkeling van 'n siftingstegniek waarmee porievorming, alfa-effekte en lise van die venoom van die skerpioengenus, Parabuthus, onderskei kan word

Abstract

Scorpions of the genus Parabuthus Pocock, 1890, including Parabuthus granulatus (Ehrenberg, 1831 ), which is regarded as the most venomous in the country, are widely distributed in southern Africa. Venom of these scorpions consists of several active components each with a different effect. The most extensively studied components are the neurotoxins, which cause the a-effect, an effect which induces Ca2+ overload in cardiac myocytes by reversing the Na+\Ca2+ exchanger. Ca2+ overload leads to cell death and hypercontraction which can easily be observed microscopically. Another effect seen with venom of the genus Parabuthus is a membrane destabilizing effect or pore-forming. The latter created a lot of interest amongst researchers; seeing that there is increasing bacterial resistance against conventional antibiotics and a new generation of pore-forming peptides might have medical potential. The cellular effects of scorpion venoms are studied mostly by specialized and expensive electrophysiological techniques and although active research on the subject has been going on for the last 3-4 years, all species found in South Africa have not yet been researched. The need for a sifting technique where effects like the a-effect, pore-forming and destabilization of the membrane can be discerned was noted. Venoms in which these effects could be identified by means of a sifting technique could then be further examined by specialized techniques such as whole-cell voltage clamping. Manual counting of live myocytes is applied in the sifting technique and veratridine- and mastoparan (melittin)-models were used to distinguish between different effects. Variations which can influence the reliability of the sifting technique were examined and haemolysis of erythrocytes was used to distinguish between cell lysis by disruption of the cell membrane and colloid osmotic lysis due to pore forming. The results showed that the a-effect can be

distinguished effectively with the veratridine model, while discernment of pore-forming with the mastoparan model was hampered by phospholipase C activity. This study led to the development of a useful, cost-effective sifting technique with several applications.