A functional comparison of the venom of three Australian jellyfish— Chironex fleckeri, Chiropsalmus sp., and Carybdea xaymacana—on cytosolic Ca 2+, haemolysis and Artemia sp. lethality

Abstract

Cnidarian venoms produce a wide spectrum of envenoming syndromes in humans ranging from minor local irritation to death. Here, the effects of Chironex fleckeri, Chiropsalmus sp., and Carybdea xaymacana venoms on ventricular myocyte cytosolic Ca 2+, haemolysis and Artemia sp. lethality are compared for the first time. All three venoms caused a large, irreversible elevation of cytosolic Ca 2+ in myocytes as measured using the Ca 2+ sensitive fluorescent probe Indo-1. The L-type Ca 2+ channel antagonist verapamil had no effect on Ca 2+ influx whilst La 3+, a non-specific channel and pore blocker, inhibited the effect. Haemolytic activity was observed for all venoms, with C. xaymacana venom displaying the greatest activity. These activities are consistent with the presence of a pore-forming toxin existing in the venoms which has been demonstrated by transmission electron microscopy in the case of C. fleckeri. The venom of C. fleckeri was found to be more lethal against Artemia sp. than the venom of the other species, consistent with the order of known human toxicities. This suggests that the observed lytic effects may not underlie the lethal effects of the venom, and raises the question of how such potent activities are dealt with by envenomed humans.