Rhythmicities of acetylcholine (ACh) and acetylcholinesterase (AChE) were studied in the mouse, Mus booduga (Gray), following intramuscular injection of scorpion, Heterometrus fulvipes (C. Koch) venom. Envenomation inhibited the activity levels of ACh and AChE in all the tissues selected for experimentation. Control animals exhibited diel rhythmicity in ACh and AChE while envenomated animals sh...

Predators feeding on toxic prey may evolve physiological resistance to the preys' toxins. Grasshopper mice (Onychomys spp.) are voracious predators of scorpions in North American deserts. Two species of grasshopper mice (Onychomys torridus and Onychomys arenicola) are broadly sympatric with two species of potentially lethal bark scorpion (Centruroides exilicauda and Centruroides vittatus) in th...

Delta-atracotoxins (delta-ACTX), isolated from the venom of Australian funnel-web spiders, are responsible for the potentially lethal envenomation syndrome seen following funnel-web spider envenomation. They are 42-residue polypeptides with four disulfides and an "inhibitor cystine-knot" motif with structural but not sequence homology to a variety of other spider and marine snail toxins. Delta-...