Complete amino acid sequence of a new type of lethal neurotoxin from the venom of the funnel-web spider Atrax robustus.

Robustoxin, the lethal neurotoxin isolated from the venom of the male Sydney funnel-web spider, Atrax robustus, is of unique structural type and physiological mode of action. The primary structure of this 42-residue peptide was determined to be H2N-Cys-Ala-Lys-Lys-Arg-Asn-Trp-Cys-Gly-Lys-Asn-Glu-Asp-Cys-Cys-Cys-Pro- Met-Lys-Cys-Ile-Tyr-Ala-Trp-Tyr-Asn-Gln-Gln-Gly-Ser-Cys-Gln-Thr-Thr-Ile- Thr-Gly-Leu-Phe-Lys-Lys-Cys-H. The disposition of disulphide-bridged cysteine residues at both the amino- and carboxy-termini and as a triplet at residues 14-16 appears to have no precedent amongst neurotoxins.

Actions of robustoxin, a neurotoxic polypeptide from the venom of the male funnel-web spider (Atrax robustus), in anaesthetized monkeys.

Robustoxin, a polypeptide consisting of a chain of 42 amino acid residues in a known sequence, has been isolated by cation exchange chromatography from the crude venom of the male funnel-web spider (Atrax robustus). Physiological activity or toxicity in the venom fractions was detected by production of fasciculation in mouse phrenic nerve-hemidiaphragm preparations and by lethality in new-born mice. In the present experiments in Macaca fascicularis monkeys anaesthetized with pentobarbitone, robustoxin (5-30 micrograms/kg infused i.v. over 5 min) produced immediate disturbances in respiration (including dyspnoea and apnoea), blood pressure and heart rate followed by severe hypotension (mean systemic blood pressure less than 50 mmHg) or death due to respiratory and circulatory failure within 196 min. Robustoxin also produced lachrymation, salivation, generalized skeletal muscle fasciculation and a parallel increase in body temperature, and increased firing in skeletal motor and autonomic nerves. These effects closely resembled those produced by i.v. infusions over 5 min of 50 micrograms/kg of crude venom from male A. robustus spiders. Crude venom from female A. robustus spiders (500 micrograms/kg i.v. over 5 min) produced some of the effects elicited by robustoxin and crude venom from male spiders, but to a much less marked extent. It was concluded that robustoxin is responsible for the neurotoxic and lethal effects of human envenomation by male A. robustus spiders.

Protection of monkeys against the lethal effects of male funnel-web spider (Atrax robustus) venom by immunization with a toxoid.

A stable toxoid was prepared from robustoxin (the lethal polypeptide neurotoxin in the venom of the male funnel-web spider, Atrax robustus) by polymerization with glutaraldehyde. This material was non-toxic in new-born mice. Administration of the toxoid to three Macaca fascicularis monkeys (50-80 micrograms/kg s.c. at 14-day intervals for 8-12 weeks) produced no toxic effects; anti-robustoxin antibodies were detected in serum samples by immunodiffusion tests within 13-27 days. In vivo evidence of successful protection with the toxoid was obtained by challenging the monkeys with male A. robustus venom (50 micrograms/kg i.v.) under anaesthesia with pentobarbitone (one monkey), or with ketamine, halothane and nitrous oxide, 1-26 weeks after the last injection of the toxoid. Only minor respiratory, cardiovascular and skeletal motor disturbances were produced, and all monkeys recovered fully and uneventfully. Challenge with the same dose of venom in non-immunized or robustoxin N-terminal decapeptide ovalbumin conjugate-treated monkeys resulted in typical lethal neurotoxic effects, culminating in severe hypotension or death from circulatory and respiratory failure within 280 min.

Caffeine-mediated effects on reproductive health over two generations in rats.

The present study was designed to investigate the mechanism(s) underlying previously observed birth weight differences found in the first litter of the second (F2) generation bred from caffeine-exposed F1 females. The effect of exposure to caffeine in utero on subsequent sexual receptivity, fertility, gestation length, parturition, nesting activity, maternal behaviour, and reproductive senescence in the F1 mothers, and the viability of the F2 offspring was investigated. This information was collected by breeding control or caffeine exposed females for 8 consecutive litters. It was demonstrated that exposure to caffeine did not affect the sexual receptivity, fertility, gestation length, or maternal behaviour of the F1 females, but parturition was prolonged and the viability of the F2 generation was seriously jeopardized. Many F2 pups were born significantly larger than their control counterparts and a significant proportion of litters (after the first two litters) were wholly stillborn. It was concluded that a changed genetic program, mediated via the F2 fetus, delayed the normal progression of parturition. This, in turn, compromised the F1 mothers and caused increased mortality of their offspring. The severity of the outcome was dose dependent.

An endogenous antitoxin to the lethal venom of the funnel web spider, Atrax robustus, in rabbit sera.

1. An endogenous antitoxin fraction was isolated from non-immune rabbit sera by affinity chromatography with robustoxin bound to the solid support. 2. Robustoxin is the sole lethal toxin in the venom of the male funnel web spider, Atrax robustus. 3. The fraction was found to contain IgG and IgM immunoglobulins. 4. This fraction prevented or reversed the lethal actions of the crude venom in newborn mice, in mouse phrenic nerve-hemidiaphragm preparations, and in anaesthetized monkeys. 5. The antitoxin fraction is of potential value in the therapy of human envenomation by A. robustus.