The structure of a novel insecticidal neurotoxin, omega-atracotoxin-HV1, from the venom of an Australian funnel web spider

A family of potent insecticidal toxins has recently been isolated from the venom of Australian funnel web spiders. Among these is the 37-residue peptide omega-atracotoxin-HV1 (omega-ACTX-HV1) from Hadronyche versuta. We have chemically synthesized and folded omega-ACTX-HV1, shown that it is neurotoxic, ascertained its disulphide bonding pattern, and determined its three-dimensional solution structure using NMR spectroscopy. The structure consists of a solvent-accessible beta-hairpin protruding from a disulphide-bonded globular core comprising four beta-turns. The three intramolecular disulphide bonds form a cystine knot motif similar to that seen in several other neurotoxic peptides. Despite limited sequence identity, omega-ACTX-HV1 displays significant structural homology with the omega-agatoxins and omega-conotoxins, both of which are vertebrate calcium channel antagonists; however, in contrast with these toxins, we show that omega-ACTX-HV1 inhibits insect, but not mammalian, voltage-gated calcium channel currents.

Whale sharks in Ningaloo Marine Park: managing tourism in an Australian marine protected area

The whale shark is the largest fish in the ocean, A tourism industry based on interacting with whale sharks has developed recently in Ningaloo Marine Park, off the coast of Western Australia, This is the only known, accessible place in the world where whale sharks congregate in significant numbers, Results from surveys of participants in the 'whale shark experience' are reported, with the experience found to be extremely satisfying for most consumers, Yet management questions relating to diver-to-shark separation distances, the appropriate number of operators, and the use of regulation, self-regulation and economic instruments, remain, The nexus between experiential aspects of the whale shark attraction and such management concerns is examined, and the usefulness of appropriate research in resolving management questions established, It is concluded that a judicious combination of management approaches is required to ensure the sustainable development of the whale shark tourism industry. (C) 1997 Elsevier Science Ltd.

Forecasting regional crop production using SOI phases: an example for the Australian peanut industry

Using peanuts as an example, a generic methodology is presented to forward-estimate regional crop production and associated climatic risks based on phases of the Southern Oscillation Index (SOI). Yield fluctuations caused by a highly variable rainfall environment are of concern to peanut processing and marketing bodies. The industry could profitably use forecasts of likely production to adjust their operations strategically. Significant, physically based lag-relationships exist between an index of ocean/atmosphere El Nino/Southern Oscillation phenomenon and future rainfall in Australia and elsewhere. Combining knowledge of SOI phases in November and December with output from a dynamic simulation model allows the derivation of yield probability distributions based on historic rainfall data. This information is available shortly after planting a crop and at least 3-5 months prior to harvest. The study shows that in years when the November-December SOI phase is positive there is an 80% chance of exceeding average district yields. Conversely, in years when the November-December SOI phase is either negative or rapidly falling there is only a 5% chance of exceeding average district yields, but a 95% chance of below average yields. This information allows the industry to adjust strategically for the expected volume of production. The study shows that simulation models can enhance SOI signals contained in rainfall distributions by discriminating between useful and damaging rainfall events. The methodology can be applied to other industries and regions.

The role of legal coercion in the treatment of offenders with alcohol and heroin problems

This article discusses the ethical justification for and reviews the American evidence on the effectiveness of; treatment for alcohol and heroin dependence that is provided under legal coercion to offenders whose alcohol and drug dependence has contributed to the commission of the offence with which they have been charged or convicted. The article focuses on legally coerced treatment for drink-driving offenders and heroin-dependent property offenders. it outlines the various arguments that have been made for providing such treatment under legal coercion, namely. the over-representation of alcohol and drug dependent persons in prison populations; the contributory causal role of alcohol and other drug problems in the offences that lead to their imprisonment; the high rates of relapse to drug use and criminal involvement after incarceration; the desirability of keeping injecting heroin users out of prisons as a way of reducing the transmission of infectious diseases such as HIV and hepatitis; and the putatively greater cost-effectiveness of treatment compared with incarceration. The ethical objections to legally coerced drug treatment are briefly discussed before the evidence on the effectiveness of legally coerced treatment for alcohol and other drug dependence is reviewed. The evidence, which is primarily from the USA, gives qualified support for some forms of legally coerced drug treatment provided that these programs are well resourced, carefully implemented, and their performance is monitored to ensure that they provide a humane and effective alternative to imprisonment. Expectations about what these programs can achieve also need to be realistic.

The recent Australian debate about the prohibition on cannabis use

This paper outlines the ethical arguments used in the Australian debate about whether or not to relax the prohibition on cannabis use by adults. Over the past two decades a rising prevalence of cannabis use in the Australian population has led to proposals for the decriminalization of the personal use of cannabis. Three states and territories have removed criminal penalties for personal use while criminal penalties are rarefy imposed in the remaining states. Libertarian arguments for legalization of cannabis use have attracted a great deal of media interest but very little public and political support. Other arguments in favour of decriminalization have attracted more support. One has been the utilitarian argument that prohibition has failed to deter cannabis use and the social costs of its continuation outweigh any benefits that it produces. Another has been the argument from hypocrisy that cannabis is less harmful than alcohol and so, on the grounds of consistency, if alcohol is legally available then so should cannabis. To date public opinion has not favoured legalization, although support for the decriminalization of personal cannabis use has increased. In the long term, the outcome of the debate may depend more upon trends in cannabis use and social attitudes among young adults than upon the persuasiveness of the arguments for a relaxation of the prohibition of cannabis.

Potential demand for hedging by Australian wheat producers

The potential for hedging Australian wheat with the new Sydney Futures Exchange wheat contract is examined using a theoretical hedging model parametised from previous studies. The optimal hedging ratio for an 'average' wheat farmer was found to be zero under reasonable assumptions about transaction costs and based on previously published measures of risk aversion. The estimated optimal hedging ratios were found by simulation to be quite sensitive to assumptions about the degree of risk aversion. If farmers are significantly more risk averse than is currently believed, then there is likely to be an active interest in the new futures market.

The structure of versutoxin (delta-atracotoxin-Hv1) provides insights into the binding of site 3 neurotoxins to the voltage-gated sodium channel

Background: Versutoxin (delta-ACTX-Hv1) is the major component of the venom of the Australian Blue Mountains funnel web spider, Hadronyche versuta. delta-ACTX-Hv1 produces potentially fatal neurotoxic symptoms in primates by slowing the inactivation of voltage-gated sodium channels; delta-ACTX-Hv1 is therefore a useful tool for studying sodium channel function. We have determined the three-dimensional structure of delta ACTX-Hv1 as the first step towards understanding the molecular basis of its interaction with these channels. Results: The solution structure of delta-ACTX-Hv1, determined using NMR spectroscopy, comprises a core beta region containing a triple-stranded antiparallel beta sheet, a thumb-like extension protruding from the beta region and a C-terminal 3(10) helix that is appended to the beta domain by virtue of a disulphide bond. The beta region contains a cystine knot motif similar to that seen in other neurotoxic polypeptides. The structure shows homology with mu-agatoxin-l, a spider toxin that also modifies the inactivation kinetics of vertebrate voltage-gated sodium channels. More surprisingly, delta-ACTX-Hv1 shows both sequence and structural homology with gurmarin, a plant polypeptide. This similarity leads us to suggest that the sweet-taste suppression elicited by gurmarin may result from an interaction with one of the downstream ion channels involved in sweet-taste transduction. Conclusions: delta-ACTX-Hv1 shows no structural homology with either sea anemone or alpha-scorpion toxins, both of which also modify the inactivation kinetics of voltage-gated sodium channels by interacting with channel recognition site 3. However, we have shown that delta-ACTX-Hv1 contains charged residues that are topologically related to those implicated in the binding of sea anemone and alpha-scorpion toxins to mammalian voltage-gated sodium channels, suggesting similarities in their mode of interaction with these channels.

Notopronocephalus peekayi gen. et sp. n. (Digenea: Pronocephalidae) from Australian freshwater turtles

Notopronocephalus peekayi gen, et sp, n. is described from the intestine of Elseya latisternum Gray, 1867, E. dentata (Gray, 1863) and Emydura signata Ahl, 1932 from rivers in Queensland. The new genus is distinguished by the absence of ventral glands, simple (neither diverticulate nor sinuous) caeca terminating at the anterior margin of the testes, excretory arms not uniting in forebody, single ovary, two opposite testes close to the posterior end of the body, intracaecal genital pore, vitelline follicles anterior to the testes, cirrus-sac orientated obliquely and not divided into two portions, and the uterus intracaecal. This is the first pronocephalid to be described from an Australian freshwater turtle and the first from the family Chelidae.