Origin, evolution and functional diversification of a chemical arsenal: venom in bony and cartilaginous fish

Venoms represent a largely unstudied, yet valuable, natural resource. Venoms are also an important evolutionary innovation in the animal kingdom and have evolved separately in a number of different animals (e.g. spiders, scorpions, octopuses, reptiles, fish, mammals). Considering venoms induce extremely potent biological activities, a major limitation of venom research has been the very narrow range of venomous species investigated - surprisingly, entire groups of venomous animals remain virtually unstudied. One such group is fish, where extraordinarily little is known about the composition, evolutionary history or bioactivity of venoms found in different species, despite fish representing the largest group of venomous vertebrates after reptiles (>2,400 species).
In contrast to the predatory venoms of reptiles, fish venoms are thought to be defensive by acting to protect the individual from predation. Some recent morphological investigations into the evolutionary history of fish suggested that venom has evolved at least 15 times in different groups of bony and cartilaginous fish. However, tracing the evolution of venom with morphological characters can be complicated, because identifying the presence or absence of a venom apparatus is difficult and doesn't reveal whether multiple character changes (i.e. gain followed by loss) have occurred over time. In contrast to these studies, a number of independent observations combine to suggest that fish venoms may have evolved much earlier and less frequently than previously proposed, for example: (i) similar venom toxins are found in the venoms of very distinct fish lineages, (ii) the functional activities of different fish venoms appear to be largely conserved and (iii) antivenom raised against the venom of a single fish species is capable of neutralising the activity of venoms from completely different fish species. This evidence suggests the origin of fish venom may have occurred in an ancestral fish that existed prior to the evolutionary split of bony and cartilaginous fish.
The key aim of this study is to undertake a thorough investigation of venoms (including their toxin components and their functional activity) found in distinct fish lineages, including fascinating taxa such as the stingray, shark and lionfish and medically important species, including the stonefish and weeverfish (which are found in the waters surrounding the UK). By characterising the biodiversity of toxins found in the venoms of different fish, the evolutionary history of venom in this major vertebrate lineage can be revealed. Notably, the investigations proposed here will also determine the functional activities of different venoms and their components. Identifying the composition and bioactivity of different fish venoms will help us to: (i) understand the medical consequences that arise from the thousands of fish envenomings that occur annually and (ii) design effective new treatments that neutralise venom toxins from a wide range of fish species. Perhaps most importantly, venoms provide an exciting and largely unstudied resource for the discovery of new pharmacological diagnostics and therapeutics, particularly following the successes of drugs previously developed from snake and cone snail venoms. The research proposed here is highly likely to reveal novel targets for future pharmacological research following the identification and functional testing of toxins isolated from previously unstudied venoms.
The proposed research will predominantly be undertaken at Bangor University's School of Biological Sciences - this institute has extensive research experience in the fields of both fish biology and venom evolution. In addition, this application provides the opportunity to utilise international collaborations with experts based at the University of Queensland, Australia for the collection of venomous fish and Monash University, Australia for determining the functional activities of different fish venoms.

The non-academic beneficiaries of the proposed research are three-fold: (i) commercial parties related to the pharmaceutical/biologicals industries, (ii) zoological institutions within the public sector and (iii) national health authorities and policy makers.

The development of novel pharmaceutical or diagnostic products from naturally-occurring toxins is of great current interest. The research proposed here will investigate the pharmacological activities of a taxonomically-diverse range of previously unstudied venom components - the results of this research is therefore highly likely to reveal novel compounds pertinent to future drug development programmes. In addition, antivenom manufacturing companies may also be interested in the outcomes of the research if the alternative hypothesis is supported. Commercial collaborations will be formed with UK-based pharmaceutical companies (where possible) willing to further the development of novel biological products.

Beneficiaries within the public sector include zoological institutions such as zoos, aquariums and museums. These institutions will be able to utilise the results of the scientific research proposed here to inform the public about the venoms different fish species possess, why fish are venomous and which fish are dangerous to humans. The advance in knowledge, communicated by lay film and print media, produced by this research project is likely to be noticeably beneficial to the public sector (particularly aquariums) and therefore also to the public themselves.

Thirdly, national health authorities and policy makers throughout the world are likely to be interested in the outputs of the proposed scientific research, particularly: (i) in regions of the world with a high incidence of fish envenoming and (ii) in the event that the alternative hypothesis is supported. The results of this study will provide a rigorous framework for determining which venomous fish species are potentially dangerous to humans and will therefore inform policies relating to the hospitalisation or delivery of antivenom therapy in the event of human envenomings. For example, at the local level, this project will greatly inform UK authorities on the function of the toxin components present in the venom of weeverfish - species capable of causing mortality that are responsible for the majority of the UK's medically-important fish envenomings.

Consequently, the scientific research proposed here has the potential to contribute to the UK's: (i) wealth, through the pharmaceutical development of novel toxins, (ii) culture, through public sector information and (iii) health, by informing national authorities on the potential dangers and requirements for hospitalisation following envenomings by certain fish species. In particular, the potential development of novel pharmaceutical or diagnostic tools from fish venoms may be valuable for the long-term economic competitiveness of the UK, especially when considering the precedents set by other pharmaceuticals developed from venom components (e.g. Captopril and Exenatide). Collaborations with UK-based pharmaceutical companies will be utilised in preference of non-UK companies where feasible. In line with NERC guidelines, in the short-term, immediate benefits are likely to be provided to beneficiaries in both the public and health sectors locally and internationally, resulting in the enhanced delivery of novel scientific information to the public and informing policy makers about the relative importance of fish envenomings occurring throughout the world.