Novel venom gene discovery in the platypus
1 Faculty of Veterinary Science, The University of Sydney, Regimental Crescent, Camperdown, NSW 2006, Australia
2 The Genome Center, Washington University School of Medicine, Forest Park Parkway, St Louis, Missouri 63108, USA
3 Bioinformatics Division, The Walter and Eliza Hall Institute of Medical Research, Royal Parade, Parkville, VIC 3052, Australia
4 School of Molecular Bioscience, The University of Sydney, Butlin Avenue, Camperdown, NSW 2006, Australia
Genome Biology 2010, 11:R95 doi:10.1186/gb-2010-11-9-r95Published: 29 September 2010
To date, few peptides in the complex mixture of platypus venom have been identified and sequenced, in part due to the limited amounts of platypus venom available to study. We have constructed and sequenced a cDNA library from an active platypus venom gland to identify the remaining components.
We identified 83 novel putative platypus venom genes from 13 toxin families, which are homologous to known toxins from a wide range of vertebrates (fish, reptiles, insectivores) and invertebrates (spiders, sea anemones, starfish). A number of these are expressed in tissues other than the venom gland, and at least three of these families (those with homology to toxins from distant invertebrates) may play non-toxin roles. Thus, further functional testing is required to confirm venom activity. However, the presence of similar putative toxins in such widely divergent species provides further evidence for the hypothesis that there are certain protein families that are selected preferentially during evolution to become venom peptides. We have also used homology with known proteins to speculate on the contributions of each venom component to the symptoms of platypus envenomation.
This study represents a step towards fully characterizing the first mammal venom transcriptome. We have found similarities between putative platypus toxins and those of a number of unrelated species, providing insight into the evolution of mammalian venom.