PLATYPUS VENOM PLUS

More recent investigations also observed histamine release and cutaneous anaphylaxis.

Early experiments injecting platypus venom into rabbits produced intravascular coagulation, a drop in blood pressure (probably due to vasodilation), and hemorrhagic edema. Much of what is currently known about platypus venom has been gleaned from experiments during the 1800s, followed by proteomic studies during the 1990s. Limited platypus envenomation events and a lack of testing in rodent models, as is commonly done with other venoms, have prevented the thorough understanding of the altered physiology that results from venom infusion into victims. A venom L-to-D-peptide isomerase and hyaluronidase have also been discovered but not sequenced the venom also has protease activity.

PLATYPUS VENOM PLUS

It is known that platypus venom contains 19 different peptide fractions plus non-protein components, but only three of these have been fully sequenced to date: C-type natriuretic peptides (OvCNPs), defensin-like peptides (OvDLPs), and nerve growth factor (OvNGF). Progress towards identifying the components of platypus venom has been hindered, in large part because of the limited quantities of venom available for study (reviewed in ).

Blood work reveals high erythrocyte sedimentation and low total protein and serum albumin levels, and symptoms such as localized pain and muscle wasting of the affected limb persist for weeks after envenomation. It also causes nausea, gastric pain, cold sweats and lymph node swelling. Envenomation of humans causes a number of unusual symptoms, including an immediate and excruciating pain that cannot be relieved through normal first-aid practices, including morphine, and generalized 'whole body' pain. The venom system is thought to have a reproductive role, such as in territory defense, although this has not been conclusively proven (reviewed in ). In adult males, the venom glands increase in size during the spring breeding season, which is to our knowledge the only such example of temporally differential venom production. Juvenile females are also in possession of these spurs, which regress prior to adulthood the venom system develops only in the male. Male platypuses possess spurs on each hind leg that are connected to paired venom glands on the dorsocaudal aspect of the abdomen to form the crural system. However, the recently sequenced platypus genome has provided a new resource for the investigation of mammalian venom and promises to vastly improve our knowledge of the contents of platypus venom, as well as to provide insight into the evolution of this unique trait. The venom of mammals such as shrews and the platypus ( Ornithorhynchus anatinus) have been poorly studied to date, despite the fact that mammalian venom is extremely unusual and that toxins are useful sources for the development of novel pharmaceuticals drugs have been developed from the venoms of many species, including various invertebrates, snakes, lizards, and insectivores (reviewed in ). We have found similarities between putative platypus toxins and those of a number of unrelated species, providing insight into the evolution of mammalian venom. This study represents a step towards fully characterizing the first mammal venom transcriptome. We have also used homology with known proteins to speculate on the contributions of each venom component to the symptoms of platypus envenomation. 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. Thus, further functional testing is required to confirm venom activity. 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. 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). We have constructed and sequenced a cDNA library from an active platypus venom gland to identify the remaining components. 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.

Platypus venom