![]() The Natural History of Shrews, Cornell University Press, Ithaca, NY (1990). These results strongly indicated that platypus venom contains tissue kallikrein-like protease(s), and its proteolytic activity might synergistically contribute to toxicity through the specific cleavage of other venom constituents.ġ M. ![]() We also established that its proteinous venom fraction strongly hydrolyzed Pro–Phe–Arg–MCA and cleaved a human low-molecular-weight kininogen (LK), similar to porcine pancreas kallikrein. This heptapeptide induced a significant increase in i in IMR-32 cells at 75 μM had relatively specific affinities for glutamate, histamine, and GABA A receptors and facilitated neurogenic twitching in guinea pig ileum specimens at 30 μM. Guided by this assay, we identified 11 unique peptides, including peptide H–His–Asp–His–Pro–Asn–Pro–Arg–OH, which coincided with the N-terminal domain residues of Ornithorhynchus venom C-type natriuretic peptide (OvCNP). We found that crude platypus venom produced potent Ca 2+ influx in human neuroblastoma IMR-32 cells. However, the structure and function of the poison’s active compounds are still imcompletely characterized. The adult male platypus carries a spur on each hind leg, which it uses to inject competitors with poison. Among them, the duckbill platypus ( Ornithorhynchus anatinus) is one of the two venomous Australian mammals. Similar spurs are found in many archaic mammal groups, indicating that this is an ancient characteristic for mammals as a whole, and not exclusive to the platypus or other monotremes.Venomous mammals are rare, and only a few species in the orders Insectivora and Monotremata produce toxic venom. Since only males produce venom and production rises during the breeding season, it may be used as an offensive weapon to assert dominance during this period. ![]() The venom appears to have a different function from those produced by non-mammalian species its effects are not life-threatening to humans, but nevertheless powerful enough to seriously impair the victim. The female platypus, in common with echidnas, has rudimentary spur buds that do not develop (dropping off before the end of their first year) and lack functional crural glands. Venom is produced in the crural glands of the male, which are kidney-shaped alveolar glands connected by a thin-walled duct to a calcaneus spur on each hind limb. ![]() Oedema rapidly develops around the wound and gradually spreads throughout the affected limb. Although powerful enough to kill smaller animals such as dogs, the venom is not lethal to humans, but the pain is so excruciating that the victim may be incapacitated. The function of defensins is to cause lysis in pathogenic bacteria and viruses, but in platypuses, they also are formed into venom for defense. The DLPs are produced by the immune system of the platypus. While both male and female platypuses are born with ankle spurs, only the spurs on the male's back ankles deliver venom, composed largely of defensin-like proteins (DLPs), three of which are unique to the platypus.
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