Mammalian toxicity: cute but deadly Ross Brockman Amanda Mondragon Monica Moya Marcelo Moya Platypus Slow loris Short-tailed shrew

Introduction Toxins are compounds produced by an organism which has adverse effects on other organisms. Toxins can be produced: –Defensively –Offensively –Both Bugs, snakes and fish can be considered toxic but mammals produce toxins too! The platypus, the slow loris and the short-tailed shrew are some of the few mammals that produce toxins.

Introduction In class we have talked about venomous spiders, snakes and other toxic compounds produced by fungi, gacteria and even plants. We have not discussed venomous mammals, some of you might not have even be aware that they even existed. Not many mammalian species produce toxins but the few that do are fascinating. We selected this topic to educate our fellow classmates about their existance, how they produce the toxins and why they would even want to engage in such a metabolically expensive process. In this presentation we will show 3 mammals that produce toxins, what the toxins do, and the evolutionary significance of mammal toxicity, among other things.

A small momotreme, found exclusively on the Eastern Australian continent and Tasmania. Males have small (2-4cm) spurs on hind limbs, which function both defensive and offensively. (Torres et. al, 2005) Defensive against pets, wild dogs, and humans. Offensive against other males during breeding season. Platypus (Ornithorhynchus anatinus)

Platypus The venom: –A C-type Natriuretic Peptide (OvCNP) is one of the more prominent and biologically active toxins. –Similar to those found in some snakes and other mammals. –Numerous compounds (30+), some called novel peptides, whos function hasn’t yet been identified. (Torres et. al, 2000) OvCNP causes oedema, mast cell histamine release, swelling of tissue near the site of injection, and excruciating pain.

Platypus OvNGF and some novel proteins have been shown to have synergistic effects on the pain response felt after injection (Torres et. al, 2000) D-amino acids (identified in bacteria, yeast, and the skin of some poisonous frogs) may help to stabilize the venom while it remains stored (Torres et. al, 2005)

Platypus Evolutionary implications: - Females have ankle spurs at birth but they do not develop or store toxins. - The location of the toxin may relate to male aggression against each other. - Ectopic site for the spur was necessary because the animal feeds with a bill that is designed for electrolocation, not injection.

Platypus Evolutionary implications: - The lack of venom producing glands in adult females implies that they are gender specific for male-male competition during breeding. - However, costs are associated with the production, storage, etc. of glands and toxins that might also account for their absence in females. - Further research is needed to identify the origination, intended function, and overall costs associated with each of the toxins.

Slow Loris (Nycticebus coucang) Distribution and environment: –Primarily located in Asian rainforests from India to Indonesia to Thailand (Wilde, 1972) –Tree dwelling, nocturnal primates with shy tendencies

Slow Loris Morphology (storage of toxins) –Stored in brachial organ, a glandular area of naked skin on the flexor surface of arm –Toxin production seen in offspring as early as 6 weeks

Slow Loris Method of venomous injection –Animal licks elbow prior to biting victim –Lower jaw has specialized teeth to spread venom through body –Bites are painful and often slow healing –Toxin can also be licked over the body surface of the young to protect from predators while the parent is away (Hagey et. al, 2007)

Slow Loris Defensive or Offensive? Both? –Not understood, but most likely only defensive Loris prey (i.e. insects) not large enough to require venom to subdue Protection of offspring and habitat likely at the root of venom production (Krane et. al, 2003) Mechanism of action –Not yet completely understood –Hypothesized to be similar to cat allergen which leads to histamine response upon exposure 70% homology with two chains of Fel d 1 (major allergen from domestic cat) (Krane et. al, 2003)

Slow Loris Physiological response –Anaphylactic shock following exposure to high levels of toxin (hypotension, cyanosis of extremities, microhematuria) (Hagey et. al, 2007) Present or future medical uses –None known –Researchers still unsure whether toxin is actually “toxic”, whether it is an acquired allergen or if it is used as a possible intraspecies communication tool –Further research required

Short-Tailed Shrew (Blarina brevicauda) Distribution and environment: Found in forest and grasslands of eastern half of united states (Smithsonian).

Short-Tailed Shrew Storage of Toxins: –Submaxillary and the Sublingual glands (Kita et al. 2004)

Short-Tailed Shrew Injects venom by biting prey Venom delivered by saliva to insect’s hemolymph through the ruptured exoskeleton Can also enter through broken skin Typically target the occipital regions of the mouse’s brain (Martin 1981)

Short-Tailed Shrew Defensive or Offensive? Both? –Typically offensive purpose to capture and incapacitate prey, –Also used for defensive purposes. Humans experience a local burning sensation around the bite mark and swelling (Kita et al. 2004).

Short-Tailed Shrew Details on use of venom: –Uses venom to collect a hoard of prey that can be stored alive –Prey kept alive sustains nutritional value –Dead prey eaten first and save the comatose mouse or immobile insect (Martin 1981)

Short-Tailed Shrew Mechanism of the Venom’s action: Characterized as a kallikrein protease (Kita et al. 2004) Cleaves kininogen into bradykinin Results in vasodilation, inhibited central nervous system, and edema (Rusiniak and Back 1995)

Short-Tailed Shrew Toxicology: –LD50 for mice injected i.p ≈1 mg/kg. Death within 3 to 5 hours (Kita et al. 2004) Physiological response: –Hypotension, hind limb paralysis, irregular breathing, and convulsions (Kita et al. 2004) –The vasodilation contributes to a decrease in blood pressure (Rusiniak and Back 1995)

Short-Tailed Shrew Present or future medical uses: –Venom has been patented as a paralytic agent for blocking neuromuscular receptors, an analgesic, and an insecticide (Stewart et al 2006)

Summary of Mammalian Toxins Species Offensive Action of Toxin Defensive Action of toxin Gender Specific? Gland Location PlatypusXXYes, in Males Heel spurs Slow Loris XNoBrachial Short- tailed Shrew XXNoSalivary

Discussion Evolutionary pressures have selected for venom production in a handful of unique mammal species. Only a few of the toxins produced have been tested and shown to be similar in structure and function to reptilian forms, but most require further research to characterize the complicated protein structures.

Conclusions Toxin is produced via glands located in different parts of the animal’s bodies. All three animals produce the toxin mainly to defend themselves and their offspring. It is possible that very few mammals are poisonous because mammals are “smarter” creatures with other means of obtaining their food. Mammals also have other ways to avoid predation such as discussed in the “Evolutionary Arms Race” case in class. Some squirrels can be immune to a snake’s venom or have other means of determining the actual threat or even avoiding it.

Conclusions Further research is needed to identify the origin, intended function, and overall metabolic costs associated with each of the toxins in all three species. Very little information is available on the slow loris, further research needs to be done on this fascinating organism. Platypus Slow loris Short-tailed shrew

References Hagey, L. R., Fry, B. G. and Fitch-Snyder, H “Talking Defensively, a Dual Use for the Brachial Gland Exudate of Slow and Pygmy Lorises.” Developments in Primatology: Progress and Prospects, Primate Anti-Predator Strategies (pp ). Springer US: Krane, S., Itagaki, Y., Nakanishi, K. and Weldon, P. J “Venom” of the slow loris: sequence similarity of prosimian skin gland protein and Fel d 1 cat allergen. Naturwissenschaften, 90, Kita, M., Nakamura, Y., Okumura, Y., Ohdachi, S.D., Oba, Y., Yoshikuni, M., Kido, H., and Uemura, D. Blarina toxin, a mammalian lethal venom from the short-tailed shrew Blarina brevicauda: Isolation and Characterization Proceedings of the National Academy of Sciences of the United States of America. Vol No. 20: Martin, I. G Venom of the Short-Tailed Shrew (Blarina Brevicauda) as an Insect Immobilizing Agent. Jouranal of Mammalogy. Vol. 62. No 2: Rusiniak, M., and Back, N Kallikrein-Kininogen-Kinin System. Molecular Biology and Biotechnology 1 st ed. Berlin, Germany: Wiley-VCH. Stewart, J., Steeves, B., and Vernes, K Parylitic Peptide for Use in Neuromuscular Therapy. U.S Patent , filed November 18, 2003 and issued February 3, Smithsonian. North American Animals : Blarina brevicauda. Retrieved on March from Torres, A. M., de Plater, G., Doverskog, M., Birinyi-Strachan, L.C., Nicholson, G.M., Gallagher, C., and Kuchel, P.W. Defensin-like Peptide-2 from Platypus Venom: Member of a Class of Peptides with a Distinct Structural Fold Biochemistry Journal. Vol. 348(Pt 3): 649–656. Torres, A. M., Tsampazi, C., Geraghty, D., Paramjit, S.B., Alewood, P.F. and and Kuchel, P.W. D-Amino Acid Residue in the C- type Natriuretic Peptide from the Vemon of the Mammal, Ornithorhynchus anatinus, the Australian Platypus Biochemistry Journal. Vol. 15; 391(Pt 2): 215–220. Wilde, H Anaphylactic shock following bite by a ‘slow loris,’ Nycticebus coucang. The American Journal of Tropical Medicine and Hygiene, 21(5),