Mammalian Venoms Charles Norton Lisa Toelle. Mammalian Venoms Of all the diversity of mammals, there...

Mammalian Venoms

Charles Norton

Lisa Toelle

Mammalian Venoms

• Of all the diversity of mammals, there are only a few species that exhibit toxicity.

• Although skunks and pangolins emit noxious fumes, they are left out of this report due to there lack of toxicity. They are, however, mild irritants.

Solenodons

• Cuban Solenodon– Solenodon cubanus

• Haitian Solenodon– Solenodon paradoxus

Solenodons

• Characteristics– Resemble large

shrews– Nocturnal– Burrowing– Insectivores

Solenodon Venom

• Mechanism of Action– Channel in second lower incisors to deliver venom– Venomous saliva is delivered from a hollow duct,

which is connected to modified submaxillary salival glands

• Ecological Benefits– Defense– Immobilization of prey

Sources for Solenodon Information

• Folinsbee, K.E, Muller, J. and Reisz, R.R. 2007. Canine grooves: morphology, function, and relevance to venom. Journal of Vertebrate Paleontology 27(2):547–551.

• Zoological Society of London. Retrieved 3-10-09. http://www.edgeofexistence.org/conservation/solenodon.php

• The City College of New York. Retrieved 4-10-09. http://www.culturequest.us/cuba/animallife.htm

Slow Lorises

• Sunda Loris– Nycticebus coucang

• Bengal Slow Loris– Nycticebus

bengalensis

• Pygmy Slow Loris– Nyciticebus pygmaeus

Slow Lorises

• Characteristics– Only toxic primate– Slow-moving

quadrapedal– Nocturnal – Arboreal

Slow Lorises

• Venom Composition– A protein very similar to cat dander

• Mechanism of Action– Venom in saliva (from sebaceous glands near

elbows)– Suck toxin into their mouths for delivery

• Ecological Benefits– Protection from enemies

Sources for Lorises Information

• Krane, S, Itagaki, Y, Nakanishi, K, Weldon, P.J. 2003. “Venom” of the slow loris: sequence similarityof prosimian skin gland protein and Fel d 1 cat allergen. Naturwissenschaften 90:60–62.

• Fry, B. Poisonous Primate?! Retrieved 3-16-2009. Venomdoc. http://www.kingsnake.com/toxinology/loris/slow_loris.html

• National Geographic. (2008). Retrieved 4-10-09. http://news.nationalgeographic.com/news/2007/06/photogalleries/animal-pictures/

• Nature. (2009). Animal Behavior: Slow Food. Retrieved 4-10-09. Nature. http://www.nature.com/nature/journal/v443/n7109/full/ 443248a.html

Shrews

• Northern Short Tailed Shrew– Blarina brevicauda

• Eurasian Water Shrew– Neomys fodiens

Shrews

• Characteristics– Small body– Long nose– Similar appearance to

a mouse or rat

Shrews

Venom Composition– Soricidin– Blarina - BLTX

• kallikrein-like protease capable of cleaving kinins

Shrews

• Mechanisms of Action– Neurotoxic– Paralytic properties in soricidin– Hypotension due to blarina

– Protease activity

Shrew Toxin Mechanisms

NeurotoxicityNeurotoxicityParalysisParalysis HypotensionHypotension

VenomVenom

Impairment of Impairment of Target OrganismTarget Organism

Shrews

• Ecological Benefits– Helps immobilize prey– Defense

• Bite is more toxic if pregnant

– Possible medicinal uses for human pain treatment

Sources for Shrew Information• Kita M, Nakamura Y, Okumura Y, Ohdachi SD, Oba Y, Yoshikuni M, Kido

H, Uemura D. Blarina toxin, a mammalian lethal venom from the short-tailed shrew Blarina brevicauda: Isolation and characterization. Proc Natl Acad Sci USA. 2004 May 18;101(20):7542-7.

• Kita M, Nakamura Y, Okumura Y, Ohdachi SD, Oba Y, Yoshikuni M, Kido H, Uemura D. Purification and characterisation of blarinasin, a new tissue kallikrein-like protease from the short-tailed shrew Blarina brevicauda: comparative studies with blarina toxin. Biological Chemistry. February 2005, Vol. 386 Issue 2, p177-182

• Gonthier, Gilles. (2009). Retrieved 4-10-09. http://www.wildlifenorthamerica.com/Mammal/Northern-Short-tailed-Shrew/Blarina/brevicauda.html

• Biology Department, Davidson College. (1999). Retrieved 4-10-09. http://www.bio.davidson.edu/Courses/anphys/1999/Rachal/rachal2.htm

Platypus

• Ornithorhycnus anatinus

• Characteristics:– Electro-sensitive– Semi-aquatic– Mostly nocturnal– Only venomous

mammal in Australia

Platypus

• Venom Composition– Defensin-like proteins (three of which are unique to

platypuses)– Made in glands in the legs– Evolved via gene duplication of immune system

genes

Platypus

• Mechanisms of action:– Leads to edema around the area of the wound and

increases the victims sensitivity to pain.– May also result in decreased blood pressure,

respiratory distress, and slightly hemolytic– Neurological effects

• Linked to decrease in pH leading to altered ion entry

Platypus Venom

NeurologicalNeurologicalEffectsEffects

CardiovascularCardiovascularEffectsEffects

Local Edema Local Edema and Painand Pain

VenomVenom

Impairment of Impairment of Target OrganismTarget Organism

Platypus Spurs

– Delivered via spurs on hind limbs of males – Only mammals to squirt venom (not mixed

with saliva)

Spur

Platypus Video

• http://www.bbc.co.uk/mediaselector/check/nature/animals/mammals/up_close/video/ovt_platypus?size=16x9&bgc=273824&nbram=1&bbram=1

Click on Hyperlink to View Video

Platypus

• Ecological Benefits– For dominance during mating season

• only found in males

– Defense– Possible uses for medicinal research in pain

in humans

Platypus Sources

• Geristen V. Platypus poison. Protein Spotlight: Issue 29, 2002.

• Plater G, Milburn P, Martin R. Venom From the Platypus, Ornithorhynchus anatinus, Induces a Calcium-Dependent Current in Cultured Dorsal Root Ganglion Cells. J Neurophysiol 85:1340-1345, 2001.

• Luna Media Pty Ltd. (2007). Evolution of Platypus Venom Revealed. Retrieved 3-26-09. Cosmos Magazine. www.cosmosmagazine.com/news/1423/evolution-platypus-venom-revealed

• Fry, B. Platypus Venom. Retreived 3-16-2009. Venomdoc. www.kingsnake.com/toxinology/old/mammals/platypus

Summary

• Few mammals posses toxins

• The diverse mammalian clades possessing toxins suggest independent evolution.

• Toxins found in these mammals appear to be primarily for defensive purposes