Kelsey Andrew, Breanna Marcum, Michelle Sandine

BLACK WIDOW VENOM

WHAT IS A TOXIN?• A substance produced by an organism that can

harm (have an adverse effect on) another organism

• Venom: a mixture of individual toxins

• Chosen Toxin: Latrotoxin, the venom produced by the Black Widow Spider

WHY WE CHOSE LATROTOXIN

• We are interested in this toxin because the Black Widow is prevalent in New Mexico and the United States. We were curious to discover the effects, as well as other uses of the toxin in its venom. Research has begun in investigating the use of Latrotoxin in medicine, agriculture, and other

fields.

LATRODECTUS MACTANS

ECOLOGY OF THE BLACK WIDOW• Distribution

• Occurs worldwide and is the most widespread venomous land animal

• within the US, as far north as MA and NH; as far south as FL; as far west as CA

• Occurs in all 4 deserts of the southwest US

• Habitat

• Prefer dark, sheltered regions close to the ground

• Webs can be found in any cluttered, dark embankments or crevices

BEHAVIOR• Usually timid, solitary, and nocturnal

• Can be cannibalistic

• Females have been known to sometimes kill and eat males after mating with them

• Important ecological role in controlling insect populations

• Have only one known natural predator

• Mud-dauber wasps will paralyze spiders and feed them to their young

ANATOMY OF THE BLACK WIDOW• Females are coal black in color, averaging 8-10mm with long slender legs and a

red hourglass mark on the abdomen

• Some have just a few red spots or no marking at all

• Males are 3-4mm in length, with longer legs than the female

• Females have larger venom glands and their venom can be up to 3 times as potent as a male’s

VENOM DELIVERY• Injection via fangs (usually enlarged in the female)

• Used both offensively and defensively• Offensively: to aid in digestion of prey outside of the body, allowing the

spider to ingest prey

• Defensively: as a defense mechanism against predators

SYMPTOMS OF A BLACK WIDOW BITE• Minimal to sharp pain, followed by

swelling and redness at site

• Muscle spasms and cramps, starting at site and spreading outwards

• Chills, fever, nausea/vomiting

• Sweating

• Severe abdominal, back, or chest pain

• Headache

• Severe high blood pressure

DEATH BY LACTODECTRUS MACTANS

• Although severe symptoms, such as coma and death have occurred, most victims of Black Widow bites fully recover without any long-lasting adverse effects

ALPHA-LATROTOXIN• Latrotoxin

• a neurotoxin found in the venom of spiders belonging to the genus Latrodectus

• -Latrotoxin (-LTX) is the most abundant protein found in the venom

SYNTHESIS OF ALPHA-LATROTOXIN• Synthesized in secretory epithelial cells of the venom

glands

• When the DNA sequence is transcribed and translated, an inactive form of the toxin is formed

• This molecule goes through post-translational processing where the active toxin is then found

FUNCTION AND MECHANISM• Acts presynaptically to release neurotransmitters from

sensory and motor neurons, as well as on endocrine cells (Frontali et al. 1976)

• Interacts with neuronal membrane receptors, which leads to the insertion of the -LTX into the membrane

• From here, three mechanisms can occur:• Pore formation

• Membrane penetration

• Cell signaling

FUNCTION AND MECHANISM (CONT.)

• Induces exocytosis of neurotransmitters from neurons and peptide hormones via calcium-dependent pathways (Hlubek et al. 2003)

• Neurotransmitters bind to and activate neuronal receptors

• Neurexins, latrophilins (Sudhof 2001)

• Triggers pain, paralysis, and other symptoms

PORE FORMATION BY -LTX• Pores are permeable to calcium ions

• Allows for an influx of Ca2+ ions into cell

• Influx induces exocytosis

• Pores are permeable to neurotransmitters

• Leakage of neurotransmitters into synaptic cleft

• Pores are permeable to water

• Causes nerve swelling to the point of cell death

NERVE SIGNALING• Latrotoxin binds to latrophilin receptor

• Activates phospholipase C

• Induces release of Ca2+

• Prompts continued exocytosis of surrounding cells

DISCOVERY OF LATROTOXIN• Black widow spider first studied by ancient Greeks

• Modern science:

• Discovered in 1930’s

• Further studied in the 1970’s after its demonstration of synaptic neurotransmitter release

• Toxin was isolated in 1976

• Studies have continued and are being done on its neurotoxic properties for application in the medical and agricultural realms

APPLICATIONS OF LATROTOXIN• Medical

• Uses in biological warfare

• Possible male contraceptive derived from the venom because of its ion channel manipulation abilities

• Agriculture

• Possible pesticide/insecticidal use

• Research on latrotoxin as a male contraceptive has been conducted, and is being continued.

• Mammalian sperm become functional as they travel through the female genital tract, due to hyperpolarization of the plasma membrane (Navarrete et al. 2011).

• Introduction of latrotoxin to sperm cells counteracts their functional activation by blocking potassium channels and causing depolarization (Navarrete et al. 2011, Parodi et al. 2010).

MALE CONTRACEPTIVES

MILITARY USE AS BIOLOGICAL WEAPON• Latrotoxin is one of many neurotoxins considered for use as a

biological weapon (Dixit 2005).

• Mainly because…

• As a neurotoxin it would be neither infectious nor contagious.

• It has rapid effects and at certain concentrations, has high lethality.

• Difficult to detect and easy to disperse.

SPIDER VENOM AS AN…INSECTICIDE?

• As recently as Feb 3 of this year, BBC News reported on the use of latrotoxin in new farming technologies to combat invertebrate pests worldwide.

• peptides in the toxin attack insects that chew on vegetables, fruits, and vines

• As a “bio pesticide,” a latrotoxin-infused product would be environmentally stable and would likely not affect mammals, fish, or other vertebrates adversely.

LATROTOXIN INSECTICIDE• Latrotoxin contains at least five insecticidal toxins, scientists have

found (Rohou et al. 2007), in addition to a vertebrate-specific toxin (-latrotoxin) and a crustacean-specific toxin (-latrocrustatoxin)

• By synthesizing a pesticide that contains only the insecticidal toxins, crops can be protected from invertebrate pests, and vertebrate consumers will be unaffected

THAT MUST REQUIRE A LOT OF SPIDER VENOM…RIGHT?• Actually, a few peptides can be isolated from the latrotoxin and

introduced to yeast

• The yeast then produces more peptides

• These peptides are then harvested by scientists for research

• So a natural, environmentally stable, and responsible insecticide might be just around the corner

• The use of an environmentally stable pesticide could drastically change agriculture all over the globe, and would have lasting and vital effect on crops for populations in developing countries

CONCLUSION• Black widows are the most venomous organisms in North America

• Latrotoxin is one of the compounds present in Black Widow Spider venom

• Latrotoxin contains various neurotoxins

• -latrotoxin is the most abundant protein found in the venom, and is vertebrate-specific

• Acts presynaptically to release neurotransmitters from neurons and endocrine cells via pore formation, membrane penetration, and nerve signaling

• Current research is being performed in a variety of fields on the uses of latrotoxin

• Possible uses:

• Male contraceptives

• Biological warfare

• Insecticide for crops

REFERENCESAbdulrahman, S. Black Widow Spider: Alpha Latrotoxin. Retrieved March 24, 2013 from http://www.slideshare.net/ShireenAbdulrahman/black-widow-spider-alpha-latrotoxin-edited.

Dixit, A. 2005. Military potential of biological neurotoxins. Toxin Reviews. 24(2): 175-207.

Hlubek, M., Tian, D., Stuenkel, E.L. 2003. Mechanism of alpha-latrotoxin action at nerve endings of neurohypophysis. Brain Res. 992(1): 30-42.

Frontali N, Ceccarelli B, Gorio A, Mauro A, Siekevitz P, Tzeng MC, Hurlbut, WP (1976) Purification from black widow spider venom of a protein factor causing the depletion of synaptic vesicles at neuromuscular junctions. J Cell Biol 68:462–479.

Melik, J. Spider venom inspires new farming methods. BBC News. Retrieved February 3, 2013 from http://www.bbc.co.uk/news/business-21296132

National Geographic. Black Widow Spider: Lactrodectus hesperus. Retrieved March 24, 2013 from http://animals.nationalgeographic.com/animals/bugs/black-widow-spider/

Navarrete, G.P., Ormeno, D., Miranda, A., Sanchez, G.R., Romero, M.F., Parodi, R.J. 2011. Molecular characterization, electrophysiological and contraceptive effect of Chilean latrodectus venom. Int. J. Morphol. 29(3): 733-741.

Parodi, J., Navarrete, P., Marconi, M., Gutierrez, R.S., Martinez-Torres, A., Mejias, F.R. 2010. Tetraethylammonium-Sensitive K+ current in the bovine spermatozoa and its blocking by the venom of the chilean latrodectus mactans. Systems Biology in Reproductive Medicine. 56: 37-43.

Rohou, A., Nield, J., Ushkaryov, Y.A. 2006. Insecticidal toxins from black widow spider venom. Toxicon. 49(4): 531-49.

Sudhof, T. 2001. Alpha-Latrotoxin and its receptors: neurexins and CIRL/latrophilins. Ann Rev Neurosci. 24: 933-62.

The deadly venom being used as medicine. 2012. Retrieved March 24, 2013 from http://www.telegraph.co.uk/health/healthnews/9248208/The-deadly-venom-being-used-as-medicine.html

Ushkaryov, Y.A., Rohov, A., Sugita, S. 2008. α-latrotoxin and its receptors. Handb Exp Pharmacol. 184:171-206.