The document discusses the venom of the black widow spider, specifically the alpha-latrotoxin neurotoxin. It describes how alpha-latrotoxin acts presynaptically to release neurotransmitters, inducing paralysis and other symptoms. Research is exploring uses of alpha-latrotoxin and other compounds in the venom in areas like male contraceptives, pesticides, and medicine.

1. Kelsey Andrew, Breanna Marcum, Michelle Sandine
BLACK WIDOW VENOM

2. 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

3. 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.

4. LATRODECTUS MACTANS

5. 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

6. 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

7. 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

8. 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

9. 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

10. 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

11. ALPHA-LATROTOXIN
• Latrotoxin
• a neurotoxin found in the
venom of spiders belonging
to the genus Latrodectus
• α-Latrotoxin (α-LTX) is the
most abundant protein found in
the venom

12. 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

13. 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 α-LTX into the membrane
• From here, three mechanisms can occur:
• Pore formation
• Membrane penetration
• Cell signaling

14. 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

15. PORE FORMATION BY Α-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

16. NERVE SIGNALING
• Latrotoxin binds to latrophilin receptor
• Activates phospholipase C
• Induces release of Ca2+
• Prompts continued exocytosis of surrounding cells

17. 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

18. 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

19. • 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

20. 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.

21. 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.

22. LATROTOXIN INSECTICIDE
• Latrotoxin contains at least five insecticidal toxins, scientists have
found (Rohou et al. 2007), in addition to a vertebrate-specific toxin
(α-latrotoxin) and a crustacean-specific toxin (α-latrocrustatoxin)
• By synthesizing a pesticide that contains only the insecticidal
toxins, crops can be protected from invertebrate pests, and
vertebrate consumers will be unaffected

23. 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

24. 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
• α-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

26. REFERENCES
Abdulrahman, 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.