Lecture 4 - funnel web spiders Flashcards Preview

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describe the spiders within Hexathelidae

> male hexathelidae spiders are the most medically important
> toxin type that is lethal to vertebrates are the delta toxins:
- inhibit tetrodotoxin -sensitive voltage-gated sodium channels by binding to site three
- slows inactivation, causes prolongation of action potential duration resulting in repetitive firing in automatic and motor nerve fibres
> antivenom for atrax/hadrochyche


describe Theraphosidae

> all species capable of causing notable envenomations are from Africa, asia or australia. no american species cause these effects
> subfamily:
- poecilotheriinae
- selenocosmiinae
> no antivenom


describe mygalomorphae

> group of basal spiders that include tarantulas and funnelwebs
> downward pointing chelicerae


describe mesothelae

> sister group to all other spiders
> retain many plesiomorphic characterisitcs
> long-thought to lack venom but recent evidence indicates otherwise


what are in the order araneae?

> mesothelae
> mygalomorphae
> aranemorphae


what are latrodectus?

> massive neurotransmitter release
> resulting in extremely painful muscle cramping including 'ironing board' stomach
> Antivenom made in australia and usa
> red backs


describe araneomorphae

> most derived spiders
> web builders
> inward facing fangs


describe neosparassus

> occupy unique ecologica niche
> fight instead of flight behaviour
> only huntsman spiders capable of causing clinically significant systemic envenomations
> feed exclusively on insects but venom also contains a unique vertebrate specific toxin that is used for defense
> no antivenom


describe phoneutria

> priapism, loss of muscle control, severe pain, difficulty breathing and if its victim is not treated with anti-venom, death due to oxygen deprivation as a consequence of respiratory failure
> priapism causing toxins, if controlled, reduced and separated from other (lethal) toxins has significant potential as a new viagra
> antivenom in brazil


describe loxosceles

> tissue destroying venom
> mexican antivenom


Describe sicariidae

> pruduce sphingomyelinase
> destroy mylein sheaths


what is the evolutionary purpose of venoms?

> defence
> competitor deterrence
> prey capture


compare and contrast veno to poison

> poison
- a toxin that gains entry to the body via the gastrointestional tract, the respiratory tract of absorbtion through intact body layers (e.g., ciguatoxin). typically alkaloidal or other ring structures
> Venom:
- a toxin or mixture of toxins that normally gain access to the body by injection through the intact skin (e.g, by a fish spine or snake fang). typically proteins or peptides


Describe venom toxins

> complex mixtures
- proteins
- salts
- organic molecules
> proteins
- result of 'toxin recruitment events'
- source from diverse tissues
- toxin genes were amplified to obtain multigene families
- extensive neofunctionalisation