Evolution of venom resistance

Evolution of venom resistance - Tetrodotoxin (TTX), a Na+...

Info iconThis preview shows pages 1–18. Sign up to view the full content.

View Full Document Right Arrow Icon
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Tetrodotoxin (TTX), a Na + channel blocker is found in diverse animals Nemertines Platyhelminthes (flatworms) Chaetognaths Tunicates Echinoderms ( Astropecten scoparius ) Xanthid crabs ( Eriphia spp.) Blue ringed octopus ( Hapalochlaena sp.) Pufferfishes A few species of gobies Reports in angelfish and parrotfish Five genera of anurans (frogs) Seven genera of newts TTX resistance also known in Thamnophis sirtalis garter snakes which prey on Taricha newts
Background image of page 2
The California newt ( Taricha torosa ) produces TTX from its skin to ward off predators. http://www.wildherps.com/images/herps/standard/022712_Sierra_Newt.jp g
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
However, population of the common garter snake, ( Thamnophis sirtalis ) that overlap with the newts   have evolved TTX-resistant Na + channels and prey on newts. http://webspinners.com/coloherp/geo/species/SpePics/PicThsi.jpg
Background image of page 4
Bear Lake, Idaho East Coast Range of Taricha (newts) in gray. Snakes from different populations show different amounts of resistance to TTX: TTX resistance has evolved at least twice in garter snakes. Relatedness of populations of garter snakes based on mtDNA. Geffeney et al., 2002
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
The four domains of the Na +  channel cluster to  form an ion-permeant pore. D E K A
Background image of page 6
Structure of a Na + channel
Background image of page 7

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Muscle action potentials from the Willow Creek population of snakes is more resistant to TTX than snakes from Benton. Geffeney et al., 2002
Background image of page 8
Muscle TTX sensitivity determined from the rise time of the action potential The estimated sensitivity (K d ) was very well related to the resistance of the whole snake. Geffeney et al., 2002
Background image of page 9

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Amino acid changes in domain IV in the pore of the Na+ channel of different populations of garter snake. Geffeney et al. 2005
Background image of page 10
Geffeney et al. 2005 Transferring TTX resistance to a human channel by making snake-human chimeras. Bear Lake Benton Open symbols = snake Closed symbols = snake-human chimera
Background image of page 11

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
The TTX resistance of the cloned channels from each population matches the TTX resistance of that population’s muscles. Geffeney et al. 2005
Background image of page 12
Newt Life cycle Hatch from eggs in water, aquatic larva. Metamorphose and go out on land. Become sexually mature and return to water to breed.
Background image of page 13

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Zimmer et al., 2006
Background image of page 14
Larval salamander flee the odor of adults of their own species Zimmer et al., 2006 p = pause Hits = when the adult odor is added into the water flow and it hits the larvae.
Background image of page 15

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
TTX is found on the skin of adult newts, and in the tank water Zimmer et al., 2006
Background image of page 16
water or a standard cause the larvae to hide more. Zimmer et al., 2006
Background image of page 17

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 18
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 03/28/2012 for the course BIO 49593 taught by Professor Wanser during the Spring '10 term at University of Texas at Austin.

Page1 / 70

Evolution of venom resistance - Tetrodotoxin (TTX), a Na+...

This preview shows document pages 1 - 18. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online