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 What do spiders
and chili peppers have in common?
11 November 2006
Jan Siemens and others at
David Julius' lab at UCSF have discovered and
characterized novel toxins from the venom of Psalmopoeus cambridgei, which
activate capsaicin receptors.
Capsaicin
is produced by chili peppers and it and related compounds cause the burning
sensation and inflammation by activating heat receptors in the skin.
Presumably, capsaicin is used by the plants to discourage
herbivores and capsaicin is also being used as a non-lethal defensive
compound in "pepper sprays", by police and the public. Now, it appears that
at least some spiders are targeting the same receptor with their venoms for
defense against predators, causing similar effects with their own customized
proteins, a very different class of chemicals.
Unfortunately, we do not know very much about these spiders.
Psalmopoeus cambridgei is an arboreal tarantulas from the tropical forests
of Trinidad. The use of a non-lethal and seemingly eco-friendly defense like
this would appear to be very beneficial for the spider and, in a fashion,
its predators since the spider may have frequent encounters with a wide
variety of potential predators. However, this is a guess and there is much
more to learn about how this group of toxins evolved and adapted and,
perhaps, why this spider chose what appears to be a non-lethal option over
many possible toxins that might be more effective and much more lethal.
Links
SFGate.com Article in the San Francisco Chronicle
Siemens, J., S.
Zhou, et al. (2006). Spider toxins activate the capsaicin receptor to
produce inflammatory pain. Nature 444(7116): 208-212.
PubMed
Capsaicin - Wikipedia, the
free encyclopedia
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