Heat shock proteins,
thermotolerance, and
biogeography in intertidal Tegula snails
Lars Tomanek
Hopkins Marine Station
Wednesday, July 21, 1999
3:00 p.m.—Pacific Forum
Heat shock
proteins (hsp’s) confer thermotolerance in organisms by preventing the denaturation
of proteins during the heat stress and by facilitating the refolding of already damaged
proteins. Their effect on interspecific differences in thermotolerance and thereby the
thermal niche that a species can occupy is still largely unknown. To examine this effect,
we compared the phenotypic variation of the heat shock response in several marine snail
species of the genus Tegula that occupy widely differing thermal niches along the
sub- to intertidal transition. Temperature at which the synthesis of hsp’s was first
induced, temperature of maximal hsp synthesis and temperature at which hsp synthesis was
heat-inactivated were lowest in the most cold-adapted (predominantly
subtidal) and highest
in the most warm-adapted (intertidal) Tegula species. Acclimation shifted induction
temperature and temperature of maximal hsp synthesis for certain hsp’s, but did not
affect the temperature at which hsp synthesis ceased. Hsp synthesis and protein synthesis
in general were heat-inactivated in cold-adapted species at 33°C, a temperature that is
commonly experienced by the warm-adapted species in the intertidal. Protein synthesis in
intertidal Tegula species was heat-inactivated at temperatures only slightly above
the highest body temperatures recorded, and because they induce the energetically costly
heat shock response frequently, intertidal species may live close to the upper end of
their thermal-tolerance range. This may make intertidal species more susceptible to the
effects of climate change.
Heat shock
proteins (hsp’s) confer thermotolerance in organisms by preventing the denaturation
of proteins during the heat stress and by facilitating the refolding of already damaged
proteins. Their effect on interspecific differences in thermotolerance and thereby the
thermal niche that a species can occupy is still largely unknown. To examine this effect,
we compared the phenotypic variation of the heat shock response in several marine snail
species of the genus Tegula that occupy widely differing thermal niches along the
sub- to intertidal transition. Temperature at which the synthesis of hsp’s was first
induced, temperature of maximal hsp synthesis and temperature at which hsp synthesis was
heat-inactivated were lowest in the most cold-adapted (predominantly
subtidal) and highest
in the most warm-adapted (intertidal) Tegula species. Acclimation shifted induction
temperature and temperature of maximal hsp synthesis for certain hsp’s, but did not
affect the temperature at which hsp synthesis ceased. Hsp synthesis and protein synthesis
in general were heat-inactivated in cold-adapted species at 33°C, a temperature that is
commonly experienced by the warm-adapted species in the intertidal. Protein synthesis in
intertidal Tegula species was heat-inactivated at temperatures only slightly above
the highest body temperatures recorded, and because they induce the energetically costly
heat shock response frequently, intertidal species may live close to the upper end of
their thermal-tolerance range. This may make intertidal species more susceptible to the
effects of climate change.