Zusammenfassung der Ressource
Mechanisms of Thermal
Tolerance
- Avoiding Protein
denaturation at
high temperatures
- the Heat Shock Response
- Through heat shock proteins
- either constitutive or inducible
- Work normally folding
proteins
- when heat shock
occurs HSPs act to
refold damaged
proteins (ATP
dependent)
- Dutton and Hoffman (2009)
HsPs in field collected
Mytilus galloprovincialis
- Found a greater
response in different
populations
- southern population were used
to higher temps so difdnt
suffer as much damage
- Lower HSP expression
- Avoiding Blood
Freezing at low
temperatures
- Freeze avoidance
- Using Antifreeze proteins
- Proteins bind to ice
surface preventing more
water molecules joining
- proteins then melt the ice
- Notothenoid fish
- Cold Tolerance
- Ice Nucleating Proteins (INPs)
- Murphy (1977) looked at blood
Ca level and freezing in Ribbed
Mussel
- Found that Ca binds to
membrane reducing cell damage
during freezing
- Calcium stabilizes the membrane,
preventing denaturation
- Maintaining reactions
over a range of
temperatures
- Short Term
- Alterations of
enzyme effective
concentration
- Alterations to
concentration on the
subtrate
- Increased energy supply
for enzyme being
catalysed
- Alterations to
intracellular environment
- Mid Term
- Alterations to isoform
- e.g. myosin in slow
muscle fibres of
Common Carp
- Evolutionary
enzyme adaptions
- Somero (2010) Looked at
Enzyme bindng to NADH
in limet
- Found enzyme activity
stopped at 42 Degrees
- Each form could tolerate a
different temp
- Only differed in one amino acid
- Maintaining
membrane stability
over a range of
temperatures
- Short Term
- have to maintain cell structure
in order to maintain
Membrane structure
- Done through variation
of lipid structure
- using short, unsaturated fatty
acids (more fluid)