A' Range of temperature limits

1
A. Range of temperature limits

• For most organisms, -2 to 50C
• Hydrothermal vents and hot springs, some
  organisms at temps above 100C (under pressure
• Supercooled organisms can be frozen solid while
  in dormant state

2
B. Limits to temperature tolerance

• Protein denaturation and coagulation
• - organisms are literally cooked.
  Proteins unravel and are unable to function (more
  on this later in the course)

3
B. Limits to temperature tolerance

• 2. Inactivation of enzymes
• Enzymes only work while in specific
  configurations (lock and key) when shape is
  changed they no longer work

4
B. Limits to temperature tolerance

• Inadequate oxygen supply
• - respiration rates increase with temperature,
  and the demand can get so high that the organism
  literally suffocates

5
B. Limits to temperature tolerance

• Limiting steps in metabolic pathways
• A B C

If this process increases with temperature...
D
E
6
B. Limits to temperature tolerance

• Limiting steps in metabolic pathways
• A B C

If this process increases with temperature...
D
E
then there might not be enough C to make E
7
B. Limits to temperature tolerance

• Changes in membrane structure
• cells can become leaky and rupture as lipid
  bilayer is compromised

8
C. Defining Lethal Temperatures

• The maximum temperature and the duration of
  exposure experienced matter
• e.g. fly larvae (Polypedium) can survive 102C
  for one minute when dehydrated

9
C. Defining Lethal Temperatures

• The maximum temperature and the duration of
  exposure experienced matter
• e.g. fly larvae (Polypedium) can survive 102C
  for one minute when dehydrated
• dormant Triops can survive 99C for short
  periods 80C for several months

10
C. Defining Lethal Temperatures

• Tolerance at the level of the population
  (individuals vary in their responses)

100
surviving
50
0
TL50 (LT50) Temperature at which 50 of
population dies
Temperature
11
C. Defining Lethal Temperatures

• Measure LT50 for a range of exposure durations

4
Time to 50 mortality (h)
2
0
Temperature
12
Linking temperature tolerance to distribution
LT50 (1 hr)
Habitat
Snail genus
13
LT50 work

• A lot done in 1950s
• Little explanation of mechanisms causing
  mortality
• Sacrifice a lot of animals
• Cant conduct repeated measurements on the same
  animal

14
D. Non-lethal (sub-lethal) effects of
temperature

• 1. Respiration rates

species 1 species 2
50
40
30
Respiration Rate (µg/h)
20
10
0
0 10 20 30
Temperature (C)
15
D. Non-lethal (sub-lethal) effects of
temperature

• 1. Respiration rates

species 1 species 2
50
40
Temp Sp. 1 Sp. 2
30
Respiration Rate (µg/h)
20
10
0
0 10 20 30
Temperature (C)
16
Q10 measurements

• Q10 proportional change in respiration with
  every 10C change in temperature (its an
  exponential relationship)

Temp Sp. 1 Sp. 2
17
Q10 measurements

• Q10 proportional change in respiration with
  every 10C change in temperature (its an
  exponential relationship)

Temp Sp. 1 Sp. 2
x2
x2
18
Q10 measurements

• Q10 proportional change in respiration with
  every 10C change in temperature (its an
  exponential relationship)

Temp Sp. 1 Sp. 2
x2
x3
x2
x3
19
Q10 measurements
T2 - T1
10
R2 R1 Q10
Rate at T2
Rate at T1
20
Q10 measurements
10
(T2-T1)
R2
Q10
R1
21
Q10 measurements
R1 5 at T1 10C Know Q10 3 What is R2 at
T2 20C?
22
Q10 measurements
R1 5 at T1 10C Know Q10 3 What is R2 at
T2 20C?
(20-10)/10
R2 5 3 15
23
Q10 measurements
R1 7 at T1 8C Know Q10 2 What is R2 at T2
14C?
24
Q10 measurements
R1 7 at T1 8C Know Q10 2 What is R2 at T2
14C?
(14-8)/10
R2 7 2 10.61
25
Q10 measurements

• R1 10 at T1 20C
• R2 15 at T2 30C
• What is the Q10 for this individual?

26
Q10 measurements

• R1 10 at T1 20C
• R2 15 at T2 30C
• What is the Q10 for this individual?

10/10
Q10 (15/10)
1.5
27
Q10 measurements
Log linear
Exponential curve
Log (Respiration rate)
Respiration rate
Temperature
Temperature
28
Q10 does not always remain constant
Q10 decreases (or increases dramatically)
Q10 constant
Death Mayhem
Log (Respiration rate)
Temperature
29
Physiological indicators of thermal stress

• Levels of ubiquitinated proteins
• Ub proteasome pathway rids cells of denatured
  proteins
• The garbage disposal of the cell
• Direct measure of irreversible protein loss to
  the organism
• Use Ub conjugate specific antibodies

• Levels of heat shock proteins
• Hsps as chaperones rescue some proteins
• Help ameliorate loss of proteins
• Indirect measure of thermally-induced
  denaturation pressure
• Use antibodies and other techniques to measure
  Hsp levels

30
Fates of protein in the cell
hsp70 binds hydrophobic regions
native protein
protein recovery
unfolding
ubiquitin
ubiquination
proteolysis
toxic aggregation Bad!
31
Levels of Ub conjugates vary with location in sea
urchins
ug protein
32
Molecular chaperones (hsps) Protectors of
Proteins

• Discovered in the 1960s
• Function unknown until 90s
• Induced by heat stress, hence heat shock
  proteins (Hsps)
• But, they are molecular chaperones
• Aid in making new proteins
• Stabilize pre-existing proteins that are damaged
  by high temperature stress
• Changes in the protein pool a good proxy for
  energetic cost
• Despite name, induced by other forms of
  physiological stress as well

(G. Hofmann, UCSB)
33
Hsp levels vary in organisms in the field

• Levels of Hsps are higher in summer than winter
• Data for intertidal mussels

Relative levels of Hsp70
Hofmann and Somero 1995
34
How do we do this?
35
Radiolabeled samples from a single individual
25o
15o
18o
20o
23o
28o
Run protein out on gel. Dry gel and expose to
x-ray film
15o
18o
20o
23o
25o
28o
X-ray shows all protein produced. Look for band
of appropriate weight that appears at higher
temperatures
Hsp70
36
(Shade)
7C
37
Relative Hsp 70 Index
Relative Hsp 70 index
(Helmuth and Hofmann 2001. Biological Bulletin)
38
Characteristics of Fluids(Water, Air, Blood,
etc.)
39
Characteristics of Fluids

• Fluids have density (r), and thus moving fluids
  have momentum (requires a force to start or stop
  them).

40
Characteristics of Fluids

• Fluids have viscosity (even air!)
• This means that
• (a) Fluids are sticky and molecules of
  the fluid tend to stick to each other
  

41
Characteristics of Fluids

• (2) Fluids have viscosity (even air!)
• This means that
• (a) Fluids are sticky and molecules of
  the fluid tend to want to stick to each other
• (b) This tends to slow down moving fluids
  

42
Characteristics of Fluids

• (2) Fluids have viscosity (even air!)
• This means that
• (a) Fluids are sticky and molecules of
  the fluid tend to want to stick to
  each other
• (b) This tends to slow down moving fluids
• (c) viscosity (stickiness) changes with
  temperature and salinity

43
Characteristics of Fluids

• When fluids contact a solid, there is a thin
  layer that sticks very tightly to the solid
  surface.
• No-slip condition

44
Characteristics of Fluids

• When fluids contact a solid, there is a thin
  layer that sticks very tightly to the solid
  surface.
• No-slip condition
• (4) Because of the effects of viscosity, the
  stuck layer slows down the fluid above it.
  That parcel of fluid slows down the layer above
  it and so on.

45
Boundary Layers

• Fluid far away from surface is moving fast
  mainstream

No-slip condition make velocity at surface 0.
46
Boundary Layers

• Length of arrows corresponds to Velocity

Stuck fluid grabs hold (through viscosity) and
slows down (removes momentum from) overlying
layer of water
No-slip condition make velocity at surface 0.
47
Boundary Layers

• Length of arrows (streamlines) corresponds to
  Velocity

No-slip condition make velocity at surface 0.
48
Boundary layer velocity gradient near a
fluid/solid interface, resulting from the
combined effects of fluid momentum, viscosity,
and the no-slip condition
49
Boundary layers region where organisms expel
substances into and remove substances from the
surrounding fluid
50
Boundary layers region where organisms expel
substances into and remove substances from the
surrounding fluid

• Boundary layer thickness distance between
  surface and point where wall effect is no
  longer felt (distance to point where velocity
  99 of mainstream)

51
Boundary layers region where organisms expel
substances into and remove substances from the
surrounding fluid

• The rate of mixing within the boundary layer
  determines rates of heat, mass and momentum
  exchange (more on this later)

52
Organisms in Benthic Boundary Layers

• Bigger organisms get farther away from bottom and
  into higher flows

53
Organisms in Boundary Layers B.L. over bottom
Benthic boundary layer

• But organism itself creates layer w/in BBL
  Momentum Boundary Layer (MBL)

54
Layers within layers
55
Organisms in Boundary Layers

• Organism shape itself determines M.b.l. and water
  flow (streamlines) over its surface.
• More mixing greater rate of exchange

Little mixing (streamlined
Lots of mixing
56
Boundary Layers in Pipes (e.g. blood vessels,
trachea, etc)
No-slip condition make velocity at surface 0.
57
Boundary Layers in Pipes (e.g. chambers in
sponges blood vessels alveoli, etc.)
The smaller the pipe, the closer every bit of
water is to a wall -gt wall effects are felt
everywhere Takes a huge amount of energy to push
fluid through a tiny pipe (try breathing through
a soda straw!)
No-slip condition makes velocity at surface 0.
58
Boundary Layers
No-slip condition make velocity at surface 0.
59

• Boundary layer thickness d distance between
  surface and point where wall effect is no
  longer felt (distance to point where velocity
  99 of mainstream)

60

• Boundary layer thickness distance between
  surface and point where wall effect is no
  longer felt (distance to point where velocity
  99 of mainstream)
• distance that a material like an oxygen
  molecule has to travel between fluid and organism
  surface before it can be taken up or eliminated

61
Boundary Layers
Boundary layers take time to form
Leading edge
No-slip condition make velocity at surface 0.
62
Boundary Layers take time to form
d
Leading edge
x
63
x ?
d 5
r?u8
u8
d
Leading edge
x
64
Boundary layers get THINNER (more mixing) Higher
U 8 Higher r Lower m
u8
d
Leading edge
x
Where r fluid density, m dynamic viscosity
65
Boundary layers take time to form

• This also means that boundary layer wont be
  fully formed when it first hits the edge of an
  organism or object, and will increase in
  thickness in the downstream direction

66
Laminar Boundary Layers

• Well-behaved good little boundary layers

No-slip condition make velocity at surface 0.
67
And then there is reality (nature)

• At any given snapshot in time may look like

No-slip condition make velocity at surface 0.
68
Turbulent Boundary Layers

• Well-behaved, laminar boundary layers are fairly
  rare in nature
• Because of changes in mainstream velocity, bottom
  roughness, etc., most fluids in nature are
  turbulent

69
Turbulent Boundary Layers

• Time-averaged turbulent b.l.s look more orderly

No-slip condition make velocity at surface 0.
70
Turbulent Boundary Layers

• Time-averaged turbulent b.l.s look more orderly

Tend to have a steep gradient in U near bottom
-gt more mixing
No-slip condition make velocity at surface 0.
71
Models of turbulent B.L.s
These are corals, in case youre wondering
72
Models of turbulent B.L.s
Flow between corals is messy, and can be close
to 0 some distance above the bottom
Organisms act asroughness elements
73
Models of Turbulent B.L.s

• We quantify the effect of roughness elements as
  a roughness parameter or, when it is large
  enough to cause flows to be zero some distance
  away from the bottom, the zero plane
  displacement height.

74
Models of Turbulent B.L.s

• Effectively, the use of roughness parameters or
  zero plane displacement shifts the bottom (no
  slip end) of our boundary upwards......

75
Models of Turbulent B.L.s

• Effectively, the use of roughness parameters or
  zero plane displacement shifts the bottom (no
  slip end) of our boundary upwards...... and then
  we admit that we cant predict flows within the
  field of corals. Cest la vie.

76
Models of turbulent B.L.s
Back to something we can handle
Little clue what goes on in here
Organisms act asroughness elements
77
Modeling B.L.s
U (s) u ln s/s0 k

Where U(s) Time-averaged velocity at height
s u shear velocity (measure of
mixing) k von Karmans constant
(0.42) s height above bottom s0
roughness height (empirically determined)
78
Why is this equation useful?

• Once you measure velocity at a few heights, can
  use this equation to calculate velocities at
  other heights

79
Why is this equation useful?

• Once you measure velocity at a few heights, can
  use this equation to calculate velocities at
  other heights
• u (shear velocity) is a very useful metric for
  comparing rates of mixing within boundary layers

80
Calculating u
Slope u/k
U(s)
ln (s)
x intercept s0
81
The bottom line

• Hydrodynamics theory can be used to estimate the
  behavior of boundary layers, but....

82
The bottom line

• Hydrodynamics theory can be used to estimate the
  behavior of boundary layers, but.... when
  conditions get rough (e.g. within field of
  corals) the theory doesnt work.... so.....

83
Reynolds number (Re)

• way to characterize a moving fluid as it
  interacts with an object (organism)

84
Reynolds number

• way to characterize a moving fluid as it
  interacts with an object (organism)
• dimensionless number (no units)

85
Reynolds number

• way to characterize a moving fluid as it
  interacts with an object (organism)
• dimensionless number (no units)
• ratio of relative importance of inertial to
  viscous forces (high Re effect of viscosity is
  small relative to momentum of fluid)

86
Reynolds number

• Re ? U L
• ?
• where ? fluid density
• U fluid velocity (relative to
• organism)
• L characteristic length (size) of
• organism
• ? fluid dynamic viscosity
• (stickiness or internal
  friction)

87
Reynolds number can also be written as

• Re U L
• n
• where U fluid velocity (relative to
• organism)
• L characteristic length (size) of
• organism
• n fluid kinematic viscosity m/r

88
Reynolds number Yeah, so what?

• ????Conservation of Re implies conservation of
  fluid flow characteristics

89
Reynolds number Yeah, so what?

• ????Conservation of Re and turbulence implies
  conservation of fluid flow characteristics
• - can model flows in one type of fluid in
  another (e.g., model water flows in a wind
  tunnel- see Lab 3)

90
Reynolds number Yeah, so what?

• (2) Can look at really tiny organisms by using
  really viscous fluid
• Re r U L / m r U L / m
• (e.g. Monster models of plankton in syrup!)

91
Reynolds number Yeah, so what?

• ????Really weird things happen at Re lt 1
• - rakes act like paddles (like using a fork
  
• to grab a bread crumb out of honey)
• (Cheer and Koehl 1987)

92
Reynolds number Yeah, so what?

• ????Really weird things happen at Re lt 1
• - rakes act like paddles (like using a fork
  
• to grab a bread crumb out of honey)
• (Cheer and Koehl 1987)
• - Kung-Fu Fighting (push on fluid, and is felt
  relatively far away)

93
Take home message

• (1) Boundary layers are the regions where
  organisms interact with the rest of the world
• - obtain food, oxygen and dissolved nutrients
• - plants obtain carbon dioxide (for
  photosynthesis) and eliminate excess oxygen (in
  high light)
• - disperse gametes, larvae and get rid of
  sediments
• - lose water and lose or gain heat

94
Take home points

• (2) Shape of organism, and height above the
  bottom, affects the characteristics of the
  momentum boundary layer

95
Take home points

• (2) Shape of organism, and height above the
  bottom, affects the characteristics of the
  overlying boundary layer
• (3) We can broadly characterize this interaction
  of flow and organism with a Reynolds number (Re)

96
30 second break
97
Trade-offs in evolutionary design

• Fluid flow affects the exchange of heat, mass and
  momentum
• Difficult to adapt to one requirement without
  affecting others

98
Trade-offs in evolutionary design

• For example, shapes that maximize mixing of fluid
  (for increased gas exchange, etc.) also increase
  drag

99
Trade-offs in evolutionary design

• This means that it is very difficult for one
  shape to be optimal for all environmental
  challenges
• Organisms are seldom perfectly designed for
  their environments, in large part because of
  these trade-offs
• e.g., structures that maximize oxygen uptake also
  maximize water loss -gt lungs

100
References

• Costa DP, Sinervo B. 2004. Field physiology
  physiological insights from animals in nature.
  Annu. Rev. Physiol. 66209--238
• Dahlhoff EP. 2004. Biochemical indicators of
  stress and metabolism applications for marine
  ecological studies. Annu. Rev. Physiol.
  66183--207
• Feder ME, Hofmann GE. 1999. Heat-shock proteins,
  molecular chaperones, and the stress response.
  Annu. Rev. Physiol. 61243--282
• Helmuth B. and GE Hofmann. 2001. Microhabitats,
  thermal heterogeneity and physiological gradients
  of stress in the rocky intertidal zone. Biol.
  Bull., 201374-384.
• Hofmann GE, Somero GN. 1995. Evidence for protein
  damage at environmental temperature seasonal
  changes in levels of ubiquitin conjugates and
  hsp70 in the intertidal mussel Mytilus trossulus.
  J. Exp. Biol. 1981509--1518
• Hofmann GE, Somero GN. 1996. Interspecific
  variation in thermal denaturation of proteins in
  the congeneric mussels Mytilus trossulus and M.
  galloprovincialis evidence from the heat-shock
  response and protein ubiquitination. Mar. Biol.
  12665--75
• Stillman JH, Somero GN. 1996. Adaptation to
  temperature stress and aerial exposure in
  congeneric species in intertidal porcelain crabs
  (genus Petrolisthes) correlation of physiology,
  biochemistry and morphology with vertical
  distribution. J. Exp. Biol. 1991845--1855

101
References (cont.)

• Buckley BA, Owen M-E, Hofmann GE. 2001. Adjusting
  the thermostat the threshold induction
  temperature for the heat-shock response in
  intertidal mussels (genus Mytilus) changes as a
  function of thermal history. J. Exp. Biol.
  2043571--3579
• Dahlhoff EP, Buckley BA, Menge BA. 2001. Feeding
  and physiology of the rocky intertidal predator
  Nucella ostrina along an environmental gradient.
  Ecology 822816--2829
• Tomanek L, Somero GN. 1999. Evolutionary and
  acclimation-induced variation in the heat-shock
  responses of congeneric marine snails (genus
  Tegula) from different thermal habitats
  implications for limits of thermotolerance and
  biogeography. J. Exp. Biol. 2022925--2936
• Tomanek L, Sanford E. 2003. Heat-shock protein 70
  (Hsp70) as a biochemical stress indicator an
  experimental field test in two congeneric
  intertidal gastropods (Genus Tegula). Biol.
  Bull. 205276--284