Anaerobiosis

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Anaerobiosis
Adaptations to Low and No Oxygen
Environments Turn off your mind, relax and
float downstream, it is Not dying, it is not
dying from Tomorrow Never Knows - Lennon and
McCartney
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Low Oxygen Environments

• Gut lumen
• Muck (Benthos)
• High altitude
• Diving
• Hypoxic Bodies of Water
• Temporal changes
• Oxygen Minimal Layer
• Eg. NE Pacific 100-900m
• Intertidal Organisms

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Anoxia Tolerance
Short Term Stored Energy (Phosphogens) creat
ine phosphate arginine phosphate
CK CP ADP ? C ATP Stored
Oxygen respiratory tract pigments
(hemo/myoglobin)
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Major effects of anoxia on cellular energetic
turnover and on intra- and
Overgaard, J. et al. J Exp Biol 20072101687-1699
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Anaerobic Glycolysis
Substrate Availability Store Glycogen- Mytilus
up to 50 of dry wgt.
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Alternative Pathways
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(No Transcript)
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Ethanol Production in Goldfish
Metabolite concentration mmol/Kg fish
Shoubridge and Hochachka, 1980
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Glycolysis (Cont.)

• Enzyme Regulation
• PFK- allosteric activation by
• Decreased ATPADP
• Decreased Citrate
• Increased Pi
• Increased NADHNAD

2. LDH isozymes H heart, M - muscle M
less sensitive to product inhibition tetramer
H4, H3M1, H2M2, H1M3, M4
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Overgaard, J. et al. J Exp Biol 20072101687-1699
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Glycolysis (Cont.)
Lactate Tolerance Buffering Strong Ion
Difference
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Metabolic Suppression
Reduction of Energy Demand (Dec.
80-99) Decrease Body Temperature Suspend
Locomotion No feeding, (no SDA) Suspend Growth
and Reproduction Organs of High Energy
Demand Heart, Brain, Kidneys Heart
Bradycardia, dec. blood pressure
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Overgaard, J. et al. J Exp Biol 20072101687-1699
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Nervous Inhibition
Channel Arrest Hypothesis Ion pumps must expend
energy to maintain transmembrane ion
gradients Na/K-ATPase anoxic turtle brain still
maintains ion gradients no change in membrane
potential decline in ATPase activity by
75 ???????????????????????????????
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Channel Arrest Model
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Patch Clamp Technique
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Control of channels?
Anoxia 42 dec. in voltage gated Na
channels 70 dec. in K efflux 65 dec. in NMDA
open probability Control Adenosine
(neurotransmitter) Increases from 2 to 20uM
during anoxia reduces NMDA mediated Ca2 influx
by 62 whole cell conductance (gw)
dec. application of A1 receptor antagonist, inc.
K efflux
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Anoxia Tolerance(Additional Challenges/)
Low Blood Flow - Anti-clotting
compounds Reperfusion Injury Antioxidant
Defense Cell Stabilization Heat Shock /
Stress Proteins - Anti Proteinase Compounds
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cDNA Microarray (gene expression)