Neuroprotecting globins in the marine mammal brain Photo credit: democraticunderground.com.
Transcript of Neuroprotecting globins in the marine mammal brain Photo credit: democraticunderground.com.
Mammalian breath hold capabilities( in minutes)
Human* 1
Polar bear 1.5
Sea otter 5
Porpoise 15
Seal 15-28
Greenland Whale 60
Sperm whale 90
Bottlenose whale 120
*Crazy Swiss man, Peter Colat, 19 min. 21 s
Photo credit: news.discovery.com
Photo credit: puertogaleradive.com
Basis for this field of research:
Energy we think they gain from one breath
<<Energy we think they spend while submerged
Basis for this field of research:
Energy we think they gain from one breath
<<Energy we think they spend while submerged
If above is true, you would expect:
Evidence heavy reliance onanaerobic metabolism
Photo credit: puertogaleradive.com
Basis for this field of research:
Energy we think they gain from one breath
<<Energy we think they spend while submerged
If above is true, you would expect:
Evidence heavy reliance onanaerobic metabolism
Photo credit: puertogaleradive.com
Basis for this field of research:
Energy we think they gain from one breath
<<Energy we think they spend while submerged
Photo credit: puertogaleradive.com
Then, above statement must not be true…
Basis for this field of research:
Energy we think they gain from one breath
<<Energy we think they spend while submerged
Photo credit: puertogaleradive.com
Then, above statement must not be true…
Now what?
Basis for this field of research:
Energy we think they gain from one breath
<<Energy we think they spend while submerged
Photo credit: puertogaleradive.com
Then, above statement must not be true…
Now what? Look for adaptations!
What researchers found:
1870 Paul Bert - limits blood volume
1930s & 1940s -• Body size• Total blood volume• RBC mass• Hematocrit • Muscle [myoglobin]
Figure credit: Hochachka and Somero 2002
What researchers found:
1870 Paul Bert - limits blood volume
1930s & 1940s -• Body size• Total blood volume• RBC mass• Hematocrit • Muscle [myoglobin]
Photo credit: doc.govt.nz
Dive response concept:
• Apnea• Bradycardia• Peripheral vasoconstriction• Hypometabolism
Helps us understand balance:• Energy in one breath• Energy used in
prolonged dive
Interrelatedness of dive response components:
Apnea Bradycardia Drop in cardiac output
(CO = stroke volume x heart rate (vol/min))
Drop in arterial BP
Interrelatedness of dive response components:
Apnea Bradycardia Drop in cardiac output
Drop in arterial BP
Interrelatedness of dive response components:
Apnea Bradycardia Drop in cardiac output
X
BP remains stable
Interrelatedness of dive response components:
Apnea Bradycardia Drop in cardiac outputwhile
Vasoconstriction
BP remains stable
Interrelatedness of dive response components:
Apnea Bradycardia Drop in cardiac outputwhile
Vasoconstriction
Hypometabolism
BP remains stable
Interrelatedness of dive response components:
Apnea Bradycardia Drop in cardiac outputwhile
Vasoconstriction
Hypometabolism
(energy saved in bypassing non-vital organs 2-3ºC drop in body temperature)
How would you monitor these responses?
• Heart monitors• Backpack cameras• Lactate dehydrogenase levels
Figure credit: Davis et al. 1999
Photo credit: ctap4.org
Dive response concept:
• Apnea• Bradycardia• Peripheral vasoconstriction• Hypometabolism
How do these relate to:
• Body size• Total blood volume• RBC mass• Hematocrit • Muscle [myoglobin]
Photo credit: wikipedia.com
Globins
• Proteins with heme group• Involved in oxygen binding and transfer
• Hemoglobin (Hb)• Myoglobin (Mb)• Cytoglobin (Cb)• Neuroglobin (Nb)
Photo credit: brainviews.com
Cerebral cortex
• Thin sheet of neural tissue• Plays role in:
• Memory• Attention• Perceptual awareness• Thought• Language• Consciousness
Researchers still think blood oxygen levels in diving mammals are too low to sustain activity…
Williams et al. 2008 Hypothesis:
• Enhanced levels of neuroprotecting globins are an additional adaptation for a diving lifestyle
Williams et al. 2008 Methods:
• Group globins:• Circulating (Hb)• Resident (Cb and Nb)
• Measure in cerebral cortex of 16 species• Running, swimming, diving• Prolonged mortality events• Spectrophotometric determination• mRNA expression
Williams et al. 2008 Results:
• Globin levels correlated with activity group
Figure credit: Williams et al. 2008
Williams et al. 2008 Results:
• Hb and RNGs significantly higher in diving marine mammals compared to terrestrial species
Figure credit: Williams et al. 2008
Williams et al. 2008 Results:
• RNG levels inversely correlated with dive duration
Figure credit: Williams et al. 2008
Williams et al. 2008 Discussion:
• Elevated RNG and Hb levels are adaptations for activity type
• Enhance diving response
• Cope with low oxygen levels during prolonged dives
• Circulating and resident globins provide complementary support