Omega-3 Fatty Acids and the DHA Principle

254 Pages·2009·8.21 MB·English

by  Raymond C. Valentine

Omega-3 Fatty Acids
and the DHA Principle
© 2010 by Taylor and Francis Group, LLC
Omega-3 Fatty Acids
and the DHA Principle
Raymond C. Valentine
David L. Valentine
Boca Raton London New York
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Library of Congress Cataloging‑in‑Publication Data
Valentine, R. C. (Raymond Carlyle), 1936-
Omega-3 fatty acids and the DHA principle / Raymond C. Valentine, David L.
Valentine.
p. cm.
Includes bibliographical references and index.
ISBN 978-1-4398-1299-0 (hardcover : alk. paper)
1. Docosahexaenoic acid--Health aspects. 2. Omega-3 fatty acids--Health aspects. I.
Valentine, David L. II. Title.
QP752.D63V35 2010
612.3’97--dc22 2009040278
Visit the Taylor & Francis Web site at
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© 2010 by Taylor and Francis Group, LLC
Dedication
To the women in our lives: Isabella, Sienna, Carla, Annalisa, Lori, Rebecca, and Cindy,
for understanding that omega-3 fatty acids are essential for any family activity.
v
© 2010 by Taylor and Francis Group, LLC
Contents
Preface......................................................................................................................xv
Acknowledgments ..................................................................................................xvii
The Authors ............................................................................................................xix
SectIon I Introduction
Chapter 1 Molecular Biology of Omega-3 Chains as Structural Lipids:
Many Central Questions Remain Unanswered ....................................3
1.1 Membrane Lipids: Contribution to Ecology ..............................6
1.2 Extraordinary Conformational Dynamics of DHA
Predicts Extraordinary Functions and Vice Versa ....................8
1.3 Reductionist Strategy for DHA Research................................10
Selected Bibliography ........................................................................12
SectIon II evolution of DHA and the Membrane
Chapter 2 Darwinian Selection of the Fittest Membrane Lipids:
From Archaeal Isoprenoids to DHA-Enriched Rhodopsin Disks ......17
2.1 Bioenergetics as the Driver of Evolution of Lipid
Structures .................................................................................19
2.2 Do Archaea Have an Achilles’ Heel? ......................................21
2.3 DHA Drives Motion to New Speeds: Evolution of
Membranes for Vision .............................................................24
2.4 Summary .................................................................................27
Selected Bibliography ........................................................................28
Chapter 3 Coevolution of DHA Membranes and Their Proteins ........................31
3.1 Did Motion or Lack of Motion Prevail in Membranes of
ProtoCells?...............................................................................31
3.2 Which Came First—Proteins or Membranes? ........................32
3.3 Ionophores Behave as Primitive Transporters and Some
Depend on the Physical State of the Membrane ......................33
3.4 Many Archaeal Membrane Proteins Are Laterally
Immobile, but Some Can Spin.................................................36
3.5 Sensory Perception Requires Membrane Lateral Motion .......38
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viii Contents
3.6 Does Rhodopsin Move Faster in a DHA (22:6) versus
DPA (22:5) Bilayer? .................................................................39
3.7 DHA Phospholipids Liberate Membrane Enzymes/
Substrates Trapped in Lipid Rafts ...........................................40
3.8 Have Some Membrane-Bound Enzymes Evolved
Dependence on a Fluid Lipid Environment for
Biocatalysis? .........................................................................40
3.9 Phospholipid-Dependent Enzymes ..........................................41
3.10 DHA as a Space-Filling Sealant around Membrane
Proteins ....................................................................................41
3.11 Summary .................................................................................43
Selected Bibliography ........................................................................44
Chapter 4 Convergent Evolution of DHA/EPA Biosynthetic Pathways .............47
4.1 Domain Analysis of DHA/EPA Gene Clusters .......................48
4.2 The PKS Pathway ....................................................................50
4.3 Mechanism of Specificity ........................................................52
4.4 Summary .................................................................................53
Selected Bibliography ........................................................................54
Chapter 5 Membrane Evolution in a Marine Bacterium:
Capitalizing on DHA for Energy Conservation in Seawater .............55
5.1 Energy Limitation Plagues the Life of a Deep-Sea
Bacterium ................................................................................55
5.2 Moritella Has Evolved Powerful Na+ Efflux Pumps ...............57
5.3 DHA/EPA Synthesis Is Osmoregulated ..................................60
5.4 DHA Conformational Dynamics Fit to Functions Needed
in the Deep Sea ........................................................................62
5.5 Summary .................................................................................65
Selected Bibliography ........................................................................66
Chapter 6 Evolution of DHA Membranes in Human Neurons ...........................69
6.1 DHA May Reduce Na+ Leakage into Neurons ........................71
6.2 Do DHA Plasmalogens Shield Cations? ..................................73
6.3 Importance of Motion ..............................................................74
6.4 Case Histories ..........................................................................74
6.5 Summary .................................................................................79
Selected Bibliography ........................................................................79
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Contents ix
SectIon III General Properties of omega-3s and
other Membrane Lipids
Chapter 7 DHA/EPA Chains as Powerful Membrane Antifreeze ......................83
7.1 Survey of Phospholipids Based on Phase Transition
Temperatures ...........................................................................85
7.2 Ecological Distribution of Phospholipids with Ultralow
Phase Transition Temperatures ................................................86
7.3 Calibrating the Fluidizing Power of Fatty Acids .....................87
7.4 Seeding Model of DHA in Disrupting Lipid Rafts .................91
7.5 Summary .................................................................................92
Selected Bibliography ........................................................................92
Chapter 8 DHA as a Mediocre Permeability Barrier against Cations:
Water Wire Theory.............................................................................95
8.1 A Membrane-Spanning Nanotube Formed by an
Antibiotic Creates a Molecular Thread of Water That
Conducts Protons at Amazing Rates .......................................96
8.2 Water Wires Likely Form Spontaneously in Membranes .......98
8.3 DHA and Water Wires ..........................................................100
8.4 Fatty Acid Bulking for “Plugging the Proton Dike” .............101
8.5 Summary ...............................................................................105
Selected Bibliography ......................................................................106
Chapter 9 DHA/EPA Membranes as Targets of Oxidative Damage ................107
9.1 Brief Chemistry of Lipoxidation of DHA/EPA
Membranes ............................................................................108
9.2 DHA Might Be Toxic to E. coli .............................................111
9.3 Growth of EPA Recombinants of E. coli Indicates O
2
Toxicity in Vivo ......................................................................112
9.4 Yeast (Saccharomyces cerevisiae) Synthesizes Only
Monounsaturated Chains and Feeding These Cells
Polyunsaturated Chains Can Be Toxic ..................................113
9.5 C. elegans Produces EPA and Seeks or Creates Low O
2
Environments .........................................................................113
9.6 Birds ......................................................................................114
9.7 Humans: Rhodopsin Disk Membranes Are Highly
Enriched with DHA, Oxidize Rapidly, and Require
Continuous Renewal ..............................................................115
9.8 Summary ...............................................................................116
Selected Bibliography ......................................................................117
© 2010 by Taylor and Francis Group, LLC
x Contents
SectIon IV cellular Biology of omega-3s and
other Membrane Lipids
Chapter 10 Bacteria:
Environmental Modulation of Membrane Lipids for
Bioenergetic Gain .............................................................................121
10.1 Methyl-Branched Fatty Acids as Membrane Bulking
Agents ....................................................................................122
10.2 Trans Fatty Acids Play Multiple Beneficial Roles .................123
10.3 Cis-Vaccenic Acid Conformation Enables Energy-
Transducing Membranes Dependent on Cholesterol-Like
Molecules ...............................................................................126
10.4 Bacteria Might Produce Plasmalogens as H+/Na+
Blockers .................................................................................130
10.5 DHA as a Virulence Factor in a Fish Pathogen? ...................132
10.6 Summary ...............................................................................133
Selected Bibliography ......................................................................134
Chapter 11 Chloroplasts:
Harnessing DHA/EPA for Harvesting Light in the Sea ...................135
11.1 Long-Distance Electron Transport as a Rate-Limiting
Step in Photosynthesis ...........................................................138
11.2 Speeding up Long-Distance Electron Transport ...................139
11.3 A Delicate Balancing Act between Proton Permeability,
Motion, and Oxidative Stability ............................................142
11.4 Summary ...............................................................................143
Selected Bibliography ......................................................................143
Chapter 12 Mitochondria:
DHA-Cardiolipin Boosts Energy Output .........................................145
12.1 Making a Case for DHA-Cardiolipin in Fast Muscles ..........145
12.2 Possible Biochemical Roles of DHA Cardiolipin ..................148
12.3 Cardiolipin Case Histories ....................................................150
12.4 Natural Doping with DHA/EPA for Endurance Flight .........153
12.5 Summary ...............................................................................154
Selected Bibliography ......................................................................156
Chapter 13 Sperm:
Essential Roles of DHA Lead to Development of a Mechanical
Stress Hypothesis .............................................................................157
13.1 Surprise Number One: DHA Is Localized in Tail
Membranes ............................................................................158
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Contents xi
13.2 Surprise Number Two: Low O Levels in the Female
2
Reproductive Tract Protect DHA from Oxidation ................160
13.3 Surprise Number Three: Motion Is Energized by Sugar, a
Weak Energy Source, Rather than Mitochondria .................161
13.4 Surprise Number Four: Sperm Tail Membranes Are
Excitatory in Nature and Must Expend Consider able
Energy for Maintaining Na+/K+ Balance ...............................161
13.5 Surprise Number Five: Dynamic Space-Filling
Conformation of DHA ...........................................................162
13.6 Surprise Number Six: Lessons from Sperm Applied
to Neurosensory Cilia and Other Mechano-Sensitive
Membranes ............................................................................164
13.7 Surprise Number Seven: Gender Determination
Influenced by Diet? ................................................................166
13.8 Summary ...............................................................................167
Selected Bibliography ......................................................................168
SectIon V Lessons and Applications
Chapter 14 DHA/EPA Mutualism between Bacteria and Marine Animals .......171
14.1 Gastrointestinal Tract of Fish Is a Suitable Habitat for
DHA/EPA Mutualism ...........................................................171
14.2 DHA/EPA-Producing Bacteria Inhabit the Intestinal
Tracts of Certain Marine Fish and Mollusks.........................175
14.3 Mechanisms for Release of DHA/EPA to Benefit the
Host ........................................................................................176
14.4 Summary ...............................................................................179
Selected Bibliography ......................................................................179
Chapter 15 Membrane Adaptations for an Oily Environment:
Lessons from a Petroleum-Degrading Bacterium ............................181
15.1 Genomic Analysis Reveals that Na+ Bioenergetics

Evolved as a Mechanism to Marginalize Proton Leakage
Caused by Petroleum .............................................................182
15.2 Outer Membrane (OM) Lipid Structure as a Physical
Barrier against Oil .................................................................185
15.3 Other Changes .......................................................................186
15.4 Ecological Support ................................................................186
15.5 Summary ...............................................................................187
Selected Bibliography ......................................................................188
© 2010 by Taylor and Francis Group, LLC