Aestivation (eBook)

Navas_FM.pdf 1
Navas_Ch01.pdf 14
Chapter 1 14
Metabolic Depression: A Historical Perspective 14
1.1 Introduction 15
1.2 Cryptobiosis 16
1.3 Dormancy 21
1.4 Ectothermic Animals 22
1.5 Endothermic Animals 26
References 31
Navas_Ch02.pdf 37
Chapter 2 37
Metabolic Regulation and Gene Expression During Aestivation 37
2.1 Introduction 38
2.2 Metabolic Control by Reversible Phosphorylation in Aestivation 39
2.2.1 Glucose-6-Phosphate Dehydrogenase 40
2.2.2 Ion Motive ATPases 41
2.2.3 Protein Synthesis 42
2.2.4 Protein Degradation 45
2.3 Signaling Cascades and Metabolic Control in Aestivation 46
2.3.1 AMP-Activated Protein Kinase 46
2.3.2 Akt Mediated Signaling 47
2.4 Gene Regulation 49
2.4.1 Global Suppression of Gene Expression 49
2.4.2 Gene Hunting and Stress Response 50
2.4.3 Aestivation-Responsive Gene Expression 51
2.5 Conclusion 53
References 54
Navas_Ch03.pdf 58
Chapter 3 58
The Connection Between Oxidative Stress and Estivation in Gastropods and Anurans 58
3.1 Biochemical and Physiological Adaptations for Estivation 59
3.2 Oxidative Stress during Estivation and Arousal 60
3.3 Dealing with ROS Associated to Estivation and Arousal 61
3.3.1 Free Radical Metabolism and Dormancy in Land Snails 61
3.3.2 Free Radical Metabolism and Dormancy in a Freshwater Snail 65
3.3.3 Reduction of ROS Production 65
3.3.4 Desert Toads, Estivation, and Oxidative Stress 66
3.4 Conclusions 68
References 69
Navas_Ch04.pdf 73
Chapter 4 73
Nitrogen Metabolism and Excretion During Aestivation 73
4.1 Introduction 74
4.2 Nonaestivating Animals and Feeding 74
4.2.1 Excess Dietary Protein and Gluconeogenesis 74
4.2.2 Ammonia is Toxic 75
4.2.3 Excretory Nitrogenous End-Products 76
4.3 Aestivation Involves Fasting, Desiccation, High Temperature and Corporal Torpor 76
4.4 Current Issues on Excretory Nitrogen Metabolism and Related Phenomena in Aestivators 78
4.4.1 Aestivation in Normoxia or Hypoxia? 78
4.4.2 Induction, Maintenance and/or Arousal? 78
4.4.3 Preservation of Biological Structures or Conservation of Metabolic Fuels? 78
4.4.4 Modifications of Structures/Functions or Static Preservation of Structures? 79
4.4.5 Increased Detoxification of Ammonia or Decreased Ammonia Production? 80
4.4.6 Nitrogenous Wastes for Excretion or Nitrogenous Products with Specific Functions? 80
4.5 Excretory Nitrogen Metabolism in Aestivators 81
4.5.1 Nitrogen Metabolism and Excretion during the Induction Phase 82
4.5.1.1 Urea as an Internal Signal in the Induction Process 82
4.5.1.2 Changes in the Permeability of the Skin to Ammonia and its Implications 83
4.5.1.3 A Decrease in Ammonia Production and an Increase in Urea Synthesis 85
4.5.2 Nitrogen Metabolism During the Maintenance Phase 86
4.5.2.1 A Decrease in Protein Synthesis in General and Increases in Syntheses of Certain Proteins in Specific Organs 86
4.5.2.2 Protein/Amino Acids as Metabolic Fuels Versus Preservation of Muscle Structure and Strength 88
4.5.2.3 Suppression of Ammonia Production and Changes in Hepatic GDH Activity 89
4.5.2.4 Changes in the Rate of Urea Synthesis and Activities of Ornithine–Urea Cycle Enzymes 91
4.5.2.5 Levels of Accumulated Urea and Mortality 93
4.5.2.6 Accumulation of Urea – Why? 93
4.5.3 Nitrogen Metabolism and Excretion during Arousal from Aestivation 95
4.5.3.1 Rehydration 95
4.5.3.2 Excretion of Accumulated Urea 96
4.5.3.3 Feeding, Tissue Regeneration and Protein Synthesis 97
4.6 Conclusion 97
References 98
Navas_Ch05.pdf 105
Chapter 5 105
Aestivation in Mammals and Birds 105
5.1 Introduction 106
5.2 Prolonged, Multiday Torpor or Hibernation 107
5.3 Daily Torpor 108
5.4 Aestivation 109
5.4.1 Torpor in Summer 110
5.4.2 Torpor during Development and Growth 112
5.4.3 Torpor in or Near the TNZ 113
5.4.4 Torpor Induction via Water Restriction 114
5.4.5 Energy Conservation at High Tb 115
5.4.6 Water Conservation 116
5.5 Conclusions 116
References 117
Navas_Ch06.pdf 122
Chapter 6 122
Metabolic Rate Suppression as a Mechanism for Surviving Environmental Challenge in Fish 122
6.1 Introduction 122
6.2 Defining Metabolic Rate Suppression 123
6.3 Metabolic Rate Suppression as a Response to Environmental Stress 125
6.3.1 Behavior Metabolic Rate Suppression Responses can Reduce Metabolic Demands 127
6.3.2 Physiology Metabolic Rate Suppression Responses can Reduce Metabolic Demands 127
6.3.3 Biochemistry Metabolic Rate Suppression Responses can Reduce Metabolic Demands 128
6.4 Aestivation 129
6.5 Environmental Hypoxia/Anoxia 136
6.6 Diapause 140
6.7 Summary 144
References 144
Navas_Ch07.pdf 149
Chapter 7 149
Energy and Water in Aestivating Amphibians 149
7.1 Introduction 150
7.2 Amphibian Aestivation as an Ecological State 151
7.3 Physiological Challenges of Amphibian Aestivation 152
7.3.1 Temperature, Water and Energy in Aestivating Amphibians 152
7.3.2 Microhabitat as a Factor Affecting Physiological Challenges During Aestivation 153
7.3.3 Behavior, Physiological Challenge, and Reproduction 156
7.3.4 Aestivation, Development, and Life History 157
7.4 Morpho-Physiological Solutions 157
7.4.1 Metabolic Depression as a Hallmark Strategy 157
7.4.2 Mechanisms Underlying Metabolic Depression 159
7.4.3 Energy Substrate Cycling during Aestivation 161
7.4.4 Cocoons as Morpho-Physiological Strategies 165
7.4.5 Water Balance 166
7.4.5.1 Urea 166
7.4.5.2 Water Stores and Uptake 167
7.4.6 Skeletal Muscle and Gastrointestinal Adjustments 168
7.5 Emergence 170
7.6 Conclusions 170
References 171
Navas_Ch08.pdf 178
Chapter 8 178
Effects of Aestivation on Skeletal Muscle Performance 178
8.1 Introduction 179
8.2 Skeletal Muscle Disuse 179
8.2.1 Clinical and Experimental Models of Muscle Disuse 179
8.2.2 Natural Models of Muscle Disuse 180
8.3 Effects of Aestivation on Skeletal Muscle Morphology 181
8.4 Effects of Aestivation on Skeletal Muscle Metabolism 182
8.5 Effects of Aestivation on Properties of the Neuromuscular Junction 183
8.6 Effects of Aestivation on Skeletal Muscle Mechanics and Relationship with Locomotor Performance 183
8.7 Discussion 185
References 186
Navas_Ch09.pdf 189
Chapter 9 189
Morphological Plasticity of Vertebrate Aestivation 189
9.1 Introduction 190
9.2 Fishes 191
9.2.1 Lungfishes 191
9.2.2 Teleost Fish 194
9.3 Amphibians 194
9.3.1 Salamanders 195
9.3.2 Anurans 196
9.3.2.1 C. alboguttata 196
9.3.2.2 Ceratophrys ornata 200
9.3.2.3 Pyxicephalus adspersus 202
9.3.2.4 Scaphiopus holbrooki 202
9.3.3 Other Anurans 203
9.4 Reptiles 203
9.4.1 Turtles 204
9.4.2 Lizards and Snakes 204
9.4.3 Crocodilians 205
9.5 Birds and Mammals 206
9.6 Integration of Form and Function During Aestivation 209
9.7 Conclusion 210
References 210
Navas_Ch10.pdf 215
Chapter 10 215
Water Management by Dormant Insects: Comparisons Between Dehydration Resistance During Summer Aestivation and Winter Diapause 215
10.1 Introduction 216
10.2 Maintenance of Water Balance 217
10.3 Mechanisms Utilized by Insects to Suppress Transpiration 217
10.3.1 Cuticular Changes 217
10.3.2 Respiratory Water Loss and Metabolism Reduction 219
10.3.3 Excretory System 220
10.3.4 Nitrogenous Waste 221
10.3.5 Behavioral Changes 222
10.4 Increases in the Water Pool during Aestivation and Diapause 222
10.4.1 Ingestion of Water 222
10.4.2 Metabolic Water Production 223
10.4.3 Water Vapor Absorption 224
10.5 Mechanisms to Reduce Water Stress 224
10.5.1 Protein and Molecular Changes 224
10.5.2 Osmolality, Solutes and Regulation of Size and Volume 225
10.5.3 Membrane Restructuring 227
10.6 Extreme Dehydration Tolerance (Anhydrobiosis) 227
10.7 Water as a Development Cue 228
10.8 Conclusions and Future Directions 228
References 230
Navas_Ch11.pdf 236
Chapter 11 236
Diapause and Estivation in Sponges 236
11.1 Introduction 237
11.2 Gemmulation 238
11.3 Diapause 241
11.4 Breaking of Diapause 242
11.5 Quiescence 243
11.6 Germination 243
11.7 Summary 244
References 246
Navas_Ch12.pdf 249
Chapter 12 249
Aestivation in the Fossil Record: Evidence from Ichnology 249
12.1 Introduction 250
12.2 Evidence of Aestivation in the Fossil Record 250
12.3 Examples of Aestivation in the Fossil Record 252
12.3.1 Annelids 252
12.3.1.1 Trace Fossil Evidence: Earthworms 253
12.3.2 Fish 254
12.3.2.1 Trace Fossil Evidence: Lungfish 254
12.3.3 Amphibians 256
12.3.3.1 Trace Fossil Evidence: Lysorophids 257
12.3.4 Amniotes 261
12.3.4.1 Trace Fossil Evidence: Dicynodonts 261
12.4 Discussion 262
12.5 Summary 263
References 263
Navas_Index.pdf 267