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Aestivation Molecular and Physiological Aspects

:	Carlos A. Navas, Jose E. Carvalho
:	Carlos Arturo Navas, José Eduardo Carvalho
:	Aestivation Molecular and Physiological Aspects
:	Springer-Verlag
:	9783642024214
:	1
:	CHF 133.30
:

:	Zoologie
:	English

:	268
:	Wasserzeichen
:	PC/MAC/eReader/Tablet
:	PDF

Numerous animal species live in environments characterized by a seasonal reduction in the availability of water, which often but not always occurs when temperatures are highest. For many such animals, survival during the toughest season requires spending long periods of time in a rather inactive state known as aestivation. But aestivation is much more than remaining inactive. Successful aestivation requires the selection of a proper microhabitat, variable degrees of metabolic arrest and responsiveness to external stimuli, the ability to sense the proper time of year for emergence, the preservation of inactive tissue, and much more. So, aestivation involves a complex collection of behaviors, ecological associations and physiological adjustments that vary across species in their type, magnitude and course. This book seeks to explore the phenomenon of aestivation from different perspectives and levels of organization, ranging from microhabitat selection to genetic control of physiological adjustments. It brings together authors from across the world working on different systematic groups, approaches, and questions, but who are all ultimately working to better understand the complex issue of aestivation.

	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