Hormones and their receptors in fish reproduction /

Contents 6
Preface 8
Chapter 1. Gonadotropin-Releasing Hormone in Fish: Evolution, Expression and Regulation of the GnRH Gene Sherwood NM and Adams BA 12
Abstract 12
Introduction 13
GnRH Structure in Fish 14
Genomics and GnRH in Fish 16
Evolution of Fish and the GnRH Gene 16
Phylogenetic Analysis of GnRH Genes 18
Orthologs and Paralogs 24
Expression of GnRH in Fish Brain 26
GnRH in Gonads of Fish 27
GnRH mRNA Expression in Fish Gonads 28
GnRH Protein in Fish Gonads 29
GnRH-Receptor Expression in Fish Gonads 30
Role(s) of GnRH in the Gonads 31
GnRH in Early Fish Development 32
GnRH Gene Regulation 35
GnRH Gene Regulation in Mammals 35
GnRH Gene Regulation in Fish 36
Acknowledgments 40
References 40
Chapter 2. GnRH Receptors in Fish: Differences in Structure-Function Relations between Mammalian and Non-mammalian GnRH Receptors Blomenrohr M, Goos H, Bogerd J, Eidne K and Willars G 51
Abstract 51
Mammalian GnRH Receptors 52
Cloning of Mammalian GnRH Receptors 52
Localization of Mammalian GnRH Receptors 53
Structure of Mammalian GnRH Receptors 54
Receptor-Ligand Interaction 56
Receptor Activation and Signaling 57
Receptor Regulation 60
Comparison of Structure-Function Relations between the Catfish GnRH Receptor and its Mammalian Counterparts 62
The Carboxyl-Terminal Tail 63
Residues in TM 2 and TM 7 66
Receptor-Ligand Interactions 68
Several GnRHs and Several GnRH Receptors in a Single Species 70
And Finally, Have We Learnt Anything from Fish? 73
Multiple Forms of GnRH and GnRH Receptors in a Single Species 73
GnRH Receptors: Structure-Function Relationship 73
References 75
Chapter 3. Molecular Regulation of Gonadotropin Gene Expression in Teleosts Chong KL, Koh M and Melamed P 87
Abstract 87
Overview 87
Sequence Analysis: Teleost and Mammalian 88
The LH Gene 88
The FSH Gene 90
Convergence of Endocrine Regulated Signals in the Nucleus 93
Gonadotropin-releasing Hormone 93
Activin 95
Other Hypothalamic Factors 96
Gonadal Steroids 96
DNA-Binding Proteins: Activation and Combinatorial Actions 97
In Regulating the LH Gene 97
The gonadotrope specific element and Sf-1 are crucial for LH gene expression 97
Pitx-1 interacts with Sf-1 and is crucial for the LH response to GnRH 99
Has the role of Egr-1 in mediating the GnRH effect on the LH in mammals been replaced in fish by AP-1 and/or ER? 100
Pitx-1, ER/AP-1 and other factors may form an upstream enhanceosome on the csLH gene 101
In Regulating the FSH Gene 102
AP-1 binding sites/EREs are conserved on FSH gene promoters across the species 102
Do Pitx-1 and Sf-1 have a direct role in activating the FSH gene? 103
Direct effects of Smad proteins and their interacting partners 103
Silencers 104
Recruitment of Coactivators and Chromatin Remodeling 105
Acknowledgments 107
References 107
Chapter 4. Evidence for Pleiotropic Effects of Prolactin in Teleost Fish Le Rouzic P and Prunet P 116
Abstract 116
Introduction 116
PRL and Reproduction 118
PRL Effects on Steroidogenesis 118
PRL and Maternal Behavior 119
PRL-R, PRL and the Gonads 120
PRL and Immune Functions 123
PRL and Stress 124
PRL Effects on Metabolism 125
Other PRL Effects 126
Conclusion 126
References 127
Chapter 5. Activin and Its Receptors in Fish Reproduction Ge W 139
Abstract 139
Introduction 140
Activin-Inhibin-Follistatin Regulatory System in Fish 143
Activin, Inhibin and Follistatin in Fish 143
Activin Receptors and Smads in Fish 145
Activin and Its Receptors in Fish Reproduction 146
Activin Regulation of Gonadotropin Expression and Secretion 146
The Activin System and Its Regulation in the Ovary 149
Expression and localization of activin and its receptors in the ovary 149
Effects of activin on oocyte maturation 150
Interaction of activin system and other local factors in the ovary 151
Regulation of activin, follistatin and activin receptors in the ovary 152
The Activin System and Its Regulation in the Testis 153
Concluding Remarks 155
Acknowledgments 155
References 155
Chapter 6. Gonadal Steroidogenesis in Teleost Fish Young G, Kusakabe M, Nakamura I, Lokman PM and Goetz FW 166
Abstract 166
Introduction 167
Gonadal Steroids in Teleost Fishes: Synthesis, Function and Excretion 168
Steroid Synthesis 168
Steroid Release 179
Steroid Action 179
Steroid Function 179
Germ cell development 180
Males 180
Females 181
Steroid feedback 182
Long-loop feedback 182
Short-loop feedback 182
Steroids and their metabolites as pheromones 182
Steroid Metabolism and Excretion 183
Molecular Cloning and Characterization of Steroidogenic Proteins 185
StAR 186
Cloning and characterization of StAR cDNAs 186
Changes in and control of expression of StAR genes 191
P450scc 192
Cloning and characterization of P450scc cDNAs 192
Changes in and control of expression of P450scc genes 192
3 -HSD 193
Cloning and characterization of 3 -HSD cDNAs 193
Changes in and control of expression of 3 -HSD genes 194
P450C17 196
Cloning and characterization of P450C17 cDNAs 196
Changes in and control of expression of P450C17 genes 196
17 -HSD 197
Cloning and characterization of 17 -HSD cDNAs 197
Changes in and control of expression of 17 -HSD genes 197
P450 Aromatase 198
Cloning and characterization of P450arom cDNAs 198
Changes in and control of expression of P450arom genes 201
P45011 204
Cloning and characterization of P45011 cDNAs 204
Changes in and control of expression of P45011 genes 206
11 -HSD 207
Cloning and characterization of 11 -HSD cDNAs 207
Changes in and control of expression of 11 -HSD genes 208
20 -HSD 209
Cloning and characterization of 20 -HSD cDNAs 209
Changes in and control of expression of 20 -HSD genes 210
Extragonadal Sources of Sex Steroids 211
Summary and Conclusions 213
References 215
Chapter 7. Regulation and Function of Estrogen Receptors: Comparative Aspects Menuet A, Adrio F, Kah O and Pakdel F 235
Abstract 235
Introduction 236
ER Structure-Function Relationships 237
Estrogen Receptors in Teleost Fish 241
A Short Isoform of Teleost ER in Oviparous Species 241
Two ER Forms from a Duplication of Genes in Teleosts 243
E2-Target Genes in Fish 246
Hepatic E2-sensitive Genes 247
Brain and Pituitary E2 Sensitive Genes 250
Conclusion and Perspectives 253
Acknowledgments 255
References 255
Chapter 8. Vitellogenesis and Vitellogenin Uptake into Oocytes Ding JL 265
Abstract 265
Introduction 266
Hormone-Induced Vitellogenesis 266
Vitellogenin Proteins \u2014 Interspecific Diversity in Molecular Size and Domain Structure 268
The Vtg Gene and Its Molecular Evolution 269
The Vtg Promoter: Regulation of the Tilapia Vtg Estrogen Responsive Elements 270
VtgR:Vtg \u2014 The Receptor: Ligand Interaction 273
Acknowledgments 276
References 277
Subject Index 288
Species Index 306