Somitogenesis / Edition 1

by Miguel Maroto, Neil V. Whittock

Overview

We visualise developmental biology as the study of progressive changes that occur within cells, tissues and organisms themselves during their life span. A good example of a field of developmental biology in which this concept is encapsulated is that of somitogenesis. The somite was identified as the primordial unit underlying the segmented organisation of vertebrates more than two centuries ago. The spectacular discoveries and achievements in molecular biology in the last fifty years have created a gene-based revolution in both the sorts of questions as well as the approaches one can use in developmental biology today. Largely as a result of this, during the 20th and 21st centuries this simple structure, the somite, has been the focus of a deluge of papers addressing multiple aspects of somite formation and patterning both at the cellular and molecular level. One of the main reasons for such interest in the process of somitogenesis stems from the fact that it is such an exquisitely beautiful example of biology working under strict temporal and spatial control in a reiterative manner that is highly conserved across the vertebrate classes. Our intention is that this book will be of interest to different kinds of scientists, including basic researchers, pathologists, anatomists, teachers and students working in the fields of cell and developmental biology. The nine chapters cover a wide array of topics that endeavour to capture the spirit of this dynamic and ever-expanding discipline by integrating both contemporary research with the classical embryological literature that concentrated on descriptions of morphological changes in embryos and the interactions of cells and tissues during development. In so doing they encompass the main aspects of somitogenesis across four vertebrate classes (frog, fish, mouse and chick) and the hope is that this will enable readers to acquire an appreciation of this developmental process in all its facets. Each of the different animal models offers alternative strategic approaches (including experimental embryology, genetics and cell biology) to tackle the same process and as such each offers an invaluable and unique insight into different aspects of somitogenesis. The topics described in these chapters cover the generation of somitic tissue during gastrulation, the molecular mechanisms by which the unsegmented pre-somitic mesoderm becomes segmented into somites, the generation of polarity within somites and the means by which the somite is directed to differentiate into a number of different cell derivatives. There are also two chapters devoted to describing the latest developments on relating spontaneous mouse mutations and mutations leading to abnormal vertebral segmentation in man to the molecular mechanisms already identified as being crucial for somite formation in the lower vertebrates. We would like to heartily thank all of the authors that have contributed their time and effort and whose work has made this book possible. Only they know how difficult it has been to conclude a book that we started more than four years ago, initially with another publisher. One year ago the project was cancelled and then re-started again when the people of Landes accepted to publish it. I am especially grateful for the understanding and patience of Cynthia Conomos and Celeste Carlton who have worked tirelessly to ensure that this project reached completion. We made it!

Product Details

ISBN-13:	9780387096056
Publisher:	Springer New York
Publication date:	08/14/2008
Series:	Advances in Experimental Medicine and Biology Series , #638
Edition description:	2009
Pages:	202
Product dimensions:	6.70(w) x 10.00(h) x 0.60(d)

About the Author

MIGUEL MAROTO is a MRC Career Development Fellow and Lecturer at the University of Dundee, UK. He received his PhD in Biochemistry and Molecular Biology from the Department of Biochemistry of the Universidad Autonoma of Madrid, Spain. His research interests include investigating the biochemical basis of different signalling mechanisms implicated in the acquisition of specific cell fates during vertebrate development. In recent years he has been involved in the analysis of the mechanism of the molecular clock in the control of the process of somitogenesis.

NEIL V. WHITTOCK gained his PhD in Human Molecular Genetics whilst working at Guys’ and St Thomas’ Hospitals in London, UK. His research focussed on developing diagnostic genetic tests for Duchenne muscular dystrophy before moving on to identifying genes involved in bullous skin disorders. He then continued his research as a postdoctoral fellow at the University of Dundee before arriving at the University of Exeter where he spent three years working alongside Dr Peter Turnpenny. The work at Exeter focussed on the identification of genes involved in human genetic disorders that affected the development of the spine and ribs, specifically the spondylocostal dysostoses. He now works as an Ambulance Technician in Devon, UK. and runs his own antique clock restoration business.

Table of Contents

1. Formation and Differentiation of Avian Somite Derivatives........ 1 Bodo Christ and Martin Scaal Abstract................ 1 Introduction ................. 1 Dermomyotome................ 2 Sclerotome................. 14 Outlook............. 29 2. Avian Somitogenesis: Translating Time and Space into Pa ttern.......... 42 Beate Brand-Saberi, Stefan Rudloff and Anton J. Gamel Abstract............. 42 Introduction.............. 42 Epithelialization of the segmental plate............. 43 The anterior posterior polarization of the paraxial mesoderm.............. 46 Resegmentation of the somitic derivatives.............. 49 Regionalization of somites and segmental plate............... 49 Oscillations in gene expression underlying somitogenesis........... 50 Conclusion and future considerations.............. 52 3. Genetic analysis of somite formation in laboratory fish models........... 58 Christoph Winkler and Harun Elmasri Abstract............. 58 Introduction........... 58 Genetically dissecting the clock in zebrafish: The Delta/Notch somitogenesis mutants.............. 60 Dissecting the wave front in zebrafish: FGF signalling and Tbx24............ 62 Other pathways implicated in somitogenesis............ 64 Medaka: a model complementary to zebrafish............ 64 Somite formation in the teleost medaka............. 65 Medaka somitogenesis mutants............. 66 Medaka somite mutants with PSM prepatterning defects............ 67 Medaka mutants with defective somite polarity............. 67 Conclusions and outlook............. 69 4. Old wa res and new: five decades of investigation of somitogenesis in Xenopus laevis......... 73 Duncan B. Sparrow Abstract............. 73 Introduction............ 73 Structure of the PSM............. 76 Morphological descriptions of segmentation in Xenopus............. 77 A comparison of Xenopus segmentation with that of amniote vertebrates.............. 78 What controls where the somitic furrow forms?.............. 78 Evidence for segmental Prepatterning of the PSM............. 79 Cycling genes—evidence of a “clock”?............. 81 Embryological insights into the nature of the “wavefront”............... 85 The molecular nature of the wavefront............ 86 What are the morphomechanical mechanisms required for somite separation?............. 87 Ena/VASP................ 89 Conclusion.............. 90 5. Role of Delta-Like-3 in Mammalian Somitogenesis and Vertebral Column Formation...... 95 Gavin Chapman and Sally L. Dunwoodie Abstract............. 95 Introduction.............. 95 Somitogenesis............. 95 The Notch Signalling Pathway........... 97 Notch Signalling and Somite Formation.......... 99 Dll1 and Dll3 Perform Different Functions during Somitogenesis in Mammals....... 102 Dll3 Conclusions and the Future........... 106 6. Mesp-Fa mily Genes are Required for Segmental Pa tterning and Segmental Border Formation.........113 Yumiko Saga and Yu Takahashi Abstract.......... 113 Introduction............ 113 Background of Mesp1 and Mesp2........... 114 Function of Mesp2 during Somitogenesis........... 114 Mesp2 Is also Involved in the Segment Border Formation.......... 118 Regulation of Mesp2 Expression during Somitogenesis........... 120 Functional Redundancy between Mesp1 and Mesp2........... 120 Mesp Genes in the Other Vertebrates......... 121 Perspective........... 122 7. bHLH Proteins and Their Role in Somitogenesis........... 124 Miguel Maroto, Tadahiro