Abercrombie / Brachet / King Advances in Morphogenesis

Volume 10
1. Auflage 2013
ISBN: 978-1-4832-1561-7
Verlag: Elsevier Science & Techn.
Format: EPUB
Kopierschutz: 6 - ePub Watermark

E-Book, Englisch, 336 Seiten

Advances in Morphogenesis, Volume 10, provides an overview of the state of knowledge in morphogenesis. The book contains six chapters and opens with a discussion of the 'organization center' of the amphibian embryo. This is followed by separate chapters on physiological gradients in development; molecular embryology of the sea urchin, mollusks, and other invertebrates; and changes in DNA, RNA, and protein during successive phases of embryonic development in vertebrates. Subsequent chapters deal with the control of growth in the filamentous prothalli and the causal factors promoting the transition to the two-dimensional gametophyte; and the development, inheritance, and origin of the plastid in Euglena.

Autoren/Hrsg.

Abercrombie, M.

Brachet, Jean

King, Thomas J.

Inhaltsverzeichnis

1;Front Cover;1
2;Advances in Morphogenesis;4
3;Copyright Page;5
4;Table of Contents;6
5;Contributors to Volume 10;8
6;Chapter 1. The "Organization Center" of the Amphibian Embryo: Its Origin, Spatial Organization, and Morphogenetic Action;10
6.1;I. Justification;11
6.2;II. The Discovery of the "Organization Center," and a Description of Its Main Properties.;11
6.3;III. The State of Determination and Capacity for Differentiation of the Various Regions of the Early Gastrula;14
6.4;IV. The Induction of the Mesoderm;22
6.5;V. The Origin of the Regional Organization of the Mesoderm; Its Dorsoventral and Craniocaudal Polarity;34
6.6;VI. Concluding Remarks;44
6.7;References;45
7;Chapter 2. Physiological Gradients in Development-A Possible Role for Messenger Ribonucleoprotein;50
7.1;I. Introduction;50
7.2;II. Gradients and Determination in Early Embryos;52
7.3;III. Some Other Gradient Systems in Development;93
7.4;IV. Some Further Possible Analogies with Embryonic Animalizations;106
7.5;V. Discussion;109
7.6;VI. Summary;111
7.7;Appendix;113
7.8;References;113
8;Chapter 3. Molecular Embryology of Invertebrates;124
8.1;I. Introduction;124
8.2;II. Molecular Embryology of the Sea Urchin;125
8.3;III. Molecular Embryology of Other Invertebrates;151
8.4;IV. Molluscs;162
8.5;Addendum;178
8.6;References;179
8.7;Note Added in Proof;182
9;Chapter 4. Biochemical Aspects of Early Differentiation in Vertebrates;184
9.1;I. Introduction: The Problems in Analyzing Differentiation;184
9.2;II. Differentiation in Early Embryonic Cells;186
9.3;III. Primary Tissue Interactions;200
9.4;IV. Protein and Nucleic Acid Changes during Organogenesis: Comparative Studies;209
9.5;V. Biochemical and Functional Differentiation in Individual Organ Systems;220
9.6;VI. Conclusions;228
9.7;References;230
10;Chapter 5. Photomorphogenesis and Nucleic Acid Metabolism in Fern Gametophytes;236
10.1;I. Introduction;236
10.2;II. Normal Growth of the Gametophyte;237
10.3;III. Growth of Filamentous Prothalli;239
10.4;IV. Transition of Filamentous Prothalli to Biplanar Gametophytes;243
10.5;V. Protein and Nucleic Acid Metabolism in the Induction of Biplanar Growth;254
10.6;VI. Hypothetical Control Mechanisms;268
10.7;References;271
11;Chapter 6. The Development, Inheritance, and Origin of the Plastid in Euglena;274
11.1;I. Introduction;274
11.2;II. The Development of the Proplastid into the Chloroplast in Euglena;279
11.3;III. How Did the Plastid Originate?;303
11.4;IV. Conclusions;317
11.5;References;318
12;AUTHOR INDEX;322
13;TOPICAL INDEX;335

Leseproben

Physiological Gradients in Development — A Possible Role for Messenger Ribonucleoprotein

Robert Wall*,     Institute of Animal Genetics, Edinburgh, Scotland

Publisher Summary

This chapter discusses a possible role for messenger ribonucleoprotein. It describes the early embryonic interactions. It presents a unifying concept for the basis of animalization and vegetalization. Vegetalizations involve the passage of ribonucleoproteins (RNPs) to the induced cells or the protection of RNPs present there. However, animalization involves reduction of bonds within RNP and release of the RNA for translation though the natural inducer(s) responsible for this are not identified. Several developmental systems have been reviewed in terms of some new hypotheses for morphogenetic control and interactions. Stable RNPs are produced in such systems. Through their information content and the pattern of control of their translation, they provide spatial information within the system. These RNPs are bonded by disulphide, sulphamino, and other oxidized groups, so that breaking them to release the RNA for translation requires reduction. Therefore, the distribution of undefined metabolic factors leading to a high reduction rate provides a second kind of spatial information.

I Introduction 41

II Gradients and Determination in Early Embryos 43

A Evidence for Two Gradient Types in Embryos 43

B Evidence for Gradients in RNA and Protein Synthesis 49

C The Hypotheses 49

D Models for Some Embryonic Types 56

E Biochemical Evidence for the Hypotheses 68

F The Specificity of Embryonic Inductions 83

III Some Other Gradient Systems in Development 84

A Intracellular Patterns in Some Protists 85

B Intercellular Patterns in Metazoan Regeneration 92

IV Some Further Possible Analogies with Embryonic Animalizations 97

A Synthetic Activation in Eggs 98

B Carcinogenesis 99

V Discussion 100

VI Summary 102

Appendix 104

References 104

I Introduction

During the recent rapid progress that developmental biology has made, particularly in biochemical analysis, many older problems have tended to be forgotten. Important examples are the actions of lithium and thiocyanate ions which, as has long been known, can alter the developmental pathways of cells in a wide variety of embryos, protozoans, hydroids, and regenerating planarians: moreover their actions are always clearly opposed. These actions are now only extensively studied in sea urchin embryos where they have led to the concepts of “vegetalization” (abnormally great extension of the primordia of the vegetal pole as occurs with lithium ions) and “animalization” (extension of animal pole primordia as in thiocyanate ions). Yet, with the more recent data using mercaptoethanol and dithiodiglycol in a variety of systems, these present quite impressive evidence for the existence of some universal physiological component of spatial determination within developmental fields.

However, students of the biochemistry of such systems are increasingly emphasizing the internal state of competence of the individual cells, concluding that this mainly determines their development, with external cues being relatively unspecific and “permissive” rather than instructive (see Holtzer, 1963, 1968). While different molecules could of course have the same formal mode of action, these workers have usually opposed such an argument, suggesting instead that inductive action on different features of metabolism is likely to occur in different systems (e.g., Holtzer, 1963). Such external information would only choose between the possibilities “to be or not to be.”

Where different agents call forth different responses from the same competent cell type (as the ionic and other treatments do), the choice seems truly between different pathways. Moreover, in many of the same developing systems, isolated tissue pieces can regulate to restore other parts of the system, sometimes without any further cell division, so that even the condition of isolation is enough to allow the cells to make a new developmental choice. Such systems have received considerable theoretical attention, (Wolpert, 1969; Goodwin and Cohen, 1969; Webster, 1971; Cohen, 1972), the theorists showing considerable optimism that the problem is formally comparable throughout the systems considered. This may not, of course, imply a biochemical comparability (usually, e.g., Goodwin and Cohen, 1969; it is stated that this level cannot usefully be considered as yet); but it has required drawing analogies between the actions of, for example, the hydroid hypostome, amphibian embryo’s dorsal lip, and sea urchin embryo’s micromeres (Webster, 1971). In the present work it is contended that these systems usefully be discussed physiologically and biochemically, but that such analysis strongly suggests that these three inductive areas cannot be the same component.

In attempting to review some of the very large mass of data relevant to these problems, I have treated the early embryonic interactions most fully in Section II. Here there are examples of choice which seem to rule out strictly permissive action of inducers, but as this choice is mediated by opposite inductive actions, I suggest that the concepts of “animalization” and “vegetalization” describe the situation better than single dominant regions. Following some earlier authors, I have tried to justify extending these terms to embryos other than the sea urchin. Next, I have tried to look for biochemical parallels that might underlie these phenomena, concentrating on what have seemed the two most rewarding aspects: the processing of genetic information through the transcription and translation levels, and the importance of the native state of proteins including the sulphydryl-disulphide balance. Specific hypotheses are advanced from these data in an attempt to suggest a unifying concept for the basis of “animalization” and “vegetalization.” Briefly these state that “vegetalizations” normally involve the passage of ribonucleoproteins (RNPs) to the induced cells or the “protection” of RNPs already there. “Animalization,” on the other hand, involves reduction of bonds within RNP and release of the RNA for translation, though the natural inducer(s) responsible for this are not identified.

It seems possible to unify a large mass of morphological and biochemical data by the use of these ideas; though it is recognized that when other aspects of embryonic metabolism are as fully studied, they may also show such comparability and perhaps be more central to the mechanism by which diversity in space is achieved. For several reasons, however, I have opposed the suggestion that this first “laying out” of the primordia is due to differential activations of specific gene batteries (Davidson and Britten, 1971), though work on the earliest transcriptions is reviewed here. Presumably such activations must soon occur in the further development of each primordium, but this question is hardly considered here.

Section III extends these ideas to some of the other systems in which pattern formation is involved, and in which information is available on the processing of genetic information and the importance of the native state of proteins. Finally, in Section IV, two problems, which do not involve pattern formation in the present sense, are considered because there are other reasons for expecting analogies with the embryonic and regenerating systems already reviewed. These problems are the activation of protein synthesis in eggs, and carcinogenesis. The latter particularly is not a subject I am competent to review, but its obvious importance has led me to raise some recent data which could be interpreted to suggest an RNP breakdown similar to that proposed for embryonic “animalizations.”

II Gradients and Determination in Early Embryos

A Evidence for Two Gradient Types in Embryos

The earliest limitation of totipotency in sea urchin blastomeres occurs along the animal-vegetal axis, and the best known disturbances of development are those along this axis, so that either the animal or vegetal tissues occupy an excessive part of the early embryo. The latter was first shown to result from development in seawater with added lithium ions (Herbst, 1892), and the former with...