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The Inconstant Gene The Evolution and Functioning of the Genetic Mechanism LAWRENCE S. DILLON The Genetic Mechanism and the Origin of Life Ultrastructure, Macromolecules, and Evolution The Inconstant Gene The Inconstant Gene LAWRENCE S. DILLON Texas A & M University College Station, Texas SPRINGER SCIENCE+BUSINESS MEDIA, LLC Library of Congress Cataloging in Publication Data Dillon, Lawrence S. The inconstant gene. Bibliography: p. Includes index. 1. Gene expression. 2. Genetic regulation. 1. Title. [DNLM: 1. Gene expression regulation. QH 450 D579i] QH450.D54 1982 574.87'322 82-20414 ISBN 978-1-4684-4312-7 ISBN 978-1-4684-4310-3 (eBook) DOI 10.1007/978-1-4684-4310-3 © 1983 Springer Science+Business Media New York Originally pub1ished by P1enum Press New York in 1983 Softcover reprint of the hardcover 1s t edition 1983 Ali rights reserved No part of this book may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, microfilming, recording, or otherwise, without written permission from the Publisher Preface Why should the gene be suggested to be inconstant when the contrary view, that gene structure is invariant except through mutagenic processes induced by potent external factors, has long been a universal doctrine of genetics? Indeed, during the early part of the present century before mutation was recognized as being of general occurrence, the seeming unvarying nature of the gene led to skepticism regarding the validity of the evolutionary theory; only later could the origins of the morphological differences between individuals and species be attributed to a combination of mutation and evolution, involving natural forces selecting between favorable and unfavorable genetic changes. But during the past several decades, as knowledge of the macromolecular constitution of or ganisms has increased to the point where even the primary structures of the genes themselves are being revealed on a routine basis, it has become increas ingly difficult to ascribe all the resulting observations to ordinary mutagenesis and natural selection. Some more profound mechanism often seems to be present that influences both the constancy and inconstancy of the genes, an ap paratus whose existence this study hopes to reveal. In seeking to demonstrate the universality of this mechanism, data are sought through the numerous activities of organisms of many types wherever gene action changes are manifest. Since the ontogenies of multicellular or ganisms, and to a lesser extent, even unicellular ones, are replete with such alterations in gene expression, the search for facts commences at the very start of the reproductive processes by examining the formative steps of ova and sperm and continues through fertilization into the development and differentia tion of the individual into the adult form. But as the changes do not cease at birth or hatching but carry on through the full life cycle, the nature of senes cence likewise receives attention. In contrast to the often long-term changes wrought during ontogeny, or ganisms experience rhythmic fluctuations in gene actions of a diversity of types. At the multicellular level of organization at least, the diurnal modula- v vi PREFACE tions are of both qualitative and quantitative nature, and are frequently so ex tensive that is has been stated that an organism is completely different at mid night than it is at noon. Regrettably, the fields of circadian and circannual rhythms are found fuller of promise for the future than valuable at the present, insofar as the nature of the involved gene changes is concerned, for the neces sary explorations at the macromolecular level are still too insufficient in quan tity to be convincing. However, the final topic to be searched for supportive data, gene changes during immune reactions, more than compensates for this lack. As a conse quence of researches conducted in literally hundreds of laboratories scattered over the face of the earth, the immunoglobulins and their coding regions in the genome have become the most thoroughly investigated macromolecules of today. The results of these studies, combined with others, make amply clear both the invariable and inconstant nature of the gene. But the facts supplied by the two previous studies in this trilogy, as well as all those contained in this one, are essential to a full appreciation of the mechanism that is involved in governing the behavior of the usual DNA-RNA protein system. Like the two preceding components, the present one is not to be con sidered merely a review of the literature but rather an analysis of the existing state of knowledge. Because of the in-depth approach into a number of biologi cal disciplines concerned in diverse ways with changes in gene expression, many novel points of view are presented. As in the other studies, areas requir ing more intensive investigation are brought to light, and weaknesses in inter preting results of experimental researches have had to be pointed out. Far too frequently in the literature, broad generalizations are advanced, based on very limited data, and these superficial hypotheses do not withstand thorough scrutiny. The assistance of a large number of scientists has been required for the completion of this book, most of whom happily can be acknowledged individu ally in association with the light or electron micrographs they have generously supplied. But the author hopes that the others who have contributed in diverse ways will know that their contribution is also deeply appreciated, although they cannot be named individually here. Conversations with a number of colleagues here at Texas A&M University and elsewhere have aided in clarifying the au thor's views, those with Drs. Sydney W. Fox, of Miami University, Dennis Opheim, of Quinnepiac College, and Donald Killebrew, of the University of Texas at Tyler, being especially profitable. Special thanks are also extended to Galen Jennings for suggesting the title for this work. Finally as always, my wife has been the most indispensable aid of all in collaborating with me throughout the long search of the literature, tedious preparation of the manu script and illustrations, and interpretation of the data. LAWRENCE S. DILLON Contents 1. GENE ACTION CHANGES IN GAMETOGENESIS 1 1.1. Gametogenesis in General ............................. . 2 1.2. Oogenesis .......................................... . 12 1.3. Spermatogenesis ..................................... . 45 1 .4. Gametogenesis in Various Eukaryotes .................... . 80 2. GENE ACTION CHANGES DURING FERTILIZATION ....................................... . 91 2. 1 . Attachment and penetration ............................ . 92 2.2. Postpenetration Events ................................ . 107 2.3. Pronuclear Interaction ................................. . Ill 2.4. Macromolecular Events Accompanying Fertilization ......................................... . 116 3. GENE ACTION CHANGES DURING EARLY EMBRYOGENESIS .................................... . 129 3 .1. The Early Embryos of Metazoa ......................... . 129 3 .2. The Blastula and Subsequent Embryonic Stages ............................................. . 143 3.3. Molecular Aspects of Later Development ................. . 162 3 .4. Inductance and Other Developmental Factors .............. . 179 4. GENE ACTION CHANGES DURING VERTEBRATE DIFFERENTIATION .................................... . 187 4 .1. Muscle Differentiation ................................ . 187 4.2. Development of Appendages ........................... . 211 4.3. Liver Differentiation .................................. . 227 4.4. Differentiation of Reproductive Organs ................... . 231 4.5. Differentiation of Blood Cells .......................... . 234 5. GENE ACTION CHANGES DURING NONVERTEBRATE DIFFERENTIATION .................................... . 249 5 .1 . Differentiation in Fungi 249 vii viii CONTENTS 5.2. Gene Action Changes in Bacteria . . . . . . . . . . . . . . . . . . . . . . . . 259 5.3. Developmental Changes in Higher Plants . . . . . . . . . . . . . . . . . . 267 5 .4. Gene Action Changes in Differentiating Invertebrates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 281 5.5. Differentiation Changes in Protista . . . . . . . . . . . . . . . . . . . . . . . 285 6. GENE EXPRESSION CHANGES IN CYCLIC FUNCTIONS 293 6 .1 . Circadian Rhythmic Fluctuations in Gene Action . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 294 6.2. Seasonal and Annual Cyclic Changes . . . . . . . . . . . . . . . . . . . . . 310 6. 3. Life-Cycle-Related Rhythmic Changes . . . . . . . . . . . . . . . . . . . . 316 7. GENE ACTION CHANGES IN IMMUNITY 333 7 .1. The Antibodies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 333 7 .2. The Cellular Components of the Immune System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 365 7.3. Noncellular Components of Immune Reactions . . . . . . . . . . . . . 381 7 .4. Cell Interactions in Immune Responses . . . . . . . . . . . . . . . . . . . . 387 7 .5. Age-Related Changes in Immune Reactions . . . . . . . . . . . . . . . . 397 B. THE NATURE OF THE GENETIC MECHANISM 399 8 .1. The Nonmechanistic Nature of the Genetic Mechanism . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 399 8 .2. The Supramolecular Genetic Mechanism . . . . . . . . . . . . . . . . . . 433 8.3. The Inconstant Gene . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 439 REFERENCES 447 INDEX 571 1 Gene Action Changes in Gametogenesis Probably nowhere else are gene action changes so rampant as they are during those earliest stages in the developmental histories of organisms represented by the preparation of the gametes. In the formation of the egg and sperm, gener alized cells become converted to types highly specialized for their respective functions. While the specializations of the spermatozoon are obvious features, those of the ovum, although not evident on the surface, are no less marked internally, as becomes even more apparent in the next two chapters. For only during and following fertilization into early development does the remarkable internal organization that exists in the egg cell become revealed. Then, too, the best indicators of gene expression changes, alterations in protein profiles, are manifested. Here then in the present discussion, one must largely be content with changes in the fine structural characteristics and similar topics that merely imply, rather than clearly demonstrate, the activation of new genes and the abandonment of former ones. Since this is thus the first of several chapters concerned with the nature of gene expression during development from the gametes to adulthood and senes cence, the method of employing certain broad terms needs to be made clear. This is especially necessitated by the wide spectrum of organisms that are viewed, including fungi to green plants and metazoans, and even bacteria on a few occasions where they are appropriate. Inevitably, in the literature a certain few of the terms have been loosely applied or given different senses in the several taxa. Development, for example, is a nonspecific word, equally appli cable to the changes found in the embryo, fetus, neonatal, or adult. Thus, development of the individual, or ontogeny, is considered to consist of the following stages:
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