The Molecular Theory of Radiation Biology

393 Pages·1981·13.629 MB·English

by  Dr. K. H. Chadwick, Dr. H. P. Leenhouts (auth.)

Monographs on
5
Theoretical and Applied Genetics
Edited by
R. Frankel (Coordinating Editor), Bet-Dagan
G.A.E. GaU, Davis . M. Grossman, Urbana
H.F. Linskens, Nijmegen . D. de Zeeuw, Wageningen
K. H. Chadwick H. P. Leenhouts
The Molecular Theory
of Radiation Biology
With 236 Figures
Springer-Verlag
Berlin Heidelberg New York 1981
Dr. K. H. CHADWICK
Dr. H. P. LEENHOUTS
Association Euratom-Ital
Keyenbergseweg 6,
Wageningen, The Netherlands
This book is contribution No. 1668 from the Biology Division of
the Commission of the European Communities and has been
written with the support of the Dutch Ministry of Agriculture.
ISBN-13:978-3-642-81521-8 e-ISBN-13:978-3-642-81519-5
DOl: 10.1007/978-3-642-81519-5
Library of Congress Cataloging in Publication Data. Chadwick, Kenneth Helme. The molecular
theory of radiation biology. (Monographs on theoretical and applied genetics; v. 5) Biblio
graphy: p. Includes index.!. Radiogenetics. 2. Radiobiology. I. Leenhouts, H.P. 1937-. II. Title.
III. Series. [DNLM: 1. Molecular biology. 2. Radiobiology. W1M057N v. 5fWN 610 C432m]
QH465.R3C48 574.19'15 80-24657.
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© by Springer-Verlag Berlin· Heidelberg 1981
Softcover reprint of the hardcover 1st edition 1981
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2131/3130-543210
"So pleas'd at first the tow'ring Alps we try,
Mount o'er the vales, and seem to tread the sky,
Th' eternal snows appear already past,
And the first clouds and mountains seem the last:
But, those attain'd, we tremble to survey
The growing labours of the lengthen'd way,
Th' increasing prospect tires our wand'ring eyes,
Hills peep o'er hills, and Alps on Alps arise:"
ALEXANDER POPE (1668-1744)
(from An Essay on Criticism)
Preface
In late 1971 we were involved in a study of the interaction of
radiation with matter and were trying to use measurements of
radiation fluorescence in biological molecules to indicate how
radiation affected living cells. It soon became apparent that we were
working in the dark; the doses we used to get a significant signal
were too large to be of interest for radiation biology and although
the DNA molecule appeared to be the most likely target molecule
we did not know which sort of events and which sort oflesions were
the most important. We decided to alter our approach to see if we
could find any consistent mathematical order in the radiobiological
dose relationships. We found that cell survival curves could be very
usefully described by a linear-quadratic dose relationship and very
soon came to the somewhat premature but, as it turned out, most
effective conclusion that the induction of DNA double strand
breaks should be linear-quadratic. In deciding that the DNA double
strand break was the crucial and all-important lesion we were able
to associate the mathematical analysis with the biology of the cell
and were able to relate known properties of the DNA molecule to
known radiobiological effects. On the other hand, we were
restricted and brought, from an abstract two-hit lesion which could
have any property one wished, down to earth, to a defined
moleccular structure of nanometer dimensions and well-known
functions and properties. We would need to be able to explain all the
varied radiobiological effects using only the functions, structure and
properties of the DNA in the cell.
As we expanded the model, and examined more radiobiological
data, it became clear that the same type of radiobiological effects
arose in several different biological end points and we sought to
develop the model to describe the other biological end points. It
was known that the linear-quadratic equation would describe the
induction of chromosomal aberrations, but "Could one double
strand break really give an aberration?" At that time the unineme
model of chromosome structure had been postulated but was not
generally accepted. By accepting it we could associate a double
strand break with a chromosome backbone break. Could one
backbone break really lead to chromosome aberration configura
tions which had always been supposed to come from two breaks? It
was not until 1976, when Resnick published a model for the repair of
a DNA double strand break, which involved the enzymatic
VIII Preface
induction of a second break in a recombinational process, that we
were able to derive a completely satisfactory solution to our
problem that one radiation-induced double strand break should
give one chromosome aberration configuration.
Mutations, and consequently malignancy were a little more
straightforward and we were eventually able to develop our
theoretical approach to the analysis of several different biological
effects. It is because we have been able to make the original analysis
applicable to all the different biological end points and to derive,
predict and find direct correlations between these end points, that
we have been motivated to write this book and present the model as
a whole.
The model has led to the introduction of several unconventional
concepts in radiation biology but the theory and the concepts
introduced in it are most amenable to experimental investigation.
Any model is a simplistic representation of the facts as they appear
at that moment and we already have indications that some
refinements of the model are going to be necessary in the future, but
at present we see these modifying factors as being of secondary
importance which do not detract from our conviction that the DNA
double strand break is the absolutely crucial type of lesion which
causes the radiobiological effect in normal cells.
For many years we had interpreted radiobiological effects in
terms of the conventional theoretical approach, which is typified by
the Target and Hit theories and the Classical and Exchange theories,
without really feeling that we understood what was going on. In the
development of this theory we have been obliged to take a
completely different approach to the problem which has led us to
formulate new concepts. We find that these new concepts do give us
a better insight into, and understanding of, how radiation interacts
with cells to cause the biological effects. One might consider this
development as an example of lateral thought (see de Bono, The
Mechanism of Mind, Penguin Books Ltd., Harmondsworth, UK,
1971), and we hope that the model presented in this book will
stimulate other scientists to examine radiation biology from a
different point of view.
In this book we have tried to gather together, in a logical
sequence, the thoughts and reasoning which have led us from the
raw and primitive beginning to the broader, more generally
applicable, model. In doing this it has been necessary to cover a wide
range of topics in both cellular biology and radiation physics, and
we apologize now to the reader who finds that we have gone into too
much detail in one area and made too rough an approximation in
the other. We have written what we feel is essential for the physicist
to follow the influence exerted on the model by the biology, and for
the biologist to follow the mathematical definition of the biological
effect. The book is written with the whole spectrum of scientists who
Preface IX
are involved in radiation biology in mind, so that whether they be
radiologist, cytologist, chemist or physicist, they can understand
our reasoning and eventually use the model to plan and interpret
their own experiments.
Independent of whether the model be proved correct or not, ifit
has caused radiation biologists to think again about basic
mechanisms; if it has given some a different insight in the field, and
if it has stimulated renewed experimentation especially at the
molecular level, then it will have achieved its goal.
We should like to thank our colleagues at the Association
Euratom-Ital who have contributed in many different ways to the
realization of this book and to mention especially J. C. Baars,
M. Drost and J. F. Eikelenstam who prepared all the figures. We
acknowledge the support we have received from Dr. G. Schuster
(Director General of Directorate General XII of the Commission of
the European Communities), Dr. F. van Hoeck (Director of the
Biology Division of the D.G. XII), Dr. D. de Zeeuw (Director of
Agricultural Research in the Netherlands) and Dr. A. Ringoet
(Director ofthe Association Euratom-Ital). Finally, we pay tribute
to both our wives, Ann and Riet, for their understanding and
tremendous moral support especially during the difficult and
frustrating periods of the past seven years. Their confidence in our
work was a constant stimulus.
Wageningen, January 1981 K. H. CHADWICK
H. P. LEENHOUTS
Contents
Chapter 1. Quantitative Radiation Biology . . . . . .. .
1.1 Radiation in Society . . . . . . . . . . . .. 1
1.2 Radiation Biology: the Interdisciplinary Discipline 2
1.3 The Importance of Cellular Biology . . . . ,. 3
1.4 The Quantitative Analysis of Radiation Action: a
Brief Historical Review. . . . . . . . . . . .. 4
1.5 Desiderata for a Quantitative Theory of Radiation
Biology. . . . . . . . . . . . . . . . . . 5
Chapter 2. The DNA Molecule and Its Role in the Cell. 7
2.1 Introduction................ 7
2.2 The Structure and Dimensions of the DNA Molecule 7
2.3 Base Sequences and the Genetic Code 10
2.4 DNA Replication . . . . . . . . . 12
2.5 DNA in Chromosomes. . . . . . . 15
2.6 The Diploid Cell, Mitosis and Meiosis 17
2.7 Radiation-Induced Damage to DNA 19
2.7.1 DNA Base Damage . . . . 20
2.7.2 DNA Single Strand Breaks . 20
2.7.3 DNA Double Strand Breaks. 22
Chapter 3. The Molecular Model for Cell Survival Following
Radiation . . . . . . . . . . . . . . . 25
3.1 Historical Development. . . . . . . . . . . . . 25
3.2 The Philosophical Framework of the Model . . . . 25
3.3 The Induction of DNA Double Strand Breaks by
Radiation. . . . . . . . . . . . . . . . . . . 26
3.3.1 The Induction of DNA Single Strand Breaks . . . 28
3.3.2 The Induction of DNA Double Strand Breaks in
One Radiation Event. . . . . . . . . . . . . . 29
3.3.3 The Induction of DNA Double Strand Breaks in
Two Radiation Events . . . . . . . . . . . . . 29
3.3.4 The Total Induction of DNA Double Strand Breaks 30
3.3.5 The Induction of DNA Double Strand Breaks with
Repair. . . . . . . . . . . . . . . . . . . . 31
3.3.6 The Influence of Base Damage on the Production of
Double Strand Breaks . . . . . . . . . . . . . 32
XII Contents
3.4 The Relationship Between Cell Survival and DNA
Double Strand Breaks 33
3.5 The Cell Survival Curve. 34
3.5.1 Cell Survival as Criterium. 34
3.5.2 Correction for Cell Multiplicity 35
3.5.3 The Shape of the Cell Survival Curve. 35
3.5.4 The Analysis of Experimental Data. 37
3.6 Variation in the Survival Curve Through the Cell
Cycle. 41
3.7 Asynchronous Cell Populations 44
3.8 The Experimental Correlation Between Cell Survival
and DNA Double Strand Breaks. 48
3.9 Summary. 50
Chapter 4. Chromosomal Aberrations 51
4.1 Introduction. 51
4.2 The Nature and Yield of Chromosomal Aberrations 52
4.3 The Classical and Exchange Theories of Radiation-
Induced Chromosomal Aberrations. 54
4.3.1 The Classical Theory. 54
4.3.2 The Exchange Theory 55
4.3.3 The Problem 56
4.4 The Molecular Theory of Radiation-Induced Chro
mosomal Aberrations. 57
4.4.1 The Yield of Chromosomal Aberrations. 58
4.4.2 The Formation of Chromosomal Aberrations by the
Process of Telomere-Break Rejoining. 59
4.4.2.1 A Possible Molecular Mechanism for Rejoining Be
tween a Telomere and a Break and the Stabilization
of a Broken End. 62
4.4.3 The Formation of Chromosomal Aberrations by the
Process of Recombinational Rejoining 65
4.4.3.1 Repetitive DNA . 67
4.4.3.2 Palindromes. 70
4.4.3.3 Incompleteness 73
4.4.4 The Experimental Evidence for Telomere-Break
Rejoining. 74
4.4.4.1 The Haplopappus Experiment . 74
4.4.4.2 Other Radiation Experiments 77
4.4.4.3 Medical Cytology 77
4.4.5 The Experimental Evidence for the Process of Recip
rocal Recombination . 79
4.4.6 Two Mechanisms for the Formation of Chromosomal
Aberrations? . 82
4.4.6.1 The Molecular Nature of the Telomere 82
4.4.6.2 The Role of Caffeine . 86
Contents XIII
4.5 Complex Chromosomal Rearrangements 87
4.6 Gene Transplantation. 88
4.7 Summary ............. . 90
Chapter 5. Somatic Mutations . . . . . . . . . . . . . 92
5.1 Point and Chromosome Mutations. 92
5.2 Some Molecular Mechanisms Which Could Give Rise
to Mutations from DNA Double Strand Breaks 93
5.2.1 The Rejoining of Single Stranded Tails . 93
5.2.2 Resnick's Model for Gene Conversion 94
5.2.3 Resnick's Model for Reciprocal Recombination 97
5.2.4 Rejoining Between a Telomere and a Single Stranded
Tail 99
5.2.5 No Repair 100
5.2.6 The Repair Processes and Mutation Induction. 100
5.3 Mutation Frequency Dose Relationships 102
5.3.1 The Induction of Mutations. 102
5.3.2 The Suppression of Mutation Expression 103
5.3.3 The Influence of Cell Killing. 107
5.4 The Analysis of Experimental Data. . . 108
5.5 Two Mutations in the Same Cell Population. 112
5.6 The Mutation Spectrum. 114
5.7 Summary. 117
Chapter 6. Correlations 118
6.1 Introduction.......... 118
6.2 The Survival-Survival Correlation 118
6.3 The Survival-Chromosomal Aberration Correlation. 120
6.4 The Correlation Between Different Chromosomal
Aberrations. . . . . . . . . . . . . . . . . . 126
6.5 The Correlation Between "Normal" Chromosomal
Aberrations and "Complex" Chromosomal Aberra-
tions. . . . . . . . . . . . . . . . . . . . . 131
6.6 The Correlation Between Survival and Somatic
Mutation. . . . . . . . . . . . . . . . . . . 132
6.7 The Correlation Between Two Different Mutations
Induced in the Same Cell Population . . . . 138
6.8 The Peak Incidence - an Implied Correlation. 139
6.9 What Do the Correlations Mean? . . . . . 141
Chapter 7. Repair. . . . . . . . . . . 143
7.1 Introduction .................. 143
7.2 The Repair of DNA Single Strand Breaks and the
Dose Rate Effect. . . . . . . . . . . . . . . . 144