Table Of ContentMonographs on
Theoretical and Applied Genetics 1
Edited by
R. Frankel (Coordinating Editor), Bet-Dagan
M. Grossman, Urbana' H.F. Linskens, Nijmegen
D. de Zeeuw, Wageningen
J. Sybenga
Meiotic
Configurations
A Source of Information for
Estimating Genetic Parameters
With 65 Figures
Springer-Verlag
Berlin Heidelberg New York 1975
Dr. J. SYBENGA
Department of Genetics of the
Agricultural University
W ageningen/N etherlands
ISBN-13: 978-3-642-80962-0 e-ISBN-13: 978-3-642-80960-6
DOl: 10.1007/978-3-642-80960-6
Library of Congress Cataloging in Publication Data. Sybenga. Jacob, 1926-. Meiotic Con
figurations. (Monographs on theoretical and applied genetics; v.l). Bibliography: p.lncludes
index. 1. Chromosomes. 2. Chromosome abnormalities. 3. Meiosis. I. Title. II. Series.
QH600.S9. 574.8'732.75-17562.
This work is subject to copyright. All rights are reserved. whether the whole or part of the
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agreement with the publisher.
© by Springer-Verlag Berlin Heidelberg 1975.
Softcover reprint of the hardcover 1st edition 1975
The use of registered names, trademarks, etc. in this publication does not imply, even in the
absence of a specific statement, that such names are exempt from the relevant protective laws
and regulations and therefore free for general use.
Foreword
The aim of the monographs is to foster effective intra- and interdisciplinary
communication between geneticists, and plant and animal breeders. This is to
be achieved by publishing authoritative up-to-date texts; concise, but at the same
time comprehensive, monographs, and multiauthor volumes on theoretical and
applied genetics.
The following broad fields of genetics and breeding are within the scope of
the series:
Evolutionary genetics Developmental genetics
Population genetics Biochemical genetics
Ecological genetics Somatic cell genetics
Biometrical genetics Agricultural genetics
Cytogenetics Mutation breeding
Radiation genetics Breeding methodology
Acceptable subjects for the Monographs on Theoretical and Applied Genetics
are basic and applied aspects of genetic variation; genetic resources; genetic
exchange and reproduction; mutagenesis; genotype-environment interaction;
gene structure, regulation, action, expression and interaction; chromosomal
and extrachromosomal inheritance of economic traits, and genetic models and
simulations.
September 1975 The Editors
Preface
Meiotic configurations are looked at from a special point of view in this book:
the extraction from them of the maximal amount of quantitative information
of genetic interest. Although this requires a certain understanding of their origin
and consequences, much of what is known about chromosomes and their for
mation into the special structures collected under the rather indiscriminate term
I
"configuration", is not considered relevant for this purpose, and simply neglected.
Nor is the qualitative significance of meiotic configurations discussed in any
detail, for instance their importance as markers of the individual in which they
occur. Interpretations of the results obtained, with the approaches discussed,
are given only with the purpose of evaluating the analysis or as a preliminary to
the further development of an analytical model. The purpose has not been to
increase our understanding of chromosome behavior, although at times this may
have been a welcome by-product.
The primary objective has been to construct a network of comparatively
generally applicable systems for estimating genetic parameters of various natures,
but all related to recombination in its widest sense, from relatively simple micro
scopic observation. Most is based on published reports, some is new. Examples
have been taken from various organisms, but no attempt has been made to make
the coverage complete. Some excellent publications may well have escaped
attention, or they may have been excluded when they did not contribute specifi
cally to the present purpose, or when satisfactory examples had been used from
other sources. Some Jess important work may have been refe(red to when it
contained material or approaches of special interest.
Thanks are due to Miss HENRIET BOELEMA for her careful typing of the manu
script, to Mr. K. KNOOP for his help with several of the illustrations, and to many
colleagues in this department and elsewhere for valuable discussions and for
permission to reproduce their photographs.
Wageningen, September 1975 J. SYBENGA
Contents
Chapter 1. Introduction 1
1.1 Genetic Variation and Genetic Mechanisms ........... 1
1.2 Meiosis as a Complex of Processes Regulating Recombination 3
1.3 The Three Central Elements of Meiosis: Chromosome Pairing, Crossing-
over, Distribution ...................... 8
1.4 The Order of Analysis: Crossing-over-Chromosome Pairing-Distri-
bution ........................... 10
1.5 The Nature and Quality of the Information Derived from Meiotic
Configurations .. . . . . . . . . . . . . . . . . . . . . . . 10
Chapter 2. The Analysis of Crossing-over 13
2.1 Unmarked Chromosomes ................ 13
2.1.1 Crossing-over Estimated Directly from Chiasma Frequencies 13
2.1.1.1 Chiasma Frequency Estimates 18
2.1.1.2 Interference within Chromosomes 20
2.1.1.3 Interchromosome Effects 33
2.1.1.4 Chiasma Localization .... 38
2.1.1.5 ChiaspIa Frequency and Distribution in Relation to Internal and
External Variables ................... 39
2.1.2 Crossing-over Estimated by Inference from Metaphase Association
in Diploids (Disomics) and Autotetraploids (Tetrasomics) .... 48
2.1.2.1 The Relation between Metaphase Association and Crossing-over;
, Mapping Functions . . . . . . . . . . . . . . . . . . . 48
2.1.2.2 Frequencies of Being "Bound" in Diploids (Disomics) and Autote-
traploids (Tetrasomics) . . . . . . 52
2.1.2.3 Interference .......... 59
2.2 Marked Chromosomes: Structural Deviants 63
2.2.1 Telocentric Substitutions 63
2.2.2 Deficiencies .... . 66
2.2.3 Inversions ..... . 68
2.2.3.1 Paracentric Inversions 68
2.2.3.1.1 Diplotene-Diakinesis 68
2.2.3.1.2 Anaphase 70
2.2.3.2 Pericentric Inversions 78
Contents IX
2.2.4 Reciprocal Translocations ....... 83
2.2.4.1 Direct Estimates of Chiasma Frequencies 83
2.2.4.1.1 Metacentric Chromosomes .... 86
2.2.4.1.2 Acrocentric Chromosomes .... 88
2.2.4.2 Crossing-over Estimated from Metaphase Association 93
2.2.4.2.1 Metacentric Chromosomes ......... 93
2.2.4.2.2 Interference ............... 100
2.2.4.2.3 Interstitial Segments: Acrocentric and Metacentric Chromo-
somes .................. 102
2.2.4.3 Crossing-over Estimated from Anaphase Segregations .... 109
2.2.4.4 Interchromosome Effects Involving Translocations ... . 113
2.2.4.5 Telocentric Substitution in Reciprocal Translocations; Crossing-
over Estimated from Metaphase Association; Interference 115
2.3 Numerical Markers .................. 121
2.3.1 Primary Trisomics ................. 121
2.3.2 Telocentric Trisomics and Monosomics for Normally Metacentric
Chromosomes ...................... 127
Chapter 3. The Analysis of Chromosome Pairing ........... 134
3.1 Non-competitive Situations 134
3.1.1 Unmarked Chromosomes 134
3.1.2 The Relation between Cross-over Frequency and Synaptic Extent 141
3.1.3 The Location of Pairing Initiation ....... . 147
3.1.4 Indirect Observation: Post-Pachytene Configurations 152
3.2 Competitive Situations: Localization of Pairing Initiation Points; Pairing
Differentiation 156
3.2.1 Trisomics ............ 156
3.2.1.1 Primary Trisomics ....... 156
3.2.1.2 Telocentric and Secondary Trisomics 157
3.2.1.3 Telocentric Trisomy in Telocentric Substitution 158
3.2.1.4 Translocation Trisomics and Telocentric Translocation Trisomics 162
3.2.1.5 Inversion Trisomics .................. 167
3.2.2 Autopolyploids ...................... 169
3.2.2.1 Autopoly,ploids and Autopolysomics without Structural Rearran-
gements ........... . 169
3.2.2.2 Autopolyploids with Inversions 178
3.2.2.3 Autopolyploids with Translocations 182
3.2.3 Allopolyploids ......... . 187
3.2.3.1 New Allopolyploids (Amphidiploids) 187
3.2.3.2 Established Allopolyploids 190
3.2.3.3 Secondary Association 195
x Contents
Chapter 4. The Analysis of Distribution: Centromere Coorientation .. 200
4.1 Orientation and Reorientation in Bivalents; Independence and Interde-
pendence ......................... 200
4.2 Orientation and Reorientation in Multivalents; Interchange Heterozy-
gotes and Polysomies .................. .. 210
References 230
Author and Subject Index 239
Chapter 1. Introduction
Although the reader may be assumed to have a reasonable background knowledge
and understanding of the basic meiotic phenomena, it may be useful to recapitulate
a few principles. The first Chapter deals primarily with this recapitulation, but
it does so from a special angle: that of interpreting meiosis in terms of recombina
tion. It also briefly considers the nature of the information that can be derived
from such an interpretation.
1.1 Genetic Variation and Genetic Mechanisms
The units of genetic function (genes, factors, cistrons, operons) appear in different
functional forms: alleles. One allele can be transformed into another by mutation.
Different alleles may differ by one or by more than one consecutive mutational
step. They may also be separate and distinct mutant derivatives from a common
ancestral form. The expression of most new mutant types is negative in comparison
to the established original form, but occasionally mutation results in functional
"progress". This may be an inherent positive effect (in the original or in a
new environment) or it may result from a favorable interaction with particular
alleles of other gene$ or even, in heterozygotes, with the parental allele. A
high rate of mutation destroys the proper functioning of the biochemical system,
and all living organisms appear to have mechanisms to prevent genetic damage
that might lead to mutations, as well as mechanisms to repair it There remains
a basic mutation rate that on one hand results in a "load" on the capacity
of the population to reproduce and maintain itself, but that on the other hand
preserves the opportunity for new useful alleles to arise. When the origin of
. new alleles is infrequent and random, the probability offormation of new complex
balanced combinations of alleles is extremely small. This situation is not actually
observed: all forms of life have systems by which mutants arisen independently
in different individuals can be recombined and the best combination selected.
With random recombination, given a relatively large variation, the extraction
of well adapted combinations of alleles would still be small but for entirely
different reasons than when the new combination depends on new mutation
alone. The balance between the immobility of strict conservation and the chaos
of random recombination is struck by the regulated manipulation of genetic
variation by mechanisms of controlled recombination. These mechanisms them
selves are under genetic control and subject to selection. Selection, although
permitting new systems to evolve, tends to be conservative rather than innovative.
Thus, once a system of regulated recombination has been established in a genetic
2 Introduction
population (either because of its success, or by chance) it may acquire considerable
stability, to a great extent because of its own restrictive properties. In this
respect it resembles most evolutionary specializations. Only by disruption of
the balance, perhaps as a result of chance introduction of new genes by hybridiza
tion or mutation, or by changing conditions favoring the selection of exceptional
recombinants, is the system of recombination to be changed. Then a change
of the entire genetic make-up of the affected population is inevitable, and only
gradually can a new balance be established.
Systems of regulation of recombination clearly are of considerable biological
importance, and their quantitative description in terms of genetic (recombination)
parameters of theoretical and practical interest.
Recombination is (almost) universally associated with reproduction, and is
effected in two steps: the combination of two gametes (male and female) into
a zygote from which a new individual develops, and the formation of the gametes.
Neither the factors affecting the combination of gametes (for instance incompatibi
lity systems preventing some and favoring other gametic combinations) nor
the factors affecting the availability of specific gene combinations (selection)
are normally considered part of the recombination system proper. The term
recombination is usually restricted to phenomena associated with the determina
tion of the genetic composition of the gametes. It means in fact that the gametes
combined into a zygote are genetically different from those combined to form
the parents, not considering the creation of new or the loss of existing genes.
It appears that the factor of major importance for the regulation of recombina
tion is the organization of the genes in large associations, the chromosomes.
The properties and the behavior of these chromosomes determine the regulation
of recombination. These are determined by factors inherent to the chromosomes
themselves and by factors acting on the chromosomes. As far as the latter
are genetic factors, they are also situated in the chromosomes, but exert their
influence indirectly.
All genes are long, linear molecules of DNA, associated end to end in the
chromosomes ana, especially in higher organisms, combined with several specific
proteins, including basic and acidic proteins, enzymes, RNA and a number
of anorganic ions. The necessity of packing large numbers of genes (several
thousands) into a small number of chromosomes (usually between 5 and 25)
may primarily be a consequence of the impossibility of properly arranging the
simultaneous separation of the daughter units after replication of individual
genes. The compound structure, in addition, offers opportunities for correlated
regulation of replication and transcription. The important genetic consequence
is that it keeps together specific alleles of different genes, preventing the free
and random formation of new allelic combinations except by mutation. Linking
genes into chromosomes is the most potent mechanism of restricting recombina
tion, but the linkage is not perfect and may be broken according to certain
rules.
Systems of recombination can be indirectly analyzed quantitatively by studying
the numerical relationships between different classes of progeny (segregations).
In contrast to this approach, this book deals directly with chromosomal structures
( configurations) visible at meiosis.
