Sex Chromosomes (eBook)

Ursula Mittwoch (Autor)

eBook Download: PDF | EPUB

2014 | 1. Auflage
316 Seiten
Elsevier Science (Verlag)
978-1-4832-5858-4 (ISBN)

Infos

Sex Chromosomes focuses on the study of sex chromosomes, including human chromosomal abnormalities, behavior and characteristics of chromosomes, and cell division. The book first offers information on the chromosomal basis of sex determination, as well as development of the cell theory, mitosis, fertilization, meiosis, and discovery of sex chromosomes. The publication also ponders on the mitosis, meiosis, and formation of gametes. Discussions focus on the special characteristics of sex chromosomes, abnormalities of cell division, and sexual differentiation. The manuscript reviews sex chromosomes in plants, Drosophila, and Lepidoptera. The book also examines sex-chromosome mechanisms that differ the classic type; sex chromosomes in fishes, amphibia, reptiles, and birds; and sex chromosomes in man. Discussions focus on normal human sex chromosomes, Turner's syndrome, Klinefelter's syndrome, true hermaphrodites, testicular feminization, and pseudohermaphrodites. Sex chromosomes in mammals other than man, including monotremata, marsupialia, insectivora, rodentia, and carnivora, are discussed. The publication is a dependable reference for readers interested in the study of sex chromosomes.

Inhalt

Front Cover 1
Sex Chromosomes 4
Copyright Page 5
Table of Contents 8
PREFACE 6
CHAPTER 1. THE CHROMOSOMAL BASIS OF SEX DETERMINATION 12
I. Introduction 12
II. The Development of the Cell Theory 12
III. Mitosis 13
IV. Fertilization 14
V. Meiosis 15
VI. The Beginning of Mendelian Genetics 16
VII. Linkage 17
VIII. Nondisjunction 18
IX. The Discovery of Sex Chromosomes 19
CHAPTER 2. MITOSIS, MEIOSIS, AND THE FORMATION OF GAMETES 26
I. Introduction 26
II. Mitosis 26
III. Meiosis 35
IV. Special Characteristics of Sex Chromosomes 38
V. Some Abnormalities of Cell Division 39
VI. The Formation of Gametes 41
VII. Sexual Differentiation 45
CHAPTER 3. SEX CHROMOSOMES IN PLANTS 48
I. Introduction 48
II. Liverworts and Mosses 48
III. Flowering Plants 51
CHAPTER 4. SEX CHROMOSOMES IN DROSOPHILA 64
I. Introduction 64
II. Sex Linkage 65
III. Nondisjunction of the X-chromosome 70
IV. Sex Determination 73
V. Gynandromorphs 76
VI. Cytological Investigations 77
VII. Salivary Gland Chromosomes 78
CHAPTER 5. SEX CHROMOSOMES IN LEPIDOPTERA 82
I. Introduction 82
II. Abraxas grossulariata, the Currant Moth 82
III. Lymantria dispar, the Gypsy Moth 85
IV. The Silkworm, Bombyx mori 87
CHAPTER 6. SEX-CHROMOSOME MECHANISMS 
90 
I. Introduction 90
II. Multiple X-Chromosomes 90
III. Multiple Y-Chromosomes 93
IV. Sex Determination by Haploid Parthenogenesis 93
V. Sex Chromosomes Which Are Not Morphologically Differentiated 98
CHAPTER 7. SEX CHROMOSOMES IN FISHES, 
100 
I. Introduction 100
II. Sex Chromosomes in Fishes 101
III. Sex Chromosomes in Amphibia 105
IV. Sex Chromosomes of Reptiles 106
V. Sex Chromosomes in Birds 107
CHAPTER 8. SEX CHROMOSOMES IN MAN 112
I. Introduction 112
II. Findings on Human Sex Chromosomes by Traditional Techniques 112
III. Normal Human Sex Chromosomes 114
IV. Klinefelter's Syndrome 120
V. Turner's Syndrome 129
VI. Female Patients with Multiple X-Chromosomes 137
VII. True Hermaphrodites 138
VIII. Pseudohermaphrodites 140
IX. Testicular Feminization 141
X. Males with XX Sex Chromosomes 142
XI. Males with XYY Sex Chromosomes 142
XII. Double Aneuploidy, Familial Aneuploidy, and Possible Causes 
143 
XIII. Sex-Linkage in Man 145
CHAPTER 9. SEX CHROMOSOMES IN MAMMALS OTHER THAN MAN 152
I. Introduction 152
II. Monotremata 152
III. Marsupialia 153
IV. Insectivora 155
V. Chiroptera 155
VI. Lagomorpha 156
VII. Rodentia 156
VIII. Carnivora 168
IX. Proboscidae 174
X. Perissodactyla 174
XI. Artiodactyla 176
XII. Primates 177
XIII. Characteristics of Mammalian Sex Chromosomes 182
CHAPTER 10. SEX CHROMATIN 186
I. Introduction 186
II. Some Landmarks in the Development of the Sex Chromatin Concept 186
III. General Properties of Barr Bodies 191
IV. Numbers of Barr Bodies per Nucleus in Man 195
V. Barr Bodies of Abnormal Size 198
VI. Late Replicating X-Chromosomes in Man 199
VII. The Origin of the Barr Body 202
VIII. Drumsticks: General Characteristics and Incidence 206
IX. Drumsticks in Patients with Chromosomal Abnormalities 210
X. The Relationship of Drumsticks to Barr Bodies 214
XI. Sex Chromatin in Mammals other than Man 216
XII. Late-Replicating X-Chromosomes in Different Mammals 218
XIII. Sex Chromatin in Animals with Female Heterogamety 219
XIV. Some Practical Applications of Sex-Chromatin Determinations 221
XV. Some Theoretical Considerations Concerning Sex Chromatin 223
CHAPTER 11. HETEROCHROMATIN 228
I. Introduction 228
II. Origin of the Concept of Heterochromatin 229
III. Cytological Characteristics of Heterochromatin 230
IV. Physicochemical Characteristics of Heterochromatin 235
V. Genetic Effects of Heterochromatin 238
CHAPTER 12. THE FUNCTION OF THE SEX CHROMOSOMES 244
I. Introduction 244
II. The Development of Sex Differences in Mammals 245
III. Experimentally Administered Sex Hormones And Sex Reversals 247
IV. Some Speculations on the Possible Mode of Action of the Sex Chromosomes 249
BIBLIOGRAPHY 258
AUTHOR INDEX 300
SUBJECT INDEX 312

Textauszug

CHAPTER 1

THE CHROMOSOMAL BASIS OF SEX DETERMINATION

Publisher Summary

It took some time until the mechanism that brought about the halving of the chromosome number during meiosis became understood; by the end of the 19th century, the basic phenomena of the cell were known. The bodies of all higher animals and plants are composed of cells, which have originated by the repeated division of the fertilized egg. The characters of the parents are transmitted to the offspring by means of the chromosomes that are situated in the nuclei of the egg and the spermatozoa. Prior to the formation of the gametes, the number of chromosomes that are present in the body cells of the parents is reduced by one-half, and the original number is restored at fertilization. The process of mitosis ensures that all newly formed cells receive the same complement of chromosomes. Mendel’s results were not merely in agreement with breeding experiments in progress at the turn of the century; the similarity shown in the behavior of Mendel’s factors and that of the chromosomes was decisive in establishing the theory that the chromosomes are the bearers of the hereditary material.

I Introduction

It was in 1908 that Edmund B. Wilson gave an address to the American Association for the Advancement of Science. The subject was: “Recent researches on the determination and heredity of sex,” and in this talk he asked the following two questions: “Does sex arise, as was long believed, as a response of the organism to external stimuli? Or is it automatically ordered by internal factors, and if so, what is their nature?” He concluded that in all probability sex was controlled by internal factors of the germ cells, and that the male or female condition does not arise primarily as a response of the developing organism to corresponding external conditions (Wilson, 1909a).

This answer was by no means self-evident. Twelve years before, Wilson himself had held that “the determination of sex is not by inheritance, but by the combined effect of external conditions” (Wilson, 1896). At the close of the nineteenth century the view prevailed that the embryo was at first sexually undifferentiated and that sex was subsequently determined by such agents as temperature and nutrition (Wilson, 1896; Doncaster, 1914). Let us therefore retrace some of the landmarks which caused this fundamental change in outlook.

II The Development of the Cell Theory

During the course of the nineteenth century the role of the cell as the basic unit of organisms became gradually understood. The detailed study of cells required the existence of optically advanced microscopes, and such instruments became available in the second quarter of the century. The introduction of achromatic lenses at that time paved the way for new investigations and discoveries (Nordenskiöld, 1927), while conversely a renewed interest in microscopic observations encouraged improvements in the instruments and their production in larger numbers (Hughes, 1959).

In 1833 the Scottish botanist Robert Brown published his discovery that cells contain a nucleus as an essential component. A few years later, the cell theory was put on its feet by Schleiden (1838) and by Schwann (1839), in Germany. They established that animals and plants are organized into basic units of comparable structure, which have an individual life and yet coordinate to form the organism as a whole. The tissues of the body are composed either entirely of cells, or of cells plus products which originated in cells.

As regards the origin of new cells, Schleiden and Schwann had thought that this might come about by either one of two processes. Cells might arise either from a parent cell, or they might be formed by a process of free cell formation, crystallizing from a material which was not itself composed of cells. Gradually it became clear that the idea of free cell formation had to be abandoned. In his book on cellular pathology, published in 1858, Rudolph Virchow insisted that every cell must be the offspring of a preexisting cell, just as an animal arises only from an animal or a plant from a plant; and gradually the concept of the continuity of cells from generation to generation was established.

III Mitosis

Although the principle that cells arise only from preexisting cells has become the foundation of modern biology, when Virchow wrote this, evidence was, as yet, unavailable. Indeed, the mechanism by which cells divide eluded investigators for another 20 years. Then, during the 1870s began an era of intense investigations into the problems of cell division and fertilization. The introduction of techniques for fixation and staining made it possible to study the different processes in considerable detail; and new discoveries followed each other in close succession. In 1873, Schneider announced that during cell division the nucleus does not disappear, as had hitherto been assumed, but undergoes a complicated process of metamorphosis. By the end of the decade, four investigators reported that they had succeeded in following the process of cell division in living cells. Flemming (1879) saw it in epithelial cells of salamander larvae, Peremeschko (1879) in epithelial cells of newt larvae (Triton cristatus), and Schleicher (1879) in cartilage cells of amphibian larvae, while Strasburger (1880) described it in the staminal hairs of the spiderwort (Tradescantia virginica). Thus, the sequence of events could be verified, and it became clear that essentially the same process of cell division occurs in animals and in plants (Flemming, 1882a; Strasburger, 1884).

The last decade of the nineteenth century saw the introduction of apochromatic lenses, which removed the residual chromatic aberration inherent in the achromatic combinations (Hughes, 1959); and thus, the resolving power of the microscope had reached the highest degree possible with visible light.

Schleicher (1879) called the process of cell division “karyokinesis” (nuclear movement), a term which is still sometimes used; it is of interest because it recognizes the kinetic nature of the nucleus, in which stages of quite different appearance give rise to one another. Flemming (1879, 1880) made the all-important discovery that the threads, into which the nucleus resolves itself prior to cell division, divide lengthwise, and van Beneden (1883) and Heuser (1884) showed that in both animals and plants one member of the two newly formed threads went to each daughter cell. Flemming also introduced the word “mitosis” (1882a), as well as the term “chromatin” to denote the substance in the cell nucleus which takes up the color from nuclear dyes (1880). The word “chromosomes” is due to Waldeyer (1888) : “I should like to permit myself the suggestion that those bodies, which Boveri has called ‘chromatic elements’ and in which occurs one of the most important acts of karyokinesis, i.e. Flemming’s lengthwise division, be given a special technical term, ‘chromosomes,’ ”*

IV Fertilization

Once the fundamental aspects of the cell were appreciated, it was at last possible to understand the facts of fertilization, and its significance. Oscar Hertwig (1876) observed, among others, the eggs of the sea urchin, Toxopneustes lividus, which are particularly favorable objects for study, since they are transparent and can be artificially inseminated. He discovered that during fertilization two nuclei unite, one of which is derived from the egg and the other from the spermatozoon, and he concluded that fertilization consists in the fusion of sexually differentiated cell nuclei. Having established this, Hertwig went one important step further: Since fertilization must be the act during which the qualities of the father are transmitted to the offspring, he concluded that the nuclear material must be the bearer of those qualities which are inherited from parents to children (Hertwig, 1885).

These conclusions were confirmed by the work of van Beneden (1883) on the fertilization of the threadworm, Parascaris equorum, (formerly Ascaris megalocephala), which lives as a parasite on the horse. In Parascaris, the eggs are transparent, and the organism has the further advantage of having a small number of large chromosomes; van Beneden was able to observe that in the variety which he studied the sperm and the egg nucleus each resolve themselves into two chromosomes and that the four chromosomes then divide longitudinally, so that each daughter nucleus receives equal amounts of paternal and maternal chromosomes. Thus, it became clear that the male and the female germ cells are equivalent from the point of view of the hereditary material which they contain and that each germ cell contributes one-half of the chromosomes that are present in the offspring.

Van Beneden’s results on Parascaris were confirmed by Boveri (1890), who also extended them to a number of other animals; he showed that in the sea urchin Echinus microtuberculatus, each parent contributed 9 chromosomes, in the worm Sagitta bipunctata, 9, in the medusa...

Produkt-Details

• Erscheint lt. Verlag: 28.6.2014
• Sprache: englisch
• Themenwelt: Naturwissenschaften ► Biologie
• Themenwelt: Naturwissenschaften ► Physik / Astronomie ► Angewandte Physik
• Themenwelt: Technik
• ISBN-10: 1-4832-5858-0 / 1483258580
• ISBN-13: 978-1-4832-5858-4 / 9781483258584