This volume is a compilation of twenty articles written by scientists from different parts of the world dealing with various aspects of repetitive sequences in chromosomes, telomeric sequences and their maintenance by telomerase, chromatin structure and gene activation, centrometric complexity in holocentric chromosomes, translocation frequencies in X and Y chromosomes and evolution of DNA repair mechanisms, cytogenetics of certain groups of animals viz. lepidoptera, fishes and birds, and radiosensitivity as an indicator of predisposition to breast cancer. The molecular genetics of various cancers viz., gastrointestinal, lung, prostate, and bladder is also discussed.

It was at the end of the 19th century that a Swiss biologist, Karl Nageli first proposed the existence of hereditary organelles that carried information from parent to offspring. Ensuing decades experienced vigorous studies that led to the development of discovery that chromosomes are indeed the carriers of genetic information. Subsequent studies, especially by Morgan and Bridges, established unequivocally the chromosome theory of inheritance. Today, the structure of chromosome is well established. At the physical level, eukaryotic chromosomes are composed of a single, linear, double helix of DNA. The elementary helical structure involves nucleosomes, comprised of histones around which the DNA is wrapped. A hierarchy of higher order of chromosomal architecture may possibly be responsible for the regulation of gene helical structures expression. The localized condensations of DNA constitute chromomeres. Uncoiled structures sometimes extending from chromomeres, which form loops, is the result of discontinuities in the regular coiling of the DNA in the chromosome.

Integrating classical knowledge of chromosome organisation with recent molecular and functional findings, this book presents an up-to-date view of chromosome organisation and function for advanced undergraduate students studying genetics. The organisation and behaviour of chromosomes is central to genetics and the equal segregation of genes and chromosomes into daughter cells at cell division is vital. This text aims to provide a clear and straightforward explanation of these complex processes. Following a brief historical introduction, the text covers the topics of cell cycle dynamics and DNA replication; mitosis and meiosis; the organisation of DNA into chromatin; the arrangement of chromosomes in interphase; euchromatin and heterochromatin; nucleolus organisers; centromeres and telomeres; lampbrush and polytene chromosomes; chromosomes and evolution; chromosomes and disease, and artificial chromosomes. Topics are illustrated with examples from a wide variety of organisms, including fungi, plants, invertebrates and vertebrates. This book will be valuable resource for plant, animal and human geneticists and cell biologists. Originally a zoologist, Adrian Sumner has spent over 25 years studying human and other mammalian chromosomes with the Medical Research Council (UK). One of the pioneers of chromosome banding, he has used electron microscopy and immunofluorescence to study chromosome organisation and function, and latterly has studied factors involved in chromosome separation at mitosis. Adrian is an Associate Editor of the journal Chromosome Research, acts as a consultant biologist and is also Chair of the Committee of the International Chromosome Conferences. The most up-to-date overview of chromosomes in all their forms. Introduces cutting-edge topics such as artificial chromosomes and studies of telomere biology. Describes the methods used to study chromosomes. The perfect complement to Turner.

A Historical Perspective on the Study of Chromosome Structure and Function R. Appels Division of Plant Industry CSIRO P.O. Box 1600 A.C.T. AUSTRALIA "Modern physical science gives us no model to explain the re duplication of the gene-string in each cell generation, or to ex plain the production of effective quantities of specific enzymes or other agents by specific genes. The precise pairing and inter change of segments by homologous gene-strings at meiosis also suggest novel physical properties of this form of matter". Stadler (1954) The very strong influence of reductionism in the history of understanding chromosome structure and function is evident in the above quotation from Stadler's 1954 paper, "The gene". Earlyob servations on the constancy of the cytological appearance of chromo somes and their regular behaviour in cell division led to specula tion on their biological importance. As genetics became more refined in the early decades of the 20th century the genes-on-a string model of chromosomes developed and greater emphasis was placed on the further dissection of these structures. As a result, in the 1980's the reductionist approach is reaching a crest as extensive regions of the genetic material are being sequenced.

Our understanding of the function and structure of chromosomes and their interrelationship has grown in recent years. The chapters in this issue describe the advances that have been made possible by combining microscope techniques with sophisticated biochemical and genetic approaches to unlock the secrets of chromosomes. The authors look at many aspects of chromosome biology, such as protein, DNA and RNA composition of chromosomes, defined chromosome structures, unusual chromosome structures and specialized chromosomes and microscope tools for chromosome analysis. 'Chromosome Structure and Function' will be an invaluable resource for undergraduate and postgraduate students in fields such as plant and animal sciences, genetics, and molecular biology. In fact, any student, teacher or researcher interested in chromosome biology will find this special issue indispensable.