Introduction to Veterinary Genetics E-Book

Frank W. Nicholas

• Herausgeber: John Wiley & Sons
• Kategorie: Fachliteratur
• Sprache: Englisch

Seitenzahl: 629

Veröffentlichungsjahr: 2013

Beschreibung

The concepts of veterinary genetics are crucial to understanding and controlling many diseases and disorders in animals.  They are also crucial to enhancing animal production. Accessible and clearly presented, Introduction to Veterinary Genetics provides a succinct introduction to the aspects of genetics relevant to animal diseases and production. Now in its third edition, this is the only introductory level textbook on genetics that has been written specifically for veterinary and animal science students.

Coverage includes: basic genetics, molecular biology, genomics, cytogenetics, immunogenetics, population genetics, quantitative genetics, biotechnology, and the use of molecular tools in the control of inherited disorders. 

This book describes in detail how genetics is being applied to artificial selection in animal production.   It also covers the conservation of genetic diversity in both domesticated and wild animals.

New for the Third Edition:

• End-of-chapter summaries provide quick recaps.
• Covers new topics: epigenetics, genomics and bioinformatics.
• Thoroughly revised according to recent advances in genetics.

Introduction to Veterinary Genetics is still the only introductory genetics textbook for students of veterinary and animal science and will continue to be an indispensable reference tool for veterinary students and practitioners alike.

Leseprobe

Contents

Preface

1 Basic genetics

Chromosomes

Meiosis and mitosis

The biochemistry of inheritance

What is a gene?

Gene regulation

Mutation

Genes, alleles, and loci

Simple or Mendelian inheritance

Linkage

Inactivation

Types of DNA

Further reading

Appendix 1.1 Banded karyotypes of domestic species

2 Molecular biology

Restriction enzymes

Recombinant DNA and DNA cloning

Complementary DNA

DNA sequencing

Polymerase chain reaction

Southern analysis and related technologies

DNA expression microarrays

The detection of variation in base sequence

Veterinary diagnosis

Variable number of tandem repeats (VNTR), DNA fingerprints, and microsatellites

Single nucleotide polymorphisms (SNPs)

Copy number variation (CNV)

Gene mapping

Whole-genome sequence assembly

Production of polypeptide from cloned DNA

Transgenesis

Antisense technology

RNA interference

Further reading

3 Single-gene disorders

Inborn errors of metabolism

Sex-limited inheritance

Genetic heterogeneity of disease

Type of gene action and type of disease

Phenocopies

A sample of single-gene disorders

A revolution in mapping and identifying the causal mutation of single-gene disorders

Further reading

Appendix 3.1 A sample of single-gene traits that have been characterized at the molecular level

4 Chromosomal aberrations

Abnormal chromosome number

Abnormal chromosome structure

Chromosomal aberrations in cancer

Evolution of karyotypes

Interspecific hybridization

Freemartins

Biological basis of sex

Classification of intersex

A sample of chromosomal aberrations

Further reading

Appendix 4.1 A sample of chromosomal aberrations in animals

5 Single genes in populations

Gene and genotype frequencies

Random mating

The Hardy–Weinberg law

Extensions to the Hardy–Weinberg law

Selection and mutation

Genetic drift and the founder effect

Extending population genetics to more than one locus

Further reading

6 Familial disorders not due to a single gene

Liability and threshold

The multifactorial model

More than one threshold

Some final points

Further reading

7 Is it inherited?

General evidence for a genetic aetiology

The four types of simple, Mendelian inheritance

Studying and analysing the data

Further reading

8 Immunogenetics

Antibodies

Red-cell antigens

The major histocompatibility complex (MHC)

Further reading

9 Pharmacogenetics

Genetic polymorphisms affecting drug metabolism

Genetics and anaesthesia

Warfarin resistance

Multifactorial pharmacogenetics

Further reading

10 Hosts, parasites, and pathogens

Host–pathogen interactions

Resistance in hosts

Resistance in parasites and pathogens

Control of parasites and pathogens

Increasing the level of resistance in hosts

Further reading

11 Single genes in animal breeding

Coat colour

Examples of coat-colour genes

Carpet wool

Prolificacy in sheep

Polledness

Muscular hypertrophy in cattle and sheep

Dwarf poultry

Genes for sexing chickens

Pedigree checking

Further reading

12 Relationship and inbreeding

The inbreeding coefficient

Relationship

The inbreeding coefficient revisited

A general expression for relationship and inbreeding

The base population

Inbreeding in populations

Inbreeding depression

Further reading

13 Quantitative variation

Quantitative traits

The performance of an individual animal

The differences between animals

Heritability

Correlations between traits

Quantitative trait loci (QTL)

Further reading

14 Selection between populations

Comparison between populations

Genotype–environment interaction

Further reading

15 Selection within populations

Estimated breeding values and accuracy of selection

Clues to a candidate’s breeding value for a trait

Combining clues from more than one source

Best linear unbiased prediction (BLUP)

Correlated traits

Selection for more than one trait

The importance of inbreeding and genetic drift

Sire-reference schemes

Marker-assisted selection (MAS) and genome-wide selection (GWS)

Further reading

16 Breed structure

The traditional pyramid

Closed-nucleus breeding schemes

Open-nucleus breeding schemes

Information nucleus

Further reading

17 Crossing

Regular crossing

Crossing to produce a synthetic

Grading-up

Further reading

18 Selection and regular crossing

Selection

Selection and regular crossing

Further reading

19 Biotechnology and the future

Artificial insemination (AI)

Multiple ovulation and embryo transfer (MOET)

In vitro maturation (IVM) and in vitro fertilization (IVF) of ova

Control of sex ratio

Recombinant proteins

Transgenesis

Animal cloning

Further reading

20 Conservation genetics

Measurement of genetic diversity within populations

Measurement of genetic diversity among populations

Importance of genetic diversity

Loss of genetic diversity

Conservation of genetic diversity

Further reading

21 Genetic and environmental control of inherited disorders

Environmental control of inherited disorders

Genetic control of single-gene disorders

Gene therapy

Genetic control of multifactorial disorders

Genetic control – some final points

Crossing: thinking outside the square

Further reading

Glossary

Index

First edition published 1996 by Oxford University PressSecond edition published 2003 by Blackwell Publishing LtdThis edition first published 2010© 2010 Blackwell Publishing Ltd

Blackwell Publishing was acquired by John Wiley & Sons in February 2007. Blackwell’s publishing programme has been merged with Wiley’s global Scientific, Technical, and Medical business to form Wiley-Blackwell.

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Library of Congress Cataloging-in-Publication Data

Nicholas, F.W.

Introduction to veterinary genetics / F.W. Nicholas. – 3rd ed.

p. ; cm.

Includes bibliographical references and index.

ISBN 978-1-4051-6832-8 (pbk. : alk. paper)

1. Veterinary genetics. I. Title.

[DNLM: 1. Genetics. 2. Veterinary Medicine. 3. Animal Population Groups–genetics. 4. Animals. SF 756.5 N638i 2010]

SF756.5.N52 2010

636.08′21–dc22

2009013260

A catalogue record for this book is available from the British Library.

1  2010

Preface

Can there ever have been a more exciting time to study genetics? Important new topics such as next-generation sequencing, genome sequence assemblies, SNP chips, copy number variation, non-coding RNA, genome-wide selection, RNA interference, and expression QTL have all been included, albeit briefly, in this new edition. Older topics that have been given a new lease of life by recent developments, such as linkage disequilibrium, have been somewhat expanded, but still the surface has been only skimmed. The fruits of the molecular revolution are now very much in evidence: in the six years since the previous edition, the number of single-locus traits characterized at the molecular level in at least one animal species has more than trebled from 81 to 265. And, given the amazing power of SNP chips in facilitating these discoveries (as also briefly discussed in this edition), this number is set to explode in the next few years. Even now, there are so many wonderful examples to illustrate basic principles that some very difficult decisions have had to be made in order to keep this edition to a reasonable length. As compensation, readers are invited to access Online Mendelian Inheritance in Animals (OMIA) at http://omia.angis.org.au for up-to-date information on all documented single-locus disorders and other traits; and, in contrast to the previous edition’s unfulfilled promise, the OMIA web site also provides access to a home page for this book. A major innovation in this edition are dot-point summaries at the end of each chapter. It is hoped that these will help readers to grasp the big picture.

Many of the topics in this book, especially those concerning population and quantitative genetics, are covered in greater detail in Veterinary Genetics (Clarendon Press, Oxford, 1987). References to that publication, particularly to its derivations, are provided in the text of the present volume.

Thanks are due to many colleagues who have provided information and/or checked drafts: Leopoldo Iannuzzi, Steve O’Brien, Marilyn Raymond, Dave Burt, Max Rothschild, Darren Griffin, Brian Kinghorn, Ross Tellam, Mehar Khatkar, Claire Wade, Sasha Graphodatsky, Roscoe Stanyon, Darren Griffin, Martin Völker, Jill Maddox, Ben Hayes, John James, Hannah Nicholas, Belinda Norris, Jonathan Usmar, Bethany Wilson, Peter Thomson, Claire Wade, Noelle Cockett, Rob Banks, Mohammad Shariflou, Malcolm Ferguson-Smith, and Xuan Zhang.

Thanks are also due to the team from Wiley-Blackwell: Justinia Wood, Amy Brown, Adam Burbage, Sophie Gillanders, James Sowden, Katy Loftus, Lesley Simon and Anne Bassett. I am very grateful for your invaluable professional guidance and assistance. Finally, very special thanks are due to my wife, Jan, for understanding that retirement does not necessarily mean walking away from it all.

F. W. NSydneyJuly 2009

1

Basic genetics

This chapter provides a review of basic genetics. It concentrates on the general principles that apply to normal, healthy animals. The exceptions to these principles are often the basis of genetic diseases, which are discussed in subsequent chapters.

Chromosomes

When a culture of rapidly dividing white blood cells is treated with the alkaloid colchicine (which halts cell division), and the cells are then stained and viewed under a light microscope, structures called chromosomes become clearly visible. They are scattered randomly within clusters, and each cluster contains all the chromosomes from just one cell. The area of genetics concerned with chromosomes is called cytogenetics.

In order to study chromosomes more closely, a suitable cluster is chosen, as shown in Fig. 1.1a. Each item in the cluster consists of two rod-like structures joined together at a constricted point. Each rod-like structure is a chromatid and the constriction is a centromere. The two chromatids that are joined at the centromere have just been formed from one original chromosome. If the cell division had been allowed to proceed, the centromere would have split and each separate chromatid would then be called a new chromosome. For convenience, we talk of each pair of chromatids joined at the centromere as being just one chromosome, referring in fact to the chromosome that has just given rise to them.

All the chromosomes in the cluster are then rearranged in order of size. An arrangement such as this provides a picture of the complete set of chromosomes or karyotype of a cell (Fig. 1.1b). If many such arrangements are examined from normal, healthy individuals of both sexes of any species of mammal or bird, two facts become evident: each species has a characteristic karyotype and, within any species, each sex has a characteristic karyotype.

Karyotypes of different species differ in the shape, size, and number of their chromosomes. Within any species, all the chromosomes occur in pairs. In individuals of one sex, both members of each chromosome pair have the same size and shape. In the other sex, all but two chromosomes occur in such pairs, with the remaining pair consisting of two chromosomes of different size and shape. In this unequal pair, one chromosome has the same shape and size as members of one of the pairs in the opposite sex.

Fig. 1.1 (a) The chromosomes of a male cat, as seen through a light microscope. (b) The karyotype of a male cat, as obtained by rearranging individual chromosomes from (a). (Reproduced courtesy of P. Muir.)

The difference in karyotype between the two sexes is the key to sex determination. In mammals, the two chromosomes that form the unequal pair occur in males, and are called the X and Y chromosomes. In female mammals, one of the pairs of chromosomes consists of two X chromosomes. Thus in mammals, males are XY and females are XX. The X and the Y chromosomes are known as sex chromosomes. In birds, the sex chromosomes are given different names, and their relationship to sex is the opposite of that in mammals: male birds are ZZ and female birds are ZW. For convenience, we shall refer only to mammals in the following discussion, although all statements apply equally to birds if the names of the sexes are reversed.