Genes And Mechanisms In Vertebrate Sex Determination

Following an opening chapter by the late Susumu Ohno on paralogues of sex-determining genes, the five best-studied genes essential for early mammalian gonadal development are portrayed in detail: SF-1 and WT1 and their roles in early events in gonadal development, SRY and SOX9 in testis determination, and the anti-testis gene DAX-1. Subsequent chapters look at the roles of these genes in sex determination in marsupial mammals, birds, reptiles, amphibians and fish, and review the different sex-determining mechanisms, genetic and environmental, that operate in these different vertebrate classes. Two insights emerge: one, that the same basic set of genes appears to operate during early gonadal development in all vertebrates, despite the differences in mechanisms; the other, that sex determination in vertebrates results from a complex network of regulatory interactions and not from a simple hierarchical cascade of gene actions.

Nature employs a wide variety of sex determining mechanisms and it is only comparatively recently that the tools have become available for these to be explored at the cellular and molecular levels. A major landmark was the discovery in 1990 of the SRY gene and the subsequent demonstration of its key role in triggering male sex determination in transgenic mice. This book reviews and discusses our current understanding of the molecular genetic pathways of sex determination, with special emphasis on vertebrates. It features comparisons with other modes of sex determination, consideration of the biology of sexual development and discussion of the evolution of sex-determining mechanisms. By bringing together an international and interdisciplinary group of experts who study many different aspects of the problem, the book highlights much new and exciting work in this area and serves to identify and stimulate promising new research directions.

During the last two decades of the 20th century, the study of chromosomes was enormously stimulated by the availability of various biological resources, valuable databases and new genetic and molecular biological techniques including PCR and fluorescent in situ hybridization. The simultaneous development of new and effective systems for targeting genes and gene transfer led to astonishing advances also in the study of vertebrate sex chromosomes. We now have considerable insight into their evolution, the dosage compensation mechanisms in mammals that involve chromosome-wide chromatin remodeling triggered by noncoding Xist RNA, and the unique properties of the human X chromosome which comprises many genes important for sex determination and reproduction. This thematic issue of Cytogenetic and Genome Research presents an excellent and highly authoritative compilation of current research findings related to vertebrate sex chromosomes. The contributions - all prepared by experts in the field - reflect both the technical advances and the enormous gain in knowledge achieved in recent years. Many of these papers also provide important historical perspectives while some contain insightful personal views of the authors. This special volume therefore represents a stimulating and critical state-of-the-art source of information for investigators and students in this fascinating field.

Reptiles are a fascinating group for the study of sexual development because they exhibit a wide range of sex-determining mechanisms, from strict genetic sex determination (GSD) to strict thermal sex determination (TSD) and intermediate systems of GSD that are to various degrees overridden by environmental effects . This thematic issue presents the latest data on different aspects of sex determination in reptiles. Following an evolutionary perspective on why reptiles might be predisposed to evolve TSD, the papers in this issue explore in detail the different genetic and molecular mechanisms of sex determination and differentiation. They consider recent findings such as the discovery of new genes differentially expressed at male and female sex-determining temperatures, a new model of the role of aromatase, and the contribution of heat-shock proteins to TSD in the American alligator. Further studies examine the role played by sex allocation, the advantage of viviparity, and the effects of anthropogenic climate change on the sex ratio in TSD reptile populations. Providing a valuable overview for both students and researchers, this publication is essential reading for developmental and reproductive biologists, herpetologists, comparative endocrinologists, evolutionary biologists and geneticists.

The cloning of the SRY gene and the attainment of XX mice transgenic for the Sry gene opened a new era in research on sex determination. This book surveys current knowledge of sex chromosomes and sex determination in all vertebrate classes, relying on the restriction of genetic recombination in sex chromosomes as the unifying concept of this subject. The book's interdisciplinary approach integrates contributions from the fields of cytogenetics, molecular biology, developmental biology, and evolutionary genetics. A detailed treatment of the meiotic behavior of sex chromosomes is featured, and the entire text is supplemented by numerous schemes, drawings, and electron micrographs. The book will be valuable to general cytogeneticists, vertebrate zoologists, and veterinarian and medical practitioners interested in the foundations of sex determination and the current knowledge of sex chromosomes. It will also interest students in advanced undergraduate and graduate courses in these areas.

Gender (sex) is a set of morphological and physiological characteristics of the organism underlying sexual reproduction, the essence of which is reduced to fertilization, i.e. the fusion of male and female gametes (gametes) zygote, which develops into a new organism.Sexual reproduction of a species is considered as one of the mechanisms of its homeostasis. Thanks to this mechanism, numerous species have an evolutionary advantage. In the book, two authors will discuss the types of genetic sex determination and differentiation, mostly in multicellular animal organisms. Sex determination is both genetic and environmental process, the sex of an individual being established through an alternative physiological solution. There are two main postulated mechanisms of sex determination: genetic (GSD, Genetical Sex Determination) and environmental (ESD, Environmental Sex Determination).

Sex Determination, Volume 134, the latest release in the Current Topics in Developmental Biology series, contains current reviews in the field of vertebrate sex determination. It covers molecular pathways of sex determination in genetic and environmental species and encompasses both sex determination of somatic lineages and commitment of germ cells to male or female fate. Chapters in this new release cover, amongst other topics, Mapping the Sox9 Enhancer Elements, Epigenetic Regulation of Sex Determination, Evolution and Management of Sex Chromosomes, Regulation of Germ Cell Sex Identity in Medaka, Control of Sex Determination in Zebrafish, Sexually Dimorphic Germ Cell Identity in Mammals, and more. Contains reviews written by leading experts in each field Includes informative figures that illustrate principle points that are useful for teaching Written in a style that is clear and simple