The beginning of life may be a miracle to some, and a mystery to others, but it is certainly one of the most exciting and perhaps controversial fields of scientific investigation in the 21st century. Among the metazoa, life begins when an egg is fertilized by a sperm. The sperm provides a genetic blueprint from the father and perhaps some critical proteins. The egg provides a genetic blueprint from the mother together with a large reservoir of mRNAs and proteins that are required for DNA replication, cell division and the onset of zygotic gene expression. All of the thousands of genes in these two mature gametes are transcriptionally silent and remain so until fertilization. This work focuses on three biological systems, providing the reader with a clear understanding of the current state of affairs, and the ability to identify common principles as well as critical differences that are responsible for beginning the process of animal development. The essays presented will be of practical value to all those who are interested in improving fertilization in vitro, in designing novel methods of contraception, in developing preimplantation genetic diagnosis for various diseases, in cloning animals by transplanting nuclei from adult cells to an enucleated egg, and in the application of embryonic stem cells to curing genetic diseases or replacing damaged tissues. But above all, this volume is offered to those who simply have an insatiable curiosity about life and its beginnings.

Epigenetics is a term in biology referring to heritable traits that do not involve changes in the underlying DNA sequence of the organism. Epigenetic traits exist on top of or in addition to the traditional molecular basis for inheritance. The "epigenome" is a parallel to the word "genome," and refers to the overall epigenetic state of a cell. Cancer and stem cell research have gradually focused attention on these genome modifications. The molecular basis of epigenetics involves modifications to DNA and the chromatin proteins that associate with it. Methylation, for example, can silence a nearby gene and seems to be involved in some cancers. Epigenetics is beginning to form and take shape as a new scientific discipline, which will have a major impact on Medicine and essentially all fields of biology. Increasingly, researchers are unearthing links between epigenetics and a number of diseases. Although in recent years cancer has been the main focus of epigenetics, recent data suggests that epigenetic plays a critical role in psychology and psychopathology. It is being realized that normal behaviors such as maternal care and pathologies such as Schizophrenia and Alzheimer's might have an epigenetic basis. It is also becoming clear that nutrition and life experiences have epigenetic consequences. Discover more online content in the Encyclopedia of Molecular Cell Biology and Molecular Medicine.

Changes in Eukaryotic Gene Expression in Response to Environmental Stress focuses on various aspects of eukaryotic cell's response to heat stress (shock) and other stress stimuli. This book is organized into two major sections, encompassing 17 chapters that reflect the emphasis on research utilizing Drosophila, a variety of animal systems, and plants. This book first provides a brief introduction to the organization, sequences, and induction of heat shock proteins and related genes. It then describes the control of transcription during heat shock from the standpoint of molecular biology and evolutionary variations of the mechanisms in organisms with diverse metabolic needs. It goes on to discuss the issue of coordinate and noncoordinate responses of heat shock genes. It presents a model for post-transcriptional regulation on certain aspects of coordinate and noncoordinate regulations. Chapters 6-12 discuss heat shock proteins and genes and the effects of stress on gene expression of sea urchin, avian, and mammalian cells. The second part of the book focuses on the physiological role of heat shock proteins and genes in plants and fungi. It includes a discussion on experimental problems encountered during studies of the mechanisms of inhibition of photosynthesis by unfavorable environmental conditions. The changes in transcription and translation of specific mRNAs in the developing embryo during heat shock at various temperatures are described. The concluding chapters deal with heat shock response in plants, particularly the response in soybeans and maize, covering both physiological and molecular analyses. Research scientists, clinicians, and agriculturists will greatly benefit from the information presented in this book.

Four of the major animal systems studied for the mechanisms of their early embryonic development are treated in this volume. The articles address the specific questions studied in the various systems, discuss the fundamental questions raised by the particular organism and explain the techniques used to find answers to these questions. Questions of patternformation, early organogenesis and the genetics of the early development arecovered as well as the question of parental imprinting phenomena in mammals which are important for the early differentiation. The development of the mouse, Drosophila, Caenorhabditis and the zebrafish is emphasized by leading experts of their fields, and current problems in each system are exposed. For the zebrafish the advantages of this new system for developmental biology studies are summarized and discussed in their values, while in the other system the emphasis is laid on one of the actual field of research.