The discovery in 1977 that genes are split into exons and introns has done away with the one gene - one protein dogma. Indeed, the removal of introns from the primary RNA transcript is not necessarily straightforward since there may be optional pathways leading to different messenger RNAs and consequently to different proteins. Examples of such an alternative splicing mechanism cover all fields of biology. Moreover, there are plenty of occurrences where deviant splicing can have pathological effects. Despite the high number of specific cases of alternative splicing, it was not until recently that the generality and extent of this phenomenon was fully appreciated. A superficial reading of the preliminary sequence of the human genome published in 2001 led to the surprising, and even deceiving to many scientists, low number of genes (around 32,000) which contrasted with the much higher figure around 150,000 which was previously envisioned. Attempts to make a global assessment of the use of alternative splicing are recent and rely essentially on the comparison of genomic mRNA and EST sequences as reviewed by Thanaraj and Stamm in the first chapter of this volume. Most recent estimates suggest that 40-60% of human genes might be alternatively spliced, as opposed to about 22% for C. elegans.

This volume focuses on the major aspects of post-transcriptional mRNA processing in the nucleus of eukaryotic cells. Each of the described mRNA reactions is required for proper gene expression and can also serve as a control point for regulating the expression of many genes, for example duringembryonic development or in different cell types. The different chapters review the assembly of newly synthesized nuclear mRNA transcripts into hnRNP particles and catalytically active spliceosomes; the structure and mechanism of action of small nuclear ribonucleoprotein particles and proteinfactors that catalyse pre-mRNA splicing in mammalian cells and in yeast; the regulation of gene expression and generation of protein isoform diversity by alternative splicing; the mechanisms of 3' end cleavage and polyadenylation; the architecture of the cell nucleus in relation to these processesand to the localization of the relevant substrates and factors; the diverse mechanisms of RNA processing by ribozymes and their potential relevance for nuclear mRNA processing; the mechanism of spliced-leader addition by trans-splicing in nematodes and trypanosomes; and the process ofinsertion/deletion mRNA editing in kinetoplasmid protozoa. In each chapter, leading researchers have provided detailed, critical reviews of the history, experimental approaches, major advances, current ideas and models, as well as future directions, for each of these active areas of research.

During the last few years, tremendous progress has been made in understanding various aspects of pre-mRNA processing. This book, with contributions from leading scientists in this area, summarizes recent advances in nuclear pre-mRNA processing in plants. It provides researchers in the field, as well as those in related areas, with an up-to-date and comprehensive, yet concise, overview of the current status and future potential of this research in understanding plant biology.

This book gives a co-ordinated review of our present knowledge of eukaryotic RNA synthesis.

Yet again Springer has reached the market before everyone. This is the first book that is solely dedicated to the topic of alternative splicing. The book contains chapters by experts in the field that cover nearly all aspects of this hugely important subject. The purpose of the text is to provide a single, authoritative source of information on alternative splicing that is accessible to researchers in diverse fields. It is suitable for beginners and experts alike.

A recent review of one of my grant applications commented on the ‘rediscovery of tropomyosin’. I was tempted to write back in my rebuttal to the reviewer that I didn’t realise it had been lost. Uncharacteristic maturity prevailed and I resisted the temptation, but I was struck by the underlying observation that research on the str- ture and function of tropomyosin has been somewhat invisible, particularly in terms of the cytoskeleton isoforms. So, how can it be that one of the two major components of the actin filament has been so thoroughly overlooked? I suspect that the answer is disappointingly pedestrian. Whereas the biochemistry of the 1980s revealed the potential of tropomyosin isoforms to diversify the function of actin filaments, the subsequent disenchantment with isoform biology in general in the 1990s inhibited growth of this field. With the development of more sophisticated experimental - proaches we are now seeing a growing realisation of the importance of tropomyosin in regulating actin filaments beyond its pivotal role in muscle contraction. The opportunity to edit this book came at a time when we had written several reviews on different aspects of tropomyosin function and I had just finished the background reading for a comprehensive review of tropomyosin biology. I realised that the field was simply beyond the capacity of any one person to do the field j- tice.