PREFACE

The last twenty years have witnessed a remarkable expansion in the definition of the Drosophila genome. The emergence of Drosophila as an organism of choice for molecular-genetic investigations of eukaryotic biology has attracted a large number of talented workers to the field, and the rapid advances in molecular technology have provided new and sophisticated tools and generated novel kinds of information.
This work is a revision of "The Genetic Variations of Drosophila melanogaster" by D. L. Lindsley and E. H. Grell, which appeared in 1968 and was essentially a complete catalogue of mutations and chromosome rearrangements of Drosophila melanogaster as of the end of 1966. The present volume purports to be such a catalogue current until the end of 1989. The illustrations are primarily the work of Edith M. Wallace, the artist employed by T. H. Morgan; they were mostly drawn between 1920 and 1940. The same illustrations were used in "The Genetic Variations of Drosophila melanogaster and its predecessor "The Mutants of Drosophila melanogaster" by Calvin B. Bridges and Katherine S. Brehme. At the time of the 1968 publication, genes were identified exclusively through the existence of mutant alleles; the only wild-type alleles considered were electrophoretic variants of a few enzymes, and the only gene for which there was any molecular information was bb. Amino-acid and nucleotide sequencing and the polymerase chain reaction were concepts for the future; cloning of DNA sequences had not been imagined; transposable elements, hybrid dysgenesis, and transformation were unsuspected. These technological advances have shifted the emphasis to normal gene structure and function rather than exclusive consideration of mutant alleles. This shift in emphasis is reflected in the title of the present volume, "The Genome of Drosophila melanogaster". The ability to identify a gene from either its protein product or the homologous product from another species, rather than the converse has lead to the discovery of many new genes for which no variant had been previously recognized. In addition new genes with interesting expression patterns are being discovered in enhancer-detection lines.
Interim versions of the majority of the material contained herein have appeared in the form of volumes 62, 64, 65, and 68 of Drosophila Information Service. This volume contains information on upwards of 4000 genes and 9000 chromosome rearrangements. There are categories of effects, little if at all represented in the 1968 edition, that have assumed major proportions in the present version. These include developmental mutations, behavioral mutations, female-sterile mutations, meiotic and mitotic mutations, Y-autosome translocations, and transposable elements; in addition many regions of the genome have been subjected to saturation mutagenesis so that large numbers of lethally mutable loci have been identified and deficiency mapped. A major consequence of the mapping efforts, utilizing both chromosome rearrangements and in situ hybridization, is that the polytene map has displaced the recombination map as the more useful standard. The 1968 volume was subdivided into seven sections: Mutations, Chromosome Aberrations, Special Chromosomes, Cytological Markers, Departures from Diploidy, Nonchromosomal Inheritance, and Wild Type Stocks. In the present version, the section on Wild-Type Stocks has been eliminated, new sections on Transposable Elements and DNA Sequences have been added, and a molecular biology category has been added to the descriptions of genes and rearrangements if the information is available.
We are grateful to our colleagues throughout the world for their contributions and corrections to draft copies. Those who have submitted entries or sections of entries are acknowledged on the first line of the entry. Special thanks are due to a number of colleagues whose efforts on behalf of this volume have been more than substantial. In particular, Jeff Hall has provided almost all of the material on behavioral and neuronal genes; George Lefevre and especially his colleague, Catherine Coyle-Thompson, provided massive amounts of information and corrections to the sections on X-linked lethals; Trudi Schüpbach provided descriptions of female-sterile and maternal-effect-lethal mutations. Jim Boyd and Scott Hawley provided the entries on mutagen-sensitive and meiotic mutants, respectively. Michael Ashburner has been especially helpful in keeping us supplied with his encyclopedic lists of mutations, chromosome rearrangements, and references; in addition he has gone over the draft copies of the work and provided detailed additions and corrections. Finally, Loring Craymer and Abraham Schalet were most helpful in reviewing material and pointing out errors and omissions.
We apologize for the omissions, inconsistencies, and errors in this compilation. Every time we reread it we find new ones, but mercifully, revision has to stop sometime.

D.L.L.

G.G.Z.