E-Book Overview
Leading drosophilists describe in step-by-step detail all the essential techniques for studying Drosophila chromosomes and suggest new avenues for scientific exploration. The chapters emphasize specimen preparation (from dissection to mounting) and cover both polytene and mitotic/meiotic chromosomes in depth. Each fully tested and readily reproducible protocol offers a background introduction, equipment and reagent lists, and tips on troubleshooting and avoiding pitfalls. A cutting-edge FISH and immunolocalization technique will be important for discovering how DNA sequence influences higher-order chromosome architecture and ultimately gene expression.
E-Book Content
Methods in Molecular Biology
TM
VOLUME 247
Drosophila Cytogenetics Protocols Edited by
Daryl S. Henderson
Drosophila Chromosomes
1
1 The Chromosomes of Drosophila melanogaster Daryl S. Henderson 1. Introduction Drosophila have two basic forms of chromosomes—mitotic and polytene— that have vastly different morphologies and cellular roles. Polytene chromosomes are found in interphase nuclei of differentiated cells, being especially prominent in certain tissues of the larva and adult ovary. They are produced by repeated rounds of chromosome replication unhitched from nuclear division in a process termed “endoreplication.” Among the largest and most familiar of polytene chromosomes are those of the larval salivary gland, which can consist of >2000 sister chromatids tightly aligned in register. Such scaled-up chromosomes permit production of large quantities of gene products in a narrow developmental window. The highly compact mitotic chromosomes, found in proliferating tissues (e.g., the larval central nervous system [CNS], imaginal discs, ovaries, and testes), are genome-packaging vehicles that, in association with the spindle apparatus, function to tr