EM METHODS FOR VISUALIZATION OF GENETIC-ACTIVITY FROM DISRUPTED NUCLEI

This chapter reviews the technique of Miller chromatin spreading and its applications to the study of Drosophila RNA transcription and processing. The Miller technique is a preparatory method for electron microscopy that yields gently dispersed interphase nuclear chromatin as the specimen. The advantage of the method are first, its ability to display chromosomal activities, such as DNA replication or RNA transcription, for analysis at the level of the individual genetic locus, while at the same time providing a view of the general population, and second, its conservation of the basic nucleoprotein structures on DNA and RNA, as opposed to most electromagnetic (EM) procedures for nucleic acids, which involve deproteination. The major drawback to the technique as applied to Drosophila is the inability to routinely visualize a specific gene of choice or to identify the genes visualized. Although individual genes on plasmid vectors can be visualized after microinjection into Xenopus oocytes, similar injection of genes into Drosophila embryos has been unsuccessful to date for the purpose of gene visualization. © 1994, Elsevier Science Publishers, B.V. All rights reserved.