New Developments in Practical Virology. Laboratory and Research Methods in Biology and Medicine. Volume 5

ribosomal subunits. The possibility for concomitant RNA processing and transport is discussed. Evidence is presented for kinase and phosphotase reactions necessary for these functions. Murty and coworkers present data and review the evidence for an increased release of nuclear RNA as effected by tryptophan. Two excellent papers summarize the conditions of transport; Maul describes the structure of the pore complex and hypothesizes three modes of travel based on its architecture, and Clawson and Smuckler review the biophysical data for RNA transport and propose a model incorporating the energy requirements and the physical limitations of the system. Significantly, four papers are presented which describe the association of DNA with the nuclear matrix. These provide evidence for attachment of the DNA at replication origins, and during DNA synthesis, at the replication forks. Contradicting previous reports, Berezney and colleagues demonstrate that the matrix-attached DNA is not enriched in repetitive DNA sequences. Pigiet and Humphrey describe the interaction of T antigen with the nuclear matrix during polyoma virus replication and transcription. The transcriptional function of DNA and the matrix is addressed at many levels. Hormone binding sites within the nuclear matrix are characterized by two groups. The topological considerations of both DNA replication and RNA transcription are discussed by Feinberg and Coffey, who cast the nuclear matrix in a central role of mediating and regulating these functions. Pogo and coworkers describe crosslinking experiments between nonhistone proteins and histones and snRNA to hnRNA. Tew reviews the data implicating an interaction of nuclear reactant drugs with the nuclear matrix in the cytotoxicity of these chemicals. Finally, a powerful argument is presented by Cavalier-Smith for the co-evolution of the nuclear matrix and the nuclear envelope by relating closed and open mitosis to these structures and the need for nuclear volume control. The Nuclear Envelope and the Nuclear Matrix summarizes our present understanding of these structures and provides an overview of the widely varied ideas associated with these topics. This book will be of great interest to all biologists and biochemists who are concerned with nuclear morphology, nuclear-cytoplasmic interactions, DNA replication, or RNA transcription.