T.W. Traut and M.E. Jones, Uracil Metabolism--UMP Synthesis from Orotic Acid or Uridine and Conversion of Uracil to b-Alanine: Enzymes and cDNAs.P.F. Agris, The Importance of Being Modified: Roles of Modified Nucleosides and Mg2+ in RNA Structure and Function.N.A. Kolchanov, I.I. Titov, I.E. Vlassova, and V.V. Vlassov, Chemical and Computer Probing of RNA Structure.Q.-P. Dou and A.B. Pardee, Transcriptional Activation of Thymidine Kinase, a Marker for Cell Cycle Control.R.O. Laine, R.G. Hutson, and M.S. Kilberg, Eukaryotic Gene Expression: Metabolite Control by Amino Acids.W.K. Joklik and M.R. Roner, Molecular Recognition in the Assembly of the Segmented Reovirus Genome.C.W. Schmid, Alu: Structure, Origin, Evolution, Significance, and Function of One-Tenth of Human DNA.H.M. Darwish and H.F. DeLuca, Recent Advances in the Molecular Biology of Vitamin D Action.G.R. Greenberg and J.M. Hilfinger, Regulation of Synthesis of Ribonucleotide Reductase and Relationship to DNA Replication in Various Systems.Chapter References.Index.