Organization and Expression of tRNA Genes in Drosophila Melanogaster.- Chemical Nature, Properties, Location, and Physiological and Pathological Variations of Modified Nucleosides intRNAs.- Session I. Modified Nucleosides in Situ in Tumors and Transformed Cells of Cell Culture.- InDNA.- Formation and Removal of Methylated Nucleosides in Nucleic Acids of Mammalian Cells.- Structural Modifications and Repair of DNA in Neuro-Oncogenesis by N-Ethyl-N-nitrosourea.- Role of Extent and Persistence of DNA Modifications in Chemical Carcinogenesis by Aromatic Amines.- Can DNA Methylation Regulate Gene Expression?.- In tRNA.- tRNA Alterations in Cancer.- Tumor-Specific tRNA Modifications in Mouse Plasmacytomas and Other Tumors.- Alterations in Post-Transcriptional Modification of the Y Base in Phenylalanine tRNA from Tumor Cells.- Why Is Tumor tRNA Hypomodified with Respect to QNucleoside?.- The Effects of Growth Factors on tRNALys Modification.- Perturbation of the Mitochondrial Lysine tRNA Population by Virus-Induced Transformation or Stress of Mammalian Cells: Functional Properties and Nucleotide Sequence of a Mitochondrially Associated Lysine tRNA.- Involvement of tRNA in Retrovirus Expression: Biological Implications of Reverse Transcriptase-Primer tRNA Interactions.- Session II. Biosynthesis and Degradation of Modified Nucleosides in Cancer Cells.- DNA-Specific Enzymes.- Enzymatic Methylation of Chicken Erythrocyte DNA Modified by Two Carcinogens, 2-(N-Acetoxyacetylamino)Fluorene and Methylnitrosourea.- Inhibition of DNA Methylation by 5-Azacytidine.- Alteration of Enzymatic DNA Methylation by Chemical Carcinogens.- tRNA-Specific Enzymes.- Ethionine-Induced Alterations of tRNA Metabolism.- Processing of tRNA Is Accomplished by a High-Molecular-Weight Enzyme Complex.- Alteration of tRNA Modification in Eukaryotes: Causes and Consequences.- Effects of Cortisol on tRNA Methylase Activities in Rat Mammary Carcinoma.- An Approach to Inhibition of Viral Replication: Inhibition of mRNA Methylation.- Specific Effects of 5-Fluoropyrimidines and 5-Azapyrimidines on Modification of the 5 Position of Pyrimidines, in Particular the Synthesis of 5-Methyluracil and 5-Methylcytosine in Nucleic Acids.- Session III. Modified Nucleosides: Type and Concentration in Body Fluids and Relevance for Cancer Therapy of Tumor-Bearing Individuals.- New Applications of Urinary Nucleoside Markers.- Multivariate Analysis of Urinary RNA Catabolites in Malignancies: Cross-Sectional and Longitudinal Studies.- Evaluation of Carcinoembryonic Antigen, Tissue Polypeptide Antigen, Placental Alkaline Phosphatase, and Modified Nucleosides as Biological Markers in Malignant Lymphomas.- Quantitative High-performance Liquid Chromatography Analysis of Modified Nucleosides in Physiological Fluids, tRNA,and DNA.- Modified Nucleosides in Body Fluids of Tumor-Bearing Patients.- Increasing Urinary Levels of Modified Nucleosides and Bases During Tumor Development in Mice.- Comparison of Urinary Modified Nucleosides and Bases in Rats with Hepatomas and Nephroblastomas.- Characterization and Analysis of Oncofetal tRNA and Its Possible Application for Cancer Diagnosis and Therapy.- Excretion of Polyamines by Children with Leukemia During Chemotherapy.- Subject lndex.