This journal provides immediate access to some articles. Volume 68(4); April 1971 Biological Sciences: Anthropology Isolation by Distance in Bougainville PMCID: PMC389024 Biological Sciences: Biochemistry Purification of Erythropoietin PMCID: PMC389022 Normal and Defective Repair of Damaged DNA in Human Cells: A Sensitive Assay Utilizing the Photolysis of Bromodeoxyuridine PMCID: PMC389025 Induction of Mitochondrial DNA Synthesis in Monkey Cells Infected by Simian Virus 40 and (or) Treated with Calf Serum PMCID: PMC389027 Regulatory Properties of an Inorganic Pyrophosphatase from the Photosynthetic Bacterium Rhodospirillum rubrum PMCID: PMC389028 Interconversion of Cyclic Nucleotide-Activated and Cyclic Nucleotide-Independent Forms of a Protein Kinase from Beef Heart PMCID: PMC389030 A Simple, Sensitive Protein-binding Assay for Guanosine 3′:5′-Monophosphate PMCID: PMC389031 Properties of a Soluble DNA Polymerase Isolated from Rous Sarcoma Virus PMCID: PMC389034 Purification and DNA Synthesis in Cell-Free Extracts: Properties of DNA Polymerase II PMCID: PMC389037 Localization of Methylated Arginine in the A1 Protein from Myelin PMCID: PMC389038 Regulation of Rat Liver Glutamine Synthetase: Activation by α-Ketoglutarate and Inhibition by Glycine, Alanine, and Carbamyl Phosphate PMCID: PMC389042 Role of the Receptor in the Mechanism of Action of Adenosine 3′:5′-Cyclic Monophosphate PMCID: PMC389043 Identification of 1,25-Dihydroxycholecalciferol, a Form of Vitamin D3 Metabolically Active in the Intestine PMCID: PMC389047 Conformational Changes in Ribosomes during Protein Synthesis PMCID: PMC389048 Neutral Sites for Calcium Ion Binding to Elastin and Collagen: A Charge Neutralization Theory for Calcification and Its Relationship to Atherosclerosis PMCID: PMC389049 Genetic Recombination in Escherichia coli: The Role of Exonuclease I PMCID: PMC389052 Release, Identification, and Isolation of Messenger RNA from Mammalian Ribosomes PMCID: PMC389054 High-Resolution X-Ray Diffraction Patterns of Crystalline Transfer RNA That Show Helical Regions PMCID: PMC389056 Altered Methylation of Ribosomal RNA in an Erythromycin-Resistant Strain of Staphylococcus aureus PMCID: PMC389059 Structural Measurements in Hemoproteins: Use of Spin-Labeled Protoheme as a Probe of Heme Environment PMCID: PMC389060 Sequences of Pituitary and Placental Lactogenic and Growth Hormones: Evolution from a Primordial Peptide by Gene Reduplication PMCID: PMC389061 Biological Sciences: Cell Biology Organelles in Neuroplasmic (“Axonal”) Flow: Neurofilaments PMCID: PMC389057 Biological Sciences: Genetics Karyotyping of Single Human Chromosomes from Dry Mass Determined by Electron Microscopy PMCID: PMC389029 The Influence of Neighboring Base Pairs upon Base-Pair Substitution Mutation Rates PMCID: PMC389040 Isolation of Transducing Particles of ϕ80 Bacteriophage That Carry Different Regions of the Escherichia coli Genome PMCID: PMC389045 The Synaptinemal Complex and Four-Strand Crossing Over PMCID: PMC389058 Biological Sciences: Immunology Radioresistance of the Enhancing Effect of Cells from Carrier-Immunized Mice in an In Vitro Primary Immune Response PMCID: PMC389023 Biological Sciences: Medical Sciences Inducers of Interferon Inhibit the Mitotic Response of Liver Cells to Partial Hepatectomy PMCID: PMC389032 ε-(γ-Glutamyl)lysine in Fibrin: Lack of Crosslink Formation in Factor XIII Deficiency PMCID: PMC389039 Mutation and Cancer: Statistical Study of Retinoblastoma PMCID: PMC389051 Viruses as an Aid to Cancer Therapy: Regression of Solid and Ascites Tumors in Rodents After Treatment with Bovine Enterovirus PMCID: PMC389055 Biological Sciences: Microbiology Further Characterization of the Cellular DNA Hybridizing with the RNA of Rous Sarcoma Virus PMCID: PMC389033 RNA-Dependent RNA Polymerase Activity Associated with Virions and Subviral Particles of Myxoviruses PMCID: PMC389035 Biological Sciences: Physiology Energy Transfer in Rhodopsin, N-Retinyl-Opsin, and Rod Outer Segments PMCID: PMC389026 Microtubules and Sensory Transduction PMCID: PMC389036 Biological Sciences: Zoology Comparative DNA Renaturation Kinetics in Amphibians PMCID: PMC389046 Physical Sciences: Applied Mathematics Pavlovian Pattern Learning by Nonlinear Neural Networks PMCID: PMC389053 Physical Sciences: Chemistry Kinetics of Heterogeneous Chemical Reactions: A Theoretical Model for the Accumulation of Pesticides in Soil PMCID: PMC389041 Physical Sciences: Mathematics Some Cohomology Classes in Principal Fiber Bundles and Their Application to Riemannian Geometry PMCID: PMC389044 The Writhing Number of a Space Curve PMCID: PMC389050 Corrections Introduction of a heterologous nucleus into enucleated cytoplasms of cultured mouse L-cells PMCID: PMC389062 Corrects: Introduction of a Heterologous Nucleus into Enucleated Cytoplasms of Cultured Mouse L-Cells. Proc Natl Acad Sci U S A. 1970 November; 67(3): 1528–1533. Posttranscriptional control of tyrosine aminotransferase synthesis by insulin PMCID: PMC389063 Corrects: Posttranscriptional Control of Tyrosine Aminotransferase Synthesis by Insulin. Proc Natl Acad Sci U S A. 1970 June; 66(2): 390–397. Journal Matter Original table of contents page Administrative content — journal masthead, notices, indexes, etc. | ||