Hiroto Naora

Deoxyribonucleic acid-dependent protein synthesis in nuclear ribosome system in vitro

Abstract A stable nuclear ribosome system was obtained from isolated calf-thymus nuclei in which the incorporation of labeled amino acids into trichloroacetic acid-insoluble proteins is stimulated by the addition of DNA. It was suggested that the amino acid composition of the labeled products reflects the base composition of the DNA added and that an adenine-containing triplet in the DNA strand codes for lysine and a thymine-containing triplet for phenylalanine. Double-stranded DNA has less stimulatory activity than single-stranded DNA. No concomitant RNA synthesis takes place during DNA stimulation. The results obtained here may suggest that genetic information from DNA is directly transferred to the products in the nuclear ribosome system without any mediation through mRNA.

Feulgen reaction and quantitative cytochemistry of desoxypentose nucleic acid IV. Microspectrophotometric study of the Feulgen reaction in situ

Abstract The development of the Feulgen reaction does not proceed in the same manner in vitro and in situ , but no evidence was obtained that the reaction in situ is affected by the change in protein/DNA ratio of nuclei.

Formation of a nuclear ribosome-deoxyribonucleic acid complex

Abstract 1. (a) Nuclear ribosomes, isolated from thymus-cell nuclei, are capable of binding DNA and thus forming a complex. The formation of such a complex was demonstrated by means of starch electrophoresis. 2. (b) There is no evidence for species specificity of DNA in forming the complex. 3. (c) Large, negatively charged molecules other than DNA are also capable of being bound to nuclear ribosomes, but these molecules are bound at different sites from those used in the binding of DNA. 4. (d) Evidence is presented that one molecule of calf-thymus DNA is capable of binding with between 3 and 27 nuclear ribosomal particles, assuming the range of sedimentation constants of the nuclear ribosomes to lie between 150 and 700 S. More than 150 particles of nuclear ribosomes of 75 S may be bound to one molecule of calf-thymus DNA. 5. (e) Binding of DNA at particular sites on the nuclear ribosomes is considered in relation to the stimulatory effect of added DNA on the incorporation of amino acids by isolated nuclear ribosomes. 6. (f) The physiological significance within the cell of the formation of the complex between DNA and nuclear ribosome is discussed in relation to the regulatory control of protein synthesis by chromosomes.

Nuclear ribonucleoprotein particles associated with DNA

Abstract 1. 1. Nuclear ribonucleoprotein particles, prepared from isolated calf thymus nuclei, under the conditions adopted in these experiments, contained 4.0±0.26% DNA. 2. 2. Sucrose density gradient electrophoresis analyses of the DNA present in the ribonucleoprotein preparations showed that DNA was present largely on ribonucleoprotein particles, but some of the DNA was found in several fast-moving peaks. 3. 3. Essentially all of the DNA present on particles was retained after treatment with deoxycholate, or after mild digestion by either ribonuclease or deoxyribonuclease. 4. 4. The possible occurrence and structure of a nuclear ribonucleoprotein-DNA complex in the cell nucleus in situ are discussed.

Incorporation of ribonucleoside triphosphates in a nuclear ribosomal system, in vitro, during the DNA-stimulated incorporation of amino acids

Abstract 1. The properties of the incorporation of [14C]ATP, CTP, GTP and UTP in the nuclear ribosomal system in which amino acid incorporation was stimulated by the addition of heat-denatured calf-thymus DNA, have been investigated. 2. The addition of heat-denatured, calf-thymus DNA to the reaction mixture did not result in appreciable stimulation of [14C]GTP- and [14C]UTP- incorporation into the alkali-labile material of the acid-insoluble fraction; nor of [14C]ATP and [14C]CTP- incorporation into the acid-insoluble fraction, while amino acid incorporation was being stimulated in this system. 3. Incorporation was not inhibited by actinomycin D in the system supplemented with heat-denatured calf-thymus DNA. 4. Marked stimulation of [14C]GTP incorporation was observed in the absence of all three remaining nucleoside triphosphates in the reaction system. 5. Addition of heat-denatured calf-thymus DNA resulted in marked stimulation of the incorporation of [14C]GTP and [14C]UTP into a terminal position of the DNA molecule. 6. Analysis of the reaction product indicates that the incorporation into RNA is mainly due to the terminal exchange of soluble RNA and the attachment of AMP to the terminal AMP residue in RNA molecules. 7. These results suggest that addition of heat-denatured calf-thymus DNA did not result in the formation of new RNA molecules.

Occurrence of labile phosphate in rat liver nuclei.

Abstract Cell nuclei and mitochondria of the rat liver were isolated with non-aqueous media and the labile phosphate (may be ATP) content of the fractions was compared with that of the total homogenate or of the crude cytoplasmic fraction. The labile phosphate was concentrated in nuclei and also in mitochondria. The cell-physiological significance of the presence in the cell nucleus of ATP is discussed.

A Histopathological Study of Infectious Hepatitis with Needle Biopsy Materials, Especially a Cytological and Microspectrophotometric Observation

It has been widely accepted that infectious hepatitis is a self-directing disease and its pathogen is a virus.(l)*(e)l(s) Recently in Japan, there was an outbreak of infectious hepatitis in Okayama Prefecture (69 patients and its mortality was 13 per cent),(4) and isolation of its virus has been performed.(5)~(6) At the 4th Meeting of the International Society of Geographic Pathology, infectious hepatitis was the main subject, and many detailed studies were reported and discussed. The authors were fortunate in obtaining the opportunity to study 10 cases of infectious hepatitis in the Tokyo area. Needle biopsy materials of the liver were taken, and the materials were investigated histopathologically, with special stress layed on cytological and microspectrophotometric observations.