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Biomedical subjects

D Mizuno

Publications and source records attributed to D Mizuno.

At least 217 records · Page 12Linked to original sources
PubMed1970

Stabilizing effect of colicin E2 on the "spheroplast membrane".

Cells of Escherichia coli W3110 and its thymineless mutant, both of which are colicin E2 sensitive, were treated with colicin E2, and then converted to spheroplasts. These spheroplasts seemed to be more stable than those from untreated cells; suspensions of spheroplasts of untreated cells were lysed spontaneously and the turbidity was reduced by approximately 45% on incubation with ethylenediaminetetraacetic acid-lysozyme, whereas suspensions of spheroplasts of colicin E2-treated cells showed 25% reduction in turbidity. This change was irreversible and 5 min of treatment with colicin E2 at 37 C was necessary for stabilization. This process was inhibited by 2,4-dinitrophenol or streptomycin. Cells harboring the colicin E2 factor were not affected by treatment in this way with colicin E2. Alteration of composition of phospholipids was not observed.

Cell Membrane↗
PubMed1969

Replication and properties of DNA in nicotinamide adenine dinucleotide deficiency of Escherichia coli cells.

When niacin-requiring E. coli was starved of niacin, a precursor of nicotinamide adenine dinucleotide (NAD), the cells elongated and synthesis of DNA was inhibited while syntheses of RNA and protein continued. The cellular NAD concentration decreased to less than one tenth of the normal level in niacin deficiency, but no change in DNA ligase level was detected. The apparent inhibition of DNA synthesis can be explained as due to reduction in the activity of the cofactor, NAD, for the enzyme. The DNA synthesized in this state was small in an alkaline sucrose gradient but of normal size in a neutral sucrose gradient. The molecules had a double-stranded structure, as judged by hydroxyapatite chromatography. The small pieces of DNA were integrated into normal-size DNA molecules on addition of niacin, when the cellular NAD concentration was restored to the normal level but DNA synthesis was not. It is suggested that this small DNA is an intermediate in DNA replication.

Bacterial Proteins↗