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Biomedical subjects

T Miki

Publications and source records attributed to T Miki.

At least 973 records · Page 54Linked to original sources
PubMed1981

Organization of the lexA gene of Escherichia coli and nucleotide sequence of the regulatory region.

The product of the lexA gene of Escherichia coli has been shown to regulate expression of the several cellular functions (SOS functions) induced by treatments which abruptly inhibit DNA synthesis. We have cloned and mapped the lexA gene on a small segment of approximately 600 base pairs. The lexA promotor was located by transcription R-loop analysis, and the lexA product of 22,000 daltons was identified by protein synthesis in vitro. An unknown gene was found which directed the synthesis of a protein of 35,000 daltons in a region downstream from the lexA gene. Nucleotide sequence of the regulatory region of the lexA gene was determined. The sequence contained inverted repeats homologous to that of the recA regulatory region. These inverted repeats may be recognized by the lexA protein, because the protein is considered to repress both the genes as a common repressor.

Bacterial Proteins↗
PubMed1981

Constriction of a fused operon consisting of the recA and kan (kanamycin resistance) genes and regulation of its expression by the lexA gene.

The kanamycin resistance gene (kan) of transposon Tn5 was cloned into a derivative of plasmid pBR322. A DNA fragment containing the promoter-operator region of the recA gene was inserted into the promoter region of the cloned kan gene to produce a fused operon, recA-kan. Plasmid pMCR685 carrying recA-kan expressed a low level of activity of the kan gene product (kanamycin phosphotransferase; KPT) in the wild-type cells of Escherichia coli, while the plasmid showed an increased level of the activity in the SPr- mutant cells which produce the inactive lexA protein. The KPT activity in the wild-type cells harboring the plasmid increased 6- to 11-fold upon treatment of the cells with mitomycin C or nalidixic acid, both of which are known to induce synthesis of recA protein. Expression of the recA-kan operon fusion was remarkably repressed by the lexA gene cloned into a plasmid carrying the operon fusion. Higher concentrations of mitomycin C were required for maximal induction of KPT activity in the cells harboring the resulting plasmid pMCR687. These results strongly suggest that the lexA gene product can be itself repress the recA gene, and that pMCR687 is a useful vector to clone genes whose expression is harmful to the host cell growth.

Cloning, Molecular↗
PubMed1981

Spinal angiolipoma. A case report.

A case report of a woman with spinal angiolipoma is presented, and it is stressed that spinal angiolipoma and spinal lipoma are two different clinicopathological entities which should be clearly distinguished.

Diagnosis, Differential↗
PubMed1981

The nucleotide sequence surrounding the promoter region of colicin E1 gene.

The nucleotide sequence of 570 bp, covering the N-terminal portion of the colicin E1 gene, was determined. The sequence of the N-terminal four amino acids of the colicin E1 protein, determined by manual Edman degradation, agreed with that predicted from the nucleotide sequence. From analysis of the 5'-terminal sequences of RNAs synthesized in vitro, the promoter and operator regions of the colicin E1 gene were assigned. These data indicate the existence of two promoters, one of which is located in the coding region for colicin E1. DNA sequence homology of 16 bp was found between the putative operator regions of the colicin E1 and recA genes.

Amino Acid Sequence↗
PubMed1981

Macrophage activation by muramyl dipeptide (MDP) without lymphocyte participation.

An increase in the numbers of spread macrophages caused by macrophage stimulants was found to be a very sensitive measure for macrophage activation. Muramyl dipeptide (MDP), bacterial lipopolysaccharide (LPS), and lymphokines were found to activate macrophages dose-dependently as measured by this parameter. Macrophage activation by MDP was strictly dependent on its adjuvant-active stereochemically specific structures. Macrophage activation by MDP and LPS occurred without lymphocyte participation. It is suggested that LPS also activates macrophages via lymphocytes.

Acetylmuramyl-Alanyl-Isoglutamine↗
PubMed1981

Electrochemical modification of vesicular stomatitis virus glycoprotein by host cell transformation.

Electrochemical properties of the glycoprotein of vesicular stomatitis virus (VSV) grown in Rous sarcoma virus (RSV)-transformed cells was compared with that of its counterpart grown in nontransformed cells. In DEAE-Sephadex column chromatography, the glycoproteins of VSV derived from transformed cells appeared more heterogeneous and had a tendency to elute with higher concentrations of NaCl than those from nontransformed cells. In isoelectric focussing, the glycoproteins of VSVs derived from transformed and nontransformed cells appeared as multiple components differing in the isoelectric point, and the glycoproteins from virus from transformed cells had isoelectric points that were more acidic than their counterparts from nontransformed cells. These results show that the glycoprotein of VSV consists of populations of molecules differing in charge and their isoelectric points were shifted to the acidic side by host cell transformation.

Animals↗
PubMed1981

Serum ratio of triiodothyronine to thyroxine, and thyroxine-binding globulin and calcitonin concentrations in Graves' disease and destruction-induced thyrotoxicosis.

The serum ratios of T3 to T4, and T4-binding globulin (TBG) and calcitonin concentrations were studied in cases of thyrotoxic Graves' disease and destruction-induced thyrotoxicosis. In 272 patients with Graves' disease, 209 of 240 (87%) untreated patients without complications had high T3 to T4 ratios (nanograms per micrograms) of more than 20. Six of 32 (19%) patients with Graves' disease who had complications (15 with pregnancy, 14 with increased TBG, and 3 with conditions associated with a low T3 syndrome) had high T3 to T4 ratios. Eleven of 74 (15%) patients with destruction-induced thyrotoxicosis (24 with subacute thyroiditis, 39 with postpartum transient thyrotoxicosis, and 11 with spontaneous transient thyrotoxicosis) had high T3 to T4 ratios. Patients who had serum T4 levels of more than 30 micrograms/dl and/or T3 levels of more than 800 ng/dl had Graves' disease. There was no significant correlation between the T3 to T4 ratio and activities of thyroid-stimulating immunoglobulins in thyrotoxic patients with Graves' disease who had no complications. The average serum levels of TBG in destruction-induced thyrotoxicosis and thyrotoxic Graves' disease were 20.7 +/- 4.3 micrograms/ml (mean +/- SD; n = 22), and 19.9 +/- 4.0 (n = 41), respectively, which were significantly lower than that in healthy subjects (22.7 +/- 4.4 micrograms/ml; n = 165), but there was no difference between the values in the two groups of thyrotoxicosis patients. The average serum level of calcitonin in destruction-induced thyrotoxicosis patients was 96.7 +/- 66.7 pg/ml (n = 21), which was significantly (P less than 0.05) higher than the values in patients with thyrotoxic Graves' disease (62.0 +/- 44.7 pg/ml; n = 26) and in healthy subjects (63.9 +/- 31.2 pg/ml; n = 29), but the difference in values in the two groups of thyrotoxicosis was not clinically useful because of considerable overlap of individual values. The T3 to T4 ratio is a simple and helpful index for the differentiation of the two types of thyrotoxicosis. A T3 to T4 ratio less than 20 in thyrotoxic patients before therapy is a laboratory signal of destruction-induced thyrotoxicosis or Graves' disease with complications, but final differentiation should be confirmed by measuring radioactive iodine uptake.

Adult↗
PubMed1980

Organization of unc gene cluster of Escherichia coli coding for proton-translocating ATPase of oxidative phosphorylation.

The proton-translocating ATPase (F1-F0) of oxidative phosphorylation (ATP phosphohydrolase, EC 3.6.1.3) is coded for by a set of structural genes comprising the unc operon in Escherichia coli. We have analyzed several new transducing phages and plasmids carrying various lengths of the DNA segments of the unc operon by complementation assay using 14 new unc- mutants and representatives of previously described strains which were made available to us. Transducing phages carrying parts of the unc gene cluster were isolated: lambda uncA-9 and lambda glmS phages converted only some of the unc- mutants to the Unc+, as determined by complementation assays. A new hybrid plasmid (pMCR533) carrying part of the unc operon was constructed by inserting the HindIII fragment of lambda asn-5 DNA (a phage carrying the entire unc operon) into the unique HindIII site of pBR322. This plasmid transformed eight unc- strains to Unc+, including uncB402 and uncA401, but did not complement uncD11 or four other strains. Two minichromosomes which carry the E. coli replication origin were also tested: plasmid pNH05 transformed the uncB402 but not the uncA401 strain to Unc+, whereas plasmid pMCF1 transformed none of the mutants tested. Analysis of the DNAs from these transducing phages and plasmids with restriction endonucleases suggested that all of the structural genes for the F1-F0 complex are localized within a DNA segment of approximately 4.5 megadaltons containing two EcoRI sites. The approximate locations of the unc- mutations were mapped on this DNA segment.

Adenosine Triphosphatases↗
PubMed1980

Copy-number mutants of the plasmid carrying the replication origin of the Escherichia coli chromosome: evidence for a control region of replication.

A composite plasmid (pXX11) was constructed by joining of an oriC plasmid (pMCR115) carrying the replication origin (oriC) of the Escherichia coli chromosome and a mini-F plasmid (pSC138) carrying the ampicillin-resistance gene (bla). Plasmid pXX11 can replicate, by using oriC, in Hfr cells and mafA mutant cells that cannot support replication of an F plasmid. This plasmid is stably maintained in these host cells during cell growth even under nonselective conditions by use of the partition mechanism of the mini-F genome. In contrast to other oriC plasmids reported previously, pXX11 has no detectable effect on host cell growth. Higher copy-number (Cop-) mutants of pXX11 were isolated, and some of them were found to carry an insertion or deletion within a region derived from the E. coli chromosome. This region, designated cop (copy number), covers about 0.7 kilobase pair and is located approximately 3 kilobase pairs away from the oriC region at the side opposite the asn gene. Evidence suggests that the normal cop region locted on the oriC plasmid acts to reduce the copy number of the plasmid. Plasmid pXX11 complements the uncB402 mutation located on the host chromosome, but some of the Cop- plasmids do not, suggesting that the cop region is vey closely linked to uncB.

DNA Replication↗