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Biomedical subjects

Y Hirota

Publications and source records attributed to Y Hirota.

At least 523 records · Page 29Linked to original sources
PubMed1979

Amplification and characterization of the proline transport carrier of Escherichia coli K-12 by using proT+ hybrid plasmids.

A previous report [Motojima, K., Yamato, I. & Anraku, Y. (1978) J. Bacteriol. 136, 5-9) described the characteristics of mutants (proT-) of Escherichia coli K-12 that are defective in proline transport carrier activity. Two hybrid plasmids from the Clarke and Carbon colony bank were found to complement the mutation by conjugation and transformation. Analysis with restriction endonucleases showed that both plasmid DNAs carried the same fragment of the E. coli chromosome. A polypeptide with a molecular weight of 24,000, specifically coded for by the proT+ plasmid, was identified in the cytoplasmic membrane by using a double-isotope labeling method in a minicell system. The strain harboring the proT+ plasmid has 6 times as much proline transport carrier as the wild strain. This amplification of the carrier makes it possible to measure proline binding to the carrier by microequilibrium dialysis. Detailed analysis of binding indicated that the maximal amount of proline bound to the carrier is 0.70 nmol/mg of protein of the cytoplasmic membrane of the amplified strain. From this value and the assumption that the carrier has one binding site per minimal molecular weight of 24,000, the content of the proline transport carrier in the cytoplasmic membrane was estimated to be 1.7%.

Bacterial Proteins↗
PubMed1979

Nucleotide sequence of Escherichia coli K-12 replication origin.

From subfragments of an EcoRI fragment (9 kilobase pairs) that contained the replication origin of the Escherichia coli chromosome and had been cloned as a recombinant with a nonreplicating DNA fragment coding for ampicillin resistance, small derivative plasmids were constructed. The smallest of these, pTSO151, contained a segment of 463 base pairs as the chromosomal component. Another plasmid, pSY134, constructed from BamHI digests of the EcoRI fragment and mini-F(pMF21), contained a region of 422 base pairs identical with a corresponding region in pTSO151. We conclude that the replication origin of E. coli chromosome is located within this 422-base-pair segment. The nucleotide sequence of this segment is presented.

Base Sequence↗
PubMed1979

Cardiovascular effects of exercise in hamsters with experimental thiamine deficiency.

The hemodynamic effects of daily treadmill exercise were evaluated in hamsters with experimental thiamine deficiency to test the hypothesis that increased energy consumption might be a contributory factor in the pathogenesis of beriberi heart disease. Daily exercise enhanced thiamine deficiency and was manifested by earlier development of symptoms of neuropathy compared to non-exercised animals. Hemodynamics of exercised thiamine deficient animals were characterized by significantly lower O2 consumption, lower cardiac output, and lower left ventricular minute work, compared to exercised, pair-fed control animals. Left ventricular end-diastolic pressure was slightly but not significantly higher in thiamine deficient animals. Left ventricular function, therefore, was depressed in this group. There was no evidence of hyperkinetic circulation, cardiomegaly or congestive heart failure. Neuropathy and depressed ventricular function, characteristic of pure thiamine deficiency, were observed in the absence of high cardiac output or high output failure, the pathogenesis of which may require other unknown factors.

Animals↗