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Biomedical subjects

I Kudo

Publications and source records attributed to I Kudo.

At least 217 records · Page 12Linked to original sources
PubMed1981

Site-specific mutagenesis on cloned DNAs: generation of a mutant of Escherichia coli tyrosine suppressor tRNA in which the sequence G-T-T-C corresponding to the universal G-T-pseudouracil-C sequence of tRNAs is changed to G-A-T-C.

We have cloned the Escherichia coli tyrosine-inserting amber suppressor tRNA gene into the recombinant single-strand phage M12mp3. By using the M13mp3SuIII+ recombinant phage DNA as template and an oligonucleotide bearing a mismatch as primer, we have synthesized in vitro an M13mp3SuIII heteroduplex DNA that has a single mismatch at a predetermined site in the tRNA gene. Transformation of E. coli with the heteroduplex DNA yielded M13 recombinant phages carrying a mutant suppressor tRNA gene in which the sequence G-T-T-C, corresponding to the universal G-T-pseudouracil-C sequence in E. coli tRNAs, is changed to G-A-T-C. The mutant DNA has been characterized by restriction mapping and by sequence analysis. In contrast to results with the wild-type suppressor tRNA gene, cells transformed with recombinant plasmids carrying the mutant tRNA gene are phenotypically Su-. Thus, the single nucleotide change introduced has inactivated the function of the tRNA gene. By using E. coli minicells for studying the expression in vivo of cloned tRNA genes, we have found that cells transformed with recombinant plasmids carrying the mutant tRNA gene contain very little, if any, mature mutant suppressor tRNA. In contrast, the predominant low molecular weight RNA in cells transformed with recombinant plasmids carrying the wild-type suppressor tRNA gene is the mature tyrosine suppressor tRNA. Thus, while our results imply an important role for the G-T-pseudouracil-C sequence common to all E. coli tRNAs, whether this sequence is essential for tRNA biosynthesis, tRNA stability in vivo, or tRNA function remains to be determined. The procedures used to generate the mutant should be of general application toward site-specific mutagenesis on cloned DNAs, including regions that possess high degrees of secondary structure. In addition, the frequency of mutants among the progeny is high enough to enable one to identify and isolate site-specific mutants on any cloned DNA without requiring phenotypic selection.

Base Sequence↗
PubMed1980

Effect of bisulfite on cell-to-substratum adhesion of Chinese hamster cells in culture.

The direct action of bisulfite on cultured mammalian cells was studied. Chinese hamster cells precultured in plastic dishes for 2 hr were treated for 1 hr with balanced salt solutions containing bisulfite. Then they were washed, and their colony-forming ability in normal medium was determined. Significant decrease in the colony formation was observed upon treatment with bisulfite solutions over 30 mM concentration. The decrease in the colony number was found to be due to detachment of the cells from the dishes during treatment with bisulfite and subsequent washing. When the preculture time was prolonged to allow the cells to adhere to the dish more firmly, the effect of bisulfite was no longer observable. These results indicate that factors required for cell-substratum adhesion are susceptible to bisulfite.

Animals↗
PubMedDate not supplied

Is paranoid schizophrenia the most common subtype? Comparison of subtype diagnoses by Japanese and European psychiatrists, using the summaries of the same patients.

We compared the subtype diagnoses of schizophrenia (ICD-10) of 58 Japanese and 61 European psychiatrists matched for clinical experience using 10 case summaries. As a result, there are marked differences between Japanese and European psychiatrists in the mode of subtype diagnoses of schizophrenia rather than in the clinical pictures of the patients themselves; the hebephrenic type (F20.1) was more likely to be diagnosed by Japanese psychiatrists, while the paranoid type (F20.0) was more frequently diagnosed by European psychiatrists. Japanese psychiatrists take into account the patient's age at onset and the clinical course of the disease in identifying the subtype, while European psychiatrists tend to focus on the presenting symptoms, particularly paranoid symptoms.

Adolescent↗