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Biomedical subjects

M Yanagida

Publications and source records attributed to M Yanagida.

At least 235 records · Page 13Linked to original sources
PubMed1981

Visualization of individual DNA molecules in solution by light microscopy: DAPI staining method.

A method was developed to visualize individual DNA molecules in solution under a fluorescent microscope connected to a highly sensitive video camera. DNA stained with a fluorescent dye, DAPI, revealed thin extended filaments, thicker filaments and rapidly transforming folded structures dependent upon the solution conditions. Structural transitions were observed and recorded as video images. Our observations indicated the possibility that DNA has the ability of supercoiling itself. This DAPI staining method will have wide possible application in the study of DNA and chromatin.

Amidines↗
PubMed1981

Sequential alterations in the nuclear chromatin region during mitosis of the fission yeast Schizosaccharomyces pombe: video fluorescence microscopy of synchronously growing wild-type and cold-sensitive cdc mutants by using a DNA-binding fluorescent probe.

Video-connected fluorescence microscopy was introduced to study the yeast nuclear chromatin region. It was defined as the nuclear area where a DNA-binding fluorescent probe 4',6-diamidino-2-phenylindole specifically bound and fluoresced. The 3-dimensional feature of the mitotic chromatin region was deduced by analysing the successive video images of a cell viewed at different angles. By investigating synchronous culture of the wild-type fission yeast Schizosaccharomyces pombe, we found sequential structural alterations in the chromatin region during mitosis. The steps found include the compaction of the chromatin region from the regular hemispherical form, the formation of a U-shaped intermediate and the rapid segregation into 2 daughter hemispherical forms. Six cs cdc mutants, apparently blocked in mitosis, were observed by fluorescence microscopy. Under the restrictive conditions their chromatin regions exhibited either hemispherical, compact, disk-like, U-shaped or partially segregated chromatin regions. Two mutants showed anomalous nuclear locations. The results of the temperature shift-up experiments of the highly reversible KM52 and KM108 strains supported the above scheme of sequential alterations in the chromatin region.

Ascomycota↗
PubMed1981

Specificity in the interaction of 4',6-diamidino-2-phenylindole with polynucleotides.

The binding of a fluorescent dye, 4',6-diamidino-2-phenylindole (DAPI) to polynucleotides was investigated by UV absorption and fluorescence spectroscopy. The results show that there are two types of bindings. In a higher concentration of DAPI, where UV spectroscopy is a suitable means for detecting the binding, the association of DAPI is independent of base compositions and the types of sugar moiety in spite of the spectral difference between DNA and RNA complexes with DAPI. On the other hand in a lower concentration of DAPI, where only fluorescence is measured to detect the binding, the degree of association is dependent upon the sugar types as well as base compositions.

Chemical Phenomena↗
PubMed1979

Seeding role of spectrin in polymerization of skeletal muscle actin.

The effect of spectrin on the polymerization of muscle actin has been investigated by hydrodynamic methods and electron microscopy. Spectrin markedly accelerated polymerization of actin. The effect was more easily observed in lower concentrations of KCl (e.g. 24 mM) where spontaneous polymerization was negligibly small. Similarly large acceleration was observed for polymerization in MgCl2 or CaCl2. The rate of polymerization of actin was proportionally increased with the concentration of spectrin added to a fixed concentration of action. The stationary level of specific viscosity also increased with the spectrin concentration, but at larger concentrations it became smaller. The flow birefringence and electron microscope measurements indicated that actin polymers formed under the influence of spectrin were shorter than those of control F-actin filaments. The structural viscosity and electron microscope observations suggested that the interaction between F-actin fibers was not increased by spectrin. These data strongly suggest a seeding role of spectrin in the polymerization of actin. Spectrin accelerates formation of the nuclei for polymerization. The more the nuclei are formed, the larger the number of the grown polymers are and this leads to rapid formation of shorter polymers since the amount of actin is limited. The acceleration activity was found only in freshly prepared spectrin from fresh ghosts taken from freshly drawn blood.

Actins↗