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Biomedical subjects

S Asakura

Publications and source records attributed to S Asakura.

At least 145 records · Page 8Linked to original sources
PubMed1980

Formation of helical filaments by copolymerization of two types of 'straight' flagellins.

Bacterial flagella undergo transition between several discrete types of left-handed and right-handed helical structures when exposed to acidic or alkaline pH, or to mechanical force. Calladine and ourselves have presented models to explain such polymorphism, assuming that protein subunits (flagellin) in a flagellum can be transformed into two conformations (L- and R-states) depending on the species of flagellin and on the environmental conditions. An obvious prediction from these 'two-state' models is that there should be two types of straight flagella (L- and R-types) that are made up exclusively of flagellins in either the L-state or the R-state. We have shown that straight flagella from two species of mutants, Salmonella SJ814 (ref. 6) and Escherichia coli hag 177 (ref. 7), are closely similar to the predicted R- and L-types, respectively. Recently we have isolated 10 strains of straight-flagellar mutants of Salmonella. We show here that their flagella can also be classified into the L- and R-types, and that copolymerization of flagellins from two heterologous types (L and R) makes discrete types of helical filaments, whereas that of homologous pairs of flagellins (L and L, or R and R) makes only straight filaments.

Antigens, Bacterial↗
PubMed1980

Individual differences in blood and breath acetaldehyde levels and urinary excretion of catecholamines after alcohol intake.

Sixty three male Japanese, aged 20-40 yr were evaluated as to the degree of facial flushing following a controlled dose of ethanol either as Japanese rice wine or ethanol 0.4 g kg body weight. Thirty four subjects responded with overt facial flushing. The acetaldehyde levels in blood and expired air were significantly higher in the flushing group without a change in ethanol elimination rate. Urinary excretion of Vanilmandelic acid (VMA) and 3 methyoxy-4-Hydroxyphenylglycol (MHPG) are reported.

Acetaldehyde↗
PubMed1976

Flagellar hook protein from Salmonella SJ25.

From acid-disintegrated flagellar hooks of Salmonella SJ25 an immunochemically pure preparation of hook protein was obtained by column chromatography. The molecular weight of the protein determined by sodium dodecyl sulfate-gel electrophoresis was 43,000, whereas that of SJ25 flagellin was 56,000. The amino-terminal residue of the hook protein was determined to be seryl. The amino acid composition of the protein was determined, the results being very similar to that for an Escheria coli hook protein reported by Silverman and Simon (1972). Within a wavelength range of 200 to 250 nm, our purified preparation of hook protein gave a circular dichroism spectrum with unusually small amplitudes, suggesting that the alpha-helix content of the protein was very low.

Amino Acids↗
PubMed1976

Cinemicrographic analysis of the movement of flagellated bacteria. II. The ratio of the propulsive velocity to the frequency of the wave propagation along flagellar tail.

We took cinemicrographs of the movement of the flagellar tail of the peritrichously flagellated bacterium, Salmonella, swimming in a medium containing methylcellulose under a dark-ground microscope. By analysing the film, the velocity of translation u, the frequency of the propagation of helical waves along the tail fF and the frequency of the induced rotation of bacterial body fB of individual organism were measured and the experimental values of the ratios u/fF, u/fB and fF/fB were obtained. On the other hand, the theoretical values of these ratios were calculated by inserting the geometrical parameters describing the shapes and the sizes of the body and the tail of individual organism into the equations previously derived for the hydrodynamic model of the propulsion of flagellated bacteria (Holwill and Burge, 1963; Chwang and Wu, 1971). For four bacterial specimens presently analysed, the experimental values of u/fF ranged from 0.5 to 0.9, whereas the theoretical values were about 0.3. As reported by the preceding paper, such a tendency for the experimental values to exceed the theoretical ones by two or three times was also seen in u/fB and, consequently, the experimental and the theoretical values of fF/fB showed good agreement. From the results of these quantitative analyses of the movements of flagellated bacteria, it was concluded that the validity of the hydrodynamic model was further supported experimentally.

Cell Movement↗
PubMed1975

Cinemicrographic analysis of the movement of flagellated bacteria. I. The ratio of the propulsive velocity to the frequency of bodily rotation.

On the basis of the hydrodynamic model that the propulsion of flagellated bacteria in a fluid is a consequence of the propagation of helical waves along the length of flagella or flagellar bundles, it is predicted that propulsion must be accompanied by a rotation of bacterial body about the direction of translation (Chwang and Wu, 1971), and that propulsive velocity u is directly proportional to the frequency of bodily rotation fB, the proportional constant being a complicated function of various parameters describing the sizes and shapes of body and flagella. In this study we have measured not only u but also fB by cinemicrography or sometimes by dual cinemicrography, using a mono- trichously flagellated Pseudomonas strain and a multitrichously flagellated Salmonella strain, and calculated the ratio u/fB. Though the values of u/fB thus determined for a number of bacteria of each strain scattered in a wide range, average values of u/fB were likely to be independent of u, in support of the theoretical prediction. Moreover, in Pseudomonas as well as in Salmonella, it was found that the experimental values of u/fB were in semiquantitative agreement with theoretical values expected from the hydrodynamic model for appropriate values of the geometrical parameters. Taking into account these results, it was concluded that the validity of this model has been supported experimentally.

Cell Movement↗