Biomedical subjects
Publications and source records attributed to R Kamiya.
The culture medium of a short-flagellum mutant of Salmonella typhimurium contained a large amount of mutant flagellin and a small amount of strong inhibitors of flagellin polymerization. After being freed of the inhibitors, the mutant flagellin could be polymerized in vitro, although under nonphysiological conditions.
Peculiar myelin figures were abundantly found in some basal-granulated cells including S, D1 and I cells in human Brunner's glands. Intense acid phosphatase activity was found in the periphery of the myelin figures, indicating that they were secondary lysosomes or residual bodies. The acid phosphatase activity was also found in some secretory granules. There were some secretory granules which were partly membranous in content, suggesting the initial stage of their degradation into myelin figures. There were also features indicating the fusion of secretory granules with the myelin figures. All these findings suggest that the myelin figures are the products of lysosomal degradation of secretory granules. The rate of occurrence of basal-granulated cells containing myelin figures in Brunner's glands tended to be higher in subjects with duodenal ulcer than in cases of gastric cancer or ulcer.
A nonmotile mutant of Salmonella typhimurium, SJW1254, has very short flagella (less than 0.1 micron long) due to a mutation in the structural gene of flagellin (H2). When ammonium sulfate was added to the culture medium of SJW1254 grown to the late-log phase, a large amount of protein precipitated. Gel electrophoresis and immunodiffusion showed that more than 90% (wt/wt) of the precipitated protein was flagellin. The mutant flagellin appeared to be excreted in the monomeric form, in an amount comparable to the amount in the flagellar filaments of wildtype bacteria. No such precipitate was obtained from the medium of wild-type bacteria. The mutant flagellin had the same apparent molecular weight (55,000) and isoelectric point (5.3) as the wild-type flagellin, but differed in mobility in polyacrylamide gel electrophoresis under nondenaturing conditions. Moreover, the mutant flagellin did not polymerize in vitro under various conditions in which wild-type flagellin polymerized. These results suggested that the mutant bacteria excreted flagellin because the flagellin polymerized poorly and therefore could not be trapped at the tip of the flagellar filament. This short-flagella mutant should be useful for studying the mechanism of flagellin transport.
Basal-granulated cells (BGC) in the human duodenal bulb were observed by light and electron microscopy, and both the cell types and their population densities in the duodenal crypts and in the Brunner's glands were compared. The number of the BGC in the Brunner's glands was much smaller than in the crypts. On the basis of their ultrastructural features, nine types of BGC, i.e. an EC cell, N cell, D cell, D1 cell, S cell, I cell, G cell, L cell and P cell were identified in the human duodenal bulb. In the duodenal crypts, as is generally recognized, EC cells were most numerous, making up 40% of the total BGC. N cells and D cells were around 10% of the total, and S cells, I cells and L cells were less than 10%, respectively. By contrast, in Brunner's glands, D cells and small granule-containing cells such as S cells, I cells and D1 cells were predominant, accounting for about 80% of the total BGC. EC cells and N cells were about 10% or less, respectively. These results indicate that the Brunner's glands are definitely different from the ordinary intestinal mucosa in regard to their BGC population, and are considered to have endocrine functions mainly performed by D1 cells, S cells and I cells.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
The basic structure of the shaft of the bacterial flagellum is described and an account is given of work on polymorphism to date. The flagellum of wild-type Salmonella SJ670 has a characteristic left-hand helical form from pH 8 to pH 6, but undergoes two sharp transitions to other definite forms as the pH is lowered. The first transition, to a tight coil, can be followed by flow-birefringence. The flow-birefringence curve shows no evidence of hysteresis. Other details of the polymorphism, including the transitions which occur at high pH and at various KCl concentrations, are shown in a 'phase diagram'. Details of the transformation were studied by observing individual reconstituted flagella under dark-field light microscopy, while varying the bathing medium. Under some conditions, stress due to flow of the medium influences the transition. Under constant flow, alteration between two helical forms of opposite hand was sometimes observed. The two-state model is introduced to account for the helical structure and the polymorphism. Its prediction, that the two possible straight forms should have definite and opposite values of twist, is shown to agree with optical diffraction studies. Certain straight mutants are mentioned which show a novel feature in the diffraction pattern, probably due to a periodic perturbation of the helical lattice. The co-polymerisation of flagellins from straight mutants of the two different types yields a range of forms similar to the natural polymorphs. The implications of this finding are discussed.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
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.
Explore the source record for details and available documents.
Dark-field microscopy with a high-powered light source revealed that the outer doublet microtubules (DMTs) from sea urchin (Pseudocentrotus depressus and Hemicentrotus pulcherrimus) sperm flagella assume helically coiled configurations (Miki-Noumura, T., and R. Kamiya. 1976. Exp. Cell Res. 97: 451.). We report here that the DMTs change shape when the pH or Ca-ion concentration is changed. The DMTs assumed a left-handed helical shape with a diameter of 3.7 +/- 0.5 micron and a pitch of 2.8 +/- 0.7 micron at pH 7.4 in the presence of 0.1 mM CaCl2, 1 mM MgSO4, and 10 mM Tris-HCl. When the pH was raised to 8.3, the helical diameter and pitch decreased to 2.1 +/- 0.1 micron and 1.3 +/- 0.3 micron, respectively. This transformation was a rapid and reversible process and was completed within 1 min. Between pH 7.2 and 8.3, the DMTs assumed intermediate shapes. When the Ca-ion concentration was depleted with EGTA, the helical structure became significantly larger in both pitch and diameter. For instance, the diameter was 3.8 +/- 0.4 micron at pH 8.3 in the presence of 1 mM EGTA and 2 mM MgSO4. Using a Ca-buffer system, we obtained results which suggested that this Ca-induced transformation took place at a Ca concentration of approximately 10(-7) M. These results were highly reproducible. The conformational changes in the DMT may play some role in the bending wave form of flagellar movement.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
A beta-actinin-like protein was isolated from plasmodia of the slime mold. The chain weight was the same as that of actin (43,000), but the amino acid composition was significantly different. The action of plasmodium beta-actinin on actin was the same as that of beta-actinin from rabbit skeletal muscle: inhibition of the recombination of F-actin fragments; formation of Mg polymer; inhibition of interfilamental interaction of F-actin and retardation of depolymerization of F-actin. The only difference observed was its sensitivity to trypsin: plasmodium actinin was less quickly digested by trypsin than rabbit beta-actinin.