Yoshiharu Toyama

Effect of sound wave on the metabolism of chrysanthemum roots

Environmental factors can greatly influence the growth of plants. In this paper, the effect of sound stimulation on the metabolism of chrysanthemum roots was studied and it was found that the growth of roots was not inhibited but accelerated under suitable sound stimulation. And the content of soluble sugar and protein and the activity of amylase all increased significantly, which indicated that sound stimulation could enhance the metabolism of roots and the growth of chrysanthemum.

Crystal structure of the C-terminal domain of Mu phage central spike and functions of bound calcium ion

Bacteriophage Mu, which has a contractile tail, is one of the most famous genus of Myoviridae. It has a wide host range and is thought to contribute to horizontal gene transfer. The Myoviridae infection process is initiated by adhesion to the host surface. The phage then penetrates the host cell membrane using its tail to inject its genetic material into the host. In this penetration process, Myoviridae phages are proposed to puncture the membrane of the host cell using a central spike located beneath its baseplate. The central spike of the Mu phage is thought to be composed of gene 45 product (gp45), which has a significant sequence homology with the central spike of P2 phage (gpV). We determined the crystal structure of shortened Mu gp45Δ1-91 (Arg92-Gln197) at 1.5Å resolution and showed that Mu gp45 is a needlelike structure that punctures the membrane. The apex of Mu gp45 and that of P2 gpV contained iron, chloride, and calcium ions. Although the C-terminal domain of Mu gp45 was sufficient for binding to the E. coli membrane, a mutant D188A, in which the Asp amino acid residue that coordinates the calcium ion was replaced by Ala, did not exhibit a propensity to bind to the membrane. Therefore, we concluded that calcium ion played an important role in interaction with the host cell membrane.

Observation of the membrane binding activity and domain structure of gpV, which comprises the tail spike of bacteriophage P2.

The P2 phage virion has tail spike proteins beneath the baseplate and uses them to adsorb to the outer membrane of Escherichia coli during the infection process. Previous immunoelectron microscopic studies suggested that the tail spikes are composed of the gene V product (gpV); however, experimental evidence of its membrane binding activity has yet to be reported. In this study, we purified and characterized recombinant full-length gpV and its C-terminal domain. Limited chymotrypsin proteolysis of gpV produced a C-terminal domain composed of Ser86-Leu211. Our experiments demonstrated that the N- and C-terminal domains have very different melting temperatures: 50 and 74 degrees C, respectively. We also found that gpV binds the E. coli membrane via its C-terminal domain. We conclude that the C-terminal domain of gpV is a stable trimer and serves as the receptor-binding domain for the second step in the phage adsorption process.

The C-terminal domain is sufficient for host-binding activity of the Mu phage tail-spike protein.

The Mu phage virion contains tail-spike proteins beneath the baseplate, which it uses to adsorb to the outer membrane of Escherichia coli during the infection process. The tail spikes are composed of gene product 45 (gp45), which contains 197 amino acid residues. In this study, we purified and characterized both the full-length and the C-terminal domains of recombinant gp45 to identify the functional and structural domains. Limited proteolysis resulted in a Ser64-Gln197 sequence, which was composed of a stable C-terminal domain. Analytical ultracentrifugation of the recombinant C-terminal domain (gp45-C) indicated that the molecular weight of gp45-C was about 58 kDa and formed a trimeric protomer in solution. Coprecipitation experiments and a quartz crystal microbalance (QCM) demonstrated that gp45-C irreversibly binds to the E. coli membrane. These results indicate that gp45 shows behaviors similar to tail-spike proteins of other phages; however, gp45 did not show significant sequence homology with the other phage tail-spike structures that have been identified.

Influence of sound wave on the microstructure of plasmalemma of chrysanthemum roots

Plants and environment are dependent on each other and environmental factors can greatly influence the growth and development of plant. Plasmalemma takes an important role in the process of signal transduction. The physical state of plasmalemma lipid and second structure of membrane protein can change with the process of signal transduction. In this paper, the effect of sound stimulation on the microstructure of plasmalemma was studied to explore the mechanism of biological effect of sound stimulation.

Effect of electric field on erythrocyte sedimentation rate. II, dependence on electric current

We measured the electric current dependence of sedimentation curves of swine erythrocytes in a saline solution at the volume fraction of erythrocytes H = 0.091 and 0.220. The sedimentation curve fitted well to the exponential type equation l = a[1-exp(-bt)] at the upward initial electric current I0 = 0.50 mA, 1.01 mA and 1.50 mA, where l is the length of the medium layer at time t, and a and b are phenomenological parameters. The initial slope v0 of sedimentation curve was enhanced from 0.68 mm/hr at I0 = 0 mA to 2.85 mm/hr, 3.87 mm/hr and 5.50 mm/hr at I0 = 0.50 mA, 1.01 mA and 1.50 mA, respectively, for H = 0.220. We also made sedimentation measurements of erythrocytes in their own plasma at H = 0.220 and 0.316. Sedimentation curves coincided with the sigmoidal type equation l = l infinity/[1 + (t50/t)beta] at I0 = 0 mA and 0.50 mA, where l infinity is l at t----infinity, t50 is the time when the plasma level falls to l infinity/2 and beta is a constant. The maximum slope vmax of sedimentation curve increased from 13.29 mm/hr at I0 = 0 mA to 18.65 mm/hr at I0 = 0.50 mA for H = 0.220.

Deformability in Hardened and Normal Erythrocytes during Sedimentation Process

In order to clarify the effect of erythrocyte deformability on the sedimentation rate, we have measured the sedimentation curve of hardened swine erythrocytes in a saline solution and have compared it with that of normal erythrocytes. The observed length of the medium along the vessel was linearly proportional to the sedimentation period. The initial slope v of the sedimentation curve decreased with increase in the volume fraction of erythrocytes. Sedimentation rate v of hardened erythrocytes was comparable to that of normal ones at low volume fractions, but was smaller at high volume fractions. These experimental data were analyzed with a theoretical formula developed by Oka Biorheology 22 (1985) 315, resulting in a deformability factor of f=0.99 for hardened erythrocytes. This value of f is reasonable for such rigid cells and is much larger than the value for normal erythrocytes, approx. 2/3.

Erythrocyte Sedimentation in Plasma Observed under Microscope

In order to elucidate the mechanism of erythrocyte sedimentation in plasma, we have measured the concentration distribution of erythrocytes in a sedimentation vessel using a newly developed image analyzing system. As time passes, erythrocyte-poor domains are formed in the suspension column. The total number of domains as well as the size of each domain, was evaluated by a series of analyses, setting up various volume fraction thresholds Hr for the domain. The total number of domains initially increases, reaches a maximum just when the interface roughness of the suspension column is maximum, and then decreases gradually. These characteristic behaviors are found in a wide range of Hr from 0.03 to 0.46. These results suggest that the sigmoidal erythrocyte sedimentation curve can be explained by an effective upflow of plasma through the erythrocyte-poor domain which is produced by aggregation of erythrocytes. Other previous experimental reports are also discussed on the basis of our results.

Effect of concentration on enhanced sedimentation rate of erythrocytes in an inclined vessel

The enhanced rate of sedimentation of erythrocytes in an inclined rectangular vessel was measured under microscopic and macroscopic conditions. The velocity profile, V(x), and the thickness, delta, of the upflow layer generated below the downward-facing wall in the sedimentation vessel were measured under a microscope with polystyrene latex as a tracer particle. Here, x is the distance from the vessel wall. All the data of the velocity profile are represented by a single curve, [Vmax- V(x)]/Vmax = [(delta -x)/delta]2, irrespective of the volume fraction, H, and tilt angle, theta, in the range of 0.05 < H < 0.30 and 10 degrees < theta < 40 degrees, where Vmax is the maximum velocity found at the upflow boundary. The rate of fall of the top surface of the suspension v(H, theta) fits the function, v(H, theta) = v(0, theta)(1-H)exp[-(aH + bH2)], well, irrespective of H and theta. These experimental results are compared with the theory of Acrivos and Herbolzheimer.

A digital sedimentator for measuring erythrocyte sedimentation rate using a linear image sensor

A digital apparatus was fabricated to determine accurately the erythrocyte sedimentation rate (ESR) using a linear image sensor. Currently, ESR is utilized for clinical diagnosis, and in the laboratory as one of the many rheological properties of blood through the settling of red blood cells (RBCs). In this work, we aimed to measure ESR automatically using a small amount of a sample and without moving parts. The linear image sensor was placed behind a microhematocrit tube containing 36 μl of RBC suspension on a holder plate; the holder plate was fixed on an optical bench together with a tungsten lamp and an opal glass placed in front. RBC suspensions were prepared in autologous plasma with hematocrit H from 25% to 44%. The intensity profiles of transmitted light in 36 μl of RBC suspension were detected using the linear image sensor and sent to a personal computer every minute. ESR was observed at the settling interface between the plasma and RBC suspension in the profile in 1024 pixels (25 μm/pixel) along...