Nucleotide specificity of the enzymatic and motile activities of dynein, kinesin, and heavy meromyosin.

The substrate specificities of dynein, kinesin, and myosin substrate turnover activity and cytoskeletal filament-driven translocation were examined using 15 ATP analogues. The dyneins were more selective in their substrate utilization than bovine brain kinesin or muscle heavy meromyosin, and even different types of dyneins, such as 14S and 22S dynein from Tetrahymena cilia and the beta-heavy chain-containing particle from the outer-arm dynein of sea urchin flagella, could be distinguished by their substrate specificities. Although bovine brain kinesin and muscle heavy meromyosin both exhibited broad substrate specificities, kinesin-induced microtubule translocation varied over a 50-fold range in speed among the various substrates, whereas heavy meromyosin-induced actin translocation varied only by fourfold. With both kinesin and heavy meromyosin, the relative velocities of filament translocation did not correlate well with the relative filament-activated substrate turnover rates. Furthermore, some ATP analogues that did not support the filament translocation exhibited filament-activated substrate turnover rates. Filament-activated substrate turnover and power production, therefore, appear to become uncoupled with certain substrates. In conclusion, the substrate specificities and coupling to motility are distinct for different types of molecular motor proteins. Such nucleotide "fingerprints" of enzymatic activities of motor proteins may prove useful as a tool for identifying what type of motor is involved in powering a motility-related event that can be reconstituted in vitro

Thickness of the basement membrane of bronchial epithelial cells in lung diseases as determined by transbronchial biopsy

AbstractThe thickness of the basement membranes of bronchial epithelial cells varies under various pathological conditions. It has been reported that this membrane is thickened in patients with bronchial asthma. By light microscopy, this parameter was measured in biopsy specimens of bronchial mucosa obtained by fibre-optic bronchoscopy. These specimens were obtained from 171 patients who had undergone bronchial biopsy between 1984 and 1994. It was demonstrated that the thickness of the basement membrane of bronchial epithelial cells was weakly correlated with the patient's age, when thickness was examined in patients with lung cancer (r=0·242, P=0·0268). The basement membranes in patients with bronchial asthma (8·193 ± 1·362 μ, mean ± sem) were significantly thicker than those without bronchial asthma (5·145 ± 0·233 μ) (P=0·0180, Mann-Whitney's U-test). In addition, it is noteworthy that the basement membranes in patients with diabetes mellitus (7·217 ± 0·753 μ) were also significantly thicker than those without diabetes mellitus (4·968 ± 0·235 μ) (P=0·0038, Mann-Whitney's U-test). The background or underlying pathophysiology in such patients should be studied further, with attention directed towards the thickness of the bronchial basement membrane in bronchial biopsy specimens

Correlation Functions and Spin

The k-electron correlation function of a free chaotic electron beam is derived with the spin degree of freedom taken into account. It is shown that it can be expressed with the help of correlation functions for a polarized electron beam of all orders up to k and the degree of spin polarization. The form of the correlation function suggests that if the electron beam is not highly polarized, observing multi-particle correlations should be difficult. The result can be applied also to chaotic photon beams, the degree of spin polarization being replaced by the degree of polarization.Comment: 6 pages, 1 eps figure, accepted to Phys. Rev.

Nonlinear Relaxation Dynamics in Elastic Networks and Design Principles of Molecular Machines

Analyzing nonlinear conformational relaxation dynamics in elastic networks corresponding to two classical motor proteins, we find that they respond by well-defined internal mechanical motions to various initial deformations and that these motions are robust against external perturbations. We show that this behavior is not characteristic for random elastic networks. However, special network architectures with such properties can be designed by evolutionary optimization methods. Using them, an example of an artificial elastic network, operating as a cyclic machine powered by ligand binding, is constructed.Comment: 12 pages, 9 figure

Inequalities for electron-field correlation functions

I show that there exists a class of inequalities between correlation functions of different orders of a chaotic electron field. These inequalities lead to the antibunching effect and are a consequence of the fact that electrons are fermions -- indistinguishable particles with antisymmetric states. The derivation of the inequalities is based on the known form of the correlation functions for the chaotic state and on the properties of matrices and determinants.Comment: 8 pages Latex2e, 2 eps figure

Uma análise sobre o emprego setorial brasileiro

The purpose of this article was to evaluate the impact of recent changes in Brazilian economy on to sectoral employment structure, in the period 1988-2006, through the identification of the main explanations of sectoral dispersion of employment, with the largest exposure of the Brazilian economy to the international market and mainly after implementation of the Plano Real. The methodology consisted in the calculation of an index of sectoral dispersion of employment followed by a correlation test between sectoral dispersion index and normalized index of the number of available jobs. The results show that before the implementation of the Plano Real changes in sectoral demand were the main reason for modifications in sectoral changes of employment. On the other hand, pure sectoral changes, attributed to the technological, organizational and productive changes, were verified after the Plano Real, in 1994. Since 2004, the results indicate that economic changes’ effects have reduced and the sectoral changes of employment happen again more owing to changes in sectoral demand.Sectoral dispersion of employment, Technological and organizational changes, Demand changes, Labor and Human Capital,

Effect of bonding of a CO molecule on the conductance of atomic metal wires

We have measured the effect of bonding of a CO molecule on the conductance of Au, Cu, Pt, and Ni atomic contacts at 4.2 K. When CO gas is admitted to the metal nano contacts, a conductance feature appears in the conductance histogram near 0.5 of the quantum unit of conductance, for all metals. For Au, the intensity of this fractional conductance feature can be tuned with the bias voltage, and it disappears at high bias voltage (above $\sim$ 200 mV). The bonding of CO to Au appears to be weakest, and associated with monotomic Au wire formation.Comment: 6 figure

Abnormal expansion of naïve B lymphocytes after unrelated cord blood transplantation – a case report

A 33-year-old woman underwent unrelated cord blood transplantation (U-CBT) for myelodysplastic syndrome (MDS)-related secondary AML. She showed impressive increases in the number of CD19(+) B cells in bone marrow and CD19(+)27(−)IgD(+) B cells in peripheral blood from about 1 month to 3 months after U-CBT. The serum level of IL-6 temporarily increased after transplantation, and this increase seemed to be correlated with the expansion of CD19(+) B cells. Although, compared with BMT, little is known about the kinetics of hematological and immunological reconstitution in U-CBT, there was initial B-cell recovery after CBT as some described. This B cell recovery may be associated with a high number of B-cell precursors present in cord blood (CB). The phenomenon of naïve B lymphocyte expansion that we found might be associated with a high number of B-cell precursors present in CB