Kosuke Nakamura

Purification and kinetic characterization of recombinant alternative oxidase from Trypanosoma brucei brucei

The trypanosome alternative oxidase (TAO) functions in the African trypanosomes as a cytochrome-independent terminal oxidase, which is essential for their survival in the mammalian host and as it does not exist in the mammalian host is considered to be a promising drug target for the treatment of trypanosomiasis. In the present study, recombinant TAO (rTAO) overexpressed in a haem-deficient Escherichia coli strain has been solubilized from E. coli membranes and purified to homogeneity in a stable and highly active form. Analysis of bound iron detected by inductively coupled plasma-mass spectrometer (ICP-MS) reveals a stoichiometry of two bound iron atoms per monomer of rTAO. Confirmation that the rTAO was indeed a diiron protein was obtained by EPR analysis which revealed a signal, in the reduced forms of rTAO, with a g-value of 15. The kinetics of ubiquiol-1 oxidation by purified rTAO showed typical Michaelis-Menten kinetics (K(m) of 338microM and V(max) of 601micromol/min/mg), whereas ubiquinol-2 oxidation showed unusual substrate inhibition. The specific inhibitor, ascofuranone, inhibited the enzyme in a mixed-type inhibition manner with respect to ubiquinol-1.

A flexible, lightweight Braille sheet display with plastic actuators driven by an organic field-effect transistor active matrix

A flexible, shock-resistant, and lightweight Braille sheet display has been successfully manufactured on a plastic film by integrating a plastic sheet actuator array with a high-quality organic transistor active matrix. This is the first demonstration, to the best of our knowledge, to integrate plastic MEMS (microelectromechanical systems) actuators with organic transistor active matrices, which opens up new versatile possibilities for flexible, large-area electronic applications including tactile displays

Alternative Oxidase (AOX) Genes of African Trypanosomes: Phylogeny and Evolution of AOX and Plastid Terminal Oxidase Families

Abstract. To clarify evolution and phylogenetic relationships of trypanosome alternative oxidase (AOX) molecules, AOX genes (cDNAs) of the African trypanosomes, Trypanosoma congolense and Trypanosoma evansi, were cloned by PCR. Both AOXs possess conserved consensus motifs (‐E‐, ‐EXXH‐). The putative amino acid sequence of the AOX of T. evansi was exactly the same as that of T. brucei. A protein phylogeny of trypanosome AOXs revealed that three genetically and pathogenically distinct strains of T. congolense are closely related to each other. When all known AOX sequences collected from current databases were analyzed, the common ancestor of these three Trypanosoma species shared a sister‐group position to T. brucei/T. evansi. Monophyly of Trypanosoma spp. was clearly supported (100% bootstrap value) with Trypanosoma vivax placed at the most basal position of the Trypanosoma clade. Monophyly of other eukaryotic lineages, terrestrial plants + red algae, Metazoa, diatoms, Alveolata, oomycetes, green algae, and Fungi, was reconstructed in the best AOX tree obtained from maximum likelihood analysis, although some of these clades were not strongly supported. The terrestrial plants + red algae clade showed the closest affinity with an α‐proteobacterium, Novosphingobium aromaticivorans, and the common ancestor of these lineages, was separated from other eukaryotes. Although the root of the AOX subtree was not clearly determined, subsequent phylogenetic analysis of the composite tree for AOX and plastid terminal oxidase (PTOX) demonstrated that PTOX and related cyanobacterial sequences are of a monophyletic origin and their common ancestor is linked to AOX sequences.

Use of Antisymmetrized Wave Function for Deuteron Stripping Reaction

The general S matrix of nuclear reaction is derived by the method of second quantization in order to take account of antisymmetrization of the total system. As an example of the general theory, a deuteron stripping reaction is treated. The amplitude obtained by this method is compared with those obtained by other theories in this reaction. The amplitude of this reaction is discussed for a special target which seems to demonstrate the effect of antisymmetrix zation most clearly. In the case of O/sup 17(d,p)O/sup 18/ the effect of antisymmetrization becomes comparable with the direct part. (auth)

Cross-modal perception of human emotion in domestic horses ( Equus caballus )

Humans have domesticated many kinds of animals in their history. Dogs and horses have particularly close relationships with humans as cooperative partners. However, fewer scientific studies have been conducted on cognition in horses compared to dogs. Studies have shown that horses cross-modally distinguish human facial expressions and recognize familiar people, which suggests that they also cross-modally distinguish human emotions. In the present study, we used the expectancy violation method to investigate whether horses cross-modally perceive human emotions. Horses were shown a picture of a human facial expression on a screen, and they then heard a human voice from the speaker before the screen. The emotional values of the visual and auditory stimuli were the same in the congruent condition and different in the incongruent condition. Horses looked at the speaker significantly longer in the incongruent condition than in the congruent condition when they heard their caretaker’s voices but not when they heard the stranger voice. In addition, they responded significantly more quickly to the voice in the incongruent condition than in the congruent one. To the best of our knowledge, this is the first study to show that horses cross-modally recognized the emotional states of their caretakers and strangers.

Effet de la polarisation chargee sur l'interaction entre ions lourds

The effects of charge polarization in the pure Coulomb interaction of two nuclei are examined. Empirical data are used where possible in order to avoid the ambiguity encountered in the use of nuclear models and nuclear wave functions. To a second order approximation, the relations between the dipole matrix element and the photonuclear cross section, and between the quadrupole matrix element and the mean radiative lifetime, may be combined to give the expectation value of the systems potential energy. Calculations are performed for the systems O16-O16, C12 C12, and O16-U238. The expectation value may also be calculated by replacing the matrix elements with the data on electron scattering, after applying the closure approximation.