Mitochondrial DNA analysis of Sporothrix schenckii clinical isolates from China

Mitochondrial DNA (mtDNA) types based on restriction fragment length polymorphism (RFLP)patterns with HaeIII were investigated in clinical isolates of Sporothrix schenckii in China. In addition to 23 mtDNA types (Types 1–23) so far reported, a new mtDNA type (Type 24) was found in this study. Type 24 was divided into two subtypes, Subtype 24A and 24B based on RFLP with EcoRV. Sixty-seven isolates in China consisted of 58 isolates of Type 4, 5 of Type 6, 1 of Type 5, 1 of Type 20 and 2 of Type 24. Based on the phylogeny of the mtDNA types (Types 1–24) constructed by estimating sequence divergences of mtDNA, mtDNA types clustered into two groups: Group A (Types 1–3, Type 11, Types 14–19 and Types 22–23) and Group B (Types 4–10, Types 12–13,Types 20–21 and Type 24). These results suggest that mostS. schenckii isolates in China belong to Group B.This revised version was published online in October 2005 with corrections to the Cover Date.     

Association of meteorological and day-of-the-week factors with emergency hospital admissions in Fukuoka, Japan

We carried out a statistical study of the influence of meteorological and day-of-the-week factors on the intrinsic emergency patients transported to hospitals by ambulance. Multiple piecewise linear regression analysis was performed on data from 6,081 emergency admissions for 1 year between April 1997 and March 1998 in Fukuoka, Japan. The response variable was the daily number of emergency patients admitted with three types of disease: cerebrovascular, respiratory and digestive diseases. The results showed that the number of emergency patients admitted daily with cerebrovascular disease was significantly associated with temperature on the day of admission and whether the day was Sunday. As it became colder than 12 degrees C, emergency admissions of patients with cerebrovascular disease increased drastically, reaching a plateau at 4 degrees C. On the 3rd and 7th days after the temperature fell below 10 degrees C, the daily admission of patients with respiratory disease significantly increased. We also observed a weak association between emergency admissions of patients suffering from digestive disease and rising barometric pressure on the day of admission.     

Dynamical Properties of Condensed Charged Polymer Melts

Abstract

Dynamical properties of condensed charged polymer melts are studied with a two-dimensional model and molecular dynamics simulation. Screened Coulombic interactions are assumed for the interactions between the monomer charges as well as the counterions which were introduced to neutralize the total monomer charges of polymer chains. Through molecular dynamics calculations, we have obtained the radial distribution function and velocity auto-correlation function, and their density dependences. As a structural characteristics in condensed charged polymer melts, we find that the monomers tend to form triangular structures locally. The radial distribution function for the center monomers implies that the polymer chains on our two-dimensional model are not entangled. The diffusion properties for both the counter-ions and innermost monomers are studied in detail. In this paper, we have also computed neutral polymer melts to study the effects of the presence of the long-range Coulombic interactions on the dynamical properties of polymer melts. We find that the Coulombic interactions significantly reduce the self diffusion. Snapshots analyses obtained from the molecular dynamics simulation suggest that the reptation model is not a proper model for two-dimensional polymer-chain melts, in which there are little entanglement effects in agreement with the result of the analyses for the radial distribution function.     

Oral administration of antigen does not influence the proliferation and IFN-γ production of responsive CD8+ T cells but enables to establish T cell clones with different lymphokine production profile.

Feeding of a whole casein diet, which abolished the α_s1-casein-specific proliferation and IFN-γ productivity of CD⁴⁺ T cells, did not affect the proliferative response of CD8⁺ T cells with regard to the antigen dose response, cell dose response, kinetics of the proliferation and epitope specificity, as well as IFN-γ production. To assess the characteristics of the CD8⁺ T cells, we established α_s1-casein-specific CD8⁺ T cell clones from both casein-fed and control mice. The established clones produced different amount of IFN-γ and IL-10, and one clone derived from the casein-fed mice produced a remarkable amount of IL-10. The clones from casein-fed mice produced considerable amounts of TGF-β, while those from control mice produced only small amounts. The possible role of CD8⁺ T cells in oral tolerance is discussed. This revised version was published online in June 2006 with corrections to the Cover Date.     

Aberrant chloroplasts in transgenic rice plants expressing a high level of maize NADP-dependent malic enzyme

 NADP-dependent malic enzyme (NADP-ME) is a major decarboxylating enzyme in NADP-ME-type C₄ species such as maize and Flaveria. In this study, chloroplastic NADP-ME was transferred to rice (Oryza sativa L.) using a chimeric gene composed of maize NADP-ME cDNA under the control of rice light-harvesting chlorophyll-a/b-binding protein (Cab) promoter. There was a 20- to 70-fold increase in the NADP-ME activity in leaves of transgenic rice compared to that in wild-type rice plants. Immunocytochemical studies by electron microscopy showed that maize NADP-ME was mostly localized in chloroplasts in transgenic rice plants, and that the chloroplasts were agranal without thylakoid stacking. Chlorophyll content and photosystem II activity were inversely correlated with the level of NADP-ME activity. These results suggest that aberrant chloroplasts in transgenic plants may be caused by excessive NADP-ME activity. Based on these results and the known fact that only bundle sheath cells of NADP-ME species, among all three C₄ subgroups, have agranal chloroplasts, we postulate that a high level of chloroplastic NADP-ME activity could strongly affect the development of chloroplasts. Received: 27 January 1999 / Accepted: 20 January 2000     

Selection of Orthologous Genes for Construction of a Highly Resolved Phylogenetic Tree and Clarification of the Phylogeny of Trichosporonales Species

The order Trichosporonales (Tremellomycotina, Basidiomycota) includes various species that have clinical, agricultural and biotechnological value. Thus, understanding why and how evolutionary diversification occurred within this order is extremely important. This study clarified the phylogenetic relationships among Tricosporonales species. To select genes suitable for phylogenetic analysis, we determined the draft genomes of 17 Trichosporonales species and extracted 30 protein-coding DNA sequences (CDSs) from genomic data. The CDS regions of Trichosporon asahii and T. faecale were identified by referring to mRNA sequence data since the intron positions of the respective genes differed from those of Cryptococcus neoformans (outgroup) and are not conserved within this order. A multiple alignment of the respective gene was first constructed using the CDSs of T. asahii, T. faecale and C. neoformans, and those of other species were added and aligned based on codons. The phylogenetic trees were constructed based on each gene and a concatenated alignment. Resolution of the maximum-likelihood trees estimated from the concatenated dataset based on both nucleotide (72,531) and amino acid (24,173) sequences were greater than in previous reports. In addition, we found that several genes, such as phosphatidylinositol 3-kinase TOR1 and glutamate synthase (NADH), had good resolution in this group (even when used alone). Our study proposes a set of genes suitable for constructing a phylogenetic tree with high resolution to examine evolutionary diversification in Trichosporonales. These can also be used for epidemiological and biogeographical studies, and may also serve as the basis for a comprehensive reclassification of pleomorphic fungi.     

Microsomal Electron Transfer in Higher Plants: Cloning and Heterologous Expression of NADH-Cytochrome b5 Reductase from Arabidopsis

AtCBR, a cDNA encoding NADH-cytochrome (Cyt) b₅ reductase, and AtB5-A and AtB5-B, two cDNAs encoding Cyt b₅, were isolated from Arabidopsis. The primary structure deduced from the AtCBR cDNA was 40% identical to those of the NADH-Cyt b₅ reductases of yeast and mammals. A recombinant AtCBR protein prepared using a baculovirus system exhibited typical spectral properties of NADH-Cyt b₅ reductase and was used to study its electron-transfer activity. The recombinant NADH-Cyt b₅ reductase was functionally active and displayed strict specificity to NADH for the reduction of a recombinant Cyt b₅ (AtB5-A), whereas no Cyt b₅ reduction was observed when NADPH was used as the electron donor. Conversely, a recombinant NADPH-Cyt P450 reductase of Arabidopsis was able to reduce Cyt b₅ with NADPH but not with NADH. To our knowledge, this is the first evidence in higher plants that both NADH-Cyt b₅ reductase and NADPH-Cyt P450 reductase can reduce Cyt b₅ and have clear specificities in terms of the electron donor, NADH or NADPH, respectively. This substrate specificity of the two reductases is discussed in relation to the NADH- and NADPH-dependent activities of microsomal fatty acid desaturases.     

N-acetylglucosamine 6-O-sulfotransferase-1 regulates expression of L-selectin ligands and lymphocyte homing

Lymphocyte homing is initiated by the binding of L-selectin on lymphocytes to its ligands on high endothelial venules (HEV). Sialyl 6-sulfo Lewis X is a major capping group of L-selectin ligands. N-Acetylglucosamine (GlcNAc) 6-sulfation is essential for the ligand activity, and is catalyzed by GlcNAc 6-O-sulfotransferases (GlcNAc6STs) of which GlcNAc6ST-1 and GlcNAc6ST-2 are expressed in HEV. Here, we report that mice deficient in GlcNAc6ST-1 were impaired in the elaboration of sialyl 6-sulfo Lewis X in HEV and that an epitope of L-selectin ligands recognized by the MECA-79 anti-body was greatly reduced or abolished in the abluminal aspect of HEV. Lymphocyte homing to peripheral lymph nodes, mesenteric lymph nodes, and Peyer's patches was significantly reduced in GlcNAc6ST-1 null mice. These results demonstrate that GlcNAc6ST-1 is involved in lymphocyte homing in vivo, and indicate that GlcNAc6ST-1 and -2 play complementary roles. The importance of GlcNAc6ST-1 is particularly high-lighted by its involvement in lymphocyte homing to Peyer's patches where GlcNAc6ST-2 expression is undetectable.     

Bio-photosensor: Cyanobacterial photosystem I coupled with transistor via molecular wire

We report on the first successful output of electrons directly from photosystem I (PSI) of thermophilic cyanobacteria to the gate of a field-effect transistor (FET) by bypassing electron flow via a newly designed molecular wire, i.e., artificial vitamin K₁, and a gold nanoparticle; in short, this newly manufactured photosensor employs a bio-functional unit as the core of the device. Photo-electrons generated by the irradiation of molecular complexes composed of reconstituted PSI on the gate were found to control the FET. This PSI-bio-photosensor can be used to interpret gradation in images. This PSI-FET system is moreover sufficiently stable for use exceeding a period of 1 year.