Influences of nitrogen load on the growth and photosynthetic responses of <Emphasis Type="Italic">Quercus serrata</Emphasis> seedlings to O<Subscript>3</Subscript>

The objectives of this study were to clarify the influences of nitrogen (N) load on the growth and photosynthetic responses of Quercus serrata seedlings to O₃ and to obtain basic data for evaluating the critical levels of O₃ for protecting Q. serrata forests in Japan. The effects of O₃ and/or N load on growth and photosynthetic activity of Q. serrata seedlings were investigated during the two growing seasons. Two-year-old seedlings were assigned to 12 experimental treatments, which were comprised of the combination of four gas treatments (charcoal-filtered air and three levels of O₃ at 1.0, 1.5 and 2.0 times ambient concentration) and three N treatments (0, 20 and 50 kg ha⁻¹ year⁻¹). During the second growing season, no significant interactive effects of O₃ and N load on the growth and net photosynthetic rate of the seedlings were detected. Threrfore, we concluded that N supply to the soil at ≤50 kg ha⁻¹ year⁻¹ does not significantly influence the growth and photosynthetic responses of Q. serrata seedlings to O₃. Based on the O₃ exposure-response relationships for the whole-plant growth of the seedlings, the critical level of O₃ for Q. serrata was estimated to be approximately 36 nmol mol⁻¹ as the average 15-h O₃ concentration during the one growing season.     

Development of experimental cerebral malaria is independent of IL-23 and IL-17

Cerebral malaria (CM) is the most severe complication of Plasmodium infection. Although inappropriate immune responses to Plasmodium falciparum are reported as the major causes of CM, the precise mechanisms for development remain unclear. IL-23 and IL-17 have critical roles in the onset of autoimmunity and inflammatory diseases triggered by microbial infections. Thus, we investigated the influence of IL-23 and IL-17 on experimental CM (ECM) using Plasmodium berghei ANKA infection of C57BL/6 mice. Both IL-23 deficient mice and wild-type (WT) mice developed ECM. IL-17 deficient mice also developed ECM, while IL-17 producing cells other than CD4⁺ T cells (Th17) were increased in WT mice that developed ECM. In conclusion, this study showed that IL-23 and IL-17 are not involved in ECM development.     

Up-regulated type I collagen expression by the inhibition of Rac1 signaling pathway in human dermal fibroblasts

Tissue remodeling is known to play important roles in wound healing. Although Rac1 is reported to be one of the key signaling molecules in cutaneous wound healing process, the exact mechanisms of Rac1-mediated tissue remodeling is still unknown. This study investigated the role of Rac1 in the regulation of extracellular matrix in cultured human dermal fibroblasts obtained by skin biopsy from three healthy donors. Protein levels of type I collagen in cultured human fibroblasts were increased by the treatment with Rac1 inhibitor NSC23766 in a dose-dependent manner. However, the mRNA levels of α2(I) collagen was not altered by the inhibitor. On the other hand, by the addition of inhibitor, half-lives of type I collagen protein were increased and MMP1 levels were reduced. These data suggest that blockade of Rac1 signaling results in accumulation of type I collagen due to decreased collagenase activity. This study also suggests that controlling Rac1 signaling is a new therapeutic approach to chronic/untreatable ulcer.     

Cytoplasmic inheritance of organelles in brown algae

Brown algae, together with diatoms and chrysophytes, are a member of the heterokonts. They have either a characteristic life cycle of diplohaplontic alternation of gametophytic and sporophytic generations that are isomorphic or heteromorphic, or a diplontic life cycle. Isogamy, anisogamy and oogamy have been recognized as the mode of sexual reproduction. Brown algae are the characteristic group having elaborated multicellular organization within the heterokonts. In this study, cytoplasmic inheritance of chloroplasts, mitochondria and centrioles was examined, with special focus on sexual reproduction and subsequent zygote development. In oogamy, chloroplasts and mitochondria are inherited maternally. In isogamy, chloroplasts in sporophyte cells are inherited biparentally (maternal or paternal); however, mitochondria (or mitochondrial DNA) derived from the female gamete only remained during zygote development after fertilization. Centrioles in zygotes are definitely derived from the male gamete, irrespective of the sexual reproduction pattern. Female centrioles in zygotes are selectively broken down within 1–2 h after fertilization. The remaining male centrioles play a crucial role as a part of the centrosome for microtubule organization, mitosis, determination of the cytokinetic plane and cytokinesis, as well as for maintaining multicellularity and regular morphogenesis in brown algae.     

Erratum to: Aromatic C–H bond hydroxylation by P450 peroxygenases: a facile colorimetric assay for monooxygenation activities of enzymes based on Russig’s blue formation

Aromatic C–H bond hydroxylation of 1-methoxynaphthalene was efficiently catalyzed by the substrate misrecognition system of the hydrogen peroxide dependent cytochrome P450_BSβ (CYP152A1), which usually catalyzes hydroxylation of long-alkyl-chain fatty acids. Very importantly, the hydroxylation of 1-methoxynaphthalene can be monitored by a color change since the formation of 4-methoxy-1-naphthol was immediately followed by its further oxidation to yield Russig’s blue. Russig’s blue formation allows us to estimate the peroxygenation activity of enzymes without the use of high performance liquid chromatography, gas chromatography, and nuclear magnetic resonance measurements.     

Research note: Analysis of expressed sequence tags from the chrysophycean alga Ochromonas danica (Heterokontophyta)

A cDNA library was constructed from the chrysophycean alga, Ochromonas danica E. G. Pringsheim. 5′‐end sequencing of about 600 cDNA clones yielded 476 authentic expressed sequence tags (EST) of which 275 showed significant matches (E‐value <10^?4) to sequences in a public database. The annotation of these ESTs was carried out to assess subcellular localization of the putative proteins using several internet‐accessible prediction programs for subcellular localization. These analyses revealed that putative plastid proteins in Ochromonas possess N‐terminal bipartite presequences with a conserved phenylalanine at the N‐terminus of the predicted transit peptide‐like domains, similar to other ‘red‐lineage’ secondary symbiotic organisms. The examination of sequences of 3′‐UTR revealed that, similarly to chlorophyte algae, UGUAA may represent a putative polyadenylation signal in O. danica.     

Network based analysis of hepatitis C virus core and NS4B protein interactions

Hepatitis C virus (HCV) is a major cause of chronic liver disease worldwide. Here we attempt to further our understanding of the biological context of protein interactions in HCV pathogenesis, by investigating interactions between HCV proteins Core and NS4B and human host proteins. Using the yeast two-hybrid (Y2H) membrane protein system, eleven human host proteins interacting with Core and 45 interacting with NS4B were identified, most of which are novel. These interactions were used to infer overall protein interaction maps linking the viral proteins with components of the host cellular networks. Core and NS4B proteins contribute to highly compact interaction networks that may enable the virus to respond rapidly to host physiological responses to HCV infection. Analysis of the interaction networks highlighted enriched biological pathways likely influenced in HCV infection. Inspection of individual interactions offered further insights into the possible mechanisms that permit HCV to evade the host immune response and appropriate host metabolic machinery. Follow-up cellular assays with cell lines infected with HCV genotype 1b and 2a strains validated Core interacting proteins ENO1 and SLC25A5 and host protein PXN as novel regulators of HCV replication and viral production. ENO1 siRNA knockdown was found to inhibit HCV replication in both the HCV genotypes and viral RNA release in genotype 2a. PXN siRNA inhibition was observed to inhibit replication specifically in genotype 1b but not in genotype 2a, while SLC25A5 siRNA facilitated a minor increase in the viral RNA release in genotype 2a. Thus, our analysis can provide potential targets for more effective anti-HCV therapeutic intervention.     

Monoclonal antibody ECCD-1 inhibits intercellular communication in teratocarcinoma PCC3 cells

The monoclonal antibody ECCD-1 recognizing a certain class of cell surface proteins inhibits the Ca²⁺-dependent cell-to-cell adhesion in teratocarcinoma stem cells. In this paper, we studied the effect of ECCD-1 on cell-to-cell communication in PCC3 cells by measuring the transfer of lucifer yellow between cells. To this aim, PCC3 cells were cultured in the presence of ECCD-1 for various periods, and then the fluorescent dye was injected into a cell located in the center of cell colonies, followed by counting number of cells to which the dye was transferred. The results showed that ECCD-1 inhibits the dye transfer between cells, suggesting that the Ca²⁺-dependent cell-to-cell adhesion system (CDS) is essential for the functions of gap junction.     

Radical intermediates in the oxidation of octaethylheme to octaethylverdoheme

Iron(III) oxyoctaethylporphyrin was isolated and purified as a dimer. The addition of tosylmethyl isocyanide to a solution of the dimer produced a monomer species, which was isolated and identified as bis(tosylmethyl isocyanide)iron(II) 5-oxyoctaethylporphyrin pi-neutral radical. The product of dissociation of the dimer by imidazole was bis(imidazole)iron(III) 5-oxyoctaethylporphyrin. The spectral properties of the product of dissociation of the dimer by pyridine and published data on bis(pyridine)oxymesoheme and bis(pyridine)oxyprotoheme were consistent with its identification as bis(pyridine)iron(II) 5-oxyoctaethylporphyrin pi-neutral radical. When this product was exposed to oxygen, a weak radical signal appeared in its electron spin resonance spectrum, which was attributed to the displacement of one of its pyridine ligands by O2 to form (pyridine)(dioxygen)iron(II) 5-oxyoctaethylporphyrin pi-neutral radical. The pyridine oxygen radical converted spontaneously to octaethylverdohemochrome, which was purified and identified as bis-(tosylmethyl isocyanide)iron(II) octaethylverdohemochrome hydroxide. The yield of verdohemochrome from iron oxyporphyrin was increased by the addition of phenylhydrazine or ascorbate. A scheme for the oxidation of iron(III) oxyporphyrin to iron(II) verdoheme by O2 that proposes a mechanism for the expulsion of CO and the replacement of a methene bridge of the porphyrin ring by an oxa bridge is presented.     

Purification and characterization of calmodulin from rat liver mitochondria

Mitochondrial calmodulin of rat liver was purified and classified. It co-migrated with bovine brain calmodulin in non-denaturing polyacrylamide gel electrophoresis, SDS-polyacrylamide gel electrophoresis and isoelectric focusing. The mitochondrial calmodulin activated Ca²⁺-dependent phosphodiesterase of bovine brain in the presence of Ca²⁺. About 80% of the mitochondrial calmodulin was proved to be of cytosol origin. It was easily detached by washing with buffer containing EGTA. The other 20% was intramitochondrial calmodulin; half of it was in the matrix space, and half in the membrane.