The Arabidopsis WAVY GROWTH 2 protein modulates root bending in response to environmental stimuli

To understand how the direction of root growth changes in response to obstacles, light, and gravity, we characterized an Arabidopsis thaliana mutant, wavy growth 2 (wav2), whose roots show a short-pitch pattern of wavy growth on inclined agar medium. The roots of the wav2 mutant bent with larger curvature than those of the wild-type seedlings in wavy growth and in gravitropic and phototropic responses. The cell file rotations of the root epidermis of wav2-1 in the wavy growth pattern were enhanced in both right-handed and left-handed rotations. WAV2 encodes a protein belonging to the BUD EMERGENCE 46 family with a transmembrane domain at the N terminus and an alpha/beta-hydrolase domain at the C terminus. Expression analyses showed that mRNA of WAV2 was expressed strongly in adult plant roots and seedlings, especially in the root tip, the cell elongation zone, and the stele. Our results suggest that WAV2 is not involved in sensing environmental stimuli but that it negatively regulates stimulus-induced root bending through inhibition of root tip rotation.     

Purification and characterization of rat liver enzyme catalyzing stereoselective reduction of acetylpyridines

Acetylpyridines (1-3) are known as aroma components of foods, perfumes, and smoking suppressants, showing several biological activities and constituting part of the structure of some important biologically active compounds. We purified and characterized an enzyme that catalyzes the stereoselective reduction of acetylpyridines so that we could clarify its function. The enzyme participating in the reductive metabolism of 4-acetylpyridine (1) in the rat liver was purified by successively applying ammonium sulfate fractionation, anion-exchange, gel filtration, and affinity chromatography, and it was definitively identified as 3alpha-HSD. It preferentially reduced acetylpyridines (1-3) and acetophenone (7) to their corresponding (S)-alcohols, with high enantioselectivity. Kinetic analyses of the compounds were performed, and the V(max)/K(m) values decreased in the order of 4-, 2-, and 3-acetylpyridine (1, 3, 2), while acetophenone (7) showed almost the same value as 3-acetylpyridine (2). These results suggested that the reduction of the substrates by 3alpha-HSD is affected by the nitrogen atom in the aromatic ring.     

Overexpression of eNOS in brain stem reduces enhanced sympathetic drive in mice with myocardial infarction

Reduced nitric oxide (NO) in the brain might contribute to enhanced sympathetic drive in heart failure (HF). The aim of this study was to determine whether increased NO production induced by local overexpression of endothelial NO synthase (eNOS) in the nucleus tractus solitarius (NTS) of the brain stem reduces the enhanced sympathetic drive in mice with HF. Myocardial infarction (MI) was induced in mice by ligating the left coronary artery. MI mice exhibited left ventricular dilatation and a reduced left ventricular ejection fraction. Urinary norepinephrine excretion in MI mice was greater than that in sham-operated mice, indicating that sympathetic drive was enhanced in this model. Thus this model has features that are typical of HF. Western blot analysis and immunohistochemical staining for neuronal NOS (nNOS) indicated that nNOS protein expression was significantly reduced in the brain stem of MI mice. MI mice had a significantly smaller increase in blood pressure evoked by intracisternal injection of N(G)-monomethyl-L-arginine than sham-operated mice. Adenoviral vectors encoding either eNOS (AdeNOS) or beta-galactosidase (Adbeta gal) were transfected into the NTS to examine the effect of increased NO production in the NTS on the enhanced sympathetic drive in HF. After the gene transfer, urinary norepinephrine excretion was reduced in AdeNOS-transfected MI mice but not in Adbeta gal-transfected MI mice. These results indicate that nNOS expression in the brain stem, especially in the NTS, is reduced in the MI mouse model of HF, and increased NO production induced by overexpression of eNOS in the NTS attenuates the enhanced sympathetic drive in this model.     

Effects of light intensity on cyclic electron flow around PSI and its relationship to non-photochemical quenching of Chl fluorescence in tobacco leaves

We tested the hypothesis that plants grown under high light intensity (HL-plants) had a large activity of cyclic electron flow around PSI (CEF-PSI) compared with plants grown under low light (LL-plants). To evaluate the activity of CEF-PSI, the relationships between photosynthesis rate, quantum yields of both PSII and PSI, and Chl fluorescence parameters were analyzed simultaneously in intact leaves of tobacco plants which had been grown under different light intensities (150 and 1,100 micromol photons m(-2) s(-1), respectively) and with different amounts of nutrients supplied. HL-plants showed a larger value of non-photochemical quenching (NPQ) of Chl fluorescence at the limited activity of photosynthetic linear electron flow. Furthermore, HL-plants had a larger activity of CEF-PSI than LL-plants. These results suggested that HL-plants dissipated the excess photon energy through NPQ by enhancing the ability of CEF-PSI to induce acidification of the thylakoid lumen.     

Nocardia cyriacigeorgica is a significant pathogen responsible for nocardiosis in Japan and Thailand

Nocardia cyriacigeorgica is a recently described species. During routine diagnostic testing of 121 clinical isolates, we found that about one fourth of the strains from Japan (19 isolates) and Thailand (8 isolates), which were identified in our laboratories as N. asteroides, in fact belong to N. cyriacigeorgica. To our knowledge, this is the first report of infection due to N. cyriacigeorgica in Japan and Thailand, and the third report of infection anywhere in the world. Although N. cyriacigeorgica is usually differentiated from other Nocardia species by utilization of glucose and gluconate, we found that it can also be differentiated by a characteristic synergistic effect between imipenem (IPM) and tobramycin (TOB).     

A DeImmunized chimeric anti-C3b/iC3b monoclonal antibody enhances rituximab-mediated killing in NHL and CLL cells via complement activation

Complement-dependent cytotoxicity (CDC) is a key mechanism of Rituximab (RTX) action in killing non-Hodgkins lymphoma (NHL) cells both in vitro and probably in vivo. A DeImmunized, mouse/human chimeric monoclonal antibody (Mab), H17, specific for cell-associated complement C3 cleavage products, C3b and iC3b, was generated to enhance RTX-mediated killing of target cells by CDC. When NHL cell lines were treated with RTX and H17 in the presence of complement for 1 h, there was 40–70% more cell death than that observed with RTX alone. The enhancing effect of H17 was also seen over longer treatment periods. H17 was tested ex vivo against primary cells from NHL and chronic lymphocytic leukemia (CLL) patients. In RTX-resistant NHL samples, H17 enhanced RTX-mediated killing; in the remaining samples RTX + complement alone promoted more than 80% killing, and no significant enhancement was observed. The H17 antibody also increased RTX-mediated killing in four out of nine CLL samples. H17 may have therapeutic applications in NHL and CLL treatment as an adjunctive therapy to RTX. It might also enhance the activity of other therapeutic antibodies that work through CDC.     

Isolation of Iodide-Oxidizing Bacteria from Iodide-Rich Natural Gas Brines and Seawaters

Iodide-oxidizing bacteria (IOB), which oxidize iodide (I⁻) to molecular iodine (I₂), were isolated from iodide-rich (63 μM to 1.2 mM) natural gas brine waters collected from several locations. Agar media containing iodide and starch were prepared, and brine waters were spread directly on the media. The IOB, which appeared as purple colonies, were obtained from 28 of the 44 brine waters. The population sizes of IOB in the brines were 10² to 10⁵ colony-forming units (CFU) mL⁻¹. However, IOB were not detected in natural seawaters and terrestrial soils (fewer than 10 CFU mL⁻¹ and 10² CFU g wet weight of soils⁻¹, respectively). Interestingly, after the enrichment with 1 mM iodide, IOB were found in 6 of the 8 seawaters with population sizes of 10³ to 10⁵ CFU mL⁻¹. 16S rDNA sequencing and phylogenetic analyses showed that the IOB strains are divided into two groups within the α-subclass of the Proteobacteria. One of the groups was phylogenetically most closely related to Roseovarius tolerans with sequence similarities between 94% and 98%. The other group was most closely related to Rhodothalassium salexigens, although the sequence similarities were relatively low (89% to 91%). The iodide-oxidizing reaction by IOB was mediated by an extracellular enzyme protein that requires oxygen. Radiotracer experiments showed that IOB produce not only I₂ but also volatile organic iodine, which were identified as diiodomethane (CH₂I₂) and chloroiodomethane (CH₂ClI). These results indicate that at least two types of IOB are distributed in the environment, and that they are preferentially isolated in environments in which iodide levels are very high. It is possible that IOB oxidize iodide in the natural environment, and they could significantly contribute to the biogeochemical cycling of iodine.     

Overexpression of human myotonic dystrophy protein kinase in Schizosaccharomyces pombe induces an abnormal polarized and swollen cell morphology

We expressed human myotonic dystrophy protein kinase (DMPK) in the fission yeast Schizosaccharomyces pombe, in which the overexpression of human DMPK affects cell growth and cell shape. The human DMPK protein has a leucine-rich domain at the N-terminus, a serine/threonine kinase domain in the middle, and a hydrophobic region at the C-terminus. C-Terminus-deleted DMPK produced a middle-swollen phenotype (lemon-like shape), indicating an abnormality in cell division. On the other hand, when both the kinase domain and C-terminus were present, the expression of DMPK resulted in polarized cell growth and multinucleated/branched cells. The lemon-like phenotype seen with the C-terminus-deleted DMPK disappeared when the ATP binding site of DMPK was disrupted by replacing the lysine at amino acid 100 with arginine (K100R mutant). However, polarized and/or multinucleated cells lacking the DMPK N-terminus were not rescued by the K100R mutation. Therefore, we conclude that the N-terminus of DMPK plays an important role in DMPK kinase activity, and that the C-terminus of DMPK determines the intracellular localization of the protein.     

Repetitive elements in mammalian telomeres suppress bacterial DNA-induced immune activation

Bacterial DNA contains immunostimulatory CpG motifs that trigger an innate immune response capable of promoting host survival following infectious challenge. Yet CpG-driven immune activation may also have deleterious consequences, ranging from autoimmune disease to death. We find that repetitive elements present at high frequency in mammalian telomeres, but rare in bacteria, down-regulate CpG-induced immune activation. Suppressive activity correlates with the ability of telomeric TTAGGG repeats to form G-tetrads. Colocalization of CpG DNA with Toll-like receptor 9 in endosomal vesicles is disrupted by these repetitive elements, although cellular binding and uptake remain unchanged. These findings are the first to establish that specific host-derived molecules can down-regulate the innate immune response elicited by a TLR ligand.     

Apoptosis-associated tyrosine kinase is a Cdk5 activator p35 binding protein

A 3(')-terminal fragment of a splice variant of KIAA0641, a human homologue of apoptosis-associated tyrosine kinase (AATYK), was screened from human brain cDNA libraries by a yeast two-hybrid system using a Cdk5 activator p35 as a bait. The cloned cDNA encoded 477 amino acids, composed of internal 458 amino acids of KIAA0641 and 19 amino acids unique to this variant after splicing, then referred to this clone as hAATYKs-p35BP (human AATYK short isoform-p35 binding polypeptide). Using GST-fusion protein, hAATYKs-p35BP was shown to bind to Cdk5/p35 in a rat brain extract. hAATYKs made by fusing the kinase domain of KIAA0641 to the N-terminus of hAATYKs-p35BP was used for binding to Cdk5/p35 in HEK293 cells. Both hAATYKs and KIAA0641 bound to and were phosphorylated by Cdk5/p35. These results suggest that both isoforms of hAATYK are novel Cdk5/p35-binding and substrate proteins.