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61.
Junichi Sugahara Kosuke Fujishima Keisuke Morita Masaru Tomita Akio Kanai 《Journal of molecular evolution》2009,69(5):497-504
The following unusual tRNAs have recently been discovered in the genomes of Archaea and primitive Eukaryota: multiple-intron-containing
tRNAs, which have more than one intron; split tRNAs, which are produced from two pieces of RNA transcribed from separate genes;
tri-split tRNAs, which are produced from three separate genes; and permuted tRNA, in which the 5′ and 3′ halves are encoded
with permuted orientations within a single gene. All these disrupted tRNA genes can form mature contiguous tRNA, which is
aminoacylated after processing by cis or trans splicing. The discovery of such tRNA disruptions has raised the question of when and why these complex tRNA processing pathways
emerged during the evolution of life. Many previous reports have noted that tRNA genes contain a single intron in the anticodon
loop region, a feature common throughout all three domains of life, suggesting an ancient trait of the last universal common
ancestor. In this context, these unique tRNA disruptions recently found only in Archaea and primitive Eukaryota provide new
insight into the origin and evolution of tRNA genes, encouraging further research in this field. In this paper, we summarize
the phylogeny, structure, and processing machinery of all known types of disrupted tRNAs and discuss possible evolutionary
scenarios for these tRNA genes. 相似文献
62.
Each symbiotic Chlorella of the ciliate Paramecium bursaria is enclosed in a perialgal vacuole derived from the host digestive vacuole to protect from lysosomal fusion. To understand the timing of differentiation of the perialgal vacuole from the host digestive vacuole, algae-free P. bursaria cells were fed symbiotic C. vulgaris cells for 1.5min, washed, chased and fixed at various times after mixing. Acid phosphatase activity in the vacuoles enclosing the algae was detected by Gomori's staining. This activity appeared in 3-min-old vacuoles, and all algae-containing vacuoles demonstrated activity at 30min. Algal escape from these digestive vacuoles began at 30min by budding of the digestive vacuole membrane into the cytoplasm. In the budded membrane, each alga was surrounded by a Gomori's thin positive staining layer. The vacuoles containing a single algal cell moved quickly to and attached just beneath the host cell surface. Such vacuoles were Gomori's staining negative, indicating that the perialgal vacuole membrane differentiates soon after the algal escape from the host digestive vacuole. This is the first report demonstrating the timing of differentiation of the perialgal vacuole membrane during infection of P. bursaria with symbiotic Chlorella. 相似文献
63.
Yurika Yogo Seitaro Fujishima Takashi Inoue Fumitake Saito Takayuki Shiomi Kazuhiro Yamaguchi Akitoshi Ishizaka 《Respiratory research》2009,10(1):80
Background
Idiopathic pulmonary fibrosis (IPF) is a chronically progressive interstitial lung disease of unknown etiology. Previously, we have demonstrated the selective upregulation of the macrophage-derived chemokine CCL22 and the thymus activation-regulated chemokine CCL17 among chemokines, in a rat model of radiation pneumonitis/pulmonary fibrosis and preliminarily observed an increase in bronchoalveolar (BAL) fluid CCL22 levels of IPF patients.Methods
We examined the expression of CCR4, a specific receptor for CCL22 and CCL17, in bronchoalveolar lavage (BAL) fluid cells, as well as the levels of CCL22 and CCL17, to elucidate their pathophysiological roles in pulmonary fibrosis. We also studied their immunohistochemical localization.Results
BAL fluid CCL22 and CCL17 levels were significantly higher in patients with IPF than those with collagen vascular diseases and healthy volunteers, and there was a significant correlation between the levels of CCL22 and CCL17 in patients with IPF. CCL22 levels in the BAL fluid did not correlate with the total cell numbers, alveolar lymphocytes, or macrophages in BAL fluid. However, the CCL22 levels significantly correlated with the numbers of CCR4-expressing alveolar macrophages. By immunohistochemical and immunofluorescence analysis, localization of CCL22 and CCR4 to CD68-positive alveolar macrophages as well as that of CCL17 to hyperplastic epithelial cells were shown. Clinically, CCL22 BAL fluid levels inversely correlated with DLco/VA values in IPF patients.Conclusion
We speculated that locally overexpressed CCL22 may induce lung dysfunction through recruitment and activation of CCR4-positive alveolar macrophages. 相似文献64.
Kubota D Ishikawa M Ishikawa M Yahata N Murakami S Fujishima K Kitakaze M Ajito K 《Bioorganic & medicinal chemistry》2006,14(12):4158-4181
To establish the in vivo efficacy of alphavbeta3/alphaIIbbeta3 dual antagonists possessing a tricyclic pharmacophore, a corresponding alphavbeta3-selective antagonist was required as a control. We initially took two synthetic approaches to obtain alphavbeta3-selective antagonists based on the RGD recognition pattern or on modification of the dihedral angle between the central benzene ring and the adjacent heterocycle, but both proved unsuccessful. However, synthesis of novel antagonists with meta-substitution of the central benzene ring generated weak selectivity for alphavbeta3 over alphaIIbbeta3 for the first time in the family of compounds with the tricyclic pharmacophore. Optimization of meta-oriented antagonists furnished an alphavbeta3-selective antagonist exhibiting inhibitory activity not only in a receptor-binding assay, but also in a cell adhesion assay. 相似文献
65.
Analyses of mitogen-activated protein kinase function in the maturation of porcine oocytes 总被引:4,自引:0,他引:4
Ohashi S Naito K Sugiura K Iwamori N Goto S Naruoka H Tojo H 《Biology of reproduction》2003,68(2):604-609
The function of mitogen-activated protein kinase (MAPK) during porcine oocyte maturation was examined by injecting oocytes with either mRNA or antisense RNA of porcine c-mos protein, an upstream kinase of MAPK. The RNAs were injected into the cytoplasm of porcine immature oocytes immediately after collection from ovaries, then the oocytes were cultured for maturation up to 48 h. The phosphorylation and activation of MAPK were observed at 6 h after injection of the c-mos mRNA injected-oocytes, whereas in control oocytes, MAPK activation was detected at 24 h of culture. The germinal vesicle breakdown (GVBD) rate at 24 h of culture was significantly higher in c-mos mRNA-injected oocytes than in control oocytes. In contrast, although injection of c-mos antisense RNA completely inhibited phosphorylation and activation of MAPK throughout the maturation period, the GVBD rate and its time course were the same in noninjected oocytes. The degree of maturation-promoting factor (MPF) activation was, however, very low in oocytes in the absence of MAPK activation. Most of those oocytes had both abnormal morphology and decondensed chromosomes at 48 h of culture. These results suggest that MAPK activation is not required for GVBD induction in porcine oocytes and that the major roles of MAPK during porcine oocyte maturation are to promote GVBD by increasing MPF activity and to arrest oocytes at the second metaphase. 相似文献
66.
Ivandini TA Sarada BV Terashima C Rao TN Tryk DA Ishiguro H Kubota Y Fujishima A 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》2003,791(1-2):63-72
Boron-doped diamond thin film (BDD) electrodes have been used to study the oxidation reactions and to detect leucine-enkephalinamide (LEA) and its metabolites, tyrosine (T), tyrosyl-alanine (TA), tyrosyl-alanine-glycine (TAG) and leucine-enkephalin (LE) using cyclic voltammetry (CV), flow-injection analysis (FIA), and gradient liquid chromatography (LC) with amperometric detection. At diamond electrodes, well-defined and highly reproducible cyclic voltammograms were obtained with signal-to-background (S/B) ratios 5-10 times higher than those observed for glassy carbon (GC) electrodes. The analytical peaks of LC for LEA and its metabolites were well resolved. No deactivation of BDD electrodes was found after several experiments with standard as well as plasma samples, indicating high stability of the electrode. Calibration curves were linear over a wide range from 0.06 to 30 microM with regression coefficients of 0.999 for all compounds. The limits of detection obtained based on a signal-to-noise ratio of 3:1 were 3, 2.2, 2.7, 20 and 11 nM for T, TA, TAG, LE and LEA, respectively. These values were at least one order lower than those obtained at GC electrodes, which has given limits of detection of 22.88, 20.64, 89.57, 116.04 and 75.67 for T, TA, TAG, LE and LEA, respectively. Application of this method to real samples was demonstrated and validated using rabbit serum samples. This work shows the promising use of conducting diamond as an amperometric detector in gradient LC, especially for the analysis of enkephalinamide and its metabolites. 相似文献
67.
Nucleotide sequence of 5' portion of srfA that contains the region required for competence establishment in Bacillus subtilus. 总被引:11,自引:1,他引:10
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S Fuma Y Fujishima N Corbell C D'Souza M M Nakano P Zuber K Yamane 《Nucleic acids research》1993,21(1):93-97
The nucleotide sequence of the 20,535 base pairs of the 5' end of the srfA operon, containing the region required for competence development, was determined. This included the srfA promoter region, the first open reading frame, srfAA, encoding surfactin synthetase I and part of the second open reading frame, srfAB, encoding surfactin synthetase II. Three amino acid-activating domains characteristic of those found in peptide synthetases could be discerned in both srfAA (activating Glu, Leu and D-Leu) and srfAB (activating Val, Asp, and D-Leu). The presence of a conserved spacer motif in the amino-terminal end of srfAA suggests that the srfAA product may not initiate surfactin synthesis. The portion of srfA that contains the region required for competence is composed of srfAA and the first amino acid-activating domain of srfAB. 相似文献
68.
Masashi Katsura Seitaro Ohkuma Da-Zhi Chen Kinya Kuriyama 《Neurochemistry international》1994,24(6):541-547
Effect of long-term exposure to ethanol (EtOH) on the phosphatidylinositol 4,5-biphosphate (PIP2)-specific and cytosolic phospholipase C (PLC) activities in neuroblastoma x glioma hybrid (NG 108-15) cells and the brains from EtOH-inhaled mice were investigated. Long-term (2 days) exposure of NG 108-15 cells to EtOH induced significant decrease in PIP2-specific PLC activity dependent on concentration and duration of exposure, although the presence of EtOH in the enzyme assay system induced no alteration in PIP2-specific PLC activity. On the other hand, cytosolic PLC activity in NG 108-15 cells significantly increased by both the long-term exposure of the cells to EtOH and the addition of EtOH into the assay system. These changes in activities of both types of PLC in NG 108-15 cells observed after EtOH exposure recovered rapidly by the removal of EtOH. Moreover, the changes in activities of PIP2-specific and cytosolic PLC in the brain of EtOH-inhaled mice were similar to those found in NG 108-15 cells. These results indicate that EtOH inhibits the activity of PIP2-specific PLC and activates cytosolic PLC in the brain. These changes in cerebral PLC activities are suggested to involve in central action of EtOH and establishment of alcohol dependence. 相似文献
69.
Hiroaki Ooboshi Seizo Sadoshima Hiroshi Yao Tatsuo Nakahara Hideyuki Uchimura Masatoshi Fujishima 《Journal of neurochemistry》1992,58(1):298-303
The effect of omega-conotoxin GVIA (CgTX), an N-and L-type voltage-sensitive calcium channel (VSCC) blocker, on the release of dopamine and 3,4-dihydroxyphenylacetic acid (DOPAC) in the striatum before and during transient cerebral ischemia in spontaneously hypertensive rats was studied using an in vivo brain dialysis technique. Continuous perfusion of CgTX in the striatum was started 20 min before ischemia and concentrations of dopamine and DOPAC in the dialysate were measured using HPLC with an electro-chemical detector. Before ischemia, both 10 and 100 microM CgTX significantly lowered the concentration of dopamine, to 49% of the basal values. DOPAC concentrations also decreased significantly, by 28 and 17%, respectively. Forebrain ischemia, produced by bilateral carotid artery occlusion, reduced striatal blood flow to less than 6% of the resting value in each group. During 20 min of ischemia, the vehicle group showed a marked increase in dopamine (175 times the basal concentration). In the 10 or 100 microM CgTX perfusion group, in contrast, dopamine release was significantly attenuated, to 38 or 29% of the vehicle group, respectively. DOPAC concentrations decreased during ischemia to 58% of the basal value in the vehicle group and 49% in both CgTX groups. These results indicate that the massive release of striatal dopamine during ischemia depends largely on the influx of extracellular calcium via CgTX-sensitive VSCCs. 相似文献
70.
1,3-Diols are frequently involved in biologically important compounds and, therefore, determination of the stereochemistry of these structural elements, in particular those in acyclic systems, has been one of the focuses of attention in natural products chemistry. The modified Mosher's method, commonly used for the determination of the absolute configuration of secondary alcohols, was applied to determine the absolute configuration of 1,3-diols with their di-MTPA esters. Several epimeric pairs of syn- and anti-1,3-diols with known absolute configurations were converted to the corresponding di-MTPA esters and the iDelta;delta values were then calculated. For the acyclic syn-1,3-diols, the iDelta;delta values were systematically arranged as predicted from the basic concept of the modified Mosher's method, demonstrating that the method is valid for these compounds. In contrast, the iDelta;delta values were irregularly arranged for the acyclic anti-1,3-diols and, accordingly, this method is not valid for these cases. These results are complementary to those of the previously reported CD exciton chirality method and, hence, the combined use of the modified Mosher's method and the CD exciton chirality method can determine the absolute configuration of the acyclic 1,3-diols. Also, this method is successfully applicable to cyclic 1,3-diols irrespective of their relative stereochemistry. 相似文献