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81.
In this study, changes in UV sensitivity, a parameter of the clonal aging that has been studied in the daily reisolation culture, were examined in the logarithmically growing Paramecium culture. Cells in logarithmically growing cultures are thought to change the internal states under rapidly changing external conditions. In contrast, cells in daily reisolation cultures gradually change the internal states, the process being called clonal development and aging, under the external conditions that are kept almost constant. Cells were sampled at regular intervals, irradiated with UV, and examined for UV sensitivity assessed by the clonal survival. We found that log-phase cells showed low sensitivity to UV until they reached 2,000-3,000 cells/ml, and beyond that cell density, abruptly became highly UV sensitive. The extent of this increase in UV sensitivity was similar to that between two age groups, 130 fissions of clonal age apart. When cells from a culture of 2,000-3,000 cells/ml were resuspended in culture medium at various cell densities, they changed to UV sensitive only when the cultures reached over approximately 2,600 cells/ml. These results suggest that paramecia become UV sensitive in response to change in the nutrient level when cell density exceeds 2,000-3,000 cells/ml. 相似文献
82.
Prostaglandin E2 production in ovarian cancer cell lines is regulated by cyclooxygenase-1, not cyclooxygenase-2 总被引:1,自引:0,他引:1
Kino Y Kojima F Kiguchi K Igarashi R Ishizuka B Kawai S 《Prostaglandins, leukotrienes, and essential fatty acids》2005,73(2):103-111
The significance of cyclooxygenase-2 (COX-2) expression in ovarian cancer has been discussed. In this study, we found increased expression of COX-1 mRNA and protein in three out of 10 ovarian cancer cell lines. Prostaglandin E 2 (PGE2) production was elevated in these three cell lines, but not in other seven cell lines. COX-2 protein was not detected in any of the cell lines. Cytosolic prostaglandin E synthase (cPGES) mRNA and protein were detected in all 10 cell lines. Membrane-associated PGES-1 (mPGES-1) was detected in some of the ovarian cell lines, but its presence did not correspond with PGE2 production. In contrast, mPGES-2 mRNA and protein were detected in all 10 cell lines. A nonselective COX inhibitor (indometacin) and a selective COX-1 inhibitor (SC-560) strongly inhibited PGE2 production by the three cell lines, while selective COX-2 inhibitors (NS-398 and rofecoxib) did not inhibit PGE2 production. In addition, increased expression of COX-1, not COX-2 protein was observed in the mass of ovarian cancer tissues from 22 patients when compared with that in normal tissue. These findings suggest that COX-1 might be a major enzyme regulating PGE2 production in ovarian cancer cells. 相似文献
83.
Ali E Araki R Zhao G Sakka M Karita S Kimura T Sakka K 《Bioscience, biotechnology, and biochemistry》2005,69(12):2389-2394
Clostridium josui xylanase Xyn10A is a modular enzyme comprising two family-22 carbohydrate-binding modules (CBMs), a family-10 catalytic module (CM), a family-9 CBM, and two S-layer homologous modules, consecutively from the N-terminus. To study the functions of the family-22 CBMs, truncated derivatives of Xyn10A were constructed: a recombinant CM polypeptide (rCM), a family-22 CBM polypeptide (rCBM), and a polypeptide composed of the family-22 CBMs and CM (rCBM-CM). Recombinant proteins were characterized by enzyme and binding assays. rCBM-CM showed the highest activity toward xylan and weak activity toward some polysaccharides such as barley beta-glucan and carboxymethyl-cellulose. Although rCBM showed an affinity for insoluble and soluble xylan as well as barley beta-glucan and Avicel in qualitative binding assays, removal of the CBMs negligibly affected the catalytic activity and thermostability of the CM. 相似文献
84.
A microtubule-beta-cyclodextrin conjugate was prepared on a kinesin-adsorbed glass surface by chemical and biochemical means. Fluorescence microscope observation and a motility assay indicated that the conjugate simultaneously expressed an inherent motor function and an inclusion property. 相似文献
85.
Hiroshi Sakiyama Tetsuya Suzuki Rie Ito Mikio Yamasaki 《Inorganica chimica acta》2005,358(6):1897-1903
Dinuclear nickel(II) complexes [Ni2(bomp)(MeCO2)2]BPh4 (1) and [Ni2(bomp)(PhCO2)2]BPh4 (2) were synthesized with the dinucleating ligand 2,6-bis[bis(2-methoxyethyl)aminomethyl]-4-methylphenol [H(bomp)]. X-Ray analysis revealed that the complex 1 · 0.5CHCl3 contains two nickel(II) ions bridged by phenolic oxygen and two acetate groups, forming a μ-phenoxo-bis(μ-acetato)dinickel(II) core. Electronic spectra were investigated for 1 and 2 in the range of 400-1800 nm, and the data were typical for the octahedral high-spin nickel(II) complexes. Obtained spectral components were well simulated based on the angular overlap model assuming the trigonally distorted octahedral geometry. Magnetic susceptibility was measured for 1 and 2 over a temperature range of 4.5-300 K. The optimized magnetic data were J = 1.75 cm−1, zJ′ = −0.234 cm−1, g = 2.21, D = 15.1 cm−1, and TIP = 370 × 10−6 cm−1 for complex 1 and J = 3.55 cm−1, zJ′ = −0.238 cm−1, g = 2.23, D = 21.8 cm−1, and TIP = 470 × 10−6 cm−1 for complex 2. The data revealed ferromagnetic interactions between the two nickel(II) ions. 相似文献
86.
87.
Spinal and supraspinal contributions to central sensitization in peripheral neuropathy 总被引:5,自引:0,他引:5
We will focus on spinal cord dorsal horn lamina I projection neurones, their supraspinal targets and involvement in pain processing. These spinal cord neurons respond to tonic peripheral inputs by wind-up and other intrinsic mechanisms that cause central hyper-excitability, which in turn can further enhance afferent inputs. We describe here another hierarchy of excitation - as inputs arrive in lamina I, neurones rapidly inform the parabrachial area (PBA) and periaqueductal grey (PAG), areas associated with the affective and autonomic responses to pain. In addition, PBA can connect to areas of the brainstem that send descending projections down to the spinal cord - establishing a loop. The serotonin receptor, 5HT3, in the spinal cord mediates excitatory descending inputs from the brainstem. These descending excitatory inputs are needed for the full coding of polymodal peripheral inputs from spinal neurons and are enhanced after nerve injury. Furthermore, activity in this serotonergic system can determine the actions of gabapentin (GBP) that is widely used in the treatment of neuropathic pain. Thus, a hierarchy of separate, but interacting excitatory systems exist at peripheral, spinal and supraspinal sites that all converge on spinal neurones. The reciprocal relations between pain, fear, anxiety and autonomic responses are likely to be subserved by these spinal-brainstem-spinal pathways we describe here. Understanding these pain pathways is a first step toward elucidating the complex links between pain and emotions. 相似文献
88.
Shibata H Akahane R Honjoh T Asano M Mominoki K Fujii K Suzuki M Ohtaishi N Ishioka K Ahmed M Soliman M Kimura K Saito M 《Journal of experimental zoology. Part A, Comparative experimental biology》2005,303(7):527-533
Several reports have been published on blood leptin concentrations in feral animals, including members of the Carnivora, using a commercially available multi-species radioimmunoassay (RIA) kit with anti-human leptin antibody. However, we observed weak immunoreactivity between recombinant canine leptin and anti-human leptin antibody, suggesting a limitation in the applicability of the RIA kit for leptin assays in Carnivora species. We tested the applicability of RIA and sandwich enzyme-linked immunosorbent assay (ELISA) with anti-canine leptin antibody to assay blood leptin in the dog (Canis familiaris) and the raccoon (Procyon lotor). When RIA was used for recombinant canine leptin and dog sera, values were much lower than those determined by ELISA at higher concentrations (>10 ng/ml), while rather higher at lower concentrations (<2 ng/ml). A similar discrepancy between the two methods was found for serum leptin concentrations in raccoons. Clear seasonal variations were observed by ELISA, but not by RIA, with high values in autumn (3.46+/-0.45 ng/ml) and low values in spring and summer (0.71+/-0.07 ng/ml). Serum leptin concentrations in raccoons correlated positively with their body weight (r=0.753) and body mass index (r=0.755), corroborating our previous findings of a strong positive correlation between serum leptin concentrations and body fat content in dogs. Thus, the canine leptin ELISA is useful for assays of dog and raccoon leptin, and blood leptin is a good marker of nutritional condition in the species of Carnivora assayed in this study. 相似文献
89.
Biochemical properties of a putative signal peptide peptidase from the hyperthermophilic archaeon Thermococcus kodakaraensis KOD1 下载免费PDF全文
We have performed the first biochemical characterization of a putative archaeal signal peptide peptidase (SppA(Tk)) from the hyperthermophilic archaeon Thermococcus kodakaraensis KOD1. SppA(Tk), comprised of 334 residues, was much smaller than its counterpart from Escherichia coli (618 residues) and harbored a single predicted transmembrane domain near its N terminus. A truncated mutant protein without the N-terminal 54 amino acid residues (deltaN54SppA(Tk)) was found to be stable against autoproteolysis and was examined further. DeltaN54SppA(Tk) exhibited peptidase activity towards fluorogenic peptide substrates and was found to be highly thermostable. Moreover, the enzyme displayed a remarkable stability and preference for alkaline pH, with optimal activity detected at pH 10. DeltaN54SppA(Tk) displayed a K(m) of 240 +/- 18 microM and a V(max) of 27.8 +/- 0.7 micromol min(-1) mg(-1) towards Ala-Ala-Phe-4-methyl-coumaryl-7-amide at 80 degrees C and pH 10. The substrate specificity of the enzyme was examined in detail with a FRETS peptide library. By analyzing the cleavage products with liquid chromatography-mass spectrometry, deltaN54SppA(Tk) was found to efficiently cleave peptides with a relatively small side chain at the P-1 position and a hydrophobic or aromatic residue at the P-3 position. The positively charged Arg residue was preferred at the P-4 position, while substrates with negatively charged residues at the P-2, P-3, or P-4 position were not cleaved. When predicted signal sequences from the T. kodakaraensis genome sequence were examined, we found that the substrate specificity of deltaN54SppA(Tk) was in good agreement with its presumed role as a signal peptide peptidase in this archaeon. 相似文献
90.