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排序方式: 共有1207条查询结果,搜索用时 15 毫秒
81.
Ismail AB Yoshinobu T Iwasaki H Sugihara H Yukimasa T Hirata I Iwata H 《Biosensors & bioelectronics》2003,18(12):1509-1514
This article reports an investigation on light-addressable potentiometric sensor (LAPS) to be used as a possible biological cell-semiconductor hybrid that will enable us to make an interface between the physical and biological system. To increase the surface potential sensitivity, we used a LAPS structure with single insulator (SiO2) coated with poly-L-ornithine and laminin (PLOL) on Si. Efficient culturing of PC-12 and nerve cells of Lymnaea stagnalis on PLOL-coated Si3N4 and SiO2 was achieved. The thickness of the PLOL layer was found to be about 4 nm by the atomic force microscope (AFM) measurement. Using the advantage of this thin layer of PLOL, we compared the performance of a novel structure to the previously reported "PLOL-coated Si3N4/SiO2/Si" structure. Due to high insulating capacitance, the photocurrent response of the novel LAPS was found to be very steep. As a result, higher sensitivity was achieved. This steepness did not degrade during 10 days when the sensor surface was kept in contact with the cell culture medium and environment. The thickness of PLOL layer, its ability to improve the biological cell adhesion, enhanced sensitivity, and experiment with simulated neural action potential (AP) applied to the novel LAPS show a good promise for LAPS to be a biological cell-semiconductor hybrid. 相似文献
82.
Miyagi N Sato K Rong Y Yamamura S Katagiri H Kobayashi K Iwata H 《Bioelectromagnetics》2000,21(2):112-121
After pulsed exposure of Dunn osteosarcoma cells (nonresistant cells) to Adriamycin (ADR) at increasing concentrations and single-cell cloning of surviving cells, ADR-resistant cells were obtained. These resistant cells expressed P-glycoprotein and had resistance more than 10 times that of their nonresistant parent cells. Compared to the nonresistant cells not exposed to pulsing electromagnetic fields (PEMF) in ADR-free medium, their growth rates at ADR concentrations of 0.01 and 0.02 micrograms/ml, which were below IC50, were 83.0% and 61.8%, respectively. On the other hand, in the nonresistant cells exposed to PEMF (repetition frequency, 10 Hz; rise time, 25 microsec, peak magnetic field intensity, 0.4-0.8 mT), the growth rate was 111.9% in ADR-free medium, 95.5% at an ADR concentration of 0.01 micrograms/ml, and 92.2% at an ADR concentration of 0.02 micrograms/ml. This promotion of growth by PEMF is considered to be a result of mobilization of cells in the non-proliferative period of the cell cycle due to exposure to PEMF. However, at ADR concentrations above the IC50, the growth rate tended to decrease in the cells not exposed to PEMF. This may be caused by an increase in cells sensitive to ADR resulting from mobilization of cells in the non-proliferative period to the cell cycle. The growth rate in the resistant cells exposed to PEMF was significantly lower than that in the non-exposed resistant cells at all ADR concentrations, including ADR-free culture (P=0.0114). Therefore, this study suggests that PEMF promotes the growth of undifferentiated cells but progressively suppresses the growth of more differentiated cells, i.e., PEMF controls cell growth depending on the degree of cell differentiation. This study also shows the potentiality of PEMF as an adjunctive treatment method for malignant tumors. 相似文献
83.
Byrne B Abramson J Jansson M Holmgren E Iwata S 《Biochimica et biophysica acta》2000,1459(2-3):449-455
Crystals of cytochrome bo(3) ubiquinol oxidase from E. coli diffract X-rays to 3.5 A and the structure determination is in progress. The limiting factor to the elucidation of the structural detail is the quality of the crystals; the diffraction spots from the crystals are diffused which leads to difficulties in processing the data beyond 4.0 A. Weak protein-protein contacts within the crystal lattice is assumed to be the cause of this problem. To improve these contacts, we have introduced protein Z to the C-terminal end of the subunit IV of cytochrome bo(3) and expressed both proteins as a single fusion. We have successfully obtained crystals of this fusion protein. The spot shape problem has clearly been solved in the crystals of the fusion protein although further optimization is necessary to obtain higher resolution. We also discuss the potential applications of this approach to the crystallization of membrane proteins in general. 相似文献
84.
Yamamoto K Kawai Y Hayashi T Ohe Y Hayashi H Toyoda F Kawahara G Iwata T Kikuyama S 《FEBS letters》2000,472(2-3):267-270
Sodefrin-like female-attracting pheromone was purified from the abdominal glands of male sword-tailed newts, Cynops ensicauda, by gel-filtration chromatography and reversed-phase high-performance liquid chromatography. The final product comprises 10 amino acid residues with the sequence SILSKDAQLK which coincided with the sequence deduced from its precursor cDNA. This peptide was designated silefrin. The sequence of silefrin was different from that of sodefrin by two amino acid residues, with substitutions Leu for Pro and Gln for Leu at positions 3 and 8, respectively. Both native and synthetic silefrin exerted an equipotent activity in attracting conspecific females. 相似文献
85.
Evolutionary aspects of gobioid fishes based upon a phylogenetic analysis of mitochondrial cytochrome B genes 总被引:5,自引:0,他引:5
Akihito Iwata A Kobayashi T Ikeo K Imanishi T Ono H Umehara Y Hamamatsu C Sugiyama K Ikeda Y Sakamoto K Fumihito A Ohno S Gojobori T 《Gene》2000,259(1-2):5-15
The Gobioidei is a large suborder in the order Perciformes and consists of more than 2000 species belonging to about 270 genera. The vast number of species and their morphological specialization adapted to diverse habits and habitats makes the classification of the gobioid fishes very difficult.A comprehensive estimation of the evolutionary scenario of all gobioid fishes using only morphological information is difficult for two major reasons: first, in addition to wide ecological diversification, there is a trend towards specialization and degeneration of morphological characters among these species; second, an appropriate outgroup of gobioid fishes has not been recognized.Based upon nucleotide sequence comparisons of gobioid mitochondrial cytochrome b genes, we established the phylogenetic relationships of their differentiation into many groups of morphological and ecological diversity. The phylogenetic trees obtained show that most species examined have diverged from each other almost simultaneously or during an extremely short period of time. 相似文献
86.
Interesting morphologies were observed when Comamonas acidovorans containing polyhydroxyalkanoates (PHA) of various compositions was freeze-fractured at temperatures far below the glass transition temperatures of PHA. In vivo granules of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) comparatively showed the most ductility, and could be stretched extensively. Contrary to the uniform needle-type deformation shown by the poly(3-hydroxybutyrate) homopolymer when fractured at -110 degrees C, copolymers containing 3-hydroxyvalerate units showed various deformation structures. Similar observations were made when in vivo granules of poly(3-hydroxybutyrate-co-4-hydroxybutyrate) were freeze-fractured, although the ductility of the latter was much reduced. In addition, it was found that fracturing at -160 degrees C resulted in decreased ductility of the PHA granules with the concomitant increase in the number of mushroom-type deformation structures. Our results suggest that PHA granules with higher resistance to freeze-fracture deformation show less ductility, and therefore produce the mushroom-type morphology. This is the first report on the freeze-fracture morphology of PHA copolymers containing short-chain-length monomers. 相似文献
87.
Cerebrosides A and C, compounds categorized as glycosphingolipids, were isolated in our previous study from the rice blast fungus (Magnaporthe grisea) as novel elicitors which induce the synthesis of rice phytoalexins. In this paper, these cerebroside elicitors showed phytoalexin-inducing activity when applied to plants by spray treatment and also induced the expression of pathogenesis-related (PR) proteins in rice leaves. This elicitor activity of the cerebrosides showed the structural specificity as that for the induction of phytoalexins. Ceramides prepared from the cerebrosides by removal of glucose also showed the elicitor activity even in lower level compared to the cerebrosides. In field experiments, the cerebroside elicitors effectively protected rice plants against the rice blast fungus, an economically devastating agent of disease of rice in Japan. The cerebrosides elicitors protected rice plants from other disease as well and were found to occur in a wide range of different phytopathogens, indicating that cerebrosides function as general elicitors in a wide variety of rice-pathogen interactions. 相似文献
88.
Usui I Haruta T Iwata M Takano A Uno T Kawahara J Ueno E Sasaoka T Kobayashi M 《Biochemical and biophysical research communications》2000,275(1):115-120
In the early phase of adipocyte differentiation, transient increase of DNA synthesis, called clonal expansion, and transient hyperphosphorylation of retinoblastoma protein (Rb) are observed. We investigated the role of these phenomena in insulin-induced adipocyte differentiation of 3T3-L1 cells. Insulin-induced clonal expansion, Rb phosphorylation and adipocyte differentiation were all inhibited by the PI 3-kinase inhibitors and rapamycin, but not the MEK inhibitor, whereas the MEK inhibitor, but not PI 3-kinase inhibitors or rapamycin, decreased c-fos induction. We conclude that insulin induces hyperphosphorylation of Rb via PI 3-kinase and mTOR dependent pathway, which promotes clonal expansion and adipocyte differentiation of 3T3-L1 cells. 相似文献
89.
Genetic linkage of Bietti crystallin corneoretinal dystrophy to chromosome 4q35 总被引:2,自引:0,他引:2
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Jiao X Munier FL Iwata F Hayakawa M Kanai A Lee J Schorderet DF Chen MS Kaiser-Kupfer M Hejtmancik JF 《American journal of human genetics》2000,67(5):1309-1313
Bietti crystalline corneoretinal dystrophy (BCD) is an autosomal recessive retinal degeneration characterized by multiple glistening intraretinal dots scattered over the fundus, degeneration of the retina, and sclerosis of the choroidal vessels, ultimately resulting in progressive night blindness and constriction of the visual field. Although BCD has been associated with abnormalities in fatty-acid metabolism and absence of fatty-acid binding by two cytosolic proteins, the genetic basis of BCD is unknown. We report linkage of the BCD locus to D4S426 (maximum LOD score [Z(max)] 4.81; recombination fraction [straight theta] 0), D4S2688 (Zmax=3.97; straight theta=0), and D4S2299 (Zmax=5.31; straight theta=0), on chromosome 4q35-4qtel. Multipoint analysis confirmed linkage to the region telomeric of D4S1652 with a Z(max) of 5.3 located 4 cM telomeric of marker D4S2930. 相似文献
90.
Masao Takahashi Susumu Miyazaki Masahiro Myojo Daigo Sawaki Hiroshi Iwata Arihiro Kiyosue Yasutomi Higashikuni Tomofumi Tanaka Daishi Fujita Jiro Ando Hideo Fujita Yasunobu Hirata Issei Komuro 《PloS one》2015,10(3)