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排序方式: 共有1124条查询结果,搜索用时 31 毫秒
941.
Matsuhashi M Pankrushina AN Takeuchi S Ohshima H Miyoi H Endoh K Murayama K Watanabe H Endo S Tobi M Mano Y Hyodo M Kobayashi T Kaneko T Otani S Yoshimura S Harata A Sawada T 《The Journal of General and Applied Microbiology》1998,44(1):49-55
Bacterial cells enhance the proliferation of neighboring cells under stress conditions by emitting a physical signal. Continuous single sine sound waves produced by a speaker at frequencies of 6-10, 18-22, and 28-38 kHz promoted colony formation by Bacillus carboniphilus under non-permissive stress conditions of high KCl concentration and high temperature. Furthermore, sound waves emitted from cells of Bacillus subtilis at frequencies between 8 and 43 kHz with broad peaks at approximately 8.5, 19, 29, and 37 kHz were detected using a sensitive microphone system. The similarity between the frequency of the sound produced by B. subtilis and the frequencies that induced a response in B. carboniphilus and the previously observed growth-promoting effect of B. subtilis cells upon B. carboniphilus through iron barriers, suggest that the detected sound waves function as a growth-regulatory signal between cells. 相似文献
942.
Shigetoh Miyachi Mikio Tsuzuki Isao Maruyama Miroslav Gantar Shizuko Miyachi Hisashi Matsushima 《Journal of phycology》1986,22(3):313-319
Effects of CO2 concentration during growth on intracellular structure were studied with ftve species of Chlorella and Scenedesmus obliquus. Cells grown under ordinary air conditions (low-CO2 cells) had a well developed pyrenoid surrounded by starch, while those grown under high CO2 conditions (high-CO2 cells) had a less developed pyrenoid or no detectable pyrenoid. Two mitochondria, one at each side of the neck of the projection of the chloroplast close to the pyrenoid, were found in low CO2 cells of C. vulgaris 11h. Usually, lamellar stacks extended in parallel in the chloroplast of low-CO2 cells of C. vulgaris 11h, while a grana-like structure was found in high-CO2 cells. However, in C. pyrenoidosa, grana like structures were found more commonly in low-CO2 cells than in high-CO2 cells. These results suggest that development of pyrenoid starch is generally correlated with growth under low CO2 conditions, whereas CO2-effects on lamellar stacking are species dependent. 相似文献
943.
Nobuo Sakura Shin-ichiro Nishimura Naoto Fujita Akira Namera Mikio Yashiki Tohru Kojima 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》1998,719(1-2)
A rapid and sensitive headspace gas chromatographic and mass spectrometric (GC–MS) method was developed for the determination of acrolein in human urine. A 0.5-ml urine sample in a glass vial containing propionaldehyde as an internal standard was heated at 80°C for 5 min. A 0.1-ml volume of headspace vapor was injected into a GC–MS instrument. Acrolein and propionaldehyde were coeluted at 3.1 min using a DB-1 capillary column, and well separated by selective ion monitoring (SIM) mode using ions m/z 56.05 and m/z 58.05. The interassay and intraassay coefficient of variation were 0.99% and 3.3%. The calibration curve demonstrated a good linearity throughout concentrations ranging from 1 to 1000 nM. However, due to a wide variation of acrolein evaporation rates from human urine, a calibration curve must be established for each urine specimen using a standard addition method and detection limit varied from 1 to 5 nM. The total analysis time for two samples from one urine specimen required about 15 min. Therefore, this method is convenient for the urgent monitoring of urinary acrolein in patients to whom alkylating agents are administered. 相似文献
944.
Kuwada M Hasumi H Maki J Furuse Y 《Biochemistry and molecular biology international》1999,47(2):255-265
Testicular cytochrome P-450 was purified by a procedure including preparative isoelectrofocusing. The cytochrome P-450 was determined to have an isoelectric point of 6.47 on analytical isoelectric focusing. The purified cytochrome P-450 was found to be homogeneous and its molecular weight was estimated to be 52,000 on polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate. The carbon monoxide difference spectrum with a peak at 448 nm exhibited absorption spectrum of a typical cytochrome P-450. 284-fold purification was achieved with an yield of 10.6%. Following preparation of the microsomes, the purification is accomplished by a two-step procedure utilizing Aniline-Sepharose 4B column chromatography and preparative isoelectric focusing. 相似文献
945.
Luigi De Bellis Pietro Giuntini Hiroshi Hayashi Makoto Hayashi Mikio Nishimura 《Physiologia plantarum》1999,106(2):170-176
Pumpkin ( Cucurbita sp.) long-chain acyl-CoA oxidase (ACOX) (EC 1.3.3.6) was purified to homogeneity by hydrophobic interaction, hydroxyapatite, affinity, and anion exchange chromatographies. The purified isoenzyme is a dimeric protein, consisting of two apparently identical 72-kDa subunits. The protein is exclusively localized in glyoxysomes. The enzyme catalyzes selectively the oxidation of CoA esters of fatty acids with 12–18 C atoms and exhibits highest activity with C-14 fatty acids, but no activity with isobutyryl-CoA and isovaleryl-CoA (branched chain) or glutaryl-CoA (dicarboxylic). The enzyme is strongly inhibited by high concentrations of palmitoyl-CoA and weakly inhibited by high concentration of myristoyl-CoA. It is also inhibited by Triton X-100 at concentrations above 0.018% (w/v) the critical micellar concentration. The consequences of the substrate inhibition for the evaluation of long-chain ACOX activity in plant tissues are discussed. 相似文献
946.
947.
Interaction of homologues of Hsp70 and Cpn60 with ferredoxin-NADP reductase upon its import into chloroplasts 总被引:4,自引:0,他引:4
A homologue of the 70-kDa heat-shock protein (Hsp70) was purified from pumpkin chloroplasts. The molecular mass of the purified protein was approximately 75 kDa and its N-terminal amino acid sequence was very similar to those of homologues of Hsp70 from bacterial cells and from the mitochondrial matrix and stroma of pea chloroplasts. The purified homologue of Hsp70 was found in the stroma of chloroplasts. To investigate the role(s) of the homologue of Hsp70 in the chloroplast stroma, we examined the possibility that the homologue of Hsp70 might interact with newly imported proteins to assist in their maturation (for example, in their folding and assembly). Ferredoxin NADP+ reductase (FNR) imported into chloroplasts in vitro could be immunoprecipitated with antisera raised against the homologue of Hsp70 from pumpkin chloroplasts and against GroEL from Escherichia coli, which is a bacterial homologue of chaperonin 60 (Cpn60), in an ATP-dependent manner, an indication that newly imported FNR interacts physically with homologues of Hsp70 and Cpn60 in chloroplasts. Time-course analysis of the import of FNR showed that imported FNR interacts transiently with the homologue of Hsp70 and that the association of FNR with the homologue of Hsp70 precedes that with the homologue of Cpn60. These results suggest that homologues of Hsp70 and Cpn60 in chloroplasts might sequentially assist in the maturation of newly imported FNR in an ATP-dependent manner. 相似文献
948.
Acyl-CoA Synthetase in Maturing Safflower Seeds 总被引:1,自引:0,他引:1
Acyl-CoA synthetase in maturing seeds of safflower (Carthamustinctorius) was membranebound, and the highest specific activitywas associated with microsomes. Activity absolutely dependedon the concentrations of fatty acid, CoA, ATP and Mg2+. Theapparent Km values were 4.2 µM for oleate, 24 µMfor CoA, and 250 µM for ATP. The optimum pH of the reactionwas 7.5. Triacsin C, a potent inhibitor of the animal and bacterialacyl-CoA synthetase, was ineffective for the safflower enzyme.The enzyme utilized C16 and C18 long-chain fatty acids preferentially,while medium-chain and very-long-chain fatty acids were poorsubstrates. The order of specificity for native fatty acidswas linoleate > oleate=palmitate > stearate. Althoughactivity per seed varied during seed maturation, it was enoughto account for the rate of triacylglycerol synthesis in vivo. (Received February 2, 1993; Accepted March 3, 1993) 相似文献
949.
950.
Characterization of Intravacuolar Pigmented Structures in Anthocyanin-Containing Cells of Sweet Potato Suspension Cultures 总被引:2,自引:0,他引:2
Nozue Masayuki; Kubo Hiroyoshi; Nishimura Mikio; Katou Akira; Hattori Chiho; Usuda Nobuteru; Nagata Tetsuji; Yasuda Hitosi 《Plant & cell physiology》1993,34(6):803-808
Intravacuolar pigmented structures occurred in anthocyanin-producingcultured cells of sweet potato (Ipomoea batatas) were characterized.Formation of the pigmented structures in sweet potato cellswas induced by transfer of callus cultured in 2,4-D containingagar medium into 2,4-D free liquid medium under continuous illumination.These structures were found in the vacuoles. The pigmented structureswere isolated from the protoplasts by precipitation in 60% (w/w)sucrose after centrifugation. Electron microscopic observationsof the anthocyanin-containing cultured cells showed these structureshad neither membrane boundary nor internal structures, and werefound as strongly osmiophilic globules in vacuoles. Numeroussmall osmiophilic globules were observed in central vacuolesat the early stage of anthocyanin accumulation, but not foundin cytoplasm. Similar pigmented structures in vacuoles werealso formed by treatment with neutral red. These observationsindicate that these pigmented structure is the high densityand insoluble globules highly concentrated with anthocyanin,which was synthesized in cytoplasm and transported to the centralvacuoles.
4Present address: Department of Cell Biology, National Institutefor Basic Biology Myodaijicho, Okazaki, 444 Japan 相似文献