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  • 1
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Measurements of H+ extrusion activity K+ influx, and Es bm in 3-d-old seedlings of the 5-2 mutant of Arabidopsis thaliana (which is partially insensitive to fusicoccin) showed the following, (i) The reduced response of 5-2 to fusicoccin (FC) does not depend on the penetration of FC to its site of action, or on decreased affinity of the FC receptor, (ii) The reduced response of H+ and K+ transport to FC does not depend on an impairment of the K+ absorption system, (iii) The mutation can influence the H+ extrusion system independently of the presence of FC. In the presence of factors other than FC known to activate the plasma membrane H+-ATPase (e.g. a cytosol-acidifying treatment), the response in 5-2 is about 50% lower than in wt. (iv) When both genotypes grow in optimal conditions, the rate of fresh weight increase and stem elongation is higher in wt than 5-2. These data indicate that the 5-2 mutation affects some intrinsic component of the H+-extrusion machinery, the limiting effect of which becomes considerable when either the physiological or the experimental conditions induce a high level of proton pump activity. An alteration either of the ATPase itself or of a factor controlling its activity is compatible with our observations.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Plant, cell & environment 19 (1996), S. 0 
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: 5-2 is a mutant of Arabidopsis thaliana which is partially resistant to fusicoccin in vivo. We have analysed fusicoccin binding and the activity and amount of H+-ATPase in plasma membrane isolated from mature leaves of the wild type and of mutant 5-2. Fusicoccin binding was similar in plasma membrane from the two genotypes, while H+-ATPase activity was markedly (c. 50%) lower in plasma membrane from mutant 5-2 than in that from the wild type. The H+-ATPase of mutant 5-2 was activated by fusicoccin as much as that of the wild type. In plasma membrane from mutant 5-2, the amount of immunodetectable H+-ATPase, quantified by densitometry of Western blots, was about half that in the wild type. These results indicate that the major defect of mutant 5-2 detectable at the plasma membrane level is a reduction in the amount of H+-ATPase.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    International archives of occupational and environmental health 67 (1995), S. 41-46 
    ISSN: 1432-1246
    Keywords: N,N-Dimethylformamide ; Urine ; DMF-mercapturic acid ; N-methylformamide ; Formamide
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Some methods for analysing N,N-dimethylformamide and its metabolites [hydroxymethyl-N-methylformamide, hydroxymethylformamide and N-acetyl-S-(N-methylcarbamoyl)cysteine] in the urine of exposed workers are described. Unchanged dimethylformamide was measured after pretreatment of urine (2 ml) with silica gel cartridges and elution with methanol. The gas chromatographic analysis using a nitrogen phosphor detector made it possible to detect N,N-dimethylformamide in urine even when workers were exposed to low concentrations of the solvent (about 1 mg/m3). N-Hydroxymethyl-N-methylformamide and N-hydroxymethylformamide were analysed as N-methylformamide and formamide respectively after direct injection of urine into the gas chromatograph. The injection port temperature played an important role in the gas chromatographic determination of these products. Reliable results were obtained when direct or split injections were performed at 250°C. The splitless injection gave the same reliable results at 150°C. In urine samples from occupationally non-exposed persons, N-methylformamide could not be detected. In contrast, formamide (or its precursor, hydroxymethylformamide) was present in every urine sample. Our results in respect of 19 urine samples analysed with the injection port of the gas chromatograph at 250°C gave a mean of 8.6 mg/l of formamide. N-Acetyl-S-(N-methylcar-bamoyl)cysteine was determined using a modified method for analysing organic acid in urine samples. The metabolite was extracted with ethyl ether in an acid environment, treated with a silylating reagent and measured by gas chromatography/mass spectrometry.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    International archives of occupational and environmental health 68 (1996), S. 22-26 
    ISSN: 1432-1246
    Keywords: Nitrous oxide ; Blood ; Urine ; Environment ; Theatre personnel ; General population
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Nitrous oxide (N2O) was assayed in 676 urine samples and 101 blood samples provided after exposure by operating theatre personnel from nine hospitals. The blood and urine assays were repeated in 25 subjects 18 h after the end of exposure. For 80 subjects, environmental N2O was also measured during intraoperative exposure. Mean urinary N2O in the 676 subjects at the end of exposure was 40 μg/l (range 1–3805 μg/l); in 10 of the 676 subjects, urinary N2O was in the range 279–3805 μg/l (mean 1202 μ/l). The 98th percentile was 120 μg/l. Mean blood N2O at the end of exposure, measured in 101 subjects, was 21 μg/l (median 16 μg/l, range 1–75 μg/l). Blood and urine N2O (1.5 μg/l and 4.9 μg/l, respectively) in 25 subjects, 18 h after exposure, was significantly higher than in occupationally non-exposed subjects (blood 0.91 μg/l, urine 1 μg/l). Environmental exposure was significantly related to blood and urinary N2O (r = 0.59 andr = 0.64, respectively). Blood and urinary N2O were significantly related to each other (r = 0.71), and were equivalent to about 25% of the environmental exposure level. The mean urinary N2O of 1202 μg/l in 10/676 subjects was not related to environmental exposure in the operating theatre. The highest urinary N2O levels measured in these 10/676 subjects could be explained by an asymptomatic urinary infection.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Plant cell reports 18 (1998), S. 255-259 
    ISSN: 1432-203X
    Keywords: Key words Fusicoccin ; Arabidopsis thaliana ; Selection method
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A mutagenised population of seeds of Arabidopsis thaliana was allowed to germinate in the presence of the positively charged aminoglycoside hygromycin (4 μg/ml) and the fungal toxin fusicoccin (5×10–6 m). This hygromycin concentration, which is non-toxic by itself, becomes toxic when used together with fusicoccin, which stimulates cation uptake. Seeds that had germinated after 3–5 days and produced seedlings with green cotyledons were potentially resistant to fusicoccin and were therefore transferred into sterile Magenta vessels containing 1/2-strength Murashige and Skoog medium. This selection procedure is non-destructive, i.e. it allows the recovery of viable seedlings and their growth into adult plants thus permitting direct physiological characterisation.
    Type of Medium: Electronic Resource
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