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1.
The psbQ gene encoding a 16-kDa polypeptide of the oxygen-evolving complex of photosystem II has been isolated from Arabidopsis thaliana and characterized. The gene consists of a 28 nucleotide long leader sequence, two introns and three exons encoding a 223-amino-acid precursor polypeptide. The first 75 amino acids act as a transit peptide for the translocation of the polypeptide into the thylakoid lumen. Expression studies show that the gene is light-inducible and expresses only in green tissues with high steady-state mRNA levels in leaves. Using this gene as a probe, restriction fragment length polymorphism between two ecotypes, Columbia and Estland, has also been detected. 相似文献
2.
R K Gaur S Paliwal P Sharma K C Gupta 《Journal of biochemical and biophysical methods》1989,18(4):323-329
A simple and sensitive method for the quantitative determination of free amino groups on solid support is described. This approach is a modification of Ngo's [(1986) J. Biochem. Biophys. Methods 12, 349-354] method reported earlier. The method is based on the reaction of the solid support with an excess of 5'-O-(4,4'-dimethoxytrityl)-thymidine-3'-O-(2,4-dinitrophenyl) succinate (DTDS) in the presence of a catalytic amount of 4-dimethylaminopyridine. After removing the excess reagent, solid support is treated with perchloric acid to release 4,4'-dimethoxytrityl cation into the solution. The released 4,4'-dimethoxytrityl cation, which has a strong absorption at 498 nm (epsilon 498 = 70,000), is then determined spectrophotometrically. A comparative study of DTDS, N-succinimidyl-3-(2-pyridyldithio)propionate and 4,4-dimethoxytrityl chloride is also included. The method was found to be very useful to determine those amino groups which are available for functionalization of solid supports, especially, monitoring the functionalization of solid supports for affinity chromatography and synthesis of biopolymers. 相似文献
3.
Changes in epilithic algal communities colonizing introduced substrata were determined in a stream polluted with oil refinery
effluent at Digboi (Assam, India). The number of algal taxa was reduced but the growth of blue-green algae, particularly two
species ofOscillatoria, was encouraged. Epilithic biomass (as chlorophylla) also declined at polluted stations. The algal community of the upstream station was markedly different from the community
occurring just after the confluence of effluent; however, the differences were gradually reduced downstream, indicating improvement
in water quality. Of the various criteria tested for possible relationships with the level of pollutants, species richness,
Shannon diversity and biomass showed significant relationships. The study demonstrates the usefulness of algal criteria for
monitoring oil pollution in running waters. 相似文献
4.
Summary Attempts were made to store pollen grains of Crotalaria retusa L. in a mineral oil (paraffin oil) and two vegetable oils (soybean oil and olive oil). Under laboratory conditions pollen grains not stored in oil lost in vitro germinability within 15–30 days, while those stored in oils maintained some degree of germinability even after 60 days. Pollen samples stored in oils at –20° C did not show any decline in germinability or pollen tube vigour even after 6 months of storage. The results amply demonstrate the feasibility of using oils for short- and long-term pollen storage. 相似文献
5.
6.
Feeding of aflatoxin B1 at the rate of 0.5 ppm to young Japanese quail resulted in significant (p<0.01) decrease in body weight gain that became apparent on the third week. There was no significant difference in the mean values of haemoglobin, packed cell volume and total erythrocyte counts of quail chicks given aflatoxin B1 in feed in comparison to those fed on a similar diet without aflatoxin. However, the total leucocyte count revealed an increase on the third week which was due to an increase in the percentage of heterophils and decrease in lymphocytes. 相似文献
7.
Summary
Fusarium oxysporum 841 produces a mixture of ethanol and acetic acid from glucose, xylose or Avicel (microcrystalline cellulose) substrates. Some metabolic inhibitors viz. sodium azide, dinitrophenol and polyethylene glycol were used for shifting product formation from acetic acid to ethanol. Using these inhibitors 1.5- to 2- fold increase in ethanol production was achieved with significant repression (by 80 to 90%) of acetic acid. Almost theoretical yields of ethanol were obtained. 相似文献
8.
Summary Four strains of Fusarium oxysporum and a strain of Monilia brunnae were screened for their ability to convert cellulosic substrates into ethanol/acetic acid. These strains were found to utilize cellulose and produce extracellular cellulases. However, only F. oxysporum 841 was found to convert glucose, xylose, and cellulose into ethanol and acetic acid as major end-products under microaerobic conditions. Acetic acid at a level of 4.7 g/l resulted in a single-step process on potato pulp medium, indicating the potential of the strain for converting cellulosic substrates into acetic acid.
Offprint requests to: K. Schügerl 相似文献
9.
Intratracheal inoculation of 2-week old quail chicks with Aspergillus flavus spores resulted in the development of clinical signs within 24 h of infection. These were characterized by dullness, depression, anorexia, accelerated breathing, gasping and prostration leading to death. These signs continued up to 7 days followed by considerable decrease in the intensity of the symptoms as well as number of birds showing clinical signs. Mortality occurred primarily in the first week with a majority of the birds dying from 2–4 days after infection. The overall mortality during a 6-week observation period was 25%. The average body weight of the infected chicks was slightly lower than that of controls; the difference being significant at 2, 3 and 42 days post-infection. There was no appreciable difference in the mean values of haemoglobin, packed cell volume and total erythrocyte count between the infected and control chicks at any stage of infection, but total leucocyte count revealed a significant increase (p<0.05) from 3–7 days post-infection. This was due to increase in the percentage of heterophils and decrease in lymphocytes. 相似文献
10.
Solubilization of an Adenosine Uptake Site in Brain 总被引:1,自引:1,他引:0
Procedures are described for the solubilization of adenosine uptake sites in guinea pig and rat brain tissue. Using [3H]nitrobenzylthioinosine [( 3H]NBI) the solubilized site is characterized both kinetically and pharmacologically. The binding is dependent on protein concentration and is saturable, reversible, specific, and high affinity in nature. The KD and Bmax of guinea pig extracts are 0.13 +/- 0.02 nM and 133 +/- 18 fmol/mg protein, respectively, with linear Scatchard plots obtained routinely. Similar kinetic parameters are observed in rat brain. Adenosine uptake inhibitors are the most potent inhibitors of [3H]NBI binding with the following order of potency, dilazep greater than hexobendine greater than dipyridamole. Adenosine receptor ligands are much less potent inhibitors of binding, and caffeine is without effect. The solubilized adenosine uptake site is, therefore, shown to have virtually identical properties to the native membrane site. The binding of the adenosine A1 receptor agonist [3H]cyclohexyladenosine [( 3H]CHA) to the solubilized brain extract was also studied and compared with that of [3H]NBI. In contrast to the [3H]NBI binding site [3H]CHA binds to two apparent populations of adenosine receptor, a high-affinity site with a KD of 0.32 +/- 0.06 nM and a Bmax of 105 +/- 30 fmol/mg protein and a lower-affinity site with a KD of 5.50 +/- 0.52 nM and Bmax of 300 +/- 55 fmol/mg protein. The pharmacology of the [3H]CHA binding site is consistent with that of the adenosine receptor and quite distinct from that of the uptake [( 3H]NBI binding) site. Therefore, we show that the adenosine uptake site can be solubilized and that it retains both its binding and pharmacologic properties in the solubilized state. 相似文献