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61.
Summary Ammonium nitrate fertilizer, labelled with15N, was applied in spring to winter wheat growing in undisturbed monoliths of clay and sandy loam soil in lysimeters; the rates
of application were respectively 95 and 102 kg N ha−1 in the spring of 1976 and 1975. Crops of winter wheat, oilseed rape, peas and barley grown in the following 5 or 6 years
were treated with unlabelled nitrogen fertilizer at rates recommended for maximum yields. During each year of the experiments
the lysimeters were divided into treatments which were either freelydrained or subjected to periods of waterlogging. Another
labelled nitrogen application was made in 1980 to a separate group of lysimeters with a clay soil and a winter wheat crop
to study further the uptake of nitrogen fertilizer in relation to waterlogging.
In the first growing season, shoots of the winter wheat at harvest contained 46 and 58% of the fertilizer nitrogen applied
to the clay and sandy loam soils respectively. In the following year the crops contained a further 1–2% of the labelled fertilizer,
and after 5 and 6 years the total recoveries of labelled fertilizer in the crops were 49 and 62% on the clay and sandy loam
soils respectively.
In the first winter after the labelled fertilizer was applied, less than 1% of the fertilizer was lost in the drainage water,
and only about 2% of the total nitrogen (mainly nitrate) in the drainage water from both soils was derived from the fertilizer.
Maximum annual loss occurred the following year but the proportion of tracer nitrogen in drainage was nevertheless smaller.
Leaching losses over the 5 and 6 years from the clay and sandy loam soil were respectively 1.3 and 3.9% of the original application.
On both soils the percentage of labelled nitrogen to the total crop nitrogen content was greater after a period of winter
waterlogging than for freely-drained treatments. This was most marked on the clay soil; evidence points to winter waterlogging
promoting denitrification and the consequent loss of soil nitrogen making the crop more dependent on spring fertilizer applications. 相似文献
62.
63.
Monoclonal antibodies against human myelomonocytic cells: detection of certain lineage-specific antigens on CFU-GM progenitor cells 总被引:1,自引:0,他引:1
A series of monoclonal antibodies (mAb) were raised against nonlymphoid leukemic cell lines. Three of them have been characterized in detail. mAb H8 (IgG2), mAB U2 (IgG1), and mAb ML143 (IgM) were established with HEL, an erythroleukemia cell line, U937, a monocytoid (histiocytic) line, and ML-1, a myeloid cell line as immunogen, respectively. A 65 to 75 KD polypeptide was precipitated from monocytes by mAb H8, a 160 KD protein from monocytes by mAb U2, and two broad bands in the regions of 150 and 195 KD from granulocytes by mAb ML143. All three mAb stained peripheral blood monocytes and granulocytes, but not lymphocytes, platelets, and erythrocytes. The mAb reacted with immature myeloid cells in bone marrow, ranging from myeloblasts to mature myelomonocytic cells. They also were reactive with various nonlymphoid cell lines and leukemia of myelomonocytic origin. They did not react with B cell lines and B cell CLL cells. By complement-mediated cytolysis and/or an immune rosette method, antigens H8 and U2 were found to be expressed on the vast majority of CFU-GM (14 days) progenitors but not on BFU-E. Antigen ML143 was not expressed by either progenitor. Furthermore, ML143 antigen was found on T leukemia cell lines, a subpopulation of mitogen-activated T cells, and certain non-T/non-B ALL cells. This reactivity was not found with mAb H8 and U2. The relationship between these mAb and those reported are discussed. The possibility of using these mAb to obtain a markedly enriched CFU-GM progenitor population is also raised. 相似文献
64.
Biosynthesis of riboflavin in Bacillus subtilis: origin of the four-carbon moiety. 总被引:2,自引:2,他引:0 下载免费PDF全文
We studied the incorporation of [1-13C]ribose and [1,3-13C2]glycerol into the riboflavin precursor 6,7-dimethyl-8-ribityllumazine, using a riboflavin-deficient mutant of Bacillus subtilis. The formation of the pyrazine ring requires the addition of a four-carbon moiety to a pyrimidine precursor. The results show that C-6 alpha, C-6, C-7, and C-7 alpha of 6,7-dimethyl-8-ribityllumazine were biosynthetically equivalent to C-1, C-2, C-3, and C-5 of a pentose phosphate. C-4 of the pentose precursor was lost through an intramolecular skeletal rearrangement. Thus, the last steps in the biosynthesis of 6,7-dimethyl-8-ribityllumazine apparently involve the same mechanism in bacteria as in fungi. 相似文献
65.
Summary The oxidation of propene by resting-cells of ethene-grown Mycobacterium E3 was inactivated by 1,2-epoxypropane. Inactivation increased with increasing epoxide concentrations with 50% inactivation at approximately 30 mM epoxide. Other lower epoxides as epoxyethane and 1,2-epoxybutane also inactivated oxidation of propene as well as of other alkenes. Propene oxidation by resting-cells of ethane-grown Mycobacterium E20 and resting-cells of methane-grown Methylosinus trichosporium OB3b was inactivated for 50% at much lower 1,2-epoxypropane concentrations of approximately 1 and 3 mM respectively. It was demonstrated that in vivo the predominant effect of 1,2-epoxypropane was on the epoxidizing enzyme, i.e. alkene mono-oxygenase (strain E3), alkane mono-oxygenase (strain E20) and methane mono-oxygenase (methylotroph) and that the effect of the epoxide on the alkene mono-oxygenase was irreversible. 相似文献
66.
C W Chi D X Zhu N Q Lin L X Xu F L Tan L X Wang 《Biological chemistry Hoppe-Seyler》1985,366(9):879-885
After reduction and alkylation of the disulfide bonds of the proteinase inhibitor B from the root of the arrowhead (Sagittaria sagittifolia L.) followed by CNBr cleavage three peptide fragments with 68, 62 and 11 amino-acid residues could be separated on DEAE-Sepharose CL-6B. The peptides or the inhibitor itself were further specifically cleaved either by trypsin or by the mixture of (CH3)2SO/HCl/HBr at the arginyl- and the tryptophyl-peptide bond, respectively. The complete amino-acid sequences of the peptides were determined by manual solid phase DABITC/PITC double coupling micro-method and the primary structure of the arrowhead inhibitor B consisting of 141 amino-acid residues was then elucidated. Twenty pairs of amino-acid residues are repeated in the molecule of this inhibitor, three of these pairs even occur three times. The possible locations of the reactive sites are discussed. On the basis of sequence comparisons between this inhibitor and all other serine proteinase inhibitors the arrowhead inhibitor may belong to a new family. 相似文献
67.
A.Q.H. Habets-Crützen S.J.N. Carlier J.A.M. de Bont D. Wistuba V. Schurig S. Hartmans J. Tramper 《Enzyme and microbial technology》1985,7(1):17-21
Resting cells of ethene grown Mycobacterium 2W produced 1,2-epoxypropane stereospecifically from propene as revealed by optical rotation, 1H n.m.r. using a chiral shift reagent, and also by complexation gas chromatography involving a glass capillary column coated with an optically active metal chelate. The gas-liquid chromatography method allowed the rapid screening of 11 strains with regard to stereospecific formation of 1,2-epoxypropane, 1,2-epoxybutane and 1-chloro-2,3-epoxypropane. Bacteria grown on either ethene, propene or butadiene all predominantly produced the R form of 1,2-epoxypropane from propene and 1,2-epoxybutane from 1-butene while the strains tested for 1-chloro-2,3-epoxypropane production from 3-chloro-1-propene predominantly accumulated the S enantiomer. 相似文献
68.
外源蜕皮激素对蓖麻蚕蛹发育的效应 总被引:2,自引:1,他引:1
本文报道蓖麻蚕蛹在室温28℃下的卵巢发育过程,以及外源20-羟基蜕皮酮对蚕蛹发育的影响。正常蛹在任何发育期内注射20-羟基蜕皮酮后,全部仍羽化成蛾,但蛹期延长约1至4天。无脑蛹经注射后出现蛹——蛾的变态,发育情况因剂量而不同:注射0.1微克后约有半数蛹发育成蛾;注射2微克羽化率较高,卵巢管的发育也最好;4微克或更高的注射量能使全部蛹发育成蛾,但卵巢管多少有些不正常。注射量超过5微克时,蛾体较小,颜色浅黄,没有或只有很少的鳞片。蛹的发育天数随剂量的增大而减少。经外源20-羟基蜕皮酮处理后,无论是有脑蛾或是无脑蛾的卵粒都明显地比正常蛾的卵粒大。当超过一定的注射量时,注射量越大,蚕蛾的自动蜕壳能力越差。 相似文献
69.
Ewa Nizankowska Angelita Q. Sheridan Marie H. Maile Carol J. Cross Rafal Nizankowski Krystyna Prochowska Andrew Szczeklik 《Prostaglandins & other lipid mediators》1985,29(3):349-362
We evaluated in a double-blind study the bronchodilatory properties of 2-decarboxy-2-hydroxymethyl prostaglandin E1 (PGE1-carbinol), described recently as a nonirritant bronchodilator in animals. Fifteen asthmatic patients received by inhalation single doses of 1, 10, and 30 μg PGE1-carbinol, 55 μg PGE2, and placebo (10% ethanol in normal saline, which was also used as diluent for the PGs). Such pulmonary function tests as forced expiratory volume in 1 second, forced vital capacity, and maximal expiratory flow were monitored during 2 hours following inhalation of each compound. 10 and 30 μg PGE1-carbinol produced significant but short-acting bronchodilation, similar to that caused by 55 μg PGE2. One-third of the patients reported mild cough and throat irritation during and shortly after inhalation of 30 μg PGE1-carbinol or 55 μg PGE2. Placebo and 1 μg PGE1-carbinol produced minimal side effects, but neither agent caused bronchodilation. In an adjunctive, unblinded trial, the same patients received 400 μg fenoterol. Fenoterol caused greater bronchodilation 15 and 30 minutes after inhalation than did the PGs in the double-blind study. 相似文献
70.