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1.
Aguiar PH Barrouin-Melo SM Franke CR dos Santos RR Silva TM Mengel JO dos-Santos WL Pontes-de-Carvalho L 《Veterinary journal (London, England : 1997)》2007,173(1):158-166
This report describes the characterisation of a monoclonal antibody (mAb), AB6, which recognises specifically a cluster of canine leukocyte surface molecules. The immunogen used for obtaining the AB6 mAb was a lysate of canine peripheral blood mononuclear cells (PBMC). This novel mAb belongs to the IgG2a isotype, and reacted in Western blot with four different canine leukocyte glycoproteins with apparent molecular weights of 180, 190, 205 and 220 kDa. The AB6 mAb recognised the majority of canine peripheral blood leukocytes as determined by flow cytometry (97%). It also exhibited a broad reactivity pattern against lymphoid and myeloid cells, inhibited the proliferation of mitogen-stimulated canine PBMC and did not recognise human PBMC and murine splenocytes. The biochemical properties, cell and tissue specificity, and in vitro biological activity of the AB6 mAb indicate that it recognises a canine CD45 homologue. The mAb could become a valuable diagnostic and research tool for the evaluation of immune functions in dogs. 相似文献
2.
Nutrient availability in the soil is not only determined by chemical, physical, and micro-biological factors but can be actively influenced by the plant root system. Various components of root activity have been studied in our laboratory during the last 10 years. The major findings are summarized and discussed with special emphasis on root morphology, cation-anion imbalance and proton release, the mechanism of proton release and anion secretion. Large species differences in root morphology were found between red clover and rye-grass. Root morphology was also found to be controlled by environmental and physiological factors. Experimental results obtained with different plant species suggest that proton release by plant roots is not primarily a consequence of excess cation uptake to achieve charge balance in the plant, but rather that active proton extrusion by ATPase activity creates a charge imbalance and a pH gradient which drive nutrient uptake. The pH gradient across the plasmalemma of root cells was also found to be essential for the retention of organic anions by plant roots. 相似文献
3.
Maize (Zea mays L.) and sunflower (Helianthus annuus L.) grown on a calcareous soil showed poor growth and/or were chlorotic in spite of abundant Fe in the roots. It has been
hypothesized that microbial siderophores chelate Fe (III) in the soil, and that in this form Fe is transported towards the
root apoplast. On the calcareous soil, total and apoplastic root Fe concentrations were high, probably because of a high apoplastic
pH depressing Fe (III)-reductase activity and thus the Fe2+ supply to the cytoplasm. On the acidic soil, total and apoplastic root Fe concentrations were low, probably because of a
low apoplastic pH favouring Fe (III) reduction, hence plants showed no Fe-deficiency symptoms. The main objective of the present
work was to investigate the role of microbial soil activity in plant Fe acquisition. For this purpose, plants were grown under
sterile and non-sterile conditions on a loess loam soil. Plants cultivated under non-sterile conditions grew well, showed
no Fe-deficiency symptoms and had fairly high Fe concentrations in the roots in contrast to plants grown in the sterile medium.
Low root and leaf Fe concentrations in the axenic treatments indicated that the production of microbial siderophores was totally
suppressed. Accordingly, sunflowers were severely chlorotic and this was associated with very poor growth, whereas in maize
only growth was drastically reduced. In maize under sterile conditions, root apoplastic and total Fe concentrations were not
as low as in sunflowers, which may have indicated that phytosiderophores produced in maize partly sustained Fe acquisition,
but due to poor growth were not as efficient in supplying Fe as microbial activity under natural conditions. It may be therefore
assumed that in natural habitats soil microbial activity is of pivotal importance for plant Fe acquisition.
Received: 11 March 1999 相似文献
4.
SUE DYSON KRISTEN McNIE JO WEEKES RACHEL MURRAY 《Veterinary radiology & ultrasound》2007,48(4):378-382
We tested the hypotheses that mature horses without lameness have a repeatable radiopharmaceutical uptake pattern in the stifle, which is bilaterally symmetric; immature horses have a different radiopharmaceutical uptake pattern; and forelimb lameness alters the radiopharmaceutical uptake pattern in the stifle. The objectives of the study were to describe the normal radiopharmaceutical uptake patterns using region of interest (ROI) analysis; to compare uptake patterns between left and right stifles of the same horse and between mature and immature horses; to compare radiopharmaceutical uptake in mature normal horses with those with forelimb lameness. Lateral scintigraphic images of the stifle from 51 horses aged 2-16 years were evaluated using seven ROIs and a reference site (midfemur). After subtraction of a background count, ratios between the mean counts per pixel for each ROI to the reference site were calculated. There was a repeatable radiopharmaceutical uptake pattern in mature normal horses that was bilaterally symmetrical. The caudoproximal aspect of the tibia and the patella had the highest ratios. Radiopharmaceutical uptake patterns in horses with forelimb lameness were not significantly different. Immature normal horses had a different symmetric pattern, with greatest radiopharmaceutical uptake ratios in the caudoproximal aspect of the tibia and the tibial crest. It was concluded that there are symmetric, repeatable radiopharmaceutical uptake patterns in both immature and mature horses, which are not altered by forelimb lameness. 相似文献
5.
6.
7.
Summary The turnover of interlayer NH
inf4
sup+
in a loess-derived agricultural soil from the Shaanxi Province in China was studied. The concentration of 15N-labeled interlayer NH
inf4
sup+
and total interlayer NH
inf4
sup+
(labeled + unlabeled) in a soil grown with winter wheat was significantly higher at the beginning of the season (March) than when the crop was mature (June). In a further experiment with winter wheat it was shown that under field conditions the concentration of interlayer NH
inf4
sup+
decreased significantly in the two upper soil layers (0–20 and 20–55 cm) during March and in the deeper soil layer (55–75 cm) during April. When the heading stage of wheat was reached, about 200 kg N ha-1 of interlayer NH
inf4
sup+
had been released. During the following growth period (heading until flowering of wheat) the concentration of interlayer NH
inf4
sup+
increased significantly in the upper soil layers. Fertilizer application in the form of 70 kg N ha-1 as urea led to a considerable increase in the nitrate concentration in the upper soil layer but had no influence on the level of interlayer NH
inf4
sup+
concentration. It is concluded that interlayer NH
inf4
sup+
takes part in the N cycle of the soil and that it contributes to the N nutrition of the crop. NH
inf4
sup+
originating from the mineralization of soil organic N may be rapidly incorporated into the interlayer of clay minerals and later released, when the N demand of the crop is high. 相似文献
8.
Summary An experiment was carried out to investigate how straw, cellulose and lignin affect the turnover and availability of inorganic labelled N in soil. The experiment comprised an incubation period in which the soil was incubated with 15NH4
15NO3 and organic materials followed by drying and by cropping the soil with Lolium perenne. The incubation period lasted 148 days during which soil samples were taken 36 and 148 days after the beginning of incubation. Addition of organic materials to the soil promoted the incorporation of inorganic N into organic matter and decreased apparent N denitrification losses during the first period of incubation (0–36 days after beginning of incubation). In this respect straw and cellulose were more effective than lignin. The organic materials also promoted the fixation of NH4
+ by clay minerals. In all treatments highest fixation of labelled NH4
+ by clay minerals was found at the end of the incubation period. During the cropping period high apparent denitrification losses were observed particularly in the straw and cellulose treatment. Hence the recovery of labelled N by Lolium was particularly low in these treatments while in the control treatment the 15N recovery was about twice as high. 相似文献
9.
The effect of potassium nutrition on growth rate, carbohydrate content, and water retention in young wheat plants The effect of potassium supply on the water content, growth rate, and content of carbohydrates has been studied in young wheat plants during a period of 22 days. Inadequate K+ supply resulted in a lower water content (water/g dry matter) and a decreased growth rate as compared with plants sufficiently supplied with K+. During the first days of the experimental period no major difference in the content of carbohydrates (glucose, fructose, sucrose, starch, fructosans) was found between both treatment. In the following days, however, the carbohydrate contents in the plants insufficiently supplied with K+ were significantly higher than in the plants with an adequate K+ nutrition. At the end of the experimental period a reverse pattern was found, the carbohydrate contents of the plants well fed with K+ were higher as compared with the plants with an insufficient K+ supply. It is concluded that K+ deficiency at first affects water retention and turgor. A reduced turgor results in a decreased growth rate which in return may lead to an accumulation of carbohydrates. Later at advanced K+ deficiency also the synthesis of carbohydrates is affected. 相似文献
10.
Effect of potassium nutrition on the content and the spectrum of soluble amino compounds in Red Clover 1. A better K nutrition of Red Clover (Trifolium pratense) resulted in higher contents of soluble amino acids of the upper plant parts. The plants of the treatment with the highest K application showed nearly double as high contents of glutamic acid, aspartic acid, alanine and γ-aminobutyric acid than the plants of the K0 treatment. The content of asparagine was not as much affected by the K nutrition and the content of glutamine was even lowered. 2. Red Clover responded on the K treatment with its content of soluble amino compounds quite different than non leguminous plant species which show decreasing contents of soluble amino acids with an increasing K nutrition. Therefore it is concluded, that the K nutrition of legumes affects the N2-fixation of Rhizobium leguminosarum. 3. The higher contents of soluble amino compounds did not influence the protein content of the upper plant parts. But with the better K supply the yields were increased considerably and therefore also higher yields of proteins were harvested. Very low K supply resulted in a high protein content, due to an inhibition of plant growth. 相似文献