排序方式： 共有8条查询结果，搜索用时 15 毫秒
1
1.
2.
Using an aluminum (Al)‐sensitive maize cultivar, we investigated the influence of Al on the apoplastic solute bypass flow and its relationship with Al‐induced (1 h, 50 μM) callose formation and root growth. We selected the fluorescent probes 8‐hydroxypyrene‐1,3,6‐trisulfonic acid, trisodium salt (MW 524) (HPTS) and dextran‐Texas Red (TR) conjugates (MW 3,000, 10,000, and 40,000) to monitor their apoplastic transport. Confocal laser–scanning microscopy (CLSM) analysis and spectrofluorometric quantification showed Al‐induced callose formation in peripheral root cells within 1 h. Pretreatment of plants with the callose synthesis inhibitor 2‐deoxy‐D‐glucose (DDG) reduced the callose formation by half. Uptake experiments with both HPTS and dextrans showed uniform dye distribution in control root apices. After Al treatment for 1 or 2 h, which inhibited root growth by 32% or 50%, respectively, the dyes accumulated in the epidermal and outer cortical cell layers, especially in the 1–2 mm apical root zone. Al treatment reduced the export of the dyes out of the apical 1 cm treatment zone. This was due to strong sorption of HPTS but not of dextrans by Al‐loaded cell walls. Aluminum treatment reduced loading into the xylem sap particularly of higher–molecular weight dextrans. Pretreatment of roots with DDG and presence of 50 mM mannitol during the Al treatment partially forestalled the inhibitory effect of Al on the dye transport, but only slightly reduced the Al‐induced growth inhibition. Exudation experiments revealed that xylem water flow remained unaffected by the Al treatment of the root tips. The results with dextran suggest that Al binding in cell walls of the root apex inhibits apoplastic bypass flow of higher–molecular weight solutes, which might contribute to Al‐induced inhibition of root growth. 相似文献
3.
4.
Ten‐day‐old seedlings of four cowpea (Vigna unguiculata Walp) genotypes were subjected to six levels of aluminum (Al) (0, 74, 148, 222, 296, and 370 μM/L) to test their tolerance to Al toxicity in a nutrient solution at pH 4.0±0.1. Seedlings were grown in the presence of Al under controlled environmental conditions in a growth chamber. The nutrient solutions were replenished once a week. After 20 days, treatments were terminated and the differences in their growth patterns were compared. Standard growth parameters, such as plant growth, dry matter production, relative growth reduction in roots (RGRS) and shoots (RGRS), and root and shoot tolerance indices (RTI and STI) have been used as markers of Al toxicity. The cowpea genotypes studied exhibited a wide range of responses in their tolerance to Al. Though the genotypes were subjected to six levels of Al, a good degree of separation in their responses was observed only at the 222 μM Al/L treatment level. Therefore, this concentration was chosen to treat and compare the performances of the genotypes. The genotype Co 3 showed an increase in growth, while Paiyur 1 and other genotypes showed severe inhibitions in the presence of Al. Furthermore, for RTI and STI, Co 3 also registered its tolerance to Al by showing increased ratios in the presence of Al. Whereas, Paiyur 1 recorded severe reductions. The RGRR and RGRS data also substantiates this finding. Based on the growth parameters, the four cowpea genotypes were ranked based on their tolerance to Al: Co 3 > Co 4 > KM > Paiyur 1. Co 3 was the most Al‐tolerant genotype which performed extremely well in the presence of Al, while Paiyur 1was the most Al‐susceptible genotype. Therefore, the Al‐tolerant genotype can be used for future breeding programmes to produce Al‐tolerant genotypes, subsequently, can be recommended for acidic infertile soils in the tropics. 相似文献
5.
Ten‐day‐old seedlings of six rice (Oryza sativa L.) cultivars were grown hydroponically for 30 days in a nutrient solution containing 222 μM aluminum (Al)/L. Leaf reflectance properties were determined at visible (400–700 nm) and near infrared (700–1100 nm) wavelengths under controlled environmental conditions. For the Al‐tolerant cultivars of rice, there was no significant difference in the visible and near infrared reflectances. By contrast, the Al‐susceptible cultivars showed a prominent increase in reflectance in both the visible (with minor shift in the peak) and in the near infrared region. Foliar chlorophyll content decreased significantly in the Al‐susceptible cultivars but not in the Al‐tolerant cultivars. Further, mineral uptake, uitilization efficiency, and pigment contents have been correlated with these reflectances. In addition, there was no correlation between foliar Al content and changes in the reflectance of the Al‐treated susceptible cultivars. 相似文献
6.
Ten‐day‐old seedlings of 22 rice (Oryza sativa.L) cultivars originated from various tropical countries were subjected to six levels of aluminum (Al) [0, 74, 148, 222, 296, and 370 μM] to test their tolerance to Al toxicity in nutrient solutions at pH 4.0±0.l. Seedlings were grown in the presence of Al under controlled environmental conditions in growth chambers. The nutrient solutions were replenished once a week. After 30 days, treatments were terminated and the differences in their growth patterns were compared. Standard growth parameters such as plant growth, dry matter production, relative growth reduction in roots (RGRS) and shoots (RGRS), root tolerance index (RTI) and shoot tolerance index (STI) have been used as markers of Al toxicity. Rice cultivars studied exhibited wide range of responses in their tolerance to Al. Though, the rice cultivars were subjected to six levels of Al, a good degree of separation in their responses was observed only at 222 μM Al. Therefore, this concentration was chosen to analyze and compare the performances of the cultivars. Further, only six cultivars showed significant changes in their expression in the presence of Al compared to control, and so data have been presented only for those cultivars for clarity. The cultivars BW 196, Bhura Rata, Basmati 370 and Co 37 recorded increases in growth, while Damodar and ADT 36 showed severe inhibitions in the presence of Al. Furthermore, in RTI and STI also Co 37 and Basmati 370 registered their tolerance to Al by showing increased growth in the presence of Al. Whereas, Damodar and ADT 36 recorded severe reductions. The RGRR and RGRS data also substantiates this finding. Based on the growth parameters, the six rice cultivars were ranked based on their tolerance to Al: Co 37 > Basmati 370 > BW 196 > Bhura Rata > Damodar > ADT 36. Co 37 and Basmati 370 are the two most tolerant cultivars which performed extremely well in the presence of Al, and Damodar and ADT 36 are the most susceptible cultivars. Therefore, the Al‐tolerant cultivars can be used for future breeding programes to develop Al‐tolerant, cultivars that subsequendy can be recommended for planting in acidic, infertile soils of the tropics. 相似文献
7.
Differential aluminum tolerance in some tropical rice cultivars. II. mechanism of aluminum tolerance
Ten‐day‐old seedlings of 22 rice (Oryza sativa L.) cultivars were subjected to aluminum (Al) stress in nutrient solutions with an initial pH of 4.0±0.1. The rice cultivars exhibited a wide range of response by changing the rhizosphere pH, and the uptake and efficiency ratio (ER) of utilization of nutrients both in the presence (222 μM Al) and absence of Al. In the presence of Al, the cultivars Co 37 and Basmati 370 recorded maximum uptake and highest ER's for calcium (Ca), potassium (K), magnesium (Mg), manganese (Mn), phosphorus (P), and iron (Fe). The cultivars Damodar and ADT 36 performed very poorly in terms of nutrient uptake. The tolerant cultivars (Al‐insensitive) efficiently took up and utilized Ca and P in the presence of Al. The susceptible (Al‐sensitive) and intermediate cultivars exhibited less Ca and P uptake and utilization. There was no apparent relationship between foliar Al content and the efficiency ratios. However, the Al‐tolerant cultivars, Co 37 and Basmati 370, accumulated less Al in their foliage which was the reverse in case for the Al‐susceptible cultivars. Among the 22 rice cultivars tested, Co 37 and Basmati 370 emerged as the most Al‐tolerant. Hence, they would be recommended for cultivation in acidic, infertile soils of the tropics. The results of this study are discussed in terms of identifying the mechanism of Al tolerance or sensitivity among the studied rice cultivars as related to their nutrient metabolism. 相似文献
8.
Development of a two-antibody model for the evaluation of copper-64 radioimmunotherapy 总被引：1，自引：0，他引：1
J. N. Bryan M. R. Lewis C. J. Henry N. K. Owen J. Zhang H. Mohsin F. Jia G. Sivaguru C. J. Anderson 《Veterinary and comparative oncology》2004,2(2):82-90
Copper‐64 emits β+ and β– particles suitable for positron emission tomography and radioimmunotherapy (RIT) of cancer. Copper‐64‐labelled antibodies have caused complete responses in laboratory animal RIT studies at far lower radiation doses than traditionally prescribed. The intracellular localization of copper radioisotopes may lead to cytotoxic effects by mechanisms beyond ionizing radiation damage. The purpose of this research was to develop a model using both internalizing and non‐internalizing antibodies for direct comparison in future RIT studies using the same animal model of cancer. The monoclonal antibodies, cBR96 and cT84.66, were conjugated with N‐hydroxysulfosuccinimidyl DOTA. All conjugates retained high immunoreactivity and labelled efficiently with 64Cu with high specific activity and radiochemical purity. Twenty‐four hour biodistributions determined in LS174T tumour‐bearing nude mice demonstrated low organ and high tumour uptakes for both monoclonal antibodies. This model constitutes a promising system for elucidating whether internalization of 64Cu is responsible for an enhanced tumour cytotoxicity in vivo. 相似文献
1