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排序方式: 共有152条查询结果,搜索用时 78 毫秒
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Yaxin Li Matthew R. Gronquist Guixia Hao Michele R. Holden Anatol Eberhard Russell A. Scott Michael A. Savka Erno Szegedi Sandor Sule Thomas J. Burr 《Physiological and Molecular Plant Pathology》2005,67(6):101
Agrobacterium vitis causes crown gall disease on grapevines. It also induces a specific necrosis on grape roots and a hypersensitive response (HR) on tobacco that are regulated by a complex quorum-sensing regulatory system. Strain F2/5 produces at least six N-acyl-homoserine lactones (AHLs) that function as signal molecules in quorum-sensing. The AHLs differ in acyl side chain length (8–16 carbons) as determined by gas chromatography/mass spectrometry and electrospray ionization tandem mass spectrometry. Mutant derivatives of F2/5 differ in ability to cause necrosis and the HR and show variable AHL profiles as determined by a thin-layer chromatography/biosensor assay. All wildtype A. vitis strains revealed the presence of long-chain AHLs regardless of tumorigenicity or ability to cause the HR. Whereas genes encoding long-chain AHLs are predicted to reside on the F2/5 chromosome, the determinants for short-chain AHLs were shown to be located on conjugal plasmids. 相似文献
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Xanthomonas axonopodis pv. glycines ( Xag ) causes bacterial pustule disease which can significantly reduce the production of soybean. A collection of 26 isolates of Xag from different soybean-production areas of Thailand was shown to differ with regard to aggressiveness on soybean. They also differed in their ability to induce a hypersensitive response (HR) on four cultivars of tobacco and on other plant species including pepper, tomato, cucumber, pea and sesame. Tomato was most sensitive to HR induction by Xag . Isolate KU-P-34017 caused an HR on all the plant species tested. The minimal concentration of KU-P-34017 needed to induce HR on tobacco was approximately 5 × 108 CFU mL−1 . A bacterium–plant interaction period of at least 2·5 h was necessary for HR, and different temperatures, relative humidity and light periods did not affect HR development. Inhibitors of eukaryotic metabolism, including cobalt chloride, lanthanum chloride and sodium orthovanadate (completely), and cycloheximide (partially) blocked the HR on tobacco, indicating the association of an active plant response. In contrast, the HR on tomato was inhibited only by cobalt chloride. 相似文献
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Personal and family backgrounds of first-year veterinary science students at The University of Queensland 总被引:1,自引:0,他引:1
TJ HEATH 《Australian veterinary journal》1997,75(12):902-905
Objective To provide information on changes in the social and educational backgrounds of veterinary students over a 10 year period in an effort to determine the extent to which they are representative of the community.
Methods Questionnaires were completed by first-year veterinary students at The University of Queensland in 1985 and 1986 (152 students), and 1995 and 1996 (154), and the data were analysed using the SAS System for Windows.
Results The gender ratio of first-year veterinary students was 50:50 (male:female) in 1985 and 1986 but 10 years later it had changed to 38:62. In 1985 and 1986 77% had come directly from school, with 43% of the total coming from government schools, 17% from Catholic schools and 34% from other private (Independent) schools. A decade later the percentage coming directly from school had decreased to 40%, that from Independent schools increased to 45% and that from cities increased from 53% to 64%. The educational backgrounds of parents varied widely though a high percentage had university degrees; mothers had received less formal education than fathers, and the educational attainments of both parents were higher at the beginning than at the end of the study. More than half (57% initially; 67% 10 years later) the fathers were in professional or managerial occupations, and a similar number (50% initially; 48% 10 years later) of mothers were teachers, nurses or clerks. The number of males from country areas decreased from 26 to 16 over this period.
Conclusion These veterinary students differed from the community generally in that progressively more were female, more were from Independent schools, their parents had more formal education and more of their parents were in professional, managerial or clerical occupations. 相似文献
Methods Questionnaires were completed by first-year veterinary students at The University of Queensland in 1985 and 1986 (152 students), and 1995 and 1996 (154), and the data were analysed using the SAS System for Windows.
Results The gender ratio of first-year veterinary students was 50:50 (male:female) in 1985 and 1986 but 10 years later it had changed to 38:62. In 1985 and 1986 77% had come directly from school, with 43% of the total coming from government schools, 17% from Catholic schools and 34% from other private (Independent) schools. A decade later the percentage coming directly from school had decreased to 40%, that from Independent schools increased to 45% and that from cities increased from 53% to 64%. The educational backgrounds of parents varied widely though a high percentage had university degrees; mothers had received less formal education than fathers, and the educational attainments of both parents were higher at the beginning than at the end of the study. More than half (57% initially; 67% 10 years later) the fathers were in professional or managerial occupations, and a similar number (50% initially; 48% 10 years later) of mothers were teachers, nurses or clerks. The number of males from country areas decreased from 26 to 16 over this period.
Conclusion These veterinary students differed from the community generally in that progressively more were female, more were from Independent schools, their parents had more formal education and more of their parents were in professional, managerial or clerical occupations. 相似文献
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OBJECTIVE: To examine the effectiveness of two methods of increasing fruit and fruit juice intake in pregnancy: midwives' advice and vouchers exchangeable for juice. DESIGN: Pregnant women were randomly allocated to three groups: a control group, who received usual care; an advice group, given advice and leaflets promoting fruit and fruit juice consumption; and a voucher group, given vouchers exchangeable for fruit juice from a milk delivery firm. Dietary questionnaires were administered at ~16, 20 and 32 weeks of pregnancy. Serum beta-carotene was measured at 16 and 32 weeks. SETTING: An antenatal clinic in a deprived area. SUBJECTS: Pregnant women aged 17 years and over. RESULTS: The study comprised 190 women. Frequency of fruit consumption declined during pregnancy in all groups, but that of fruit juice increased substantially in the voucher group. Serum beta-carotene concentration increased in the voucher group, from 106.2 to 141.8 micromol l(-1) in women with measurements on both occasions (P = 0.003), decreased from 120.0 to 99.8 micromol l(-1) in the control group (P = 0.005), and was unchanged in the advice group. CONCLUSIONS: Pregnant women drink more fruit juice if they receive vouchers exchangeable for juice supplied by the milk delivery service. Midwives' advice to eat more fruit has no great effect. Providing vouchers for fruit juice is a simple method of increasing its intake in a deprived population and may be useful for other sections of the community. 相似文献