Nicotiana tabaccum ovule extracts induced nuclear reconstitution of demembranated Xenopus leavis sperm in a cell-free system. Demembranated Xenopus sperm began to swell after 15 min of incubation with Nicotiana ovule ...Nicotiana tabaccum ovule extracts induced nuclear reconstitution of demembranated Xenopus leavis sperm in a cell-free system. Demembranated Xenopus sperm began to swell after 15 min of incubation with Nicotiana ovule extracts. Accompanying the process of incubation, Xenopus sperm decondensed and their shapes changed gradually from long and ellipse to round. The completely decondensed chromatin was surrounded with membrane structure, which was a mixture envelope of a double membrane and a single membrane. Nucleosome assembly was verified by means of micrococcal nuclease digestion to re-constituted nuclei and DNA electrophoresis. Nicotiana ovule extracts supplied one more experimental model and system. The new system could promote powerfully the research on mechanisms of cell division and cell cycle regulation.展开更多
Trehalose is a non-reducing disaccharide of glucose that functions as a protectant in the stabilization of biological structures and enhances the tolerance of organisms to abiotic stress. In the present study, we repo...Trehalose is a non-reducing disaccharide of glucose that functions as a protectant in the stabilization of biological structures and enhances the tolerance of organisms to abiotic stress. In the present study, we report on the expression of the Grifola frondosa Fr. Trehalose synthase (Tsase) gene for manipulating abiotic stress tolerance in tobacco (Nicotiana tabaccum L.). The expression of the transgene was under the control of two tandem copies of the CaMV3 5 S promoter and was transferred into tobacco by Agrobacterium tumefaciens EHA105. Compared with non-transgenic plants, transgenic plants were able to accumulate high levels of products of trehalose, which were increased up to 2.126–2.556 mg/g FW, although levels were undetectable in non-transgenic plants. This level of trehalose in transgenic plants was 400-fold higher than that of transgenic tobacco plants cotransformed with Escherichia coli TPS and TPP on independent expression cassettes, twofold higher than that of transgenic rice plants transformed with a bi functional fusion gene (TPSP) of the trehalose-6-phosphate (T-6-P) synthase (TPS) and T-6-P phosphatase (TPP) of E. coli, and 12-fold higher than that of transgenic tobacco plants transformed the yeast TPS1 gene. It has been reported that transgenic plants with E. coli TPS and/or TPP were severely stunted and had morphological alterations of their roots. Interestingly, our transgenic plants have obvious morphological changes, including thick and deep-coloured leaves, but show no growth inhibition; moreover, these morphological changes can restore to normal type in T2 progenies. Trehalose accumulation in 35S–35S:Tsase plants resulted in increased tolerance to drought and salt, as shown by the results of tests on drought, salt tolerance, and drought physiological indices, such as water content in excised leaves, malondialdehyde content, chlorophyll a and b contents, and the activity of superoxide dismutase and peroxidase in excised leaves. These results suggest that transgenic plants transformed with the Tsase gene can accumulate high levels of trehalose and have enhanced tolerance to drought and salt.展开更多
A 1050 bp up-stream regulatory fragment of the transcription factor gene NAC1in Arabidopsis thaliana was isolated using polymerase chain reaction (PCR) based techniques. Thefragment was used to substitute the 35S prom...A 1050 bp up-stream regulatory fragment of the transcription factor gene NAC1in Arabidopsis thaliana was isolated using polymerase chain reaction (PCR) based techniques. Thefragment was used to substitute the 35S promoter of the pBI121 plasmid to construct abate-glucuronidase gene (GUS) expression system. The construct was introduced into tobacco(Nico-tiana tabaccum) plants by the Agrobacterium-med\aled transferring method. GUS expressionpattern was studied by using the transgenic lines. The results showed that the GUS driven by theNAC1 up-stream regulatory region was specifically expressed in the root meristem region, basal areasof the lateral root primordium and the lateral roots. The GUS expression was induced by3-indolebutyric acid (IBA)and gibberellins (GA_3 and GA_(4+7)). The results indicated that theup-stream regulatory fragment of NAC1 responded to plant hormones. The fragment might be involved inboth auxins and gibberellins signaling in promoting the development of lateral roots.展开更多
基金This work was supported by the National Natural Science Foundation of China (Grant Nos. 19890380 and 39730240).
文摘Nicotiana tabaccum ovule extracts induced nuclear reconstitution of demembranated Xenopus leavis sperm in a cell-free system. Demembranated Xenopus sperm began to swell after 15 min of incubation with Nicotiana ovule extracts. Accompanying the process of incubation, Xenopus sperm decondensed and their shapes changed gradually from long and ellipse to round. The completely decondensed chromatin was surrounded with membrane structure, which was a mixture envelope of a double membrane and a single membrane. Nucleosome assembly was verified by means of micrococcal nuclease digestion to re-constituted nuclei and DNA electrophoresis. Nicotiana ovule extracts supplied one more experimental model and system. The new system could promote powerfully the research on mechanisms of cell division and cell cycle regulation.
文摘Trehalose is a non-reducing disaccharide of glucose that functions as a protectant in the stabilization of biological structures and enhances the tolerance of organisms to abiotic stress. In the present study, we report on the expression of the Grifola frondosa Fr. Trehalose synthase (Tsase) gene for manipulating abiotic stress tolerance in tobacco (Nicotiana tabaccum L.). The expression of the transgene was under the control of two tandem copies of the CaMV3 5 S promoter and was transferred into tobacco by Agrobacterium tumefaciens EHA105. Compared with non-transgenic plants, transgenic plants were able to accumulate high levels of products of trehalose, which were increased up to 2.126–2.556 mg/g FW, although levels were undetectable in non-transgenic plants. This level of trehalose in transgenic plants was 400-fold higher than that of transgenic tobacco plants cotransformed with Escherichia coli TPS and TPP on independent expression cassettes, twofold higher than that of transgenic rice plants transformed with a bi functional fusion gene (TPSP) of the trehalose-6-phosphate (T-6-P) synthase (TPS) and T-6-P phosphatase (TPP) of E. coli, and 12-fold higher than that of transgenic tobacco plants transformed the yeast TPS1 gene. It has been reported that transgenic plants with E. coli TPS and/or TPP were severely stunted and had morphological alterations of their roots. Interestingly, our transgenic plants have obvious morphological changes, including thick and deep-coloured leaves, but show no growth inhibition; moreover, these morphological changes can restore to normal type in T2 progenies. Trehalose accumulation in 35S–35S:Tsase plants resulted in increased tolerance to drought and salt, as shown by the results of tests on drought, salt tolerance, and drought physiological indices, such as water content in excised leaves, malondialdehyde content, chlorophyll a and b contents, and the activity of superoxide dismutase and peroxidase in excised leaves. These results suggest that transgenic plants transformed with the Tsase gene can accumulate high levels of trehalose and have enhanced tolerance to drought and salt.
基金supported by the National Natural Science Foundation of China(Grant No.30200169)the Specialized Research Fund for the Doctoral Program of Higher Education(Grant No.20010019008).
文摘A 1050 bp up-stream regulatory fragment of the transcription factor gene NAC1in Arabidopsis thaliana was isolated using polymerase chain reaction (PCR) based techniques. Thefragment was used to substitute the 35S promoter of the pBI121 plasmid to construct abate-glucuronidase gene (GUS) expression system. The construct was introduced into tobacco(Nico-tiana tabaccum) plants by the Agrobacterium-med\aled transferring method. GUS expressionpattern was studied by using the transgenic lines. The results showed that the GUS driven by theNAC1 up-stream regulatory region was specifically expressed in the root meristem region, basal areasof the lateral root primordium and the lateral roots. The GUS expression was induced by3-indolebutyric acid (IBA)and gibberellins (GA_3 and GA_(4+7)). The results indicated that theup-stream regulatory fragment of NAC1 responded to plant hormones. The fragment might be involved inboth auxins and gibberellins signaling in promoting the development of lateral roots.
