RESUMEN
C-repeat-binding factor (CBF)/dehydration-responsive element (DREB) transcription factors play key roles in plant stress responses. However, little information is available on the regulation of CBF/DREB expression. In this study, we isolated and characterized the FeDREB1 promoter sequence from the common buckwheat accession Xinong 9976. To identify the upstream region of the FeDREB1 gene required for promoter activity, we constructed a series of FeDREB1 promoter deletion derivatives. Each deletion construct was analyzed through Agrobacterium-mediated transient transformation in tobacco leaves treated with 4°C cold or drought stress. Promoter-beta-glucuronidase fusion assays revealed that the pCD1 (-270 bp) deletion in the upstream region of FeDREB1 could activate expression of the GUS gene at 4°C. The pCD1 (-270 bp), pCD2 (-530 bp), and pCD3 (-904 bp) deletion induced low-level GUS expression under drought stress. However, the pCD4 (-1278 bp) deletion clearly activated GUS gene expression. Our results suggest that sections pCD1 (-270 bp) and pCD4 (-1278 bp) in the FeDREB1 gene promoter are new sources of induced promoters for adversity-resistance breeding in plant genetic engineering.
Asunto(s)
Frío , Sequías , Fagopyrum/genética , Fagopyrum/fisiología , Regulación de la Expresión Génica de las Plantas , Proteínas de Plantas/genética , Regiones Promotoras Genéticas , Secuencia de Bases , Glucuronidasa/metabolismo , Datos de Secuencia Molecular , Hojas de la Planta/genética , Proteínas de Plantas/metabolismo , Análisis de Secuencia de ADN , Eliminación de Secuencia , Estrés Fisiológico/genética , Nicotiana/genética , Transformación GenéticaRESUMEN
In recent years, improvements in the sensitivity of nuclear magnetic resonance have made it possible to detect progressively smaller numbers of nuclei. Experiments and studies previously thought to be impractical can now be undertaken, for example, the study of phenomena at surfaces. Nuclear magnetic resonance has been applied to study simple molecules (carbon monoxide, acetylene, and ethylene) adsorbed on metal surfaces (ruthenium, rhodium, palladium, osmium, iridium, and platinum). The metals, in the form of clusters 10 to 50 angstroms in diameter, supported on alumina, are typical of real catalysts. The experiments provide information about the bonding of the molecules to the metal, the structures the molecules assume after adsorption, the motion of molecules on the surface, the breakup of molecules induced by heating, and the products of such breakup.
RESUMEN
The mean and variance of an image reconstructed by Fourier multiaperture emission tomography are estimated by a physical experiment and by simulations. Results correspond closely to those obtained from a stochastic model of the noise process. A new scheme to enhance the statistical performance is proposed which improves the signal-to-noise ratio by 35 percent.
RESUMEN
Extremely low-frequency (ELF) magnetic field exposure systems are usually subject to field disturbances induced by external sources. Here, a method for designing a feedback control system for cancelling the effect of external ELF magnetic field disturbances on the magnetic field over the exposure area is presented. This method was used in the design of a feedback-controlled exposure system for an inverted microscope stage. The effectiveness of the proposed feedback control system for disturbance rejection was verified experimentally and by means of computer simulation.