Asunto(s)
Potenciales de Acción , Fibrilación Atrial/cirugía , Ablación por Catéter/efectos adversos , Técnicas Electrofisiológicas Cardíacas , Frecuencia Cardíaca , Venas Pulmonares/cirugía , Taquicardia Supraventricular/etiología , Anciano , Fibrilación Atrial/diagnóstico , Fibrilación Atrial/fisiopatología , Femenino , Humanos , Masculino , Persona de Mediana Edad , Valor Predictivo de las Pruebas , Venas Pulmonares/fisiopatología , Recurrencia , Reoperación , Factores de Riesgo , Taquicardia Supraventricular/diagnóstico , Taquicardia Supraventricular/fisiopatología , Taquicardia Supraventricular/cirugía , Factores de Tiempo , Resultado del TratamientoRESUMEN
Plants are able to sense and respond to changes in the balance between carbon (C) and nitrogen (N) metabolite availability, known as the C/N response. During the transition to photoautotrophic growth following germination, growth of seedlings is arrested if a high external C/N ratio is detected. To clarify the mechanisms for C/N sensing and signaling during this transition period, we screened a large collection of FOX transgenic plants, overexpressing full-length cDNAs, for individuals able to continue post-germinative growth under severe C/N stress. One line, cni1-D (carbon/nitrogen insensitive 1-dominant), was shown to have a suppressed sensitivity to C/N conditions at both the physiological and molecular level. The CNI1 cDNA encoded a predicted RING-type ubiquitin ligase previously annotated as ATL31. Overexpression of ATL31 was confirmed to be responsible for the cni1-D phenotype, and a knock-out of this gene resulted in hypersensitivity to C/N conditions during post-germinative growth. The ATL31 protein was confirmed to contain ubiquitin ligase activity using an in vitro assay system. Moreover, removal of this ubiquitin ligase activity from the overexpressed protein resulted in the loss of the mutant phenotype. Taken together, these data demonstrated that CNI1/ATL31 activity is required for the plant C/N response during seedling growth transition.
Asunto(s)
Proteínas de Arabidopsis/fisiología , Arabidopsis/enzimología , Carbono/metabolismo , Nitrógeno/metabolismo , Ubiquitina-Proteína Ligasas/fisiología , Arabidopsis/genética , Arabidopsis/crecimiento & desarrollo , Proteínas de Arabidopsis/análisis , Proteínas de Arabidopsis/genética , Membrana Celular/metabolismo , Germinación , Proteínas Fluorescentes Verdes/análisis , Mutación , Cebollas/genética , Plantas Modificadas Genéticamente/crecimiento & desarrollo , Plantas Modificadas Genéticamente/metabolismo , Proteínas Recombinantes de Fusión/análisis , Plantones/enzimología , Plantones/genética , Plantones/crecimiento & desarrollo , Ubiquitina-Proteína Ligasas/análisis , Ubiquitina-Proteína Ligasas/genética , UbiquitinaciónRESUMEN
A cDNA encoding a predicted 15-kDa protein was earlier isolated from sugar-induced genes in rice embryos (Oryza sativa L.) by cDNA microarray analysis. Here we report that this cDNA encodes a novel Ca2+-binding protein, named OsSUR1 (for Oryza sativa sugar-up-regulated-1). The recombinant OsSUR1 protein expressed in Escherichia coli had 45Ca2+-binding activity. Northern analysis showed that the OsSUR1 gene was expressed mainly in the internodes of mature plants and in embryos at an early stage of germination. Expression of the OsSUR1 gene was induced by sugars that could serve as substrates of hexokinase, but expression was not repressed by Ca2+ signaling inhibitors, calmodulin antagonists and inhibitors of protein kinase or protein phosphatase. These results suggested that Os-SUR1 gene expression was stimulated by a hexokinase-dependent pathway not mediated by Ca2+.