RESUMO
Plants are continuously exposed to agents that can generate DNA lesions. Nucleotide Excision Repair (NER) is one of the repair pathways employed by plants to protect their genome, including from sunlight. The Xeroderma Pigmentosum type B (XPB) protein is a DNA helicase shown to be involved in NER and is also an essential subunitof the Transcription Factor IIH (TFIIH) complex. XPB was found to be a single copy gene in eukaryotes, but found as a tandem duplication in the plant Arabidopsis thaliana, AtXPB1 and AtXPB2. We aimed to investigate whether the XPB in tandem duplication was common within members of the Brassicaceae. We analyzed genomic DNA of species from different tribes of the family and the results indicate that the tandem duplication occurred in Camelineae tribe ancestor, of which A. thaliana belongs, at approximately 8 million years ago. Further experiments were devised to study possible functional roles for the A. thaliana AtXPB paralogs. A non-coincident expression profile of the paralogs was observed in various plant organs, developmental and cell cycle stages. AtXPB2 expression was observed in proliferating cells and clustered with the transcription of other components of the TFIIH such as p44, p52 and XPD/UVH6 along the cell cycle. AtXPB1 gene transcription, on the other hand, was enhanced specifically after UV-B irradiation in leaf trichomes. Altogether, our results reported herein suggest a functional specialization for the AtXPB paralogs: while the AtXPB2 paralog may have a role in cell proliferation and repair as XPB of other eukaryotes, the AtXPB1 paralog is most likely implicated in repair functions in highly specialized A. thaliana cells.
Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/crescimento & desenvolvimento , Arabidopsis/genética , Dano ao DNA , Reparo do DNA/genética , Duplicação Gênica , Fatores de Transcrição/metabolismo , Proteínas de Arabidopsis/genética , Ciclo Celular , Fator de Transcrição TFIIH/genética , Fator de Transcrição TFIIH/metabolismo , Fatores de Transcrição/genética , Raios UltravioletaRESUMO
Introducción Nuestra comprensión de la organización funcional del cerebro se debe a los avances en las técnicas de neuroimagen y a una intensa investigación clínica. Recientemente, la ciencia cognitiva (neurociencia cognitiva) en combinación con los avances tecnológicos han cambiado nuestra comprensión sobre la relación cerebro-conducta. Esta relación simbiótica ha permitido una mejor caracterización del sitio de la lesión en pacientes con trastornos cerebrales y de los patrones de activación en sujetos sanos. Objetivo En el presente artículo se discute la contribución del hemisferio izquierdo y la participación del hemisferio derecho en la regulación de la conducta motora; esto nos permitirá comprender mejor la lateralización de las funciones motoras. Desarrollo Los resultados apoyan la visión de un predominio del hemisferio izquierdo para el lenguaje y el control motor, y un predominio del hemisferio derecho para las funciones espaciales y la atención. Las áreas especializadas son probablemente predeterminadas y ciertas funciones están lateralizadas a uno u otro hemisferio, esto debido a la eficiente organización y procesamiento de la información en el cerebro. Conclusión En los estudios revisados, se observaron funciones específicas para cada hemisferio, lo que sugiere la existencia de una compleja organización que recluta a varias áreas del Sistema Nervioso para el adecuado desempeño de una tarea.
Introduction Our understanding of functional brain organization is due to advances in neuroimaging technologies and intensive clinical research. Recently, cognitive science (cognitive neuroscience), combined with advances in technology, have changed our understanding of brain-behavior relationship. This symbiotic relationship has allowed a better characterization of the lesion site in patients with brain disorders and patterns of activation in healthy subjects. Objective In this article we discuss the contribution of the left hemisphere and right hemisphere involvement in the regulation of motor behavior; this will allow us to better understand the lateralization of motor functions. Development The results support the view of a left hemisphere dominance for language and motor control, and a right hemisphere dominance for spatial functions and attention. Specialized areas are probably predetermined and certain functions are lateralized to one or other hemisphere due to the efficient organization and information processing in the brain. Conclusion In the studies reviewed, specific functions for each hemisphere were observed, suggesting the existence of a complex organization that recruits several areas of the Nervous System for proper task performance.