Temporal Electrical Response of V/W-shaped Chiral Smectic Liquid Crystal Displays

Chiral smectic liquid crystal cells showing V-shaped electrooptical switching have been reported as one of the most promising technologies for high-end display applications. In this work, time-resolved electrical behaviour of these devices has been obtained through a set of systematic measurements. The electrical equivalent circuit has been derived, a number of simulations at different frequencies have been performed using commercial software for analogue circuits. Performance of this electrical model to account for time domain variations of switching currents in chiral smectic LC displays with V/W-shaped electrooptical response has been analyzed as well

Genes involved in brassinosteroids's metabolism and signal transduction pathways Genes envolvidos nas vias de biossíntese e de transdução de sinal de brassinoesteróides

Brassinosteroids (BRs) are plant steroids essential for the normal growth and development, which carry an oxygen moiety at C-3 and additional ones at one or more of the C-2, C-6, C-22 and C-23 carbon atoms. In the past few years, application of molecular genetics allowed significant progress on the understanding of the BRs biosynthetic pathway regulation and on the identification of several components of their signal transduction pathway, as well. Search in eletronic databases show dozens of records for brassinosteroid-related genes for the last twelve months, demonstrating the big efforts being carried out in this field. This review highlights the recent advances on the characterization of genes and mutations that are helping to unravel the molecular mechanisms involved in the BRs synthesis/metabolism, perception and response, with especial emphasis on their role in plant cell elongation. Aspects of the involvement of BRs on the regulation of cell cycle-controlling proteins are discussed as well.<br>Brassinoesteróides são esteróides vegetais, essenciais para o crescimento e o desenvolvimento, que apresentam um oxigênio no carbono C-3 e oxigênios adicionais em um ou mais dos átomos de carbono C-2, C-6, C-22 e C-23. Nos últimos anos, a aplicação de técnicas de genética molecular possibilitou progresso significativo no entendimento da regulação da via biossintética e na identificação de vários componentes da via de transdução de sinal de brassinoesteróides. Buscas em bases de dados eletrônicas mostram dúzias de registros para genes relacionados a brassinoesteróides nos últimos doze meses, demonstrando os grandes esforços desenvolvidos neste campo. Esta revisão destaca os recentes avanços na caracterização de genes e mutações que estão auxiliando na elucidação dos mecanismos moleculares envolvidos na síntese/metabolismo, e percepção e resposta de brassinoesteróides, com ênfase especial no seu papel no alongamento de células vegetais. Aspectos do envolvimento de BRs na regulação de proteínas que controlam o ciclo cellular também são discutidos