Rho GTPase function in flies: insights from a developmental and organismal perspective.

Morphogenesis is a key event in the development of a multicellular organism and is reliant on coordinated transcriptional and signal transduction events. To establish the segmented body plan that underlies much of metazoan development, individual cells and groups of cells must respond to exogenous signals with complex movements and shape changes. One class of proteins that plays a pivotal role in the interpretation of extracellular cues into cellular behavior is the Rho family of small GTPases. These molecular switches are essential components of a growing number of signaling pathways, many of which regulate actin cytoskeletal remodeling. Much of our understanding of Rho biology has come from work done in cell culture. More recently, the fruit fly Drosophila melanogaster has emerged as an excellent genetic system for the study of these proteins in a developmental and organismal context. Studies in flies have greatly enhanced our understanding of pathways involving Rho GTPases and their roles in development

The sugarcane signal transduction (SUCAST) catalogue: prospecting signal transduction in sugarcane

EST sequencing has enabled the discovery of many new genes in a vast array of organisms, and the utility of this approach to the scientific community is greatly increased by the establishment of fully annotated databases. The present study aimed to identify sugarcane ESTs sequenced in the sugarcane expressed sequence tag (SUCEST) project (<A HREF="http://sucest.lad.ic.unicamp.br/">http://sucest.lad.ic.unicamp.br</A>) that corresponded to signal transduction components. We also produced a sugarcane signal transduction (SUCAST) catalogue (<A HREF="http://sucest.lad.ic.unicamp.br/private/mining-reports/QG/QG-mining.htm">http://sucest.lad.ic.unicamp.br/private/mining-reports/QG/QG-mining.htm</A>) that covered the main categories and pathways. Expressed sequence tags (ESTs) encoding enzymes for hormone (gibberellins, ethylene, auxins, abscisic acid and jasmonic acid) biosynthetic pathways were found and tissue specificity was inferred from their relative frequency of occurrence in the different libraries. Whenever possible, transducers of hormones and plant peptide signaling were catalogued to the respective pathway. Over 100 receptors were found in sugarcane, which contains a large family of Ser/Thr kinase receptors and also photoreceptors, histidine kinase receptors and their response regulators. G-protein and small GTPases were analyzed and compared to known members of these families found in mammalian and plant systems. Major kinase and phosphatase pathways were mapped, with special attention being given to the MAP kinase and the inositol pathway, both of which are well known in plants.<br>O sequenciamento de ESTs (etiquetas de sequencias transcritas) tem possibilitado a descoberta de muitos novos genes em uma ampla variedade de organismos. Um aumento do aproveitamento desta informação pela comunidade científica tem sido possível graças ao desenvolvimento de base de dados contendo seqüências completamente anotadas. O trabalho aqui relatado teve como objetivo a identificação de ESTs de cana de açúcar seqüenciadas através do projeto SUCEST (<A HREF="http://sucest.lad.ic.%20unicamp.br/">http://sucest.lad.ic. unicamp.br</A>) que codificam para proteínas envolvidas em mecanismos de transdução de sinal. Nós também preparamos um catálogo dos componentes de transdução de sinal da cana de açúcar (SUCAST) englobando as principais categorias e vias conhecidas (<A HREF="http://sucest.lad.ic.unicamp.%20br/private/mining-reports/QG/QG-mining.htm">http://sucest.lad.ic.unicamp. br/private/mining-reports/QG/QG-mining.htm</A>). ESTs codificadoras de enzimas envolvidas nas rotas de biossíntese de hormônios (giberelinas, etileno, auxinas, ácido abscíssico, ácido jasmônico) foram encontradas e sua expressão específica nos tecidos foi inferida a partir de seu enriquecimento nas diferentes bibliotecas. Quando possível, transmissores do sinal hormonal e da resposta a peptídeos produzidos pela planta foram associados a suas respectivas vias. Mais de 100 receptores foram encontrados na cana de açúcar, entre os quais uma grande família de receptores Ser/Thr quinase e também de fotoreceptores, receptores do tipo histidina quinase e seus respectivos reguladores da resposta. Proteínas G e GTPases pequenas foram também analisadas e comparadas com membros destas famílias já conhecidos em mamíferos e plantas. As vias principais que envolvem a participação de proteínas quinases e fosfatases foram mapeadas, em especial as vias da quinase MAP quinase e do inositol que são bem estudadas em plantas

Unravelling cell wall formation in the woody dicot stem

Populus is presented as a model system for the study of wood formation (xylogenesis). The formation of wood (secondary xylem) is an ordered developmental process involving cell division, cell expansion, secondary wall deposition, lignification and programmed cell death. Because wood is formed in a variable environment and subject to developmental control, xylem cells are produced that differ in size, shape, cell wall structure, texture and composition. Hormones mediate some of the variability observed and control the process of xylogenesis. High-resolution analysis of auxin distribution across cambial region tissues, combined with the analysis of transgenic plants with modified auxin distribution, suggests that auxin provides positional information for the exit of cells from the meristem and probably also for the duration of cell expansion. Poplar sequencing projects have provided access to genes involved in cell wall formation. Genes involved in the biosynthesis of the carbohydrate skeleton of the cell wall are briefly reviewed. Most progress has been made in characterizing pectin methyl esterases that modify pectins in the cambial region. Specific expression patterns have also been found for expansins, xyloglucan endotransglycosylases and cellulose synthases, pointing to their role in wood cell wall formation and modification. Finally, by studying transgenic plants modified in various steps of the monolignol biosynthetic pathway and by localizing the expression of various enzymes, new insight into the lignin biosynthesis in planta has been gained.Journal ArticleResearch Support, Non-U.S. Gov'tReviewinfo:eu-repo/semantics/publishe