ESTADO DA ARTE DAS PESQUISAS COM O CARANGUEJO-UÇÁ, Ucides cordatus

A member of Ocypodidae, the mangrove land crab, Ucides cordatus, is endemic to the Atlantic Coast of the Americas. It has considerable economic value to underpriviledged communities, which depend on it as a source of income and food. Ucides cordatus is considered as one of the most important biological components of mangrove ecosystems, particularly due to its role in the cycling of organic matter. Possibly as a consequence of the intense harvesting, the destruction of its habitats – the mangroves – and disease, there has been a decrease in the fishery stocks of the mangrove crab throughout the Brazilian coast. However, in spite of the cultural, ecological, and socio-economic importance of the species, the number of scientific studies on the mangrove land crab is still limited. The aim of the present study is to identify and relat the main studies published on the species until 2007.Pertencente a Ocypodidae, o caranguejo-uçá, Ucides cordatus, é uma espécie endêmica da costa atlântica do Continente Americano. Possui grande importância econômica para populações de baixo poder aquisitivo, que dependem de sua captura como fonte de renda e alimento. Ucides cordatus é considerado um dos componentes biológicos mais importantes do ecossistema dos manguezais por seu papel na ciclagem de matéria orgânica. Possivelmente, em virtude do intenso esforço de captura somado à destruição de seus habitats - os manguezais – e a uma enfermidade específica, têm-se observado uma tendência de redução dos estoques pesqueiros de caranguejo-uçá no litoral brasileiro. Porém, a despeito de sua importância cultural, ecológica e sócio-econômica, o número de pesquisas científicas desenvolvidas com a espécie ainda é limitado. O objetivo deste trabalho foi identificar e apresentar os principais estudos publicados sobre a espécie até o ano de 2007

Effect of promoter architecture on the cell-to-cell variability in gene expression

According to recent experimental evidence, the architecture of a promoter, defined as the number, strength and regulatory role of the operators that control the promoter, plays a major role in determining the level of cell-to-cell variability in gene expression. These quantitative experiments call for a corresponding modeling effort that addresses the question of how changes in promoter architecture affect noise in gene expression in a systematic rather than case-by-case fashion. In this article, we make such a systematic investigation, based on a simple microscopic model of gene regulation that incorporates stochastic effects. In particular, we show how operator strength and operator multiplicity affect this variability. We examine different modes of transcription factor binding to complex promoters (cooperative, independent, simultaneous) and how each of these affects the level of variability in transcription product from cell-to-cell. We propose that direct comparison between in vivo single-cell experiments and theoretical predictions for the moments of the probability distribution of mRNA number per cell can discriminate between different kinetic models of gene regulation.Comment: 35 pages, 6 figures, Submitte

Corporate governance for sustainability : Statement

The current model of corporate governance needs reform. There is mounting evidence that the practices of shareholder primacy drive company directors and executives to adopt the same short time horizon as financial markets. Pressure to meet the demands of the financial markets drives stock buybacks, excessive dividends and a failure to invest in productive capabilities. The result is a ‘tragedy of the horizon’, with corporations and their shareholders failing to consider environmental, social or even their own, long-term, economic sustainability. With less than a decade left to address the threat of climate change, and with consensus emerging that businesses need to be held accountable for their contribution, it is time to act and reform corporate governance in the EU. The statement puts forward specific recommendations to clarify the obligations of company boards and directors and make corporate governance practice significantly more sustainable and focused on the long term

Nucleosomes in gene regulation: theoretical approaches

This work reviews current theoretical approaches of biophysics and bioinformatics for the description of nucleosome arrangements in chromatin and transcription factor binding to nucleosomal organized DNA. The role of nucleosomes in gene regulation is discussed from molecular-mechanistic and biological point of view. In addition to classical problems of this field, actual questions of epigenetic regulation are discussed. The authors selected for discussion what seem to be the most interesting concepts and hypotheses. Mathematical approaches are described in a simplified language to attract attention to the most important directions of this field

Dynamic Chromatin Organization during Foregut Development Mediated by the Organ Selector Gene PHA-4/FoxA

Central regulators of cell fate, or selector genes, establish the identity of cells by direct regulation of large cohorts of genes. In Caenorhabditis elegans, foregut (or pharynx) identity relies on the FoxA transcription factor PHA-4, which activates different sets of target genes at various times and in diverse cellular environments. An outstanding question is how PHA-4 distinguishes between target genes for appropriate transcriptional control. We have used the Nuclear Spot Assay and GFP reporters to examine PHA-4 interactions with target promoters in living embryos and with single cell resolution. While PHA-4 was found throughout the digestive tract, binding and activation of pharyngeally expressed promoters was restricted to a subset of pharyngeal cells and excluded from the intestine. An RNAi screen of candidate nuclear factors identified emerin (emr-1) as a negative regulator of PHA-4 binding within the pharynx, but emr-1 did not modulate PHA-4 binding in the intestine. Upon promoter association, PHA-4 induced large-scale chromatin de-compaction, which, we hypothesize, may facilitate promoter access and productive transcription. Our results reveal two tiers of PHA-4 regulation. PHA-4 binding is prohibited in intestinal cells, preventing target gene expression in that organ. PHA-4 binding within the pharynx is limited by the nuclear lamina component EMR-1/emerin. The data suggest that association of PHA-4 with its targets is a regulated step that contributes to promoter selectivity during organ formation. We speculate that global re-organization of chromatin architecture upon PHA-4 binding promotes competence of pharyngeal gene transcription and, by extension, foregut development