Grupo Poéticas Digitais: projetos desluz e amoreiras

O Grupo Poéticas Digitais foi criado em 2002, no Departamento de Artes Plásticas da ECA-USP, com a intenção de gerar um núcleo multidisciplinar, promovendo o desenvolvimento de projetos experimentais e a reflexão sobre o impacto das novas tecnologias no campo das artes. O Grupo é um desdobramento do projeto wAwRwT, iniciado em 1995 por Gilbertto Prado e tem como participantes professores, artistas, pesquisadores e estudantes. O objetivo deste texto é apresentar algumas experimentações recentes de projetos poéticos como Desluz, de 2009/2010, e Amoreiras, de 2010.

Origins of the Xylella fastidiosa Prophage-Like Regions and Their Impact in Genome Differentiation

Xylella fastidiosa is a Gram negative plant pathogen causing many economically important diseases, and analyses of completely sequenced X. fastidiosa genome strains allowed the identification of many prophage-like elements and possibly phage remnants, accounting for up to 15% of the genome composition. To better evaluate the recent evolution of the X. fastidiosa chromosome backbone among distinct pathovars, the number and location of prophage-like regions on two finished genomes (9a5c and Temecula1), and in two candidate molecules (Ann1 and Dixon) were assessed. Based on comparative best bidirectional hit analyses, the majority (51%) of the predicted genes in the X. fastidiosa prophage-like regions are related to structural phage genes belonging to the Siphoviridae family. Electron micrograph reveals the existence of putative viral particles with similar morphology to lambda phages in the bacterial cell in planta. Moreover, analysis of microarray data indicates that 9a5c strain cultivated under stress conditions presents enhanced expression of phage anti-repressor genes, suggesting switches from lysogenic to lytic cycle of phages under stress-induced situations. Furthermore, virulence-associated proteins and toxins are found within these prophage-like elements, thus suggesting an important role in host adaptation. Finally, clustering analyses of phage integrase genes based on multiple alignment patterns reveal they group in five lineages, all possessing a tyrosine recombinase catalytic domain, and phylogenetically close to other integrases found in phages that are genetic mosaics and able to perform generalized and specialized transduction. Integration sites and tRNA association is also evidenced. In summary, we present comparative and experimental evidence supporting the association and contribution of phage activity on the differentiation of Xylella genomes.

PAMM: A Redox Regulatory Protein That Modulates Osteoclast Differentiation

The central role of reactive oxygen species (ROS) in osteoclast differentiation and in bone homeostasis prompted us to characterize the redox regulatory system of osteoclasts. In this report, we describe the expression and functional characterization of PAMM, a CXXC motif-containing peroxiredoxin 2-like protein expressed in bone marrow monocytes on stimulation with M-CSF and RANKL. Expression of wild-type (but not C to G mutants of the CXXC domain) PAMM in HEK293 cells results in an increased GSH/GSSG ratio, indicating a shift toward a more reduced environment. Expression of PAMM in RAW264.7 monocytes protected cells from hydrogen peroxide-induced oxidative stress, indicating that PAMM regulates cellular redox status. RANKL stimulation of RAW 264.7 cells caused a decrease in the GSH/GSSG ratio (reflecting a complementary increase in ROS). In addition, RANKL-induced osteoclast formation requires phosphorylation and translocation of NF-kappa B and c-Jun. In stably transfected RAW 264.7 cells, PAMM overexpression prevented the reduction of GSH/GSSG induced by RANKL. Concurrently, PAMM expression completely abolished RANKL-induced p100 NF-kappa B and c-Jun activation, as well as osteoclast formation. We conclude that PAMM is a redox regulatory protein that modulates osteoclast differentiation in vitro. PAMM expression may affect bone resorption in vivo and help to maintain bone mass. Antioxid. Redox Signal. 13, 27-37.

Cross-Talk Between Mitochondria and NADPH Oxidase: Effects of Mild Mitochondrial Dysfunction on Angiotensin II-Mediated Increase in Nox Isoform Expression and Activity in Vascular Smooth Muscle Cells

Mitochondria and NADPH oxidase activation are concomitantly involved in pathogenesis of many vascular diseases. However, possible cross-talk between those ROS-generating systems is unclear. We induced mild mitochondrial dysfunction due to mitochondrial DNA damage after 24 h incubation of rabbit aortic smooth muscle (VSMC) with 250 ng/mL ethidium bromide (EtBr). VSMC remained viable and had 29% less oxygen consumption, 16% greater baseline hydrogen peroxide, and unchanged glutathione levels. Serum-stimulated proliferation was unaltered at 24 h. Although PCR amplification of several mtDNA sequences was preserved, D-Loop mtDNA region showed distinct amplification of shorter products after EtBr. Such evidence for DNA damage was further enhanced after angiotensin-II (AngII) incubation. Remarkably, the normally observed increase in VSMC membrane fraction NADPH oxidase activity after AngII was completely abrogated after EtBr, together with failure to upregulate Nox1 mRNA expression. Conversely, basal Nox4 mRNA expression increased 1.6-fold, while being unresponsive to AngII. Similar loss in AngII redox response occurred after 24 h antimycin-A incubation. Enhanced Nox4 expression was unassociated with endoplasmic reticulum stress markers. Protein disulfide isomerase, an NADPH oxidase regulator, exhibited increased expression and inverted pattern of migration to membrane fraction after EtBr. These results unravel functionally relevant cross-talk between mitochondria and NADPH oxidase, which markedly affects redox responses to AngII. Antioxid Redox Signal 11, 1265-1278.

Evaluating Theobroma grandiflorum for comparative genomic studies with Theobroma cacao

The seeds of Theobroma cacao (cacao) are the source of cocoa, the raw material for the multi-billion dollar chocolate industry. Cacao`s two most important traits are its unique seed storage triglyceride (cocoa butter) and the flavor of its fermented beans (chocolate). The genome of T. cacao is being sequenced, and to expand the utility of the genome sequence to the improvement of cacao, we are evaluating Theobroma grandiflorum, the closest economically important species of Theobroma for its potential use in a comparative genomic study. T. grandiflorum differs from cacao in important agronomic traits such as flavor of the fermented beans, disease resistance to witches` broom and abscission of mature fruits. By comparing genomic sequences and analyzing viable inter-specific hybrids, we hope to identify the key genes that regulate cacao`s most important traits. We have investigated the utility in T. grandiflorum of three types of markers (microsatellite markers, single-strand conformational polymorphism markers and single nucleotide polymorphism (SNP) markers) developed in cacao. Through sequencing of amplicons of 12 diverse individuals of both cacao and T. grandiflorum, we have identified new intra- and inter-specific SNPs. Two markers which had no overlap of alleles between the species were used to genotype putative inter-specific hybrid seedlings. Sequence conservation was significant and species-specific differences numerous enough to suggest that comparative genomics of T. grandiflorum and T. cacao will be useful in elucidating the genetic differences that lead to a variety of important agronomic trait differences.

Skewness, splitting number and vertex deletion of some toroidal meshes

The skewness sk(G) of a graph G = (V, E) is the smallest integer sk(G) >= 0 such that a planar graph can be obtained from G by the removal of sk(C) edges. The splitting number sp(G) of C is the smallest integer sp(G) >= 0 such that a planar graph can be obtained from G by sp(G) vertex splitting operations. The vertex deletion vd(G) of G is the smallest integer vd(G) >= 0 such that a planar graph can be obtained from G by the removal of vd(G) vertices. Regular toroidal meshes are popular topologies for the connection networks of SIMD parallel machines. The best known of these meshes is the rectangular toroidal mesh C(m) x C(n) for which is known the skewness, the splitting number and the vertex deletion. In this work we consider two related families: a triangulation Tc(m) x c(n) of C(m) x C(n) in the torus, and an hexagonal mesh Hc(m) x c(n), the dual of Tc(m) x c(n) in the torus. It is established that sp(Tc(m) x c(n)) = vd(Tc(m) x c(n) = sk(Hc(m) x c(n)) = sp(Hc(m) x c(n)) = vd(Hc(m) x c(n)) = min{m, n} and that sk(Tc(m) x c(n)) = 2 min {m, n}.

Double disruption of alpha(2A)- and alpha(2C)-adrenoceptors results in sympathetic hyperactivity and high-bone-mass phenotype

Evidence demonstrates that sympathetic nervous system (SNS) activation causes osteopenia via beta(2)-adrenoceptor (beta(2)-AR) signaling. Here we show that female mice with chronic sympathetic hyperactivity owing to double knockout of adrenoceptors that negatively regulate norepinephrine release, alpha(2A)-AR and alpha(2C)-AR(alpha(2A)/alpha(2C)-ARKO), present an unexpected and generalized phenotype of high bone mass with decreased bone resorption and increased formation. In alpha(2A)/alpha(2C)-ARKO versus wild-type (WT) mice, micro-computed tomographic (mu CT) analysis showed increased, better connected, and more plate-shaped trabeculae in the femur and vertebra and increased cortical thickness in the vertebra, whereas biomechanical analysis showed increased tibial and femoral strength. Tibial mRNA expression of tartrate-resistant acid phosphatase (TRACP) and receptor activator of NF-kappa B (RANK), which are osteoclast-related factors, was lower in knockout (KO) mice. Plasma leptin and brain mRNA levels of cocaine amphetamine-regulated transcript (CART), which are factors that centrally affect bone turnover, and serum levels of estradiol were similar between mice strains. Tibial beta(2)-AR mRNA expression also was similar in KO and WT littermates, whereas alpha(2A)-, alpha(2B)- and alpha(2C)-AR mRNAs were detected in the tibia of WT mice and in osteoblast-like MC3T3-E1 cells. By immunohistochemistry, we detected alpha(2A)-, alpha(2B)-, alpha(2C)- and beta(2)-ARs in osteoblasts, osteoclasts, and chondrocytes of 18.5-day-old mouse fetuses and 35-day-old mice. Finally, we showed that isolated osteoclasts in culture are responsive to the selective alpha(2)-AR agonist clonidine and to the nonspecific alpha-AR antagonist phentolamine. These findings suggest that beta(2)-AR is not the single adrenoceptor involved in bone turnover regulation and show that alpha(2)-AR signaling also may mediate the SNS actions in the skeleton. (c) 2011 American Society for Bone and Mineral Research.

LIMITS OF TILTING MODULES

We study the problem of when a direct limit of tilting modules is still a tilting module.

Surface-enhanced Raman scattering study of alizarin red S

This paper presents the application of surface-enhanced resonance Raman spectroscopy (SERRS) for the structural study of alizarin red S (ARS) and the nature of its interaction with silver nanoparticles. SERRS data for ARS over nanostructured silver electrodes suggest a surface-induced reaction of the adsorbed dye and the formation of an ion stabilized by the dye and alkali ions adsorbed at the metal surface. We found that precoating the SERS active substrate with 1-propanethiol inhibits the surface-induced modification of ARS. In addition to preventing structural modifications of ARS, the coating also concentrates the hydrophobic dye close enough to the SERS active interface enabling the observation of excellent Raman spectra of ARS in aqueous environment at ppm levels. The influence of resonance Raman effect and of the pH on the SERS spectra of ARS was also investigated. (C) 2010 Elsevier B.V. All rights reserved.