Enhanced expression of genes involved in coagulation and fibrinolysis in murine arthritis

INTRODUCTION: Accumulation of fibrin in the joints remains one of the most striking histopathological features of rheumatoid arthritis (RA). Recently, we have provided evidence of the deleterious role of synovial fibrin deposition in arthritic joints in antigen-induced arthritis (AIA), a well-established murine model of RA. A local imbalance between fibrin formation and fibrin dissolution may result in fibrin deposition in the joints. On the one hand, fibrin formation is mainly initiated by tissue factor (TF), a transmembrane protein serving as a receptor for factor VII. Under normal conditions, TF expression and activity are tightly regulated. Constitutive TF expression is restricted to perivascular and epithelial cells, and the catalytic activity of the TF/VIIa complex can be inhibited by tissue factor pathway inhibitor (TFPI). Pathological conditions can perturb the cell-type-restricted pattern of TF expression. In particular, recent reports have shown that transcriptional activation of TF can be mediated by molecular mechanisms involving induction of the early growth response gene 1 (EGR1) or of the protease-activated receptor (PAR1) or vascular endothelial growth factor (VEGF) genes. On the other hand, fibrin degradation is mediated primarily by plasmin, which is the active form of the zymogen plasminogen. Conversion of plasminogen to plasmin is under the control of serine protease plasminogen activators, such as the urokinase plasminogen activator (uPA), and their inhibitors, such as the plasminogen activator inhibitor (PAI-1). AIMS: We hypothesized that the deposition of fibrin in the joints may result from an imbalance in the local expression of key genes involved in coagulation and fibrinolytic pathways. To test this hypothesis, we investigated mRNA levels in arthritic versus nonarthritic joint tissues from two murine models of RA: AIA and collagen-induced arthritis (CIA). Genes that are directly implicated in coagulation (TF, TFPI) and fibrinolysis (UPA, PAI1), and other genes that may influence the expression of TF (EGR1, PAR1, VEGF), were investigated using a novel multiprobe RNase protection assay (RPA). Furthermore, we evaluated coagulation activity in arthritic and nonarthritic mice. METHODS: Mice with AIA or CIA were sacrificed at different time points: 2, 4, and 16 h and 3, 7, and 14 d after intra-articular antigen injection for AIA; 42 d after the first immunization for CIA. Total RNA was prepared from arthritic and nonarthritic knees for AIA, or arthritic and nonarthritic hind paws for CIA. Messenger RNA (mRNA) levels of the genes described above were determined by RPA and normalized to glyceraldehyde-3-phosphate dehydrogenase (GAPDH) mRNA levels. Coagulation assays were performed on joint tissue extracts and concentrations of thrombin-antithrombin III (TAT) complex were measured in plasma. RESULTS: In AIA, all the genes studied except VEGF were upmodulated as early as 2 h. PAR1, TFPI, EGR1, and UPA expression decreased to control levels by 16 h, whereas the expression of TF and PAI1 remained elevated. At later times, only TF, PAI1, and UPA showed sustained overexpression. In CIA, gene expression was assayed at only one time point (42 d after immunization) and all genes showed higher mRNA levels in the affected paws than in control paws. In AIA mice, procoagulant activity and TF activity were significantly increased in arthritic joints, and in CIA mice, plasma TAT levels were significantly enhanced. DISCUSSION: Fibrin deposition in synovia is prominent in both RA and experimental arthritis, suggesting that this protein may play a role in the pathogenesis of chronic inflammation. In this study, we have tried to shed some light on the molecular mechanisms leading to extravascular fibrin deposition, using two well-established mouse models of RA: AIA and CIA. The kinetics of gene expression was first analyzed in mice with AIA, because this model allows for an accurate, temporally controlled sampling of synovial inflammation. We then extended our observations by analyzing one time point in CIA, 42 d after immunization, when chronic inflammation is present. We found that in both models, coagulation and fibrinolysis in arthritic joints were significantly increased, and that the most significant increases were in TF and PAI-1. Although the molecular mechanism or mechanisms responsible for the transcriptional changes observed are not completely understood, the increases in TF, PAI-1, and uPA are probably due to the production of proinflammatory cytokines such as IL-1 and TGF-α. These cytokines, whose presence in the inflamed synovium is well documented, are known to induce these genes through the activation of nuclear factor κB (NF-κB), a transcription factor. TF induction is also under the control of a proximal enhancer containing a binding site for the inducible transcription factor EGR1. Indeed, the early rise of EGR1 expression in AIA is consistent with its classification as immediate-early gene and may be responsible for the induction of early expression of TF. Early TF stimulation in AIA can also be accounted for by the transient overexpression of PAR1. Contrary to what has been shown in RA, VEGF expression remained essentially unchanged throughout the progression of AIA, probably reflecting a peculiarity of this murine model. The alteration of the patterns of gene expression was accompanied by increased functional coagulation activity, which was more marked in AIA than in CIA. CONCLUSION: Prominent fibrin deposition in two different animal models of RA – AIA and CIA – can be attributed to modulations in key regulatory genes for coagulation and fibrinolysis

Ostracod and Foraminifer Responses to Late Pleistocene–Holocene Volcanic Activity in Northern Victoria Land as Recorded in Ross Sea (Antarctica) Marine Sediments

The impacts on ostracods and foraminifers caused by three Late Quaternary ashfalls of different intensities and recovered in the ANTA02-NW2 core sediments (Drygalski Basin, western Ross Sea) were analysed for the first time. Albeit with different timing, both associations demonstrated similar response patterns associated with the deposition of material from volcanic eruptions. In particular, based on the palaeontological evidence, it was possible to divide the cores into four intervals/phases recording the evolution of the ecosystem before and after the deposition events: (1) Pre-extinction phase (high abundance and high diversity values). (2) Extinction phase, characterised by the complete disappearance of ostracod fauna; the foraminiferal assemblage, although not entirely absent, records extremely low values of abundance and diversity (survivor assemblage). (3) Recovery phase (increasing abundance and diversity values), characterised by the recolonisation of some opportunistic taxa; species such as Australicythere devexa and Australicythere polylyca dominate the ostracod assemblage. (4) Post-extinction phase (high abundance and high diversity values), with the return to an environmental equilibrium characterised by the colonisation of specialised taxa such as Argilloecia sp., Cytheropteron sp., Echinocythereis sp., and Hemicytherura spp. Our results may aid in the understanding of how communities (i.e., ostracods and foraminifers) recovered after the impact of direct deposits of volcanic ash into ocean waters. The mechanisms by which disappearance and/or mortality was induced are still not clear. The release of toxic metals during the reaction of the volcanic ash with seawater, the resulting chemical alteration in the seawater, and the change in pH, together with the possible suppression of planktonic organisms, may have caused the two main extinction phases recorded by the ANTA02-NW2 core sediments

CORPO, IMAGEM, CONCEITO: MAIS DE UM LIMIAR

Partindo de um diagnóstico a respeito da crise da instituição filosófica em sua relação com a literatura, tal como ela se apresenta especificamente na experiência brasileira, em especial paulistana, propomos repensar o agenciamento da enunciação literária em seus elos e atritos com a filosofia, tentando abordar mais de perto a historicidade dos nexos entre corpo, imagem e conceito. Para tanto, a inscrição do corpo heterotópico e cinemático num poema de Herberto Helder abriria uma via de diálogo com a reflexão de Marco Antônio Valentim sobre o “conceito de conceito” indígena-kopenawano utupë. A partir desse diálogo, procuramos, ao final, retirar algumas contribuições para compreender a atual crise da democracia e do papel de mediação do espaço público, cuja formulação moderna estava calcada, precisamente, na distinção, agora em crise, entre filosofia e literatura, entre linguagens de argumentação intramundana e linguagens de abertura de mundo

Genetic dissection of maize phenology using an intraspecific introgression library

Background: Collections of nearly isogenic lines where each line carries a delimited portion of a donor source genome into a common recipient genetic background are known as introgression libraries and have already shown to be instrumental for the dissection of quantitative traits. By means of marker-assisted backcrossing, we have produced an introgression library using the extremely early-flowering maize (Zea mays L.) variety Gasp\ue9 Flint and the elite line B73 as donor and recipient genotypes, respectively, and utilized this collection to investigate the genetic basis of flowering time and related traits of adaptive and agronomic importance in maize.Results: The collection includes 75 lines with an average Gasp\ue9 Flint introgression length of 43.1 cM. The collection was evaluated for flowering time, internode length, number of ears, number of nodes (phytomeres), number of nodes above the ear, number and proportion of nodes below the ear and plant height. Five QTLs for flowering time were mapped, all corresponding to major QTLs for number of nodes. Three additional QTLs for number of nodes were mapped. Besides flowering time, the QTLs for number of nodes drove phenotypic variation for plant height and number of nodes below and above the top ear, but not for internode length. A number of apparently Mendelian-inherited phenotypes were also observed.Conclusions: While the inheritance of flowering time was dominated by the well-known QTL Vgt1, a number of other important flowering time QTLs were identified and, thanks to the type of plant material here utilized, immediately isogenized and made available for fine mapping. At each flowering time QTL, early flowering correlated with fewer vegetative phytomeres, indicating the latter as a key developmental strategy to adapt the maize crop from the original tropical environment to the northern border of the temperate zone (southern Canada), where Gasp\ue9 Flint was originally cultivated. Because of the trait differences between the two parental genotypes, this collection will serve as a permanent source of nearly isogenic materials for multiple studies of QTL analysis and cloning. \ua9 2011 Salvi et al; licensee BioMed Central Ltd

Root system architecture phenotyping of durum wheat reveals differential selection for a major QTL in contrasting environments

This study reports the characterization of 183 elite durum wheat (Triticum turgidum ssp. durum Desf.) for RSA and shoot developmental traits. Plants were grown in controlled conditions up to the 7th leaf appearance (late tillering) using the phenotyping platform GROWSCREEN-Rhizo at the Institut f\ufcr Bio und Geowissenschaften Pflanzenwissenschaften

Determinação de parâmetros microestruturais e reconstrução de imagens 3-D de rochas reservatório por microtomografia de raios X

A microtomografia computadorizada de raios X (µ-CT) tem se mostrado uma técnica bastante útil para a análise de rochas reservatório, pois fornece parâmetros microestruturais importantes, tais como, porosidade, permeabilidade e distribuição de tamanho de poros. A microtomografia de raios X é uma técnica não destrutiva, que além de possibilitar a reutilização das amostras já medidas, também fornece imagens 2-D e 3-D da amostra. Para a aquisição dos dados microtomográficos das rochas reservatório foi utilizado um microtomógrafo Skyscan, modelo 1172, o primeiro instalado no Brasil. Este equipamento forneceu imagens com resolução espacial de 2,5 µm para a amostra analisada. As imagens microtomográficas 2-D foram analisadas com o software Imago. Este trabalho apresenta resultados para um siltito da Formação Rio Bonito (MC16), coletado na Bacia do Rio Tibagi no Estado do Paraná, Brasil. Para esta amostra foram obtidas 490 seções 2-D, as quais foram usadas para a análise microestrutural. A amostra MC16 apresentou uma porosidade total média de (7,0 ± 0,2) %. A distribuição de tamanho de poros da amostra mostrou que, 95 % da fase porosa refere-se a poros com raios entre 2,5 e 10,2 µm. Foi reconstruído a imagem 3-D real da amostra através do software CTan

Prioritizing quantitative trait loci for root system architecture in tetraploid wheat

Optimization of root system architecture (RSA) traits is an important objective for modern wheat breeding. Linkage and association mapping for RSA in two recombinant inbred line populations and one association mapping panel of 183 elite durum wheat (Triticum turgidum L. var. durum Desf.) accessions evaluated as seedlings grown on filter paper/polycarbonate screening plates revealed 20 clusters of quantitative trait loci (QTLs) for root length and number, as well as 30 QTLs for root growth angle (RGA). Divergent RGA phenotypes observed by seminal root screening were validated by root phenotyping of field-grown adult plants. QTLs were mapped on a high-density tetraploid consensus map based on transcript-Associated Illumina 90K single nucleotide polymorphisms (SNPs) developed for bread and durum wheat, thus allowing for an accurate cross-referencing of RSA QTLs between durum and bread wheat. Among the main QTL clusters for root length and number highlighted in this study, 15 overlapped with QTLs for multiple RSA traits reported in bread wheat, while out of 30 QTLs for RGA, only six showed co-location with previously reported QTLs in wheat. Based on their relative additive effects/significance, allelic distribution in the association mapping panel, and co-location with QTLs for grain weight and grain yield, the RSA QTLs have been prioritized in terms of breeding value. Three major QTL clusters for root length and number (RSA-QTL-cluster-5#, RSA-QTL-cluster-6#, and RSA-QTL-cluster-12#) and nine RGA QTL clusters (QRGA.ubo-2A.1, QRGA.ubo-2A.3, QRGA.ubo-2B.2/2B.3, QRGA.ubo-4B.4, QRGA.ubo-6A.1, QRGA.ubo-6A.2, QRGA.ubo-7A.1, QRGA.ubo-7A.2, and QRGA.ubo-7B) appear particularly valuable for further characterization towards a possible implementation of breeding applications in marker-Assisted selection and/or cloning of the causal genes underlying the QTLs