VISUAL-CC system uncovers the role of GSK3 as an orchestrator of vascular cell type ratio in plants

The phloem transports photosynthetic assimilates and signalling molecules. It mainly consists of sieve elements (SEs), which act as "highways" for transport, and companion cells (CCs), which serve as "gates" to load/unload cargos. Though SEs and CCs function together, it remains unknown what determines the ratio of SE/CC in the phloem. Here we develop a new culture system for CC differentiation in Arabidopsis named VISUAL-CC, which almost mimics the process of the SE-CC complex formation. Comparative expression analysis in VISUAL-CC reveals that SE and CC differentiation tends to show negative correlation, while total phloem differentiation is unchanged. This varying SE/CC ratio is largely dependent on GSK3 kinase activity. Indeed, gsk3 hextuple mutants possess many more SEs and fewer CCs, whereas gsk3 gain-of-function mutants partially increase the CC number. Taken together, GSK3 activity appears to function as a cell-fate switch in the phloem, thereby balancing the SE/CC ratio. Tamaki et al. develop VISUAL-CC to study SE-CC (sieve elements-companion cells) complex formation. They show that the balance in the SE/CC ratio is dependent on GSK3 activity using different genetic backgrounds. Their work provides insights on the role of GSK3 as a cell-fate switch in the phloem.Peer reviewe

The involvement of Gab1 and PI 3-kinase in β1 integrin signaling in keratinocytes

金沢大学大学院医学系研究科血管分子科学The control of the stem cell compartment in epidermis is closely linked to the regulation of keratinocyte proliferation and differentiation. β1 integrins are expressed 2-fold higher by stem cells than transit-amplifying cells. Signaling from these β1 integrins is critical for the regulation of the epidermal stem cell compartment. To clarify the functional relevance of this differential expression of β1 integrins, we established HaCaT cells with high β1integrin expression by repeated flow cytometric sorting of this population from the parental cell line. In these obtained cells expressing β1 integrins by 5-fold, MAPK activation was markedly increased. Regarding the upstream of MAPK, Gab1 phosphorylation was also higher with high β1 integrin expression, while Shc phosphorylation was not altered. In addition, enhanced phosphatidylinositol 3-kinase activation was also observed. These observations suggest that Gab1 and phosphatidylinositol 3-kinase play pivotal roles in the β1 integrin-mediated regulation of the epidermal stem cell compartment. © 2007 Elsevier Inc. All rights reserved

Methanogenic archaea use a bacteria-like methyltransferase system to demethoxylate aromatic compounds

Methane-generating archaea drive the final step in anaerobic organic compound mineralization and dictate the carbon flow of Earth’s diverse anoxic ecosystems in the absence of inorganic electron acceptors. Although such Archaea were presumed to be restricted to life on simple compounds like hydrogen (H(2)), acetate or methanol, an archaeon, Methermicoccus shengliensis, was recently found to convert methoxylated aromatic compounds to methane. Methoxylated aromatic compounds are important components of lignin and coal, and are present in most subsurface sediments. Despite the novelty of such a methoxydotrophic archaeon its metabolism has not yet been explored. In this study, transcriptomics and proteomics reveal that under methoxydotrophic growth M. shengliensis expresses an O-demethylation/methyltransferase system related to the one used by acetogenic bacteria. Enzymatic assays provide evidence for a two step-mechanisms in which the methyl-group from the methoxy compound is (1) transferred on cobalamin and (2) further transferred on the C(1)-carrier tetrahydromethanopterin, a mechanism distinct from conventional methanogenic methyl-transfer systems which use coenzyme M as final acceptor. We further hypothesize that this likely leads to an atypical use of the methanogenesis pathway that derives cellular energy from methyl transfer (Mtr) rather than electron transfer (F(420)H(2) re-oxidation) as found for methylotrophic methanogenesis

Estudo dos Métodos de Detecção de mudanças em Modelos de Previsão de Séries Temporais.

Os modelos estatísticos de previsão são ferramentas importantes que ajudam a antecipar futuros cenários. Assim, estes contribuem para o planejamento, dimensionamento e alocação de recursos que permitem a redução de custos decorrentes de decisões equivocadas. Utilizar estes modelos tem como objetivo central prever acontecimentos futuros com o propósito de reduzir o risco na tomada de decisão. Entretanto, para utilizá-los é necessário que se faça um bom projeto de sistema de previsão. Aliado a este projeto, é essencial que existam procedimentos que ajudem na avaliação e no monitoramento de seu desempenho ao longo do tempo. Não importa quanto esforço foi realizado no desenvolvimento do modelo de previsão e o quão eficiente é o modelo inicialmente, com o tempo é provável que o desempenho deste modelo se deteriore. As previsões são realizadas com base em séries temporais e para monitorá-las é necessário utilizar os erros que essas previsões geram. Estes erros, que também geram séries temporais, são avaliados de acordo com diversos métodos. Portanto, para saber se uma previsão continua eficiente, é necessário monitorar os seus erros e, caso apresente mudanças, de acordo com os métodos de avaliação, será necessário refazer a previsão. Esta dissertação apresenta o estudo comparativo dos métodos que fazem o monitoramento dos modelos de previsão. Os métodos estudados são as cartas de controle de média móvel exponencialmente ponderada (EWMA), carta de controle de soma acumulada (CUSUM) e os Tracking Signals (TS). O objetivo deste estudo é identificar o melhor método para a detecção de séries lineares e analisar, através da simulação, qual o melhor método e também estabelecer regras e/ou padrões dessas detecções, fazendo a combinação do método com a carta farol. Para isso foram utilizadas e simuladas as séries temporais lineares e não lineares. As séries temporais lineares demonstram que a previsão está sob controle e as séries não lineares apresentam o pior cenário de uma previsão. Neste estudo foram realizados testes com a junção de séries lineares e não lineares no ponto determinado para verificar se os métodos eram capazes de detectar essa mudança. Foram realizadas quatro etapas para o estudo, sendo a última etapa a mais importante na combinação da carta farol com o TS. A conclusão presente na dissertação aponta que o Tracking Signal possui um desempenho superior quando combinado com a carta farol

Transverse microhardness of artificial teeth

Objetivo: A dureza é tida como indicador de várias propriedades mecânicas de dentes artificiais, e relacionada a resistência ao desgaste. O objetivo foi mapear a microdureza de dentes artificiais de 9 marcas em função da profundidade. Método: foi medida a microdureza Knoop de segundos molares cortados num plano sagital em intervalos de 200 µm a partir da profundidade de 100 µm até 4700 µm, das marcas: Premium (Pr), Orthosit (Or), SR Postaris DCL (Po), Biotone (Bi), Artiplus IPN (Ar), VITA MFT (Vi), Natusdent (Na), Trilux (Tr) and Biolux (Bx). A ANOVA de medidas repetidas e o teste de Tukey (5%) analisaram os resultados. Resultados: A marca SR Orthosit PE apresentou a maior dureza (até a profundidade de 3,1 mm foi da ordem de 30 N/mm2), significativamente maior que todas as outras medidas realizadas (da ordem de 20 N/mm2). Conclusões: A dureza Knoop não evidenciou diferenças entre camadas para oito das nove marcas estudadas. Foi constatada diferente dureza entre a superfície e a região cervical para a marca SR Orthosit PE.Objective: Hardness is an indicator of several mechanical properties of artificial teeth, also related to wear resistance. The purpose of this article is to map the microhardness of artificial teeth as a function of depth and commercial brand. Methods: Knoop microhardness of sectioned artificial second molars was measured every 200 µm starting at a depth of 100 µm up until 4700 µm of the following brands: Premium (Pr), Orthosit (Or), SR Postaris DCL (Po), Biotone (Bi), Artiplus IPN (Ar), VITA MFT (Vi), Natusdent (Na), Trilux (Tr), and Biolux (Bx). Results were analyzed with ANOVA for repeated measures and Tukey test (5%). Results: SR Orthosit PE commercial brand presented higher hardness values (until the depth of 3.1 mm was 30 N/mm2), significantly higher than the other brands analyzed. Conclusion: Knoop hardness did not present differences between layers for eight of the nine brands studied. Different hardness values were found between superficial and cervical areas for the brand SR Orthosit PE

Recyclable and efficient polyurethane-Ir catalysts for direct borylation of aromatic compounds

Four polyurethanes comprising 2,2'-bipyridyl moieties incorporated in the main chain were synthesized as a novel polymer ligand for the Ir(I)-catalyzed direct borylation of aromatic compounds. The polyurethanes were insoluble in common organic solvents and soluble in dimethylsulfoxide. The borylation reaction of benzene catalyzed by Ir(I) in the presence of the polymer prepared from 4,4'-bis(hydroxylmethyl)-2,2'-bipyridyl and 1,6-diisocyanatohexane led to the catalytic activities comparable to that in the presence of 2,2'-bipyridyl, while the polymers prepared by the reactions of 4,4'-bis(hydroxylmethyl)-2,2'-bipyridyl with 1,4-diisocyanatobenzene, 1,4-diisocyanato-3-methylbenzene, and bis(4-isocyanatophenyl)methane possesed lower catalytic activities. The high activity observed using the 1,6-diisocyanatohexane-based polyurethane catalyst could have a connection to the fact that this polymer has the highest tendency to form the inter-chain hydrogen bond. The borylation reaction systems with the polymers were biphasic, where the top and bottom layers contained the product and the polymer-based catalysts, respectively. Due to the phase separation, the product isolation and catalyst recycle were readily performed through a simple decantation. The catalyst prepared from 1,6-diisocyanatohexane-based polyurethane was able to be recycled at least five times without a significant decrease in activity. Further, the regio-selectivity in borylation of toluene, anisole, and trifluoromethybenzene was studied using the polyurethane ligands as well as the corresponding small-molecular ligands