187 research outputs found

    Simulating microbial degradation of organic matter in a simple porous system using the 3-D diffusion-based model MOSAIC

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    This paper deals with the simulation of microbial degradation of organic matter in soil within the pore space at a microscopic scale. Pore space was analysed with micro-computed tomography and described using a sphere network coming from a geometrical modelling algorithm. The biological model was improved regarding previous work in order to include the transformation of dissolved organic compounds and diffusion processes. We tested our model using experimental results of a simple substrate decomposition experiment (fructose) within a simple medium (sand) in the presence of different bacterial strains. Separate incubations were carried out in microcosms using five different bacterial communities at two different water potentials of −10 and −100 cm of water. We calibrated the biological parameters by means of experimental data obtained at high water content, and we tested the model without changing any parameters at low water content. Same as for the experimental data, our simulation results showed that the decrease in water content caused a decrease of mineralization rate. The model was able to simulate the decrease of connectivity between substrate and microorganism due the decrease of water content

    Obtenção de marcadores moleculares por meio de PCR-RFLP de genes relacionados com qualidade em café.

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    A qualidade de bebida do café é fator fundamental para sua comercialização, pois agrega valor ao produto, garantindo maior competitividade e melhores preços no mercado. A composição química do café é um dos fatores que determinam a qualidade da bebida. Seu sabor e seu aroma são resultantes da presença combinada de vários constituintes, dentre os quais os ácidos clorogênicos, os diterpenos e os açúcares. O objetivo deste trabalho foi buscar polimorfismos a partir de PCR-RFLP utilizando primers baseados em sequências ESTs de genes relacionados com a qualidade de bebida. Para isso foi utilizado o DNA de uma população F2 formada a partir da autofecundação de um híbrido interespecífico de Coffea arabica e C. canephora. Os resultados revelaram um total de doze marcas polimórficas na população. Dentre essas marcas, quatro foram obtidas através da presença e da ausência da amplificação dos genes. Oito combinações polimórficas foram obtidas através da clivagem do produto de PCR por quatro enzimas de restrição (TaqI, BsuRI, RsaI e HhaI). Com a validação dos polimorfismos encontrados nos amplicons, essas marcas estão sendo utilizadas para trabalhos de mapeamento na população de arabustas com objetivo de identificar QTLs relacionados à concentração de compostos como cafeína, ácidos clorogênicos, diterpenos, açúcares, bem como de proteases

    Novos marcadores para fins de mapeamento e localização de QTLs a partir de PCR-RFLP de genes de genoma café brasileiro.

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    O mapeamento genético é uma das estratégias mais visadas para fins de melhoramento genético e ganha maior importância a partir do surgimento de marcadores do tipo SNPs ou INDELs, facilitado pelos projetos genomas, sobretudo de ESTs. Assim, análises in silico de busca de polimorfismo SNPs em seqüências relacionadas com qualidade de bebida e derivadas de C.arabica e C.canephora foram analisadas e o polimorfismo entre as duas espécies validado para seis genes (quatro proteases e dois de sacarose) a partir de estudos de laboratório utilizando a técnica PCR-RFLP. Para tanto, após confirmação do polimorfismo nas duas espécies parentais, foram genotipadas 90 plantas F2 derivadas da autofecundação de um híbrido interespecífico de Coffea arabica e C. canephora 4x. Após a obtenção dos amplificados, estes foram digeridos com diversas enzimas de restrição de quatro bases (Alu I, Dde I, Eco RI, Hae III, Mse I e Msp, Fnu DII, Taq I; Scr FI). Dos seis genes analisados, quatro deles apresentaram segregação do tipo 3:1 na população F2 (Cisteína 8, Cisteína 5, B-Fructosidase e Sacarose Fosfato Síntase), demonstrando a utilização dos mesmos para fins de mapeamento

    Transcriptome Analysis of Leaves, Flowers and Fruits Perisperm of Coffea arabica L. Reveals the Differential Expression of Genes Involved in Raffinose Biosynthesis.

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    Coffea arabica L. is an important crop in several developing countries. Despite its economic importance, minimal transcriptome data are available for fruit tissues, especially during fruit development where several compounds related to coffee quality are produced. To understand the molecular aspects related to coffee fruit and grain development, we report a largescale transcriptome analysis of leaf, flower and perisperm fruit tissue development. Illumina sequencing yielded 41,881,572 high-quality filtered reads. De novo assembly generated 65,364 unigenes with an average length of 1,264 bp. A total of 24,548 unigenes were annotated as protein coding genes, including 12,560 full-length sequences. In the annotation process, we identified nine candidate genes related to the biosynthesis of raffinose family oligossacarides (RFOs). These sugars confer osmoprotection and are accumulated during initial fruit development. Four genes from this pathway had their transcriptional pattern validated by quantitative reverse transcription polymerase chain reaction (qRT-PCR). Furthermore, we identified ~24,000 putative target sites for microRNAs (miRNAs) and 134 putative transcriptionally active transposable elements (TE) sequences in our dataset. This C. arabica transcriptomic atlas provides an important step for identifying candidate genes related to several coffee metabolic pathways, especially those related to fruit chemical composition and therefore beverage quality. Our results are the starting point for enhancing our knowledge about the coffee genes that are transcribed during the flowering and initial fruit development stages

    An IL-27-Driven Transcriptional Network Identifies Regulators of IL-10 Expression across T Helper Cell Subsets.

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    Interleukin-27 (IL-27) is an immunoregulatory cytokine that suppresses inflammation through multiple mechanisms, including induction of IL-10, but the transcriptional network mediating its diverse functions remains unclear. Combining temporal RNA profiling with computational algorithms, we predict 79 transcription factors induced by IL-27 in T cells. We validate 11 known and discover 5 positive (Cebpb, Fosl2, Tbx21, Hlx, and Atf3) and 2 negative (Irf9 and Irf8) Il10 regulators, generating an experimentally refined regulatory network for Il10. We report two central regulators, Prdm1 and Maf, that cooperatively drive the expression of signature genes induced by IL-27 in type 1 regulatory T cells, mediate IL-10 expression in all T helper cells, and determine the regulatory phenotype of colonic Foxp3 <sup>+</sup> regulatory T cells. Prdm1/Maf double-knockout mice develop spontaneous colitis, phenocopying ll10-deficient mice. Our work provides insights into IL-27-driven transcriptional networks and identifies two shared Il10 regulators that orchestrate immunoregulatory programs across T helper cell subsets

    The Swiss Multiple Sclerosis Cohort-Study (SMSC): A Prospective Swiss Wide Investigation of Key Phases in Disease Evolution and New Treatment Options.

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    The mechanisms leading to disability and the long-term efficacy and safety of disease modifying drugs (DMDs) in multiple sclerosis (MS) are unclear. We aimed at building a prospective cohort of MS patients with standardized collection of demographic, clinical, MRI data and body fluids that can be used to develop prognostic indicators and biomarkers of disease evolution and therapeutic response. The Swiss MS Cohort (SMSC) is a prospective observational study performed across seven Swiss MS centers including patients with MS, clinically isolated syndrome (CIS), radiologically isolated syndrome or neuromyelitis optica. Neurological and radiological assessments and biological samples are collected every 6-12 months. We recruited 872 patients (clinically isolated syndrome [CIS] 5.5%, relapsing-remitting MS [RRMS] 85.8%, primary progressive MS [PPMS] 3.5%, secondary progressive MS [SPMS] 5.2%) between June 2012 and July 2015. We performed 2,286 visits (median follow-up 398 days) and collected 2,274 serum, plasma and blood samples, 152 cerebrospinal fluid samples and 1,276 brain MRI scans. 158 relapses occurred and expanded disability status scale (EDSS) scores increased in PPMS, SPMS and RRMS patients experiencing relapses. Most RRMS patients were treated with fingolimod (33.4%), natalizumab (24.5%) or injectable DMDs (13.6%). The SMSC will provide relevant information regarding DMDs efficacy and safety and will serve as a comprehensive infrastructure available for nested research projects
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