Geometria dell’anello di distribuzione e materiale utilizzato

La qualità chimica e microbiologica delle acque di dialisi è un requisito fondamentale per la biocompatibilità del trattamento emodialitico. Numerosi lavori in letteratura mostrano infatti come la composizione del liquido di dialisi rappresenti uno dei fattori responsabili dello stato microinfiammatorio cronico del paziente emodializzato con importanti conseguenze cliniche Al fine di garantire al paziente un trattamento dialitico con elevati standard di qualità e sicurezza si dovrebbe giungere oggi alla produzione di un dialisato che si definisce ultrapuro (carica batterica <0.1 UFC/ml e concentrazione endotossinica <0.03 UI/ml). Questo ha particolare importanza nelle metodiche “on-line” che consentono l’autoproduzione del liquido di sostituzione durante i trattamenti convettivi

Atypical epigenetic mark in an atypical location: cytosine methylation at asymmetric (CNN) sites within the body of a non-repetitive tomato gene

Background: Eukaryotic DNA methylation is one of the most studied epigenetic processes, as it results in a direct and heritable covalent modification triggered by external stimuli. In contrast to mammals, plant DNA methylation, which is stimulated by external cues exemplified by various abiotic types of stress, is often found not only at CG sites but also at CNG (N denoting A, C or T) and CNN (asymmetric) sites. A genome-wide analysis of DNA methylation in Arabidopsis has shown that CNN methylation is preferentially concentrated in transposon genes and non-coding repetitive elements. We are particularly interested in investigating the epigenetics of plant species with larger and more complex genomes than Arabidopsis, particularly with regards to the associated alterations elicited by abiotic stress.Results: We describe the existence of CNN-methylated epialleles that span Asr1, a non-transposon, protein-coding gene from tomato plants that lacks an orthologous counterpart in Arabidopsis. In addition, to test the hypothesis of a link between epigenetics modifications and the adaptation of crop plants to abiotic stress, we exhaustively explored the cytosine methylation status in leaf Asr1 DNA, a model gene in our system, resulting from water-deficit stress conditions imposed on tomato plants. We found that drought conditions brought about removal of methyl marks at approximately 75 of the 110 asymmetric (CNN) sites analysed, concomitantly with a decrease of the repressive H3K27me3 epigenetic mark and a large induction of expression at the RNA level. When pinpointing those sites, we observed that demethylation occurred mostly in the intronic region.Conclusions: These results demonstrate a novel genomic distribution of CNN methylation, namely in the transcribed region of a protein-coding, non-repetitive gene, and the changes in those epigenetic marks that are caused by water stress. These findings may represent a general mechanism for the acquisition of new epialleles in somatic cells, which are pivotal for regulating gene expression in plants. © 2011 González et al; licensee BioMed Central Ltd.Fil:González, R.M. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.Fil:Ricardi, M.M. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.Fil:Iusem, N.D. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina

Protocol: fine-tuning of a Chromatin Immunoprecipitation (ChIP) protocol in tomato

<p>Abstract</p> <p>Background</p> <p>Searching thoroughly for plant <it>cis</it>-elements corresponding to transcription factors is worthwhile to reveal novel gene activation cascades. At the same time, a great deal of research is currently focused on epigenetic events in plants. A widely used method serving both purposes is chromatin immunoprecipitation, which was developed for Arabidopsis and other plants but is not yet operational for tomato (<it>Solanum lycopersicum</it>), a model plant species for a group of economically important crops.</p> <p>Results</p> <p>We developed a chromatin immunoprecipitation protocol suitable for tomato by adjusting the parameters to optimise <it>in vivo </it>crosslinking, purification of nuclei, chromatin extraction, DNA shearing and precipitate analysis using real-time PCR. Results were obtained with two different antibodies, five control loci and two normalisation criteria.</p> <p>Conclusion</p> <p>Here we provide a chromatin immunoprecipitation procedure for tomato leaves that could be combined with high-throughput sequencing to generate a detailed map of epigenetic modifications or genome-wide nucleosome positioning data.</p

A pathogenic long non-coding RNA redesigns the epigenetic landscape of the infected cells by subverting host Histone Deacetylase 6 activity

[EN] Viroids - ancient plant-pathogenic long noncoding RNAs - have developed a singular evolutionary strategy based on reprogramming specific phases of host-metabolism to ensure that their infection cycle can be completed in infected cells. However, the molecular aspects governing this transregulatory phenomenon remain elusive. Here, we use immunoprecipitation assays and bisulfite sequencing of rDNA to shown that, in infected cucumber and Nicotiana benthamina plants, Hop stunt viroid (HSVd) recruits and functionally subverts Histone Deacetylase 6 (HDA6) to promote host-epigenetic alterations that trigger the transcriptional alterations observed during viroid pathogenesis. This notion is supported by the demonstration that, during infection, the HSVd-HDA6 complex occurs invivo and that endogenous HDA6 expression is increased in HSVd-infected cells. Moreover, transient overexpression of recombinant HDA6 reverts the hypomethylation status of rDNA observed in HSVd-infected plants and reduces viroid accumulation. We hypothesize that the host-transcriptional alterations induced as a consequence of viroid-mediated HDA6 recruitment favor spurious recognition of HSVd-RNA as an RNA Pol II template, thereby improving viroid replication. Our results constitute the first description of a physical and functional interaction between a pathogenic RNA and a component of the host RNA silencing mechanism, providing novel evidence of the potential of these pathogenic lncRNAs to physically redesign the host-cell environment and reprogram their regulatory mechanisms.The authors thank Dr M. Fares for the contribution to the statistical analysis of the data and Dr G. Martinez for the critical reading of this manuscript. This work was supported by grants AGL2013-47886-R and BIO2014-61826-EXP (GG) and BIO2014-54862-R (VP) from the Spanish Granting Agency (Direccion General Investigacion Cientifica).Castellano Perez, M.; Pallás Benet, V.; Gomez, GG. (2016). A pathogenic long non-coding RNA redesigns the epigenetic landscape of the infected cells by subverting host Histone Deacetylase 6 activity. New Phytologist. 211(4):1311-1322. doi:10.1111/nph.14001S13111322211

Vegetation and climate changes in the forest of Campinas, São Paulo State, Brazil, during the last 25,000 cal yr BP

A paleoenvironmental reconstruction was performed in a Riparian Forest near Campinas to improve knowledge of paleoclimate and paleoenvironment in the State of São Paulo, Brazil. A sediment core of 182 cm depth was collected in a swamp located within a Cerrado/Seasonal Semi-deciduous ecotone forest. Te chronological frame is given by eight radiocarbon dating methods. Pollen and stable isotope analyses (d 13C and d 15N) were performed all along the core. Modern pollen rain is based on fve surface samples collected along the Riparian Forest. Results show a sequence of changes in vegetation and climate between 25 and 13 cal kyr before present (BP), and from 4 cal kyr BP to the present time, with a hiatus between 11 and 4 kyr cal BP. Drier climatic conditions characterized the late Pleistocene and early Holocene, although they had moisture peaks able to maintain an open forest. Te Riparian Forest became fully installed from 4 cal kyr BP onward. Our results are in agreement with other regional studies and contribute to build a regional frame for past climatic conditions at the latitude of São Paulo.493CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQCOORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR - CAPESFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESPSem informaçãoSem informação2010/16507-