advanced electric propulsion diagnostic tools at iom

Abstract Recently, we have set up an Advanced Electric Propulsion Diagnostic (AEPD) platform [1] , which allows for the in-situ measurement of a comprehensive set of thruster performance parameters. The platform utilizes a five-axis-movement system for precise positioning of the thruster with respect to the diagnostic heads. In the first setup (AEPD1) an energy-selective mass spectrometer (ESMS) and a miniaturized Faraday probe for ion beam characterization, a telemicroscope and a triangular laser head for measuring the erosion of mechanical parts, and a pyrometer for surface temperature measurements were integrated. The capabilities of the AEPD1 platform were demonstrated with two electric propulsion thrusters, a gridded ion thruster RIT 22 (Airbus Defence & Space, Germany, [13]) and a Hall effect thruster SPT 100D EM1 (EDB Fakel, Russia, [1] , [4] ), in two different vacuum facilities

Perfil comparativo do transcriptoma em Psidium guajava L. e Psidium friedrichsthalianum fornece expressão gênica em resposta à resistencia ao Meloidogyne enterolobii.

A goiabeira (Psidium guajava L.), espécie tropical da América do Sul, é considerada uma frutífera de relevância econômica no Brasil. Entretanto, interações sinérgicas entre o nematoide Meloidogyne enterolobii e o fungo Fusarium solani nas raízes destas lantas acarretam a formação de galhas e apodrecimento das raízes. Nesse contexto, P. friedrichsthalianum (Araçá Costa Rica) foi identificada como espécie resistente ao nematoide. Para melhor entender a relação de suscetibilidade e resistência à infecção por M. enterolobii, foi realizado o sequenciamento do transcriptoma de folhas das espécies P. guajava L. e P. friedrichsthalianum (de plantas controle e de plantas inoculadas com o nematoide) pela metodologia de RNA-seq, seguida pela montagem de sequências. Foram obtidos 60.836 contigs com N50 de 786 pb utilizando o sequenciador ILLUMINA (Illumina HiSeq 2000). As transcrições foram anotadas via Genomes Kyoto (KEGG) e Gene Ontology (GO). Para as quatro bibliotecas disponibilizadas no NCBI (National Center for Biotetchnology Information) sob acesso PRJNA779437, realizou-se o mapeamento comparativo com o genoma de Eucalyptus grandis v2.0, por meio de ferramentas de bioinformática. Considerando os genes que possuem anotação no Phytozome e com expressão acima de 50 TPM, construíram-se um heatmap e uma rede de interação do tipo interactoma, com 68 genes. Desses, 21 estão intimamente relacionados à regulação dos fotossistemas I e II. Os demais estão envolvidos na produção de clorofila, rubisco e cadeia transportadora de elétrons. Também verificou-se alteração da expressão gênica relacionada às enzimas do estresse oxidativo, com redução de catalase, peroxidase e tiredoxina (mRNA splicing) em plantas de P. guajava inoculadas e aumento das mesmas enzimas em P. friedrichsthalianum na mesma condição. Com isso, sugere-se a ocorrência de um efeito sistêmico nas folhas de Psidium spp. como resposta à infecção nas raízes, refletido por alterações nas vias fotossintéticas. Adicionalmente, também ocorre alteração da expressão de genes relacionados ao metabolismo fenólico, atuante na defesa de plantas contra os estresses bióticos e abiótico

Repression of Flowering by the miR172 Target SMZ

The flowering repressors SMZ and FLM, members of the AP-2 and MADS domain transcription factor families, unexpectedly work together to regulate flowering time via their effects on expression of the FT gene

Brahma Is Required for Proper Expression of the Floral Repressor FLC in Arabidopsis

This is an open-access article distributed under the terms of the Creative Commons Attribution License.[Background]: BRAHMA (BRM) is a member of a family of ATPases of the SWI/SNF chromatin remodeling complexes from Arabidopsis. BRM has been previously shown to be crucial for vegetative and reproductive development. [Methodology/Principal Findings]: Here we carry out a detailed analysis of the flowering phenotype of brm mutant plants which reveals that, in addition to repressing the flowering promoting genes CONSTANS (CO), FLOWERING LOCUS T (FT) and SUPPRESSOR OF OVEREXPRESSION OF CO1 (SOC1), BRM also represses expression of the general flowering repressor FLOWERING LOCUS C (FLC). Thus, in brm mutant plants FLC expression is elevated, and FLC chromatin exhibits increased levels of histone H3 lysine 4 tri-methylation and decreased levels of H3 lysine 27 tri-methylation, indicating that BRM imposes a repressive chromatin configuration at the FLC locus. However, brm mutants display a normal vernalization response, indicating that BRM is not involved in vernalization-mediated FLC repression. Analysis of double mutants suggests that BRM is partially redundant with the autonomous pathway. Analysis of genetic interactions between BRM and the histone H2A.Z deposition machinery demonstrates that brm mutations overcome a requirement of H2A.Z for FLC activation suggesting that in the absence of BRM, a constitutively open chromatin conformation renders H2A.Z dispensable. [Conclusions/Significance]: BRM is critical for phase transition in Arabidopsis. Thus, BRM represses expression of the flowering promoting genes CO, FT and SOC1 and of the flowering repressor FLC. Our results indicate that BRM controls expression of FLC by creating a repressive chromatin configuration of the locus.This work was supported by Ministerio de Educacin y Ciencia (BFU2008-00238, CSD2006-00049), and by Junta de Andaluca (P06-CVI-01400) to J.C.R. and by the National Institutes of Health (grant no. 1R01GM079525), and the National Science Foundation (grant no. 0446440) to R.A. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.Peer reviewe

Arabidopsis Homologs of Retinoblastoma-Associated Protein 46/48 Associate with a Histone Deacetylase to Act Redundantly in Chromatin Silencing

RNA molecules such as small-interfering RNAs (siRNAs) and antisense RNAs (asRNAs) trigger chromatin silencing of target loci. In the model plant Arabidopsis, RNA–triggered chromatin silencing involves repressive histone modifications such as histone deacetylation, histone H3 lysine-9 methylation, and H3 lysine-27 monomethylation. Here, we report that two Arabidopsis homologs of the human histone-binding proteins Retinoblastoma-Associated Protein 46/48 (RbAp46/48), known as MSI4 (or FVE) and MSI5, function in partial redundancy in chromatin silencing of various loci targeted by siRNAs or asRNAs. We show that MSI5 acts in partial redundancy with FVE to silence FLOWERING LOCUS C (FLC), which is a crucial floral repressor subject to asRNA–mediated silencing, FLC homologs, and other loci including transposable and repetitive elements which are targets of siRNA–directed DNA Methylation (RdDM). Both FVE and MSI5 associate with HISTONE DEACETYLASE 6 (HDA6) to form complexes and directly interact with the target loci, leading to histone deacetylation and transcriptional silencing. In addition, these two genes function in de novo CHH (H = A, T, or C) methylation and maintenance of symmetric cytosine methylation (mainly CHG methylation) at endogenous RdDM target loci, and they are also required for establishment of cytosine methylation in the previously unmethylated sequences directed by the RdDM pathway. This reveals an important functional divergence of the plant RbAp46/48 relatives from animal counterparts