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Patients with Parkinson’s disease (PD) exhibit differences in their gut microbiomes compared to healthy individuals. Although differences have most commonly been described in the abundances of bacterial taxa, changes to viral and archaeal populations have also been observed. Mechanistic links between gut microbes and PD pathogenesis remain elusive but could involve molecules that promote α-synuclein aggregation. Here, we show that 2-hydroxypyridine (2-HP) represents a key molecule for the pathogenesis of PD. We observe significantly elevated 2-HP levels in faecal samples from patients with PD or its prodrome, idiopathic REM sleep behaviour disorder (iRBD), compared to healthy controls. 2-HP is correlated with the archaeal species Methanobrevibacter smithii and with genes involved in methane metabolism, and it is detectable in isolate cultures of M. smithii. We demonstrate that 2-HP is selectively toxic to transgenic α-synuclein overexpressing yeast and increases α-synuclein aggregation in a yeast model as well as in human induced pluripotent stem cell derived enteric neurons. It also exacerbates PD-related motor symptoms, α-synuclein aggregation, and striatal degeneration when injected intrastriatally in transgenic mice overexpressing human α-synuclein. Our results highlight the effect of an archaeal molecule in relation to the gut-brain axis, which is critical for the diagnosis, prognosis, and treatment of PD.

Most bacteria are able to grow in biofilms in which they effectively resist antimicrobial agents. This leads to a general problem, since traditional treatments of bacteria and prevention strategies become mostly ineffective. Novel strategies for biofilm inhibition are thus urgently required. Compounds interfering with cell-cell communication (quorum sensing) crucial for biofilm formation are promising targets for alternative strategies. Here, we report on a recently established assay enabling identification of quorum quenching compounds from environmental samples.

Tendo como referência a teoria piagetiana de equilibração, este artigo examina aspectos da construção do conhecimento, especial do conhecimento científico, retirando exemplos de conteúdos específicos de Ciências. Discute a função do professor na construção do conhecimento pelo aluno, buscando subsidiar a pesquisa em ensino em uma perspectiva construtivista.

In addition to well-characterized non-coding RNAs like ribosomal RNAs and transfer RNAs, a plethora of non-coding RNAs exists in organisms of all three domains of life (Huttenhofer et al., 2005; Storz, 2002). In Eukaryotes the non-coding miRNAs and siRNAs are small RNAs of about 21 nucleotides and they function primarily by base pairing with their target mRNAs, mediating the inhibition of translation or triggering degradation as part of the RISC complex (Krol et al., 2010). The miRNAs act always as part of the RISC complex, where they primarily bind to the Argonaute protein. Homologs to Argonaute proteins have been detected in Archaea but the function of the archaeal Argonaute proteins is not clear yet (Li et al., 2010; Makarova et al., 2009).

OBJECTIVES: We have added a block detector model to the Simulation System for Emission Tomography (SimSET) software version 2.9. METHODS: The new model simulates the detector system as a collection of right rectangular boxes and allows for very flexible positioning of these boxes. This model allows users to simulate typical block-based cylindrical tomographs, pixelated positron emission mammography (PEM) detectors, and many more imaginative tomograph designs. We have tested the block detector software against analytically derived results and against SimSET simulations of dual-headed and cylindrical detector tomographs. We have also compared experimental and simulated sensitivities for a General Electric DSTE PET for 3 different phantom diameters in 2d and 3d acquisition modes. RESULTS: The tests against analytically derived results and against simulations were validated both statistically using the t-test and visually by comparing profiles through the sinograms. Within the limits of statistical fluctuation, the new software passed all tests. In comparisons with data from the PET scanner, the simulation showed better agreement than previous SimSET releases, but still showed substantially increased coincidence sensitivity. CONCLUSIONS: We believe the increased sensitivity is a result of the very simple default models used for energy resolution and scintillation light collection, and the lack of any livetime correction. The new release provides a user-modifiable function where all these factors can be realistically modeled for a given tomograph. The SimSET software, including source code, remains in the public domain.

Marine macroalgae are constantly exposed to epibacterial colonizers. The epiphytic bacterial patterns and their temporal and spatial variability on host algae are poorly understood. To investigate the interaction between marine macroalgae and epiphytic bacteria, this study tested if the composition of epibacterial communities on different macroalgae was specific and persisted under varying biotic and abiotic environmental conditions over a 2-year observation time frame. Epibacterial communities on the co-occurring macroalgae Fucus vesiculosus, Gracilaria vermiculophylla and Ulva intestinalis were repeatedly sampled in summer and winter of 2007 and 2008. The epibacterial community composition was analysed by denaturing gradient gel electrophoresis (DGGE) and 16S rRNA gene libraries. Epibacterial community profiles did not only differ significantly at each sampling interval among algal species, but also showed consistent seasonal differences on each algal species at a bacterial phylum level. These compositional patterns re-occurred at the same season of two consecutive years. Within replicates of the same algal species, the composition of bacterial phyla was subject to shifts at the bacterial species level, both within the same season but at different years and between different seasons. However, 7-16% of sequences were identified as species specific to the host alga. These findings demonstrate that marine macroalgae harbour species-specific and temporally adapted epiphytic bacterial biofilms on their surfaces. Since several algal host-specific bacteria were highly similar to other bacteria known to either avoid subsequent colonization by eukaryotic larvae or to exhibit potent antibacterial activities, algal host-specific bacterial associations are expected to play an important role for marine macroalgae.

Marine microbial communities are highly diverse and have evolved during extended evolutionary processes of physiological adaptations under the influence of a variety of ecological conditions and selection pressures. They harbor an enormous diversity of microbes with still unknown and probably new physiological characteristics. Besides, the surfaces of marine multicellular organisms are typically covered by a consortium of epibiotic bacteria and act as barriers, where diverse interactions between microorganisms and hosts take place. Thus, microbial diversity in the water column of the oceans and the microbial consortia on marine tissues of multicellular organisms are rich sources for isolating novel bioactive compounds and genes. Here we describe the sampling, construction of large-insert metagenomic libraries from marine habitats and exemplarily one function based screen of metagenomic clones.

ObjectivesWe here investigated whether experimental gingivitis enhances systemic markers of inflammation which are also known as surrogate markers of atherosclerotic plaque development.BackgroundGingivitis is a low-level oral infection induced by bacterial deposits with a high prevalence within Western populations. A potential link between the more severe oral disease periodontitis and cardiovascular disease has already been shown.Methods37 non-smoking young volunteers with no inflammatory disease or any cardiovascular risk factors participated in this single-subject interventional study with an intra-individual control. Intentionally experimental oral inflammation was induced by the interruption of oral hygiene for 21 days, followed by a 21-days resolving phase after reinitiation of oral hygiene. Primary outcome measures at baseline, day 21 and 42 were concentrations of hsCRP, IL-6, and MCP-1, as well as adhesion capacity and oxLDL uptake of isolated blood monocytes.ResultsThe partial cessation of oral hygiene procedures was followed by the significant increase of gingival bleeding (34.0%, PConclusionsBacterial-induced gingival low-level inflammation induced a systemic increase in inflammatory markers. Dental hygiene almost completely reversed this experimental inflammatory process, suggesting that appropriate dental prophylaxis may also limit systemic markers of inflammation in subjects with natural gingivitis. International Clinical Trials Register Platform of the World Health Organization, registry number: DRKS00003366, URL: http://apps.who.int/trialsearch/Default.aspx.

Resumen basado en el de la publicación Resumen en inglés Se sugieren y analizan algunas etapas de un curso sobre calor y temperatura en el que el conocimiento del as ideas del pasado y la solución proporcionada pueden permitir una mejor comprensión del contenido. La hipótesis que guió a la planificación de las actividades fue que el contenido científico estudiado a lo largo de su historia se acerca más al universo cognitivo, no solo del estudiante, sino del hombre mismo. ESP

A idéia de que a abordagem histórica pode ser útil e frutífera para cursos de física encontra suporte entre as variadas concepções de ensino. Neste artigo analisamos a pertinência, a relevância e os efeitos do uso desta abordagem na formação do professor de ciências e na aprendizagem dos conteúdos científicos.

This PhD project investigates the impact of Fe limitation i) on heme b abundance in phytoplankton and marine particulate matter, and ii) on the production, utilization and degradation processes of heme b by field work and laboratory experiments. The main research questions driving this work are 1) Can heme b be used as a proxy of Fe limitation in field phytoplankton populations? 2) Is phytoplankton able to regulate their heme b pool to reduce Fe requirements under Fe limitation? 3) Does heme b regulation originate from a modification in the gene expression of proteins involved in its cycling?