Microbially-mediated transformations of estuarine dissolved organic matter

Microbially-mediated transformations of dissolved organic matter (DOM) in a marsh-dominated estuarine system were investigated at the molecular level using ultrahigh resolution mass spectrometry. In addition to observing spatial and temporal variability in DOM sources in the estuary, multiple incubations with endogenous microorganisms identified the influence of DOM composition on biodegradation. A clear microbial preference for degradation of compounds associated with marine DOM relative to those of terrestrial origin was observed, resulting in an overall shift of the remaining DOM toward a stronger terrigenous signature. During short, 1-day long incubations of samples rich in marine DOM, the molecular formulae that were enriched had slightly smaller mass (20-30 Da) and number of carbon atoms compared to the molecular formulae that were depleted. Over longer time scales (70 days), the mean differences in molecular mass between formulae that were depleted and enriched were substantially larger (~270 Da). The differences in elemental composition over daily time scales were consistent with transformations in functional groups; over longer time scales, the differences in elemental composition may be related to progressive transformations of functional groups of intermediate products and/or other reactions. Our results infused new data toward the understanding of DOM processing by bacterioplankton in estuarine systems

Microbial Niche Diversification in the Galápagos Archipelago and Its Response to El Niño

The Galápagos Archipelago is located at the intersection of several major oceanographic features that produce diverse environmental conditions around the islands, and thus has the potential to serve as a natural laboratory for discerning the underlying environmental factors that structure marine microbial communities. Here we used quantitative metagenomics to characterize microbial communities in relation to archipelago marine habitats, and how those populations shift due to substantial environmental changes brought on by El Niño. Environmental conditions such as temperature, salinity, inorganic dissolved nutrients, and dissolved organic carbon (DOC) concentrations varied throughout the archipelago, revealing a diversity of potential microbial niches arising from upwelling, oligotrophic to eutrophic gradients, physical isolation, and potential island mass effects. The volumetric abundances of microbial community members shifted with these environmental changes and revealed several taxonomic indicators of different water masses. This included a transition from a Synechococcus dominated system in the west to an even mix of Synechococcus and Prochlorococcus in the east, mirroring the archipelago’s mesotrophic to oligotrophic and productivity gradients. Several flavobacteria groups displayed characteristic habitat distributions, including enrichment of Polaribacter and Tenacibaculum clades in the relatively nutrient rich western waters, Leeuwenhoekiella spp. that were enriched in the more nutrient-deplete central and eastern sites, and the streamlined MS024-2A group found to be abundant across all sites. During the 2015/16 El Niño event, both environmental conditions and microbial community composition were substantially altered, primarily on the western side of the archipelago due to the reduction of upwelling from the Equatorial Undercurrent. When the upwelling resumed, concentrations of inorganic nutrients and DOC at the western surface sites were more typical of mesopelagic depths. Correspondingly, Synechococcus abundances decreased by an order of magnitude, while groups associated with deeper water masses were enriched, including streamlined roseobacters HTCC2255 and HIMB11, Thioglobacaceae, methylotrophs (Methylophilaceae), archaea (Nitrosopumilaceae), and distinct subpopulations of Pelagibaceriales (SAR11 clade). These results provide a quantitative framework to connect community-wide microbial volumetric abundances to their environmental drivers, and thus incorporation into biogeochemical and ecological models

Horizontal Branch Stars: The Interplay between Observations and Theory, and Insights into the Formation of the Galaxy

We review HB stars in a broad astrophysical context, including both variable and non-variable stars. A reassessment of the Oosterhoff dichotomy is presented, which provides unprecedented detail regarding its origin and systematics. We show that the Oosterhoff dichotomy and the distribution of globular clusters (GCs) in the HB morphology-metallicity plane both exclude, with high statistical significance, the possibility that the Galactic halo may have formed from the accretion of dwarf galaxies resembling present-day Milky Way satellites such as Fornax, Sagittarius, and the LMC. A rediscussion of the second-parameter problem is presented. A technique is proposed to estimate the HB types of extragalactic GCs on the basis of integrated far-UV photometry. The relationship between the absolute V magnitude of the HB at the RR Lyrae level and metallicity, as obtained on the basis of trigonometric parallax measurements for the star RR Lyrae, is also revisited, giving a distance modulus to the LMC of (m-M)_0 = 18.44+/-0.11. RR Lyrae period change rates are studied. Finally, the conductive opacities used in evolutionary calculations of low-mass stars are investigated. [ABRIDGED]Comment: 56 pages, 22 figures. Invited review, to appear in Astrophysics and Space Scienc

Evaluation of the antinociceptive and anti-inflammatory effects of the acetone extract from Anacardium occidentale L

The stem bark of Anacardium occidentale L. (Anacardiaceae), commonly called cashew, is used in Brazilian traditional medicine for the treatment of gastric and inflammatory disorders. The present study was carried out to investigate the in vivo anti-inflammatory activities of the acetone extract (AE) of the stem bark of A. occidentale. We evaluated the pharmacological activities of this plant material through the analgesic, antiedematogenic and chemotaxic inhibitory effects produced by the AE. The oral administration (p.o.) of mice with the AE (0.1, 0.3 and 1.0 g/kg) or positive control indomethacin (10 mg/kg) inhibited acetic acid-induced writhing by 18.9, 35.9, 62.9 and 68.9%, respectively (ID50% = 530 mg/kg). The highest dose of the AE was able to inhibit croton oil-induced ear edema formation by 56.8% (indomethacin at 10 mg/kg, p.o. - 57.6% inhibition). When submitted to the carrageenan-induced peritonitis test, the AE (0.1, 0.3 and 1.0 g/kg, p.o.) impaired leukocyte migration into the peritoneal cavity by 24.8, 40.5 and 49.6%, respectively. The positive control, dexamethasone (2 mg/kg, s.c.), inhibited leukocyte migration by 66.9%. These results indicate the presence of anti-inflammatory and antinociceptive principles in the acetone extract of Anacardium occidentale, and reinforce the plant's potential therapeutic use against pain and inflammatory diseases.As cascas do caule do Anacardium occidentale L. (Anacardiaceae), conhecido como cajueiro, são popularmente utilizadas no Brasil para o tratamento de doenças gástricas e inflamatórias. Este estudo teve como objetivo a avaliação farmacológica in vivo da atividade antiinflamatória do extrato acetônico (AE) obtido das cascas do A. occidentale, investigando os efeitos analgésico, antiedematogênico e inibitório sobre a quimiotaxia deste material botânico. A administração oral (p.o.) em camundongos com o AE (0,1; 0,3 e 1 g/kg) ou o controle positivo indometacina (10 mg/kg) inibiu as contorções abdominais induzidas pelo ácido acético em 18,9; 35,9; 62,9 e 68,9% respectivamente (ID50% = 530 mg/kg). Esta maior dose do AE também inibiu o edema de orelha produzido pelo óleo de cróton em 56,8% (indometacina, 10 mg/kg, p.o. - 57,6% de inibição). No teste da peritonite induzido pela carragenina, o AE (0,1; 0,3; e 1,0 mg/kg, p.o.) reduziu a migração de leucócitos para a cavidade peritoneal em 24,8; 40,5; e 49,6% respectivamente, enquanto que o controle positivo dexametasona (2 mg/kg, s.c.) inibiu a migração de leucócitos em 66,9%. Estes resultados indicam a presença de princípios ativos antiinflamatórios e antinociceptivos no extrato acetônico de Anacardium occidentale e reforçam o potencial terapêutico da planta em doenças que envolvem dor e inflamação

Macrófitas aquáticas do sistema lacustre do Vale do Rio Doce, Minas Gerais, Brasil

Resumo Esta pesquisa trata da composição e da ocorrência de espécies de macrófitas aquáticas em área de proteção ambiental e áreas não protegidas, que compõem o conjunto de lagos do Vale do Rio Doce em Minas Gerais, terceiro maior sistema lacustre brasileiro. As informações foram levantadas a partir de publicações, material depositado em herbários e coletas botânicas entre os anos de 2007 e 2010, em ambientes aquáticos localizados no Parque Estadual do Rio Doce (PERD) e zona de amortecimento. Foram registradas 184 espécies pertencentes a distintos grupos taxonômicos, hábitos e formas biológicas, sendo aqui proposta a criação de uma nova categoria destas, designada embalsada, para contemplar plantas que se estabelecem em ilhas flutuantes. A pesquisa contribuiu com 152 novas citações para o Vale do Rio Doce em Minas Gerais, com dois primeiros registros nesse estado e com a descrição de uma espécie inédita para a ciência. A similaridade florística entre áreas protegidas e não protegidas indicou que o PERD guarda 74% das espécies de macrófitas aquáticas encontradas. Entretanto, 26% do total de espécies estão desprotegidas, pois não ocorrem nessa unidade de conservação