16 research outputs found

    Molecular mechanism of dynein recruitment to kinetochores by the Rod-Zw10-Zwilch complex and Spindly

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    The molecular motor dynein concentrates at the kinetochore region of mitotic chromosomes in animals to accelerate spindle microtubule capture and to control spindle checkpoint signaling. In this study, we describe the molecular mechanism used by the Rod-Zw10-Zwilch complex and the adaptor Spindly to recruit dynein to kinetochores in Caenorhabditis elegans embryos and human cells. We show that Rod's N-terminal beta-propeller and the associated Zwilch subunit bind Spindly's C-terminal domain, and we identify a specific Zwilch mutant that abrogates Spindly and dynein recruitment in vivo and Spindly binding to a Rod beta-propeller-Zwilch complex in vitro. Spindly's N-terminal coiled-coil uses distinct motifs to bind dynein light intermediate chain and the pointed-end complex of dynactin. Mutations in these motifs inhibit assembly of a dynein-dynactin-Spindly complex, and a null mutant of the dynactin pointed-end subunit p27 prevents kinetochore recruitment of dynein-dynactin without affecting other mitotic functions of the motor. Conservation of Spindly-like motifs in adaptors involved in intracellular transport suggests a common mechanism for linking dynein to cargo.This work was supported by a European Research Council Starting Grant (Dyneinome 338410) and a European Molecular Biology Organization Installation Grant to R. Gassmann. This work was also supported by funding from the Fundacao para a Ciencia e a Tecnologia to R. Gassmann (IF/01015/2013/CP1157/CT0006), C. Pereira (SFRH_BPD_95648_2013), and D.J. Barbosa (SFRH_BPD_101898_2014). Some C. elegans strains were provided by the Caenorhabditis Genetics Center, which is funded by the National Institutes of Health Office of Research Infrastructure Programs (P40 OD010440)

    Ácido cianídrico em tecidos de mandioca em função da idade da planta e adubação nitrogenada

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    O objetivo deste trabalho foi avaliar o teor de ácido cianídrico em tecidos de mandioca, em função da idade da planta e níveis de adubação nitrogenada. Utilizou-se o delineamento experimental de blocos ao acaso, em arranjo de parcelas subdivididas, com quatro repetições. As doses de nitrogênio em cobertura (0, 30, 60, 150 e 330 kg ha-1) foram alocadas nas parcelas, e as épocas de avaliação (90, 120, 150, 180, 240, 300 e 360 dias após o plantio), nas subparcelas. Os teores de ácido cianídrico foram avaliados em tecidos da folha, caule, polpa e córtex da raiz da cultivar Aciolina. Os efeitos das doses de N e das épocas de avaliação foram independentes. Doses entre 219 e 241 kg ha-1 de N em cobertura proporcionam os maiores teores de ácido cianídrico, que variaram de 332 a 401 mg kg-1 de matéria fresca nos tecidos avaliados. O teor de ácido cianídrico nos tecidos reduz-se linearmente com a idade da planta. O córtex da raiz acumula o maior teor de ácido cianídrico, e a polpa da raiz o menor. Por ocasião da colheita, aos 360 dias após o plantio, essa cultivar é classificada como mandioca mansa

    Effects of ultraviolet radiation and CO2 increase on winter phytoplankton assemblages in a temperate coastal lagoon

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    Increases in ultraviolet radiation (UVR) and CO2 affect phytoplankton growth and mortality in a variety of different ways. However, in situ responses of natural phytoplankton communities to climate change, as well as its effects on phytoplankton annual cycles, are still largely unknown. Although temperature and UVR have been increasing in temperate latitudes during winter, this season is still particularly neglected in climate change studies, being considered a non-active season regarding phytoplankton growth and production. Additionally, coastal lagoons are highly productive ecosystems and very vulnerable to climate change. This study aims, therefore, to evaluate the short-term effects of increased UVR and CO2 on the composition and growth of winter phytoplankton assemblages in a temperate coastal lagoon. During winter 2012, microcosm experiments were used to evaluate the isolated and combined effects of UVR and CO2, under ambient and high CO2 treatments, exposed to ambient UV levels and photosynthetically active radiation (PAR), or to PAR only. Phytoplankton composition, abundance, biomass and photosynthetic parameters were evaluated during the experiments. Significant changes were observed in the growth of specific phytoplankton groups, leading to changes in community composition. The cyanobacterium Synechococcus was dominant at the beginning of the experiment, but it was negatively affected by UVR and CO2. Diatoms clearly benefited from high CO2 and UVR, particularly Thalassiosira. Despite the changes observed in specific phytoplankton groups, growth and production of the whole phytoplankton community did not show significant responses to UVR and/or CO2

    Museu de Ciências Morfológicas: um lugar diferente na Universidade Federal de Minas Gerais The Museum of Morphological Sciences: a different place at the Universidade Federal de Minas Gerais

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    Este trabalho mostra um novo museu de ciências, cujo trabalho junto ao público é um convite enfático ao conhecimento da estrutura e funcionamento do organismo humano, como forma de entender a vida, para preservá-la com qualidade.<br>The article introduces a new science museum, one that works actively to engage its audience in learning about the structure and functioning of the human organism, so that it can understand life and thus protect its quality

    Elements and polycyclic aromatic hydrocarbons in exhaust particles emitted by light-duty vehicles

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    The main purpose of this work was to evaluate the chemical composition of particulate matter (PM) emitted by eight different light-duty vehicles. Exhaust samples from petrol and diesel cars (Euro 3 to Euro 5) were collected in a chassis dynamometer facility. To simulate the real-world driving conditions, three ARTEMIS cycles were followed: road, to simulate a fluid traffic flow and urban with hot and cold starts, to simulate driving conditions in cities. Samples were analysed for the water-soluble ions, for the elemental composition and for polycyclic aromatic hydrocarbons (PAHs), respectively, by ion chromatography, inductively coupled plasma atomic emission spectroscopy (ICP-AES), inductively coupled plasma mass spectrometry (ICP-MS) and gas chromatography-mass spectrometry (GC-MS). Nitrate and phosphate were the major water-soluble ions in the exhaust particles emitted from diesel and petrol vehicles, respectively. The amount of material emitted is affected by the vehicle age. For vehicles ≥Euro 4, most elements were below the detection limits. Sodium, with emission factors in the ranges 23.5-62.4 and 78.2-227μg km(-1), for petrol and diesel Euro 3 vehicles, respectively, was the major element. The emission factors of metallic elements indicated that diesel vehicles release three to five times more than petrol automobiles. Element emissions under urban cycles are higher than those found for on-road driving, being three or four times higher, for petrol vehicles, and two or three times, for diesel vehicles. The difference between cycles is mainly due to the high emissions for the urban cycle with hot start-up. As registered for elements, most of the PAH emissions for vehicles ≥Euro 4 were also below the detection limits. Regardless of the vehicle models or driving cycles, the two- to four-ring PAHs were always dominant. Naphthalene, with emission factors up to 925 μg km(-1), was always the most abundant PAH. The relative cancer risk associated with naphthalene was estimated to be up to several orders of magnitude higher than any of the chemical species found in the PM phase. The highest PAH emission factors were registered for diesel-powered vehicles. The condition of the vehicle can exert a decisive influence on both element and PAH emissions.This work was funded by the Portuguese Science Foundation through the project “Source apportionment of URBan Emissions of primary particulate matter”, PTDC/AAC-AMB/117956/2010 (URBE). The ICP-MS and ICP-AES analyses were supported by the AIRUSE project—Testing and Development of air quality mitigation measures in Southern Europe, LIFE 11 ENV/ES/000584.Peer reviewe
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