117 research outputs found

    The radii of SU Cas and TU Cas

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    It is possible to obtain the masses of Cepheid variables by several methods involving the pulsation theory. However, these masses are frequently smaller than those indicated by the theory of stellar evolution. The cause of this discrepancy is not fully understood. Since the pulsation theory indicates that there is a relation among the mass, the radius and the period, the discrepancy also manifests itself in the radii of these stars. With this in mind, radius determinations for two Cepheids, SU Cas and TU Cas, were undertaken. It is concluded that because of the agreement between the present radius and the beat radius of TU Cas, the pulsation theory is giving correct information about the radii of beat Cepheids. This implies that the luminosities of short period Cepheids have been overestimated. Thus, the solution to the mass discrepancy should perhaps be sought in the theory of stellar evolution or in the possibility of mass loss

    Chronic granulomatous disease, the McLeod phenotype and the contiguous gene deletion syndrome-a review

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    Chronic Granulomatous Disease (CGD), a disorder of the NADPH oxidase system, results in phagocyte functional defects and subsequent infections with bacterial and fungal pathogens (such as Aspergillus species and Candida albicans). Deletions and missense, frameshift, or nonsense mutations in the gp91phox gene (also termed CYBB), located in the Xp21.1 region of the X chromosome, are associated with the most common form of CGD. When larger X-chromosomal deletions occur, including the XK gene deletion, a so-called "Contiguous Gene Deletion Syndrome" may result. The contiguous gene deletion syndrome is known to associate the Kell phenotype/McLeod syndrome with diseases such as X-linked chronic granulomatous disease, Duchenne muscular dystrophy, and X-linked retinitis pigmentosa. These patients are often complicated and management requires special attention to the various facets of the syndrome

    Abundância de enquitreídeos estimada por diferentes métodos de coleta e extração num fragmento de Floresta Ombrófila Mista no Paraná.

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    Enquitreídeos (Enchytraeidae, Oligochaeta) são organismos da mesofauna edáfica encontrados no mundo inteiro, mas ainda pouco estudados no Brasil. A abundância desses organismos determinada por diferentes métodos de coleta e extração, bem como as vantagens e desvantagens de cada método são apresentadas neste trabalho. Os métodos de amostragem com formol e por escavação de monólitos seguidos de triagem manual foram comparados aos métodos de coleta com trado desmontável seguido de extração úmida fria por três dias e extração úmida quente por três horas, que são recomendados para amostragens quantitativas de enquitreídeos. As coletas foram realizadas em 8-9 pontos num fragmento de floresta ombrófila mista em Colombo, PR, em 1-3 ocasiões entre setembro 2011 e abril 2012. O número médio de indivíduos encontrados por metro quadrado (ind./ m2) através de cada método foi de aproximadamente 5, 90, 2.000-12.000 e 5.000-12.000 respectivamente. Os métodos de coleta e extração originalmente usados para as minhocas, formol e monólitos subestimaram grandemente a abundância de enquitreídeos, pois na triagem manual, as espécies de tamanho menor são ignoradas. Como esperado, a coleta com trado desmontável seguida de extração úmida é a mais adequada para estudos quantitativos de enquitreídeos, porém, a extração quente, além de ser mais rápida, causa menos dano aos espécimes coletados facilitando o processo de identificação taxonômica que deve ser feito in vivo. O número máximo obtido nesse estudo foi de aproximadamente 44.000 ind./ m2, um dos maiores valores relatados até hoje no Brasil.Resumo expandido

    Toxicity of AMPA to the earthworm Eisenia andrei Bouché, 1972 in tropical artificial soil.

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    Aminomethylphosphonic acid (AMPA) - one of glyphosate's main metabolites - has been classified as persistent in soils, raising concern regarding the widespread use of glyphosate in agriculture and forestry. Glyphosate may have negative or neutral effects on soil biota, but no information is available on the toxicity of AMPA to soil invertebrates. Therefore our aim was to study the effect of AMPA on mortality and reproduction of the earthworm species Eisenia andrei using standard soil ecotoxicologica I methods (ISO). Field-relevant concentrations of AMPA had no significant effects on mortality in acute or chronic assays. Except at the highest concentration tested, a significant biomass loss was observed compared to controls in the chronic assay. The number of juveniles and cocoons increased with higher concentrations of AMPA applied, but their mean weights decreased. This mass loss indicates higher sensitivity of juveniles than adults to AMPA. Our results suggest that earthworms coming from parents grown in contaminated soils may have reduced growth, limiting their beneficial roles in key soil ecosystem functions. Nevertheless, further research is needed to better understand the mechanisms underlying the sublethal effects observed here

    Prospecting environmental mycobacteria: combined molecular approaches reveal unprecedented diversity

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    Background: Environmental mycobacteria (EM) include species commonly found in various terrestrial and aquatic environments, encompassing animal and human pathogens in addition to saprophytes. Approximately 150 EM species can be separated into fast and slow growers based on sequence and copy number differences of their 16S rRNA genes. Cultivation methods are not appropriate for diversity studies; few studies have investigated EM diversity in soil despite their importance as potential reservoirs of pathogens and their hypothesized role in masking or blocking M. bovis BCG vaccine. Methods: We report here the development, optimization and validation of molecular assays targeting the 16S rRNA gene to assess diversity and prevalence of fast and slow growing EM in representative soils from semi tropical and temperate areas. New primer sets were designed also to target uniquely slow growing mycobacteria and used with PCR-DGGE, tag-encoded Titanium amplicon pyrosequencing and quantitative PCR. Results: PCR-DGGE and pyrosequencing provided a consensus of EM diversity; for example, a high abundance of pyrosequencing reads and DGGE bands corresponded to M. moriokaense, M. colombiense and M. riyadhense. As expected pyrosequencing provided more comprehensive information; additional prevalent species included M. chlorophenolicum, M. neglectum, M. gordonae, M. aemonae. Prevalence of the total Mycobacterium genus in the soil samples ranged from 2.3×107 to 2.7×108 gene targets g−1; slow growers prevalence from 2.9×105 to 1.2×107 cells g−1. Conclusions: This combined molecular approach enabled an unprecedented qualitative and quantitative assessment of EM across soil samples. Good concordance was found between methods and the bioinformatics analysis was validated by random resampling. Sequences from most pathogenic groups associated with slow growth were identified in extenso in all soils tested with a specific assay, allowing to unmask them from the Mycobacterium whole genus, in which, as minority members, they would have remained undetected

    Enchytraeids in two phytophysiognomies of Brazilian Cerrado.

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    This is the first study on enchytraeid diversity in phytophysiognomies of the Brazilian Cerrado Biome carried out with standard sampling and extraction methods. Shrubby woodland (Cerrado sensu stricto, CSR) and gallery forest (MG) was sampled in the Brasilia Botanical Garden Ecological Station and the Brasilia National Park, respectively, with samplings performed at the end of the rainy season in 2017 and 2018. Enchytraeid population density in MG was higher than in CSR, reaching more than 30 thousand individuals/ m2 in MG and 5 thousand in CSR. Enchytraeid abundance was influenced by soil organic matter and moisture. So far, six genera and six potentially new species taxa were identified. Dominant genera were Guaranidrilus and Hemienchytraeus
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