3,545 research outputs found

    Comparing reverse complementary genomic words based on their distance distributions and frequencies

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    In this work we study reverse complementary genomic word pairs in the human DNA, by comparing both the distance distribution and the frequency of a word to those of its reverse complement. Several measures of dissimilarity between distance distributions are considered, and it is found that the peak dissimilarity works best in this setting. We report the existence of reverse complementary word pairs with very dissimilar distance distributions, as well as word pairs with very similar distance distributions even when both distributions are irregular and contain strong peaks. The association between distribution dissimilarity and frequency discrepancy is explored also, and it is speculated that symmetric pairs combining low and high values of each measure may uncover features of interest. Taken together, our results suggest that some asymmetries in the human genome go far beyond Chargaff's rules. This study uses both the complete human genome and its repeat-masked version.Comment: Post-print of a paper accepted to publication in "Interdisciplinary Sciences: Computational Life Sciences" (ISSN: 1913-2751, ESSN: 1867-1462

    Dissimilar Symmetric Word Pairs in the Human Genome

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    In this work we explore the dissimilarity between symmetric word pairs, by comparing the inter-word distance distribution of a word to that of its reversed complement. We propose a new measure of dissimilarity between such distributions. Since symmetric pairs with different patterns could point to evolutionary features, we search for the pairs with the most dissimilar behaviour. We focus our study on the complete human genome and its repeat-masked version.Comment: Submitted 13-Feb-2017; accepted, after a minor revision, 17-Mar-2017; 11th International Conference on Practical Applications of Computational Biology & Bioinformatics, PACBB 2017, Porto, Portugal, 21-23 June, 201

    Diet of non-breeding leach’s storm-petrels ( Hydrobates leucorhous ) in the sub-polar frontal zone of the North Atlantic

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    In order to understand the drivers of the distribution and abundance of pelagic seabirds it is necessary to know what they eat, yet there remains little detailed, geo-referenced information on the diets of pelagic seabird. In particular, due to sampling difficulties, information is lacking for non-breeding stages, smaller species, such as storm-petrels, and remote oceanic areas, which may include important diversity hotspots. In this study, we aimed to characterize the trophic ecology of Leach’s storm-petrels foraging in the vicinity of the North Atlantic Current and Evlanov Seamount Marine Protected Area using a combination of survey methods. On a cruise undertaken in June 2017 to characterize the distribution and ecology of seabirds in the region, nineteen Leach’s storm-petrels were caught, sampled and released unharmed. Regurgitations and faecal samples were collected, as well as blood and feather tissues for stable isotope analyses. Of the 12 males, 6 females and 1 unsexed bird, 84% were in active flight feather moult, suggesting they were non-breeders. Prey species, assayed via molecular metabarcoding, were dominated by mesopelagic fish, principally lanternfishes (Myctophidae) and hatchetfishes (Sternoptychidae), but also included cephalopods and crustaceans. Additionally, almost half of the birds had microplastics in their regurgitates. Stable isotopic ratios did not differ significantly between sexes. Our results, combined with those of previous studies, suggest that within the oceanic North Atlantic, Leach’s storm-petrels feed at a similar trophic level to much larger seabirds, targeting mesopelagic fishes that are a key component of the North Atlantic pelagic food web

    Compounds identified on hexane and dichloromethane extracts of Salicornia ramosissima

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    3rd Portuguese Meeting on Medicinal Chemistry and 1st Portuguese-Spanish-Brazilian Meeting on Medicinal Chemistry, Aveiro, 28-30 Novembro 2012.Salicornia ramosissima J. Woods (common purple glasswort) is an annual halophyte, widely distributed in the salt marsh of Ria de Aveiro (Portugal), that belongs to the Salicornia L. genus (Chenopodiaceae).[4] Although phytochemical studies genus on this genus report the presence of compounds which are well-recognized for their biological activities, such as flavonoids, chromones and alkaloids,[3] too little is known about secondary metabolites on purple glasswort. In our previous work we were able to isolate and identify ethyl o-hydroxycinnamate, (E)-fatty alcohol ferulic acid and scopoletin from the dichloromethane extract of S. ramosissima aerial parts. The structure and spectroscopic characterization of some secondary metabolites isolated from dichloromethane crude extract also will be presented and discussed.Thanks are due to the University of Aveiro, Fundação para a Ciência e a Tecnologia (FCT) and FEDER for funding the Organic Chemistry Research Unit (project PEst-C/QUI/UI0062/2011) and Portuguese National NMR Network (RNRMN)

    Some aromatic compounds from dichloromethane extract of Salicornia ramosissima.

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    6th Spanish-Portuguese-Japanese Organic Chemistry Symposium, Lisboa, de 18 a 20 de Julho de 2012 (Poster Communication).Salicornia ramosissima J. Woods, is an annual halophyte, confined to saline habitats, widely distributed in the salt marsh of Ria de Aveiro (Portugal) and also present in many salt marshes of the Iberian Peninsula. Our interest in the phytochemical study of this specie, which belongs to the genus Salicornia and family Chenopodiaceae, is based on previous knowledge that plants of this genus presented compounds such as flavonoids, chromones and alkaloids which are well-recognized for their biological activities. Salicornia ramosissima was subject to some studies of growth conditions and salinity, but its phytochemical composition remains unknown. The analysis of the dichloromethane extract from S. ramosissima aerial parts allowed the isolation of some aromatic compounds, from which we present here their unequivocal structure elucidation.Thanks are due to the University of Aveiro, Fundação para a Ciência e a Tecnologia (FCT) and FEDER for funding the Organic Chemistry Research Unit (project PEst-C/QUI/UI0062/2011) and Portuguese National NMR Network (RNRMN). The authors also wish to acknowledge generous contribution of José M G Pereira for the original photographs of Salicornia in Aveiro region

    Both cetaceans in the Brazilian Amazon show sustained, profound population declines over two decades

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    <div><p>Obligate river dolphins occur only in the rivers of Asia and South America, where they are increasingly subject to damaging pressures such as habitat degradation, food competition and entanglement in fishing gear as human populations expand. The Amazon basin hosts two, very different, dolphins—the boto or Amazon river dolphin (<i>Inia geoffrensis</i>) and the smaller tucuxi (<i>Sotalia fluviatilis</i>). Both species have wide geographical ranges and were once considered to be relatively abundant. Their IUCN Red List conservation status of Data Deficient (DD), due to limited information on threats, ecology, population numbers and trends, did not initially cause alarm. However, the development of dolphin hunting to provide fish bait at around the beginning of this millennium broadly coincided with the onset of a widespread perception that numbers of both species were in decline. Consequently, the need for population trend data to inform conservation advice and measures became urgent. This paper presents a 22-year time series of standardised surveys for both dolphins within the Mamirauá Reserve, Amazonas State, Brazil. Analysis of these data show that both species are in steep decline, with their populations halving every 10 years (botos) and 9 years (tucuxis) at current rates. These results are consistent with published, independent information on survival rates of botos in this area, which demonstrated a substantial drop in annual survival, commencing at around the year 2000. Mamirauá is a protected area, and is subject to fewer environmental pressures than elsewhere in the region, so there is no reason to suspect that the decline in dolphins within the Reserve is more pronounced than outside it. If South America's freshwater cetaceans are to avoid following their Asian counterparts on the path to a perilous conservation status, effective conservation measures are required immediately. Enforcement of existing fishery laws would greatly assist in achieving this.</p></div

    An overview of Salicornia genus : the phytochemical and pharmacological profile

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    Copyright © 2014 Daya Publishing House.Salicornia L. (Chenopodiaceae) is a genus of annual, apparently leafless halophytic herb that have articulated and succulent stems. The Salicornia species comprise the most salttolerant land plant and frequently occur in saline areas. The use of glasswort as food is referred by the forensic palynology as a reality at least from 550 years ago. Nowadays it is much appreciated as a gourmet product in Europe but particularly in Asian countries, where is used in fresh salads and pickles. Some of the Salicornia species display applications on folk medicine (for treatment of bronchitis, hepatitis and diarrhea) and showed important biological properties such as antioxidant, anti-inflammatory, hypoglycemic and cytotoxic activities. The phythochemical studies on this genus reported the presence of fatty acids, sterols, saponins, chlorogenic acid derivatives, alkaloids, flavonoids and other kind of phenolic compounds.The purpose of this review is to highlight the advances in Salicornia genus knowledge by presenting its biological and medicinal applications, phytochemical studies and the relationship between the isolated compounds with the described biological and/or medicinal properties.Thanks are due to the Universities of Aveiro and Azores and also to Fundação para a Ciência e a Tecnologia (FCT) and FEDER for funding the Organic Chemistry Research Unit (project PEst-C/QUI/UI0062/2011). The authors also wish to acknowledge generous contribution of José M G Pereira for the original photographs of Salicornia in Aveiro region (Ecomuseu da Troncalhada, 40° 38' 32.32" N, 8° 39' 47.52" W)

    Valuable compounds on conifers, macroalgae and halophyte species

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    XXIII Encontro Nacional da Sociedade Portuguesa de Química, Aveiro 12 a 14 de Junho de 2013.As part of our on-going investigation on bioactive secondary metabolites, we carried out the phytochemical study of the endemic conifer Juniperus brevifolia and the macroalga Cystoseira abies-marine from Azores Islands, and also of the halophyte Salicornia ramosissima from Aveiro lagoon. This communication gives an overview on the isolation, structural characterization and bioactivity of the most interesting secondary metabolites found in these species.University of Aveiro, Portuguese Foundation for Science and Technology (FCT), European Union, QREN, FEDER and COMPETE for funding the QOPNA research unit (project PEst-C/QUI/UI0062/2011), the Portuguese NMR Network

    Análise das condições de instabilidade atmosférica associadas à ocorrência de um sistema convectivo de mesoescala sobre a região metropolitana de Fortaleza – Ceará.

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    This work presents atmospheric instability conditions associated to the occurrence of Mesoescale Convective System (MCS) in the metropolitan region of Fortaleza – CE, at 06/04/2002. The investigation is based in instability indexes (K, TT, LI) and Convective Available Potential Energy (CAPE). Radiossondes and Radar images were used in the investigation. The data were collected during the Experiment of Microphisics of Clouds (EMfiN!) from 02 to 12/04/2002. Preliminary results show that MCS produced a high rainfall on the metropolitan region of Fortaleza. In addition, the paper shows meteorological diagrams (Skew T, Log P) that identify the presence and conditions of instability associated to these meteorological systems.Nesse trabalho investigaram-se as condições de instabilidade atmosférica associadas à ocorrência de um Sistema Convectivo de Mesoescala (SCM) na região metropolitana de Fortaleza — CE, no dia 06/04/2002. O estudo é baseado em índices (K, TT e LI), que quantificam o grau de instabilidade na atmosfera, e na Energia Potencial Disponível para Convecção — CAPE (Convective Available Potential Energy). São usados dados de radiossondagens e imagens de um radar meteorológico coletados durante o Experimento de Microfísica de Nuvens (EMfiN!), realizado na cidade de Fortaleza - CE, no período de 02 a 12 de abril de 2002. Resultados preliminares mostram que o SCM do dia 06/04/2002 produziu uma grande quantidade de precipitação na região metropolitana de Fortaleza, equivalente a da média histórica do município no mês de abril. Em adição, apresentaram-se diagramas meteorológicos (Skew T, Log P) que possibilitam identificar a presença e as condições de instabilidade associadas a esses tipos de sistemas meteorológicos
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