384 research outputs found

    Effects of different combinations of Hoagland’s solution and Azolla filiculoides on photosynthesis and chlorophyll content in Beta vulgaris subsp. Cycla ‘fordhook giant’ grown in hydroponic cultures

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    The assessments of photosynthetic rate, stomatal conductance,  evapotranspiration, intercellular CO2 concentration and chlorophyll content in Beta vulgaris subsp. cycla ‘Fordhook Giant’ grown in hydroponic cultures containing different compositions of hydroponic solutions were evaluated in this study. The aim of the study was to quantify the effects of different combinations of Hoagland’s solution and Azolla filiculoides on photosynthesis processes and chlorophyll content in B. vulgaris grown in hydroponic cultures. The following treatments were evaluated in four replications: (1) Control (Hoagland’s solution minus N solution excluding Azolla; (2) Hoagland’s minus N solution including Azolla; (3) full Hoagland’s solution plus Azolla; and (4) full Hoagland’s solution excluding Azolla. Results show that photosynthetic rate, evapotranspiration, intercellular CO2 concentration and chlorophyll were generally higher in full Hoagland’s solution. This was closely followed by full Hoagland’s solution plus Azolla, and Hoagland’s minus N solution plus Azolla treatments. The lowest photosynthetic rates and chlorophyll contents were found in the control (Hoagland’s minus N solution) treatment.Keywords: Photosynthetic rate, stomatal conductance, evapotranspiration, intercellular CO2 concentration, chlorophyll a, chlorophyll bAfrican Journal of Biotechnology Vol. 12(16), pp. 2006-201

    The Temperature Structure of Be Star Disks in the Small Magellanic Cloud

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    The temperature structure of Be star circumstellar disks at the sub-solar metallicity appropriate to the Small Magellanic Cloud (SMC) is investigated. It is found that for central stars of the same spectral type, Be star disks in the SMC are systematically hotter by several thousand degrees compared to Milky Way (MW) disks with the same density structure. For early spectral types (B0e - B3e), this results in systematically smaller H{\alpha} equivalent widths for Be stars in the SMC. The implication of this result on Be star frequency comparisons between MW and SMC clusters is shown to be a 5 - 10% lowering of the detection efficiency of Be stars in SMC clusters. These calculations are also compared to the known H{\alpha} equivalent width distributions in the MW and SMC. For the MW, reasonable agreement is found; however, for the SMC, the match is not as good and systematically larger Be star disks may be required.Comment: 31 pages, 10 figures, Accepted for publication in the astrophysical Journa

    Patients with anorectal malformation and upper limb anomalies: genetic evaluation is warranted

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    The objective of this study was to compare the prevalence of genetic disorders in anorectal malformation (ARM) patients with upper limb anomalies to that in ARM patients with other associated anomalies. A retrospective case study was performed in two pediatric surgery centers. All patients born between 1990 and 2012 were included. VACTERL (vertebral defects (V), anal atresia (A), cardiac malformations (C), tracheoesophageal fistula with esophageal atresia (TE), renal dysplasia (R), and limb anomalies (L)) was defined as at least three components present. We included 700 ARM patients: 219 patients (31 %) had isolated ARM, 43 patients (6 %) had a major upper limb anomaly, and 438 patients (63 %) had other associated anomalies. The most prevalent upper limb anomalies were radial dysplasia (n = 12) and hypoplastic thumb (n = 11). Ten of the 43 patients (23 %) with an upper limb anomaly were diagnosed with a genetic disorder—nine also met the VACTERL criteria—vs. 9 % of ARM patients with other anomalies (p = 0.004, chi-squared test). Conclusion: Genetic disorders are twice as frequently diagnosed in ARM patients with upper limb anomalies than in those with other anomalies. As they also frequently meet the VACTERL criteria, it is important to consider VACTERL as a diagnosis per exclusionem. Genetic counseling is certainly warranted in these patients.What is Known:• Anorectal malformations (ARMs) often co-occur with other congenital anomalies, including upper limb anomalies, mainly of pre-axial origin.• Co-occurrence of ARMs and upper limb anomalies is seen in disorders such as Townes-Brocks syndrome, Fanconi anemia, and VACTERL association.What is New:• ARM patients with a major upper limb anomaly—with or without other congenital anomalies—have a twofold greater chance of a genetic disorder than have non-isolated ARM patients without upper limb anomalies.• Not all upper limb anomalies in ARM patients are part of the VACTERL association; a workup for genetic evaluation is proposed

    The Effect of Starburst Metallicity on Bright X-Ray Binary Formation Pathways

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    We investigate the characteristics of young ( 1e36 erg/s) High-Mass X-ray Binaries (HMXBs) and find the population to be strongly metallicity-dependent. We separate the model populations among two distinct formation pathways: (1) systems undergoing active Roche Lobe Overflow (RLO), and (2) wind accretion systems with donors in the (super)giant (SG) stage, which we find to dominate the HMXB population. We find metallicity to primarily affect the number of systems which move through each formation pathway, rather than the observable parameters of systems which move through each individual pathway. We discuss the most important model parameters affecting the HMXB population at both low and high metallicities. Using these results, we show that (1) the population of ultra-luminous X-Ray sources can be consistently described by very bright HMXBs which undergo stable Roche Lobe overflow with mild super-Eddington accretion and (2) the HMXB population of the bright starburst galaxy NGC~1569 is likely dominated by one extremely metal-poor starburst cluster.Comment: 12 pages, 10 figures, Accepted by Ap

    Clinical relevance of rapid FOXF1-targeted sequencing in patients suspected of alveolar capillary dysplasia with misalignment of pulmonary veins

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    Alveolar capillary dysplasia with misalignment of pulmonary Veins (ACDMPV) is a lethal congenital lung disorder that presents shortly after birth with respiratory failure and therapy-resistant pulmonary hypertension. It is associated with heterozygous point mutations and genomic deletions that involve the FOXF1 gene or its upstream regulatory region. Patients are unresponsive to the intensive treatment regiments and suffer unnecessarily, because ACDMPV is not always timely recognized and histological diagnosis is invasive and time-consuming. Here, we demonstrate the usefulness of a non-invasive, fast genetic test for FOXF1 variants that we previously developed to rapidly diagnose ACDMPV and reduce the time of hospitalization.</p

    Intrinsic Cellular Susceptibility to Barrett’s Esophagus in Adults Born with Esophageal Atresia

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    The prevalence of Barrett’s esophagus (BE) in adults born with esophageal atresia (EA) is four times higher than in the general population and presents at a younger age (34 vs. 60 years). This is (partly) a consequence of chronic gastroesophageal reflux. Given the overlap between genes and pathways involved in foregut and BE development, we hypothesized that EA patients have an intrinsic predisposition to develop BE. Transcriptomes of Esophageal biopsies of EA patients with BE (n = 19, EA/BE); EA patients without BE (n = 44, EA-only) and BE patients without EA (n = 10, BE-only) were compared by RNA expression profiling. Subsequently, we simulated a reflux episode by exposing fibroblasts of 3 EA patients and 3 controls to acidic conditions. Transcriptome responses were compared to the differential expressed transcripts in the biopsies. Predisposing single nucleotide polymorphisms, associated with BE, were slightly increased in EA/BE versus BE-only patients. RNA expression profiling and pathway enrichment analysis revealed differences in retinoic acid metabolism and downstream signaling pathways and inflammatory, stress response and oncological processes. There was a similar effect on retinoic acid signaling and immune response in EA patients upon acid exposure. These results indicate that epithelial tissue homeostasis in EA patients is more prone to acidic disturbances

    Intrinsic Cellular Susceptibility to Barrett’s Esophagus in Adults Born with Esophageal Atresia

    Get PDF
    The prevalence of Barrett’s esophagus (BE) in adults born with esophageal atresia (EA) is four times higher than in the general population and presents at a younger age (34 vs. 60 years). This is (partly) a consequence of chronic gastroesophageal reflux. Given the overlap between genes and pathways involved in foregut and BE development, we hypothesized that EA patients have an intrinsic predisposition to develop BE. Transcriptomes of Esophageal biopsies of EA patients with BE (n = 19, EA/BE); EA patients without BE (n = 44, EA-only) and BE patients without EA (n = 10, BE-only) were compared by RNA expression profiling. Subsequently, we simulated a reflux episode by exposing fibroblasts of 3 EA patients and 3 controls to acidic conditions. Transcriptome responses were compared to the differential expressed transcripts in the biopsies. Predisposing single nucleotide polymorphisms, associated with BE, were slightly increased in EA/BE versus BE-only patients. RNA expression profiling and pathway enrichment analysis revealed differences in retinoic acid metabolism and downstream signaling pathways and inflammatory, stress response and oncological processes. There was a similar effect on retinoic acid signaling and immune response in EA patients upon acid exposure. These results indicate that epithelial tissue homeostasis in EA patients is more prone to acidic disturbances

    Una nueva hipótesis sobre la sucesión de los bosques tropicales húmedos y secos

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    In this paper 221 forest trees are grouped according to their habitat preferences into species preferring humid or dry and/or saline habitats or indifferent to the habitat type. Eleven functional traits classes (seeds per tree, seed size, seed weight, seeds per fruit, tolerance to shade, selectivity to habitat, sclerophylly, wood density, foliar area, tree height and tree volume) are arranged 1 to 4 according to a successional gradient. The strategies of forest trees are identified by analyzing the species matrices for humid forest ecosystems (joining species preferring humid habitats together with those indifferent to the habitat type) and for dry and/or saline ecosystems (joining species preferring dry and/or saline habitats and the ones indifferent to the habitat type). Both matrices are processed using the average taxonomic distance as the interval coefficient and by clustering analysis to discover successional organization patterns. The complexity of r-K continuum is discussed by focusing the K behavior of some variables among Pioneers (commonly r strategists) or the r behavior of some variables among Stabilizers (commonly K strategists). A new system of classification is presented as a hypothesis for discovering successional patterns in tropical forests.En el presente artículo agrupamos 221 especies forestales sobre la base de sus preferencias por tipos de hábitat húmedo o seco y/o salino, considerando aparte aquellas que son indiferentes al tipo de hábitat. El sistema de clasificación se sustentó en el empleo de clases de 11 variables funcionales (semillas por árbol, tamaño de las semillas, peso de las semillas, semillas por fruto, tolerancia a la sombra, selectividad al hábitat, esclerofilia, densidad de la madera, área foliar, altura del árbol y volumen del árbol) ordenadas de 1 a 4 de acuerdo con un gradiente sucesional. Las estrategias de las especies arbóreas se identificaron mediante el análisis de las matrices para ecosistemas forestales húmedos (uniendo las especies que prefieren hábitat húmedo con las que son indiferentes al tipo de hábitat) y para ecosistemas secos y/o salinos (uniendo las especies que prefieren hábitat seco y/o salino con las que son indiferentes al tipo de hábitat). Ambas matrices fueron procesadas mediante el uso del coeficiente de distancia taxonómica promedio y por análisis de clasificación para descubrir los patrones de organización sucesional. Se discutieron la complejidad del continuum r-K exponiendo el comportamiento K de algunas variables entre las Pioneras (que comúnmente son estrategas r) y el comportamiento r de algunas variables entre las Estabilizadoras (que comúnmente son estrategas K). Presentamos el nuevo sistema de clasificación como una hipótesis para descubrir los patrones sucesionales en bosques tropicales.Depto. de Biodiversidad, Ecología y EvoluciónFac. de Ciencias BiológicasTRUEInternational Foundation for Science (IFS) (Sweden)MacArthur Foundation and D. W. Reynolds Foundation (USA)David Rockefeller Center for Latin-American Studies (Cambridge, USA)The Ecological Society of America (ESA)( Washington, USA)pu
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