86 research outputs found
PAHs, PCBs, PBDEs and Pesticides in Cold-Pressed Vegetable Oils
The aim of this study was to investigate levels of polychlorinated biphenyls (marker and dioxin-like congeners), polycyclic aromatic hydrocarbons (EPA 15 + 1), polybrominated diphenyl ethers (14 predominant congeners) and pesticides (74 compounds) in various cold-pressed vegetable oils. Poppy seed oil, rapeseed oil, sesame seed oil, pumpkinseed oil, hempseed oil, linaire oil, borage oil and evening star oil were investigated. Results of this study revealed that concentrations of PCBs, PBDEs and PAHs were low in majority of the investigated samples. However, high concentrations of organophosphorus insecticides were found. Chlorpyrifos methyl and pirimiphos methyl were the pesticide residues most commonly found in the studied oils. Concentration of 15 + 1 EPA PAHs was within the 17.85–37.16 μg kg−1 range, concentration of (marker) PCBs varied from 127 to 24,882 pg g−1, dioxin-like TEQ values were below 0.1 pg TEQ g−1. Concentration of PBDEs was below LOQ in most cases
In vitro biocompatibility evaluation of functional electrically stimulating microelectrodes on primary glia
Neural interfacing devices interact with the central nervous system to alleviate functional deficits arising from disease or injury. This often entails the use of invasive microelectrode implants that elicit inflammatory responses from glial cells and leads to loss of device function. Previous work focused on improving implant biocompatibility by modifying electrode composition; here, we investigated the direct effects of electrical stimulation on glial cells at the electrode interface. A high-throughput in vitro system that assesses primary glial cell response to biphasic stimulation waveforms at 0 mA, 0.15 mA, and 1.5 mA was developed and optimized. Primary mixed glial cell cultures were generated from heterozygous CX3CR-1+/EGFP mice, electrically stimulated for 4 h/day over 3 days using 75 μm platinum-iridium microelectrodes, and biomarker immunofluorescence was measured. Electrodes were then imaged on a scanning electron microscope to assess sustained electrode damage. Fluorescence and electron microscopy analyses suggest varying degrees of localized responses for each biomarker assayed (Hoescht, EGFP, GFAP, and IL-1β), a result that expands on comparable in vivo models. This system allows for the comparison of a breadth of electrical stimulation parameters, and opens another avenue through which neural interfacing device developers can improve biocompatibility and longevity of electrodes in tissue
Contested Knowledges of the Commons in Southeast Asia
Environmental questions are at the heart of many development dilemmas in Southeast Asia. New actors and technologies, changing domestic politics, policies, and economies - as well as shifting geopolitical contexts, are remaking nature-society relations in the region. A failure to address transnational environmental challenges could not only undermine ASEAN’s legitimacy but also have drastic consequences for the region’s security and its political and economic stability. In addressing these questions in Work Package 1 (WP1), we are particularly concerned with contested knowledges of “the commons” and competition over resources. We consider the environment as a driver of processes of regional integration, but also of conflicts between various actors in the region. Our research focuses on three environmental contexts namely: sea; rivers; and air. In addressing all three our emphasis is on the transition to a low-carbon economy. The aim of this paper is to present the theoretical framework of our work as well as the three main strands of our research. In the first section, we explain our understanding of the concept of ecological knowledge. This is followed by a presentation of our methodological approaches, while the last section presents the individual research projects in the WP, arranged in three modules.This project has received funding from the European Union’s Horizon 2020 Research and Innovation Programme under grant agreement N°770562
Coordination of Cell Differentiation and Migration in Mathematical Models of Caudal Embryonic Axis Extension
Vertebrate embryos display a predominant head-to-tail body axis whose formation is associated with the progressive development of post-cranial structures from a pool of caudal undifferentiated cells. This involves the maintenance of active FGF signaling in this caudal region as a consequence of the restricted production of the secreted factor FGF8. FGF8 is transcribed specifically in the caudal precursor region and is down-regulated as cells differentiate and the embryo extends caudally. We are interested in understanding the progressive down-regulation of FGF8 and its coordination with the caudal movement of cells which is also known to be FGF-signaling dependent. Our study is performed using mathematical modeling and computer simulations. We use an individual-based hybrid model as well as a caricature continuous model for the simulation of experimental observations (ours and those known from the literature) in order to examine possible mechanisms that drive differentiation and cell movement during the axis elongation. Using these models we have identified a possible gene regulatory network involving self-repression of a caudal morphogen coupled to directional domain movement that may account for progressive down-regulation of FGF8 and conservation of the FGF8 domain of expression. Furthermore, we have shown that chemotaxis driven by molecules, such as FGF8 secreted in the stem zone, could underlie the migration of the caudal precursor zone and, therefore, embryonic axis extension. These mechanisms may also be at play in other developmental processes displaying a similar mode of axis extension coupled to cell differentiation
Multiple Wnts Redundantly Control Polarity Orientation in Caenorhabditis elegans Epithelial Stem Cells
During development, cell polarization is often coordinated to harmonize tissue patterning and morphogenesis. However, how extrinsic signals synchronize cell polarization is not understood. In Caenorhabditis elegans, most mitotic cells are polarized along the anterior-posterior axis and divide asymmetrically. Although this process is regulated by a Wnt-signaling pathway, Wnts functioning in cell polarity have been demonstrated in only a few cells. We analyzed how Wnts control cell polarity, using compound Wnt mutants, including animals with mutations in all five Wnt genes. We found that somatic gonadal precursor cells (SGPs) are properly polarized and oriented in quintuple Wnt mutants, suggesting Wnts are dispensable for the SGPs' polarity, which instead requires signals from the germ cells. Thus, signals from the germ cells organize the C. elegans somatic gonad. In contrast, in compound but not single Wnt mutants, most of the six seam cells, V1–V6 (which are epithelial stem cells), retain their polarization, but their polar orientation becomes random, indicating that it is redundantly regulated by multiple Wnt genes. In contrast, in animals in which the functions of three Wnt receptors (LIN-17, MOM-5, and CAM-1) are disrupted—the stem cells are not polarized and divide symmetrically—suggesting that the Wnt receptors are essential for generating polarity and that they function even in the absence of Wnts. All the seam cells except V5 were polarized properly by a single Wnt gene expressed at the cell's anterior or posterior. The ectopic expression of posteriorly expressed Wnts in an anterior region and vice versa rescued polarity defects in compound Wnt mutants, raising two possibilities: one, Wnts permissively control the orientation of polarity; or two, Wnt functions are instructive, but which orientation they specify is determined by the cells that express them. Our results provide a paradigm for understanding how cell polarity is coordinated by extrinsic signals
The Role of Glypicans in Wnt Inhibitory Factor-1 Activity and the Structural Basis of Wif1's Effects on Wnt and Hedgehog Signaling
Proper assignment of cellular fates relies on correct interpretation of Wnt and Hedgehog (Hh) signals. Members of the Wnt Inhibitory Factor-1 (WIF1) family are secreted modulators of these extracellular signaling pathways. Vertebrate WIF1 binds Wnts and inhibits their signaling, but its Drosophila melanogaster ortholog Shifted (Shf) binds Hh and extends the range of Hh activity in the developing D. melanogaster wing. Shf activity is thought to depend on reinforcing interactions between Hh and glypican HSPGs. Using zebrafish embryos and the heterologous system provided by D. melanogaster wing, we report on the contribution of glypican HSPGs to the Wnt-inhibiting activity of zebrafish Wif1 and on the protein domains responsible for the differences in Wif1 and Shf specificity. We show that Wif1 strengthens interactions between Wnt and glypicans, modulating the biphasic action of glypicans towards Wnt inhibition; conversely, glypicans and the glypican-binding “EGF-like” domains of Wif1 are required for Wif1's full Wnt-inhibiting activity. Chimeric constructs between Wif1 and Shf were used to investigate their specificities for Wnt and Hh signaling. Full Wnt inhibition required the “WIF” domain of Wif1, and the HSPG-binding EGF-like domains of either Wif1 or Shf. Full promotion of Hh signaling requires both the EGF-like domains of Shf and the WIF domains of either Wif1 or Shf. That the Wif1 WIF domain can increase the Hh promoting activity of Shf's EGF domains suggests it is capable of interacting with Hh. In fact, full-length Wif1 affected distribution and signaling of Hh in D. melanogaster, albeit weakly, suggesting a possible role for Wif1 as a modulator of vertebrate Hh signaling
Inheritance of resistance to Ustilago nuda [Jens.] Rostr. in some spring barley cultivars
The inheritance of resistance to loose smut (Ustilago nuda) in seven cultivars of spring barley has been examined. The performed studies showed that, resistance to two different groups of U. nuda races in respect of their virulence is determined by a single allele pair in the cvs. Anoidium and Inerme 2-r and by two allele pairs in the cvs. CI 13 662, Dorsett, Jet and OAC 21. In the cv. Abyssinian, resistance to a group of races 2 is determined by a single allele pair, whereas that to a group of races 4 - by two allele pairs. In all studied cultivars (except Anoidium) the resistance dominates over sensitivity. Resistance to the both studied groups of U. nuda races is determined by similar genes in the cvs. Dorsett and CI 13 662, as well as in Dorsett and OAC21, and additionally to a group of races 4 in the cvs. Abyssinian and OAC 21. No similarity was found between resistance genes in the case of two allele pairs in the cvs. Jet, Abyssinian and CI 13 662 (group of races 4) as well as in Jet, Dorsett and OAC 21 (in both groups of races), and in the case of a single allele pair in the cvs. Inerme-2-rowed and Abyssinian (group races 2)
Effect of laser irradiation on the quality of carrot seeds
Wykorzystanie światła lasera jest jedną z metod stosowanych w celu poprawienia wartości siewnej nasion. W latach 1998 i 2000 nasiona marchwi odmiany 'Dolanka' poddano biostymulacji różnymi dawkami światła lasera, a następnie oceniano ich zdolność i dynamikę kiełkowania, wschody w polu oraz plon korzeni w czteropowtórzeniowym doświadczeniu.
W przypadku marchwi biostymulacja nasion okazała się nieskuteczna, gdyż nie stwierdzono różnic badanych parametrów między nasionami traktowanymi i kontrolnymi. Nie uzyskano również przyspieszenia wschodów siewek w polu. Plon ogólny i handlowy korzeni marchwi otrzymany z poletek obsianych nasionami kontrolnymi nie różnił się od plonu z poletek obsianych nasionami po laserowej biostymulacji.Laser irradiation is the method used to improve the seed quality. In 1998 and 2000, the seeds of carrot 'Dolanka' cv. were irradiated with various doses of laser beams and next their germination dynamics and ability were assessed. In a four- replication field trial the carrot emergence and root yield were also noted.
In case of carrot, the biostimulation by laser beams was ineffective as there was no difference in assessed parameters between treated and control seeds. There was also no increase of seed emergence in field. Total and marketable root yield from control plots did not differ from those obtained from laser beam treated seeds
The heat transfer and flow structure analyses of low concentration copper nanofluids in a strong magnetic field
Main aim of this paper was to analyze the influence of strong magnetic field on the enhancement or suppression of nanofluids transport processes. The second objective was to determine how the flow structure changed under the influence of a magnetic field. Analyzed diamagnetic nanofluids composed of distilled water and the copper nanoparticles of 40–60 nm size in three different concentrations (50, 500, and 1000 ppm). The experimental enclosure position in the magnet test section caused the most intricate interaction of the acting forces: the gravitational and magnetic buoyancy ones, and made the interpretation of results very difficult. The Nusselt number ratio and the thermomagnetic Rayleigh number were determined for heat transfer analysis, while the fast Fourier transform was performed for the nanofluid flow structure analysis. Spectral analysis for all examined nanofluids was presented. Influence of nanoparticles concentration was clearly visible, while the direct impact of magnetic field on the heat transfer and flow structure should be still investigated
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