730 research outputs found

    Ridesourcing and Travel Demand: Potential Effects of Transportation Network Companies in Bogotá

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    This paper proposes a modal-shift analysis methodology based on a mix of small-scale primary data and big data sources to estimate the total amount of trips that are reallocated to transportation network companies (TNCs) services in Bogotá, Colombia. The analysis is focused on the following four modes: public transportation, private vehicles, conventional taxis, and TNC services. Based on a stated preferences survey and secondary databases of travel times and costs, the paper proposes a methodology to estimate the reallocation of travel demand once TNCs start operating. Results suggests that approximately one third of public transportation trips are potentially transferred to TNCs. Moreover, potential taxi and private vehicle–transferred trips account for almost 30% of the new TNC demand. Additionally, approximately half of the trips that are reallocated from public transport demand can be considered as complementary, while the remaining share can be considered as potential replacing trips of public transportation. The paper also estimates the potential increase in Vehicle-km travelled in each of the modes before and after substitution as a proxy to the effects of demand reallocation on sustainability, finding increases between 1.3 and 14.5 times the number of Vehicle-km depending on the mode. The paper highlights the role of open data and critical perspectives on available information to analyze potential scenarios of the introduction of disruptive technologies and their spatial, social, and economic implications

    An Actinobacterium strain from soil of Cerrado promotes Phosphorus solubilization and plant growth in soybean plants.

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    Abstract: The huge biological diversity of the Brazilian Cerrado is an important source of economically interesting microbial agents. The phylum Actinobacteria plays an important role in nutrient cycling, potentially improving their availability to plants. In this study, we isolated an actinobacteria (strain 3AS4) from wheat rhizospheres of crops cultivated in the Cerrado biome. Strain 3AS4 was identified as belonging to the genus Streptomyces and had phosphorus mobilization ability, mineralizing approximately 410 mg ml-1 from phytate, 300 mg ml-1 from calcium phosphate, and 200 mg ml-1 from rock phosphate. The analysis of the actinobacteria crude extract by spectrometric techniques revealed the presence of gluconic and 2-ketogluconic acid, and a greenhouse experiment was carried out to evaluate its plant growth promotion activity in soybean. Soil in its natural condition (with no phosphorus addition), 40 kg ha􀀀1 rock phosphate from Bayovar (RP) added to soil, and triple super phosphate (SPT) added to soil were used. Significant differences in plant height were observed at 6 weeks when the plants were inoculated with the 3AS4 strain. The growth of inoculated plants in natural condition was promoted in 17% compared with the RP and SPT non-inoculated conditions, suggesting that inoculation can enable plants to grow with lower chemical P fertilizers. In the plants that were inoculated with the 3AS4 strain in the RP condition, the plant height increased by approximately 80% and the shoot:root ratio was approximately 30% higher compared to control conditions (non-inoculated plants in natural conditions). 3AS4 has P-solubilizing potential and can be exploited as an inoculant for soybean cultivation. These results suggest that this actinobacterium is a valuable resource for sustainable agriculture and will allow the reduction of phosphate fertilization in the future

    Inducible nitric oxide synthase (iNOS) expression in monocytes during acute Dengue Fever in patients and during in vitro infection

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    ABSTRACT: Mononuclear phagocytes are considered to be main targets for Dengue Virus (DENV) replication. These cells are activated after infection, producing proinflammatory mediators, including tumour-necrosis factor-α, which has also been detected in vivo. Nitric oxide (NO), usually produced by activated mononuclear phagocytes, has antimicrobial and antiviral activities. METHODS: The expression of DENV antigens and inducible nitric oxide synthase (iNOS) in human blood isolated monocytes were analysed by flow cytometry using cells either from patients with acute Dengue Fever or after DENV-1 in vitro infection. DENV-1 susceptibility to iNOS inhibition and NO production was investigated using N(G)-methyl L-Arginine (N(G)MLA) as an iNOS inhibitor, which was added to DENV-1 infected human monocytes, and sodium nitroprussiate (SNP), a NO donor, added to infected C6/36 mosquito cell clone. Viral antigens after treatments were detected by flow cytometry analysis. RESULTS: INOS expression in activated monocytes was observed in 10 out of 21 patients with Dengue Fever and was absent in cells from ten healthy individuals. DENV antigens detected in 25 out of 35 patients, were observed early during in vitro infection (3 days), significantly diminished with time, indicating that virus replicated, however monocytes controlled the infection. On the other hand, the iNOS expression was detected at increasing frequency in in vitro infected monocytes from three to six days, exhibiting an inverse relationship to DENV antigen expression. We demonstrated that the detection of the DENV-1 antigen was enhanced during monocyte treatment with N(G)MLA. In the mosquito cell line C6/36, virus detection was significantly reduced in the presence of SNP, when compared to that of untreated cells. CONCLUSION: This study is the first to reveal the activation of DENV infected monocytes based on induction of iNOS both in vivo and in vitro, as well as the susceptibility of DENV-1 to a NO production

    Structural Maintenance of Chromosomes (SMC) Proteins Promote Homolog-Independent Recombination Repair in Meiosis Crucial for Germ Cell Genomic Stability

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    In meiosis, programmed DNA breaks repaired by homologous recombination (HR) can be processed into inter-homolog crossovers that promote the accurate segregation of chromosomes. In general, more programmed DNA double-strand breaks (DSBs) are formed than the number of inter-homolog crossovers, and the excess DSBs must be repaired to maintain genomic stability. Sister-chromatid (inter-sister) recombination is postulated to be important for the completion of meiotic DSB repair. However, this hypothesis is difficult to test because of limited experimental means to disrupt inter-sister and not inter-homolog HR in meiosis. We find that the conserved Structural Maintenance of Chromosomes (SMC) 5 and 6 proteins in Caenorhabditis elegans are required for the successful completion of meiotic homologous recombination repair, yet they appeared to be dispensable for accurate chromosome segregation in meiosis. Mutations in the smc-5 and smc-6 genes induced chromosome fragments and dismorphology. Chromosome fragments associated with HR defects have only been reported in mutants, which have disrupted inter-homolog crossover. Surprisingly, the smc-5 and smc-6 mutations did not disrupt the formation of chiasmata, the cytologically visible linkages between homologous chromosomes formed from meiotic inter-homolog crossovers. The mutant fragmentation defect appeared to be preferentially enhanced by the disruptions of inter-homolog recombination but not by the disruptions of inter-sister recombination. Based on these findings, we propose that the C. elegans SMC-5/6 proteins are required in meiosis for the processing of homolog-independent, presumably sister-chromatid-mediated, recombination repair. Together, these results demonstrate that the successful completion of homolog-independent recombination is crucial for germ cell genomic stability

    Spermatogenesis-Specific Features of the Meiotic Program in Caenorhabditis elegans

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    In most sexually reproducing organisms, the fundamental process of meiosis is implemented concurrently with two differentiation programs that occur at different rates and generate distinct cell types, sperm and oocytes. However, little is known about how the meiotic program is influenced by such contrasting developmental programs. Here we present a detailed timeline of late meiotic prophase during spermatogenesis in Caenorhabditis elegans using cytological and molecular landmarks to interrelate changes in chromosome dynamics with germ cell cellularization, spindle formation, and cell cycle transitions. This analysis expands our understanding C. elegans spermatogenesis, as it identifies multiple spermatogenesis-specific features of the meiotic program and provides a framework for comparative studies. Post-pachytene chromatin of spermatocytes is distinct from that of oocytes in both composition and morphology. Strikingly, C. elegans spermatogenesis includes a previously undescribed karyosome stage, a common but poorly understood feature of meiosis in many organisms. We find that karyosome formation, in which chromosomes form a constricted mass within an intact nuclear envelope, follows desynapsis, involves a global down-regulation of transcription, and may support the sequential activation of multiple kinases that prepare spermatocytes for meiotic divisions. In spermatocytes, the presence of centrioles alters both the relative timing of meiotic spindle assembly and its ultimate structure. These microtubule differences are accompanied by differences in kinetochores, which connect microtubules to chromosomes. The sperm-specific features of meiosis revealed here illuminate how the underlying molecular machinery required for meiosis is differentially regulated in each sex

    Organization of multiprotein complexes at cell–cell junctions

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    The formation of stable cell–cell contacts is required for the generation of barrier-forming sheets of epithelial and endothelial cells. During various physiological processes like tissue development, wound healing or tumorigenesis, cellular junctions are reorganized to allow the release or the incorporation of individual cells. Cell–cell contact formation is regulated by multiprotein complexes which are localized at specific structures along the lateral cell junctions like the tight junctions and adherens junctions and which are targeted to these site through their association with cell adhesion molecules. Recent evidence indicates that several major protein complexes exist which have distinct functions during junction formation. However, this evidence also indicates that their composition is dynamic and subject to changes depending on the state of junction maturation. Thus, cell–cell contact formation and integrity is regulated by a complex network of protein complexes. Imbalancing this network by oncogenic proteins or pathogens results in barrier breakdown and eventually in cancer. Here, I will review the molecular organization of the major multiprotein complexes at junctions of epithelial cells and discuss their function in cell–cell contact formation and maintenance

    Design and implementation of the international genetics and translational research in transplantation network

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    Test beam performance of a CBC3-based mini-module for the Phase-2 CMS Outer Tracker before and after neutron irradiation

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    The Large Hadron Collider (LHC) at CERN will undergo major upgrades to increase the instantaneous luminosity up to 5–7.5×1034^{34} cm2^{-2}s1^{-1}. This High Luminosity upgrade of the LHC (HL-LHC) will deliver a total of 3000–4000 fb-1 of proton-proton collisions at a center-of-mass energy of 13–14 TeV. To cope with these challenging environmental conditions, the strip tracker of the CMS experiment will be upgraded using modules with two closely-spaced silicon sensors to provide information to include tracking in the Level-1 trigger selection. This paper describes the performance, in a test beam experiment, of the first prototype module based on the final version of the CMS Binary Chip front-end ASIC before and after the module was irradiated with neutrons. Results demonstrate that the prototype module satisfies the requirements, providing efficient tracking information, after being irradiated with a total fluence comparable to the one expected through the lifetime of the experiment
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