669 research outputs found

    THE EXPRESSION OF HLA-G ANTIGEN IN DIFFERENT HUMAN TISSUES AND PLACENTAS AT DIFFERENT STAGES OF PREGNANCY

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    The distribution of HLA-G antigens in human tissues including placents was examined by immunohistochemical methods, using monoclonal antibody (Mab) specific to HLA-G antigen (87 G). Comparatively, class â…  specific Mab, W 6/32 was also employed for the detection of the antigen. W 6/32 reacted with a wide variety of cells and tissues throughout the body, whereas Mab 87 G did not react at all with these W 6/32 reactive cells except for those of placental tissues. Mab 87 G reacted with extravillous cytotrophoblast cells such as cytotrophoblastic cell columns, cytotrophoblastic shell and invasive cytotrophoblast but not other parts of placentas throughout the pregnant periods. Essentially the same results were obtained with W 6/32 staining in placentas. These results indicate that HLA-G antigens are exclusively expressed in extravillous cytotrophoblast cells although we cannot rule out the possibility that undetectable amounts of the HLA-G antigen or its isoforms which cannot be recognized by the Mabs used in this study are synthesized in some other tissues

    The Non-Canonical Hydroxylase Structure of YfcM Reveals a Metal Ion-Coordination Motif Required for EF-P Hydroxylation

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    EF-P is a bacterial tRNA-mimic protein, which accelerates the ribosome-catalyzed polymerization of poly-prolines. In Escherichia coli, EF-P is post-translationally modified on a conserved lysine residue. The post-translational modification is performed in a two-step reaction involving the addition of a β-lysine moiety and the subsequent hydroxylation, catalyzed by PoxA and YfcM, respectively. The β-lysine moiety was previously shown to enhance the rate of poly-proline synthesis, but the role of the hydroxylation is poorly understood. We solved the crystal structure of YfcM and performed functional analyses to determine the hydroxylation mechanism. In addition, YfcM appears to be structurally distinct from any other hydroxylase structures reported so far. The structure of YfcM is similar to that of the ribonuclease YbeY, even though they do not share sequence homology. Furthermore, YfcM has a metal ion-coordinating motif, similar to YbeY. The metal ion-coordinating motif of YfcM resembles a 2-His-1-carboxylate motif, which coordinates an Fe(II) ion and forms the catalytic site of non-heme iron enzymes. Our findings showed that the metal ion-coordinating motif of YfcM plays an essential role in the hydroxylation of the β-lysylated lysine residue of EF-P. Taken together, our results suggested the potential catalytic mechanism of hydroxylation by YfcM

    Developing Methods to Evaluate Phenotypic Variability in Biological Nitrification Inhibition (BNI) Capacity of \u3cem\u3eBrachiaria\u3c/em\u3e Grasses

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    As part of the nitrogen (N) cycle in the soil, nitrification is an oxidation process mediated by microorganisms that transform the relatively immobile ammonium (NH4+)to the water soluble nitrate (NO3-), enabling the production of nitrous oxide (N2O, a potent greenhouse gas) by denitrification as a by-product (Canfield et al. 2010). Researchers at CIAT-Colombia in collaboration with JIRCAS-Japan, reported that Brachiaria humidicola forage grasses have the ability to inhibit the nitrification process by exuding chemical compounds from its roots to the soil. A major hydrophobic compound was discovered and named brachial-actone (Subbarao et al. 2009). This capacity of Brachiaria grasses is known as biological nitrification inhibition (BNI) and it could contribute to better N use efficiency in crop-livestock systems by improving recovery of applied N while reducing NO3- leaching and N2O emission. The current methodologies for quantifying the BNI trait need further improvement to facilitate high throughput evaluation to quantify genotypic differences. In this paper, we aim to develop new (or improve the existing) phenotyping methods for this trait. Preliminary results were obtained using three different methods to quantify BNI: (1) a mass spectrometry method to quantify brachialactone; (2) a static chamber method to quantify N2O emission from soils under greenhouse conditions; and (3) an improved molecular method to quantify microbial populations by Real-Time PCR. Using these three methods we expect to score a bi-parental hybrid population (n=134) of two B. humidicola accessions differing in their BNI capacity CIAT26146 (medium to low BNI) x CIAT16888 (high BNI), in an attempt to identify QTLs associated with the BNI trait

    Bowing of the band gap pressure coefficients in InGaN alloys

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    The hydrostatic pressure dependence of photoluminescence, dEPL/dp, of InxGa1−xN epilayers has been measured in the full composition range 0_x_1. Furthermore, ab initio calculations of the band gap pressure coefficient dEG/dp were performed. Both the experimental dEPL/dp values and calculated dEG/dp results show pronounced bowing and we find that the pressure coefficients have a nearly constant value of about 25 meV/GPa for epilayers with x_0.4 and a relatively steep dependence for x_0.4. On the basis of the agreement of the observed PL pressure coefficient with our calculations, we confirm that band-to-band recombination processes are responsible for PL emission and that no localized states are involved. Moreover, the good agreement between the experimentally determined dEPL/dp and the theoretical curve of dEG/dp indicates that the hydrostatic pressure dependence of PL measurements can be used to quantify changes of the band gap of the InGaN ternary alloy under pressure, demonstrating that the disorder-related Stokes shift in InGaN does not induce a significant difference between dEPL/dp and dEG/dp. This information is highly relevant for the correct analysis of pressure measurement

    Biological Nitrification Inhibition (BNI) in \u3cem\u3eBrachiaria\u3c/em\u3e Pastures: A Novel Strategy to Improve Eco-Efficiency of Crop-Livestock Systems and to Mitigate Climate Change

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    Up to 70% of the nitrogen (N) fertilizers applied to agricultural systems are lost due to nitrification and denitrification. Nitrification is a microbiological process that generates nitrate (NO3-) and promotes the losses of N fertilizers by leaching and denitrification. Nitrification and denitrification are the only known biological processes that generate nitrous oxide (N2O), a powerful greenhouse gas contributing to global warming. There is an urgent need to suppress nitrification process in soil to improve N-recovery and N use efficiency (NUE) of agricultural systems and to mitigate climate change (Subbarao et al. 2012). Certain Brachiaria grasses (B. humidicola) can suppress soil-nitrification by releasing biological nitrification inhibitors (BNIs) from roots, thereby reducing N2O emissions. This phenomenon, termed biological nitrification inhibition (BNI), has been the subject of recent research to characterize and validate the concept under field conditions (Subbarao et al. 2009). Advances on three aspects of BNI research are reported here: (1) gene quantification of soil nitrifying microorganisms to determine BNI activity in B. humidicola; (2) screening of B. humidicola breeding materials to identify hybrids with contrasting levels of BNI: and (3) quantification of the BNI-residual effect from B. humidicola on N-recovery and agronomic-NUE of the subsequent maize crop

    Regulation of Nitrification in Soil: Advances in Integration of \u3cem\u3eBrachiaria\u3c/em\u3e Hybrids to Intensify Agriculture and to Mitigate Climate Change

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    Higher rates of nitrification in soil facilitate nitrogen (N) losses from agricultural systems through nitrate-leaching and denitrification. Plants’ ability to produce and release nitrification inhibitors from roots and suppress soil-nitrifier activity is termed ‘biological nitrification inhibition’ (BNI) (Subbarao et al., 2015). Up to 70% of applied N-fertilizer is lost (via NO3−leaching and gaseous-N emissions) from agricultural systems and the annual economic loss from lost N-fertilizer is estimated at 90 US$ billion. Previous research has indicated that Brachiaria humidicola (Bh), a tropical forage grass that is well adapted to infertile and waterlogged soils, has high capacity to inhibit nitrification in soil and reduce emissions of a highly potent greenhouse gas, nitrous oxide (N2O) (Subbarao et al., 2009). CIAT has an on-going Brachiaria breeding program that generates interspecific (B. decumbens, B. brizantha, B. ruziziensis) and intraspecific (Bh) hybrids that combine several desirable attributes. An interinstitutional and multidisciplinary project was initiated in 2012 to integrate Brachiaria hybrids into crop-livestock systems of smallholders to improve livestock productivity and mitigate climate change by reducing nitrification in soil (Rao et al., 2014). Here we report the major advances from the last three years of work from this project

    CDK19-related disorder results from both loss-of-function and gain-of-function de novo missense variants

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    Purpose To expand the recent description of a new neurodevelopmental syndrome related to alterations in CDK19. Methods Individuals were identified through international collaboration. Functional studies included autophosphorylation assays for CDK19 Gly28Arg and Tyr32His variants and in vivo zebrafish assays of the CDK19(G28R) and CDK19(Y32H). Results We describe 11 unrelated individuals (age range: 9 months to 14 years) with de novo missense variants mapped to the kinase domain of CDK19, including two recurrent changes at residues Tyr32 and Gly28. In vitro autophosphorylation and substrate phosphorylation assays revealed that kinase activity of protein was lower for p.Gly28Arg and higher for p.Tyr32His substitutions compared with that of the wild-type protein. Injection of CDK19 messenger RNA (mRNA) with either the Tyr32His or the Gly28Arg variants using in vivo zebrafish model significantly increased fraction of embryos with morphological abnormalities. Overall, the phenotype of the now 14 individuals with CDK19-related disorder includes universal developmental delay and facial dysmorphism, hypotonia (79%), seizures (64%), ophthalmologic anomalies (64%), and autism/autistic traits (56%). Conclusion CDK19 de novo missense variants are responsible for a novel neurodevelopmental disorder. Both kinase assay and zebrafish experiments showed that the pathogenetic mechanism may be more diverse than previously thought.Peer reviewe

    A etnografia como método de pesquisa em Informática na Educação: Revisão Sistemática de Literatura

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    Etnografia é um método de pesquisa qualitativa pouco citado em pesquisas na área de informática na educação no Brasil. Com o objetivo de demonstrar o potencial de utilização deste método e sua aplicação para a comunidade da área no Brasil, foi realizada uma Revisão Sistemática da Literatura (RSL) na base da Association for Computing Machinery (ACM), avaliando artigos publicados entre 2015 e 2016. O método etnográfico é muito relevante para pesquisas onde o foco está no fator humano, inclusive pesquisas em educação. Assim, consideramos que os resultados deste trabalho podem contribuir para que grupos de pesquisa da área no Brasil conheçam a aplicação do método no contexto internacional, assegurando a assertividade da abordagem etnográfica afim de incentivar sua apropriação pelos pesquisadores área de Informática na Educação, amplificando a confiabilidade dos resultados das pesquisas, e por consequência, beneficiando a prática educacional em seus vários níveis e modalidades

    Technologies, Policies, and Measures for Mitigating Climate Change

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    This Technical Paper provides an overview and analysis of technologies and measures to limit and reduce greenhouse gas (GHG) emissions and to enhance GHG sinks under the United Nations Framework Convention on Climate Change (FCCC). The paper focuses on technologies and measures for the countries listed in Annex I of the FCCC, while noting information as appropriate for use by non- Annex I countries. Technologies and measures are examined over three time periods -- with a focus on the short term (present to 2010) and the medium term (2010-2020), but also including discussion of longer-term (e.g., 2050) possibilities and opportunities. For this analysis, the authors draw on materials used to prepare the IPCC Second Assessment Report (SAR) and previous IPCC assessments and reports. The Technical Paper includes discussions of technologies and measures that can be adopted in three energy end-use sectors (commercial/residential/institutional buildings, transportation, and industry), as well as in the energy supply sector and the agriculture, forestry, and waste management sectors. Broader measures affecting national economies are discussed in a final section on economic instruments. A range of potential measures are analyzed, including market-based programs; voluntary agreements; regulatory measures; research, development, and demonstration (RD&D); taxes on GHG emissions; and emissions permits/quotas. It should be noted that the choice of instruments could have economic impacts on other countries. The paper identifies and evaluates different options on the basis of three criteria. Because of the difficulty of estimating the economic and market potential (see Box 1) of different technologies and the effectiveness of different measures in achieving emission reduction objectives, and because of the danger of double-counting the results achieved by measures that tap the same technical potentials, the paper does not estimate total global emissions reductions. Nor does the paper recommend adoption of any particular approaches
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