945 resultados para Kléber, Gal
Resumo:
Recent work has demonstrated that some actively transcribed genes closely associate with nuclear pore complexes (NPC) at the nuclear periphery. The Saccharomyces cerevisiae Mlp1 and Mlp2 proteins are components of the inner nuclear basket of the nuclear pore that mediate interactions with these active genes. To investigate the physical link between the NPC and active loci, we identified proteins that interact with the carboxyl-terminal globular domain of Mlp1 by tandem affinity purification coupled with mass spectrometry. This analysis led to the identification of several components of the Spt-Ada-Gcn5-acetyltransferase ( SAGA) histone acetyltransferase complex, Gcn5, Ada2, and Spt7. We utilized co-immunoprecipitation and in vitro binding assays to confirm the interaction between the Mlp proteins and SAGA components. Chromatin immunoprecipitation experiments revealed that Mlp1 and SAGA components associate with the same region of the GAL promoters. Critically, this Mlp-promoter interaction depends on the integrity of the SAGA complex. These results identify a physical association between SAGA and the NPC, and support previous results that relied upon visualization of GAL loci at the nuclear periphery by microscopy ( Cabal, G. G. Genovesio, A., Rodriguez-Navarro, S., Zimmer, C., Gadal, O., Lesne, A., Buc, H., Feuerbach- Fournier, F., Olivo-Marin, J.-C., Hurt, E. C., and Nehrbass, U. ( 2006) Nature 441, 770-773). We propose that a physical interaction between nuclear pore components and the SAGA complex can link the actively transcribed GAL genes to the nuclear pore.
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We report a study of the stellar content of the near-infrared (NIR) cluster [DBS2003] 157 embedded in the extended H ii region GAL 331.31-00.34, which is associated with the IRAS source 16085-5138. JHK photometry was carried out in order to identify potential ionizing candidates, and the follow-up NIR spectroscopy allowed the spectral classification of some sources, including two O-type stars. A combination of NIR photometry and spectroscopy data was used to obtain the distance of these two stars, with the method of spectroscopic parallax: IRS 298 (O6 V, 3.35 +/- 0.61 kpc) and IRS 339 (O9 V, 3.24 +/- 0.56 kpc). Adopting the average distance of 3.29 +/- 0.58 kpc and comparing the Lyman continuum luminosity of these stars with that required to account for the radio continuum flux of the H ii region, we conclude that these two stars are the ionizing sources of GAL 331.31-00.34. Young stellar objects (YSOs) were searched by using our NIR photometry and mid-infrared (MIR) data from the Galactic Legacy Infrared Mid-Plane Survey Extraordinaire (GLIMPSE) survey. The analysis of NIR and MIR colourcolour diagrams resulted in 47 YSO candidates. The GLIMPSE counterpart of IRAS 16085-5138, which presents IRAS colour indices compatible with an ultracompact H ii region, has been identified. The analysis of its spectral energy distribution between 2 and m revealed that this source shows a spectral index a= 3.6 between 2 and m, which is typical of a YSO immersed in a protostellar envelope. Lower limits to the bolometric luminosity and the mass of the embedded protostar have been estimated as L= 7.7 x 10(3) L? and M= 10 M?, respectively, which correspond to a B0B1 V zero-age main sequence star.
Resumo:
BACKGROUND: Natural xenoreactive antibodies (Abs) directed against the Bdi-epitope (Gal alpha 1-3Gal beta) on the cells of non-primate mammals take part in hyperacute rejection of xenotransplanted organs. We found that some Abs, which were one-step affinity purified on Bdi-Sepharose, cross-reacted with the disaccharide Gal alpha 1-4GlcNAc beta. The epitope Gal alpha 1-4GlcNAc has not been identified on mammals or bacterial polysaccharides yet. METHODS: To isolate the antibodies of the corresponding specificity the disaccharide was immobilized on Sepharose and antibodies were affinity purified from pooled serum of blood group O individuals. RESULTS: These one-step purified Abs cross-reacted with Bdi, but after a prior absorption step on Bdi-Sepharose no cross-reactivity with Bdi was observed any longer. Surprisingly, the quantity of anti-Gal alpha 1-4GlcNAc isolated from the same serum pool, 4-7 microg/ml, was equal to that of anti-Bdi or more. Independently of ABO blood groups all the tested healthy donors had anti-Gal alpha 1-4GlcNAc Abs at a similar level. Monospecific anti-Gal alpha 1-4GlcNAc Abs were not cytotoxic towards porcine cells. CONCLUSIONS: 1. The actual concentration of monospecific, xenoreactive Gal alpha 1-3Gal beta Abs in blood may be considerably lower than the value referred to in the literature for 'anti-alpha Gal' or 'anti-Galili' antibodies. 2. Anti-Gal alpha 1-4GlcNAc Abs seem not to be important for xenotransplantation.
Resumo:
BACKGROUND: Xenoreactive human natural antibodies (NAb) are predominantly directed against galactose-alpha(1,3)galactose (Gal). Binding of immunoglobulin (Ig) G and IgM NAb activates porcine endothelial cells (pEC) and triggers complement lysis responsible for hyperacute xenograft rejection. In vitro, IgG NAb induce human natural killer (NK) cell-mediated lysis of pEC by antibody-dependent cell-mediated cytotoxicity (ADCC). The present study examined the levels of anti-porcine NAb in a large number of individuals and addressed the functional role of non-Gal anti-porcine NAb. METHODS: Sera from 120 healthy human blood donors were analyzed for the presence of anti-porcine NAb by flow cytometry using porcine red blood cells (pRBC), lymphoblastoid cells (pLCL), and pEC derived from control or Gal-deficient pigs. Xenogeneic complement lysis was measured by flow cytometry using human serum and rabbit complement. ADCC was analyzed by chromium-release assays using human serum and freshly isolated NK cells. RESULTS: Human IgM binding to pRBC was found in 93% and IgG binding in 86% of all samples. Non-Gal NAb comprised 13% of total IgM and 36% of total IgG binding to pEC. NAb/complement-induced lysis and ADCC of Gal-deficient compared to Gal-positive pEC were 21% and 29%, respectively. The majority of anti-Gal and non-Gal IgG NAb were of the IgG2 subclass. CONCLUSIONS: The generation of Gal-deficient pigs has overcome hyperacute anti-Gal-mediated xenograft rejection in nonhuman primates. Non-Gal anti-porcine NAb represent a potentially relevant immunological hurdle in a subgroup of individuals by inducing endothelial damage in xenografts.
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Autore Bonauentura Cornelio Bertramo, vtriusque illius linguae Professore
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Lukas [der Jüngere] Kranach
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[Adolf Anton Lieb]
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hrsg. von Koppelmann Lieben