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The extraembryonic endoderm of the elongating ovine conceptus was analyzed by scanning and transmission electron microscopy and by whole mount actin staining and immunofluorescence. Morphological and functional differences between the visceral endoderm (VE), the founding cell layer, and the parietal endoderm (PE) are presented. During the elongation process, the PE differentiated to fusiform multinucleated cells aligned parallel to the elongation axis of the conceptus, whereas the VE cells retained the aspect of typical epithelial cells. The multinucleated PE cells however, expressed cellular and nuclear markers typical of endodermal and polarized epithelial cells. The proteins of the extracellular matrix, laminin, and fibronectin, were specifically expressed in the PE. The presence of pairs of nuclei linked by mid-bodies positively stained with tubulin antibodies, indicated that the syncytial differentiation of the PE was due to karyokinesis which was not followed by cytokinesis rather than by cell fusion. 相似文献
84.
Susi Anheuser Bernadette Breiden Günter Schwarzmann Konrad Sandhoff 《Journal of lipid research》2015,56(9):1747-1761
Ganglioside GM2 is the major lysosomal storage compound of Tay-Sachs disease. It also accumulates in Niemann-Pick disease types A and B with primary storage of SM and with cholesterol in type C. Reconstitution of GM2 catabolism with β-hexosaminidase A and GM2 activator protein (GM2AP) at uncharged liposomal surfaces carrying GM2 as substrate generated only a physiologically irrelevant catabolic rate, even at pH 4.2. However, incorporation of anionic phospholipids into the GM2 carrying liposomes stimulated GM2 hydrolysis more than 10-fold, while the incorporation of plasma membrane stabilizing lipids (SM and cholesterol) generated a strong inhibition of GM2 hydrolysis, even in the presence of anionic phospholipids. Mobilization of membrane lipids by GM2AP was also inhibited in the presence of cholesterol or SM, as revealed by surface plasmon resonance studies. These lipids also reduced the interliposomal transfer rate of 2-NBD-GM1 by GM2AP, as observed in assays using Förster resonance energy transfer. Our data raise major concerns about the usage of recombinant His-tagged GM2AP compared with untagged protein. The former binds more strongly to anionic GM2-carrying liposomal surfaces, increases GM2 hydrolysis, and accelerates intermembrane transfer of 2-NBD-GM1, but does not mobilize membrane lipids. 相似文献
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Pages N Maurois P Delplanque B Bac P Martin JC Du Q Rapoport SI Vamecq J 《Prostaglandins, leukotrienes, and essential fatty acids》2011,85(2):53-60
Diets given for 30 days with various mono-(MUFA) and poly-(PUFA) unsaturated fatty acid contents were evaluated for brain protection in magnesium-deficient mice: a commercial and three synthetic diets (n-6PUFA, n-3PUFA and MUFA-based chows enriched with 5% corn/sunflower oils 1:3, with 5% rapeseed oil and with 5% high oleic acid sunflower oil/sunflower oil 7:3, respectively). Unlike magnesium deprivation, they induced significant differences in brain and erythrocyte membrane phospholipid fatty acid compositions. n-3PUFA but not other diets protected magnesium-deficient mice against hyperactivity and moderately towards maximal electroshock- and NMDA-induced seizures. This diet also inhibited audiogenic seizures by 50%, preventing animal deaths. Because, like n-6PUFA diet, matched control MUFA diet failed to induce brain protections, alpha-linolenate (ALA) rather than reduced n-6 PUFA diet content is concluded to cause n-3PUFA neuroprotection. Present in vivo data also corroborate literature in vitro inhibition of T type calcium channels by n-3 PUFA, adding basis to ALA supplementation in human anti-epileptic/neuroprotective strategies. 相似文献
87.
Dyson A Bryan NS Fernandez BO Garcia-Saura MF Saijo F Mongardon N Rodriguez J Singer M Feelisch M 《Free radical biology & medicine》2011,51(6):1137-1145
Most studies examining the metabolic fate of NO during systemic inflammation have focused on measuring the quantitatively predominating, stable anions nitrite and nitrate within the circulation. However, these are not necessarily the NO-related products that govern NO metabolism and signaling in tissues. We assessed all major NO derivatives temporally in blood and vital organs during inflammation and explored their relationship to insult severity and redox status. Male rats receiving intraperitoneal endotoxin or vehicle were sacrificed for organ and blood sampling between 0 and 24 h. Endotoxin induced transient and organ-specific changes in a variety of NO metabolites. Nitrite and nitrate increased, peaking at 8 and 12 h, respectively. S- and N-nitrosation and heme-nitrosylation products also peaked at 8 h; these posttranslational protein modifications were associated with decreased myocardial function (echocardiography). Evidence of oxidative stress and systemic inflammation was also obtained. The rise in most NO derivatives was proportional to insult severity. All metabolite levels normalized within 24 h, despite evidence of persisting myocardial dysfunction and clinical unwellness. Our findings point to a complex interplay between NO production, antioxidant defense, and redox status. Although the precise (patho)physiologic roles of specific NO derivatives and their diagnostic/prognostic utility await further investigation, nitroso species in erythrocytes are the most sensitive markers of NO in systemic inflammation, detectable before clinical symptoms manifest. 相似文献
88.
Aweda TA Eskandari V Kukis DL Boucher DL Marquez BV Beck HE Mitchell GS Cherry SR Meares CF 《Bioconjugate chemistry》2011,22(8):1479-1483
We describe the synthesis and development of new reactive DOTA-metal complexes for covalently targeting engineered receptors in vivo, which have superior tumor uptake and clearance properties for biomedical applications. These probes are found to clear efficiently through the kidneys and minimally through other routes, but bind persistently in the tumor target. We also explore the new technique of Cerenkov luminescence imaging to optically monitor radiolabeled probe distribution and kinetics in vivo. Cerenkov luminescence imaging uniquely enables sensitive noninvasive in vivo imaging of a β(-) emitter such as (90)Y with an optical imager. 相似文献
89.
Arnaud Foulquier Florian Mermillod-Blondin Bernard Montuelle Sylvain Dolédec Bernadette Volat Janine Gibert 《Ecosystems》2011,14(8):1339-1353
Groundwaters are increasingly viewed as resource-limited ecosystems in which fluxes of dissolved organic carbon (DOC) from
surface water are efficiently mineralized by a consortium of microorganisms which are grazed by invertebrates. We tested for
the effect of groundwater recharge on resource supply and trophic interactions by measuring physico-chemistry, microbial activity
and biomass, structure of bacterial communities and invertebrate density at three sites intensively recharged with surface
water. Comparison of measurements made in recharge and control well clusters at each site showed that groundwater recharge
significantly increased fluxes of DOC and phosphate, elevated groundwater temperature, and diminished dissolved oxygen (DO).
Microbial biomass and activity were significantly higher in recharge well clusters but stimulation of autochthonous microorganisms
was not associated with a major shift in bacterial community structure. Invertebrate assemblages were not significantly more
abundant in recharge well clusters and did not show any relationship with microbial biomass and activity. Microbial communities
were bottom-up regulated by DOC and nutrient fluxes but trophic interactions between microorganisms and invertebrates were
apparently limited by environmental stresses, particularly DO depletion and groundwater warming. Hydrological connectivity
is a key factor regulating the function of DOC-based groundwater food webs as it influences both resource availability for
microorganisms and environmental stresses which affect energy transfer to invertebrates and top-down control on microorganisms. 相似文献