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71.
Using a competitive reconstitution assay, we measured the free energy spent in nucleosome formation of eight telomeric DNAs, differing in sequence and/or in length. The obtained values are in satisfactorily good agreement with those derived from a theoretical model that allows the calculation of the free energy of nucleosome formation on the basis of sequence-dependent DNA elasticity, using a statistical thermodynamic approach. Both theoretical and experimental evaluations show that telomeres are characterized by the highest free energies of nucleosome formation among all the DNA sequences so far studied. The free energy of nucleosome formation varies according to the different telomeric sequences and the length of the fragments. Theoretical analysis and experimental mapping by lambda exonuclease show that telomeric nucleosomes occupy multiple positions spaced every telomeric repeat. Sequence-dependent DNA elasticity appears as the main determinant of the stability of telomeric nucleosomes and their multiple translational positioning. 相似文献
72.
Marina Prendes MG García JV Fernández MA Pérez MJ Perazzo JC Savino EA Varela A 《Journal of physiology and biochemistry》2005,61(3):447-456
This investigation aimed to assess whether the mitochondrial ATP-sensitive potassium channel blocker 5-hydroxydecanoate (5-HD) could abolish the protection conferred by fasting and ischemic preconditioning (IPC) and to ascertain whether these effects are associated with glycogen breakdown and glycolytic activity. Langendorff perfused hearts of fed and 24-h fasted rats were exposed to 25 min ischemia plus 30 min reperfusion. IPC was achieved by a 3 min ischemia plus a 5 min reperfusion cycle. 5-HD (100 microM) perfusion begun 5 min before IPC or 13 min before sustained ischemia in the non preconditioned groups. Fasting improved the reperfusion recovery of contraction, decreased the contracture and the lactate production, increased glycogenolysis and did not affect the percentage of viable tissue. 5-HD abolished the effects of fasting on the contractile recovery but did not affect the contracture. 5-HD decreased the lactate production in the fed group, increased the preischemic glycogen content in both nutritional groups and did not affect the ischemic glycogen fall. IPC improved the contractile function but prevented the contracture only in the fed group, reduced lactate accumulation and glycogenolysis and evoked an increase of the viable tissue. 5-HD abolished the effects of IPC on the contractile recovery and did not affect its effect on the contracture, lactate production, glycogenolysis and viable tissue. These data suggest that the mitocondrial ATP-sensitive potassium channel is involved in the effects of fasting and IPC on the contractile function but the other cardioprotective and metabolic effects appear evoked through other mechanisms. Also suggest that besides the inhibition of the mitochondrial potassium channel, other mechanisms mediate the effects of 5-HD. 相似文献
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S R Dalmau C S Freitas W Savino 《Cellular and molecular biology, including cyto-enzymology》2001,47(1):75-86
We used irradiation-induced thymic regression/reconstitution to study phosphotyrosine (PTyr) levels and expression of extracellular matrix receptors in thymocyte subsets by flow cytometry. High PTyr levels (PTyr(hi)) characterized cells from the CD4-CD8-(DN)CD25in/hi to the "early" CD4-CD8+(DP)CD25- stage. Correlation indexes (R) between the percentages of these PTyrhi cells and cells with up-regulated expression of alpha4 integrin (alpha4hi) were strongly positive (R= 0.91, P= 0.002, for DN; R= 0.98, P= 0.0001 for DP). At the "early" DP stage, R between PTyrhi cells and cells with up-regulated expression of alpha5 integrin and L-selectin (alpha5hi and L-sel(hi)) also rendered strongly positive (R>0.95, p<0.0003). "Late" expanding DP cells exhibited intermediate PTyr levels (PTyr(in)), associated with a down-regulation of the adhesion receptors assessed. Triple-labeling suggested that in most early CD3-/lo cells, alpha4hi and alpha5hi, but not L-sel(hi) expression preceded a PTyr(hi) content. CD3in/hi-enriched CD8+ cells were also PTyr(hi), but conversely to the immature ones exhibited a tendency for a negative R between PTyr(hi) and alpha4hi (R = -0.93, P = 0.067, n= 4) or alpha5hi cells (R = -0.77, P = 0.23, n = 4). CD4+ cells were either PTyr(hi) or PTyr(in), exhibiting a tendency for a positive R (R = 0.59, P = 0.124, n= 8) between PTyr(hi) and L-sel(hi) cells only. In conclusion, our results associate an up-regulation of alpha4 and alpha5 chains expression with PTyr(hi) levels and, as elsewhere published, with increased adhesion to fibronectin up to the "early" DP stage, but not afterwards. 相似文献
75.
M Dardenne M Debray-Sachs W Savino J F Bach 《Comptes rendus de l'Académie des sciences. Série III, Sciences de la vie》1984,298(18):523-526
Monoclonal autoantibodies cytotoxic for murine islet cells have been obtained by cell fusion using spleen cells from non-immunized diabetic C57BL/KsJ (db/db) Mice. These monoclonals, of IgG2a subclass, blocked in vitro insulin secretion induced by arginine in Mouse pancreatic cells. 相似文献
76.
Phospholipid composition and phenotypic correction of an envC division mutant of Escherichia coli. 下载免费PDF全文
The cytoplasmic and outer membranes of a nonconditional chain-forming mutant, Escherichia coli PM61 envC, were separated by sucrose density gradient centrifugation. The phosphatidylglycerol/cardiolipin ratio in both membrane fractions was about one-third as high as in the parental strain P678. The increased level of cardiolipin in PM61 membranes is the result of an alteration of the polyglycerophosphatide cycle. It was found that the turnover rate of phosphatidylglycerol is more rapid in PM61 than in the parental strain but that its cardiolipin turnover is not significantly different. The envC mutation can be corrected phenotypically by increasing the osmolarity of the medium. In the presence of 0.6 M sucrose, the population of PM61 is composed of short rods, and the phosphatidylglycerol/cardiolipin ratio is shifted to that of the parent. The phosphatidylglycerol turns over more slowly, whereas the cardiolipin turns over more rapidly in both strains. Thus, the increase of external osmolarity acts on phospholipid metabolism as well as on an unknown step involved in the mechanism of cell division of the envC mutant. 相似文献
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79.
Juliana Barreto-de-Albuquerque Danielle Silva-dos-Santos Ana Rosa Pérez Luiz Ricardo Berbert Eliane de Santana-van-Vliet Désio Aurélio Farias-de-Oliveira Otacilio C. Moreira Eduardo Roggero Carla Eponina de Carvalho-Pinto José Jurberg Vinícius Cotta-de-Almeida Oscar Bottasso Wilson Savino Juliana de Meis 《PLoS neglected tropical diseases》2015,9(6)
Oral transmission of Chagas disease has been documented in Latin American countries. Nevertheless, significant studies on the pathophysiology of this form of infection are largely lacking. The few studies investigating oral route infection disregard that inoculation in the oral cavity (Oral infection, OI) or by gavage (Gastrointestinal infection, GI) represent different infection routes, yet both show clear-cut parasitemia and heart parasitism during the acute infection. Herein, BALB/c mice were subjected to acute OI or GI infection using 5x104 culture-derived Trypanosoma cruzi trypomastigotes. OI mice displayed higher parasitemia and mortality rates than their GI counterparts. Heart histopathology showed larger areas of infiltration in the GI mice, whereas liver lesions were more severe in the OI animals, accompanied by higher Alanine Transaminase and Aspartate Transaminase serum contents. A differential cytokine pattern was also observed because OI mice presented higher pro-inflammatory cytokine (IFN-γ, TNF) serum levels than GI animals. Real-time PCR confirmed a higher TNF, IFN-γ, as well as IL-10 expression in the cardiac tissue from the OI group compared with GI. Conversely, TGF-β and IL-17 serum levels were greater in the GI animals. Immunolabeling revealed macrophages as the main tissue source of TNF in infected mice. The high mortality rate observed in the OI mice paralleled the TNF serum rise, with its inhibition by an anti-TNF treatment. Moreover, differences in susceptibility between GI
versus
OI mice were more clearly related to the host response than to the effect of gastric pH on parasites, since infection in magnesium hydroxide-treated mice showed similar results. Overall, the present study provides conclusive evidence that the initial site of parasite entrance critically affects host immune response and disease outcome. In light of the occurrence of oral Chagas disease outbreaks, our results raise important implications in terms of the current view of the natural disease course and host-parasite relationship. 相似文献
80.
Alfredo Benso Stefano Di Carlo Hafeez ur Rehman Gianfranco Politano Alessandro Savino Prashanth Suravajhala 《Proteome science》2013,11(Z1):S1