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51.
Leslie E. Stefanyk Nicole Coverdale Brian D. Roy Sandra J. Peters Paul J. LeBlanc 《The Journal of membrane biology》2010,234(3):207-215
The phospholipid composition of membranes can influence the physiological functioning of the cell or subcellular organelle.
This association has been previously demonstrated in skeletal muscle, where cellular or subcellular membrane, specifically
mitochondria, phospholipid composition is linked to muscle function. However, these observations are based on whole mixed
skeletal muscle analysis, with little information on skeletal muscles of differing fiber-type compositions. These past approaches
that used mixed muscle may have misidentified outcomes or masked differences. Thus, the purpose of this study was to compare
the phospholipid fatty acid composition of subsarcolemmal (SS) mitochondria isolated from slow-twitch postural (soleus), fast-twitch
highly oxidative glycolytic locomotory (red gastrocnemius), and fast-twitch oxidative glycolytic locomotory (plantaris) skeletal
muscles. The main findings of the study demonstrated unique differences between SS mitochondrial membranes from postural soleus
compared to the other locomotory skeletal muscles examined, specifically lower percentage mole fraction of phosphatidylcholine
(PC) and significantly higher percentage mole fraction of saturated fatty acids (SFA) and lower n6 polyunsaturated fatty acids
(PUFA), resulting in a lower unsaturation index. We also found that although there was no difference in the percentage mole
fraction of cardiolipin (CL) between skeletal muscle types examined, CL of soleus mitochondrial membranes were approximately
twofold more SFA and approximately two-thirds less PUFA, resulting in a 20–30% lower unsaturation and peroxidation indices.
Thus, the results of this study indicate unique membrane lipid composition of mitochondria isolated from different skeletal
muscle types, a potential consequence of their respective duty cycles. 相似文献
52.
We develop a new method for describing patient characteristics associated with extreme good or poor outcome. We address the problem with a regression model composed of extrema (maximum and minimum) functions of the predictor variables. This class of models allows for simple regression function inversion and results in level sets of the regression function which can be expressed as interpretable Boolean combinations of decisions based on individual predictors. We develop an estimation algorithm and present clinical applications to symptoms data for patients with Hodgkin's disease and survival data for patients with multiple myeloma. 相似文献
53.
Membrane lipid composition is thought to influence the function of integral membrane proteins; however, the potential for
lipid composition to influence overall mitochondrial long-chain fatty acids (LCFA) oxidation is currently unknown. Therefore,
the naturally occurring variability of LCFA oxidation rates within subsarcolemmal (SS) and intermyofibrillar (IMF) mitochondria
in muscles with varying oxidative potentials (heart → red → white) was utilized to examine this relationship. To this end,
SS and IMF mitochondria were isolated and palmitate oxidation rates were compared to membrane phospholipid composition. Among
tissues, rates of palmitate oxidation in mitochondria displayed a 2.5-fold range, creating the required range to determine
potential relationships with membrane lipid composition. In general, the percent mole fraction of phospholipid head groups
and major fatty acid subclasses were similar in all mitochondria studied. However, rates of palmitate oxidation were positively
correlated with both the unsaturation index and relative abundance of cardiolipin within mitochondria (r = 0.57 and 0.49, respectively; p < 0.05). Thus, these results suggest that mitochondrial LCFA oxidation may be significantly influenced by the total unsaturation
and percent mole fraction of cardiolipin of the mitochondrial membrane, whereas other indices of membrane structure (e.g.,
percent mole fraction of other predominant membrane phospholipids, chain length, and ratio of phosphatidylcholine to phosphatidylethanolamine)
were not significantly correlated. 相似文献
54.
Patrauchan MA Miyazawa D LeBlanc JC Aiga C Florizone C Dosanjh M Davies J Eltis LD Mohn WW 《Applied and environmental microbiology》2012,78(18):6714-6725
Rhodococcus jostii RHA1, a catabolically diverse soil actinomycete, is highly resistant to long-term nutrient starvation. After 2 years of carbon starvation, 10% of the bacterial culture remained viable. To study the molecular basis of such resistance, we monitored the abundance of about 1,600 cytosolic proteins during a 2-week period of carbon source (benzoate) starvation. Hierarchical cluster analysis elucidated 17 major protein clusters and showed that most changes occurred during transition to stationary phase. We identified 196 proteins. A decrease in benzoate catabolic enzymes correlated with benzoate depletion, as did induction of catabolism of alternative substrates, both endogenous (lipids, carbohydrates, and proteins) and exogenous. Thus, we detected a transient 5-fold abundance increase for phthalate, phthalate ester, biphenyl, and ethyl benzene catabolic enzymes, which coincided with at least 4-fold increases in phthalate and biphenyl catabolic activities. Stationary-phase cells demonstrated an ~250-fold increase in carbon monoxide dehydrogenase (CODH) concurrent with a 130-fold increase in CODH activity, suggesting a switch to CO or CO(2) utilization. We observed two phases of stress response: an initial response occurred during the transition to stationary phase, and a second response occurred after the cells had attained stationary phase. Although SigG synthesis was induced during starvation, a ΔsigG deletion mutant showed only minor changes in cell survival. Stationary-phase cells underwent reductive cell division. The extreme capacity of RHA1 to survive starvation does not appear to involve novel mechanisms; rather, it seems to be due to the coordinated combination of earlier-described mechanisms. 相似文献
55.
56.
Daniela Pontes Silvia Innocentin Silvina del Carmen Juliana Franco Almeida Jean-Guy LeBlanc Alejandra de Moreno de LeBlanc Sébastien Blugeon Claire Cherbuy Fran?ois Lefèvre Vasco Azevedo Anderson Miyoshi Philippe Langella Jean-Marc Chatel 《PloS one》2012,7(9)
Lactococci are noninvasive lactic acid bacteria frequently used as protein delivery vectors and, more recently, as DNA delivery vehicles. We previously showed that Lactococcus lactis (LL) expressing the Fibronectin-Binding Protein A of Staphylococcus aureus (LL-FnBPA+) showed higher internalization rates in vitro in Caco-2 cells than the native (wt) lactococci and were able to deliver a eukaryotic Green Fluorescent Protein (GFP) expression plasmid in 1% of human Caco-2 cells. Here, using the bovine beta-lactoglobulin (BLG), one of the major cow''s milk allergen, and GFP we characterized the potential of LL-FnBPA+ as an in vivo DNA vaccine delivery vehicle. We first showed that the invasive strain LL-FnBPA+ carrying the plasmid pValac:BLG (LL-FnBPA+ BLG) was more invasive than LL-BLG and showed the same invasivity as LL-FnBPA+. Then we demonstrated that the Caco-2 cells, co-incubated with LL-FnBPA+ BLG produced up to 30 times more BLG than the Caco-2 cells co-incubated with the non invasive LL-BLG. Using two different gene reporters, BLG and GFP, and two different methods of detection, EIA and fluorescence microscopy, we showed in vivo that: i) in order to be effective, LL-FnBPA+ required a pre-coating with Fetal Calf Serum before oral administration; ii) plasmid transfer occurred in enterocytes without regard to the strains used (invasive or not); iii) the use of LL-FnBPA+ increased the number of mice producing BLG, but not the level of BLG produced. We thus confirmed the good potential of invasive recombinant lactic acid bacteria as DNA delivery vector in vivo. 相似文献
57.
White RM Sessa A Burke C Bowman T LeBlanc J Ceol C Bourque C Dovey M Goessling W Burns CE Zon LI 《Cell Stem Cell》2008,2(2):183-189
The zebrafish is a useful model for understanding normal and cancer stem cells, but analysis has been limited to embryogenesis due to the opacity of the adult fish. To address this, we have created a transparent adult zebrafish in which we transplanted either hematopoietic stem/progenitor cells or tumor cells. In a hematopoiesis radiation recovery assay, transplantation of GFP-labeled marrow cells allowed for striking in vivo visual assessment of engraftment from 2 hr-5 weeks posttransplant. Using FACS analysis, both transparent and wild-type fish had equal engraftment, but this could only be visualized in the transparent recipient. In a tumor engraftment model, transplantation of RAS-melanoma cells allowed for visualization of tumor engraftment, proliferation, and distant metastases in as little as 5 days, which is not seen in wild-type recipients until 3 to 4 weeks. This transparent adult zebrafish serves as the ideal combination of both sensitivity and resolution for in vivo stem cell analyses. 相似文献
58.
Nicolette S Bradley George J F Heigenhauser Brian D Roy Elizabeth M Staples J Greig Inglis Paul J LeBlanc Sandra J Peters 《Journal of applied physiology》2008,104(1):1-9
Pyruvate dehydrogenase (PDH) is an important regulator of carbohydrate oxidation during exercise, and its activity can be downregulated by an increase in dietary fat. The purpose of this study was to determine the acute metabolic effects of differential dietary fatty acids on the activation of the PDH complex (PDHa activity) at rest and at the onset of moderate-intensity exercise. University-aged male subjects (n = 7) underwent two fat-loading trials spaced at least 2 wk apart. Subjects consumed approximately 300 g saturated (SFA) or n-6 polyunsaturated fatty acid (PUFA) fat over the course of 5 h. Following this, participants cycled at 65% of their maximum oxygen uptake for 15 min. Muscle biopsies were taken before and following fat loading and at 1 min exercise. Plasma free fatty acids increased from 0.15 +/- 0.07 to 0.54 +/- 0.19 mM over 5 h with SFA and from 0.11 +/- 0.04 to 0.35 +/- 0.13 mM with n-6 PUFA and were significantly lower throughout the n-6 PUFA trial. PDHa activity was unchanged following fat loading but increased at the onset of exercise in the SFA trial, from 1.18 +/- 0.27 to 2.16 +/- 0.37 mmol x min(-1) x kg wet wt(-1). This effect was negated in the n-6 PUFA trial (1.04 +/- 0.20 to 1.28 +/- 0.36 mmol x min(-1) x kg wet wt(-1)). PDH kinase was unchanged in both trials, suggesting that the attenuation of PDHa activity with n-6 PUFA was a result of changes in the concentrations of intramitochondrial effectors, potentially intramitochondrial NADH or Ca(2+). Our findings suggest that attenuated PDHa activity contributes to the preferential oxidation of n-6 PUFA during moderate-intensity exercise. 相似文献
59.
Rhodobacter capsulatus contains lhaA and pucC genes that have been implicated in light-harvesting complex 1 and 2 (LH1 and LH2) assembly. The proteins encoded by these
genes, and homologues in other photosynthetic organisms, have been classified as the bacteriochlorophyll delivery (BCD) family
of the major facilitator superfamily. A new BCD family phylogenetic tree reveals that several PucC, LhaA and Orf428-related
sequences each form separate clusters, while plant and cyanobacterial homologues cluster more distantly. The PucC protein
is encoded in the pucBACDE superoperon which also codes for LH2 α (PucA) and β (PucB) proteins. PucC was previously shown to be necessary for formation
of LH2. This article gives evidence indicating that PucC has a shepherding activity that keeps the homologous α and β proteins
of LH1 and LH2 apart, allowing LH1 to assemble properly. This shepherding function was indicated by a 62% reduction in LH1
levels in ΔLHII strains carrying plasmids encoding pucBA along with a C-terminally truncated pucC gene. More severe reductions in LH1 were seen when the truncated pucC gene was co-expressed in the presence of C-terminal PucC::PhoA fusion proteins. It appears that interaction between truncated
PucC::PhoA fusion proteins and the truncated PucC protein disrupts LH1 assembly, pointing towards a PucC dimeric or multimeric
functional unit. 相似文献
60.
LeBlanc AJ Shipley RD Kang LS Muller-Delp JM 《American journal of physiology. Heart and circulatory physiology》2008,295(6):H2280-H2288
Impairment of flow-induced vasodilation in coronary resistance arterioles may contribute to the decline in coronary vasodilatory reserve that occurs with advancing age. This study investigated the effects of age on flow-induced signaling and activation of nitric oxide (NO)-mediated vasodilation in coronary resistance arterioles. Coronary arterioles were isolated from young (approximately 6 mo) and old (approximately 24 mo) male Fischer-344 rats to assess vasodilation to flow, vascular endothelial growth factor (VEGF), and ACh. Flow- and VEGF-induced vasodilation of coronary arterioles was impaired with age (P相似文献