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To learn whether autophagy might be dependent on any of the major cytoskeletal elements, the effect of various cytoskeleton inhibitors on autophagy and cytoskeletal organization was studied in isolated rat hepatocytes. Autophagy, measured as the sequestration of endogenous lactate dehydrogenase, was completely inhibited in isolated rat hepatocytes by the protein phosphatase inhibitor okadaic acid (30 nM). Only small effects were seen with vinblastine (10 μM) or cytochalasin D (10 μM). Indirect immunofluorescence microscopy with antibody to a 55-kDa cytokeratin, corresponding to human cytokeratin 8 (CK8), revealed that whereas control cells contained a well-organized network of cytokeratin intermediate filaments, okadaic acid disrupted this network into small spherical aggregates. Treatment with cytochalasin D or vinblastine, which disrupt microfilaments and microtubules, respectively, had no detectable effect on the cytokeratin filament distribution. Neither the microtubule network (detected by indirect immunofluorescence with antibodies against α- and β-tubulin) nor the actin microfilament network (detected by rhodamine-palloidin) was disrupted by okadaic acid. Naringin (100 μM), a putative protein kinase-inhibitory flavonoid, offered complete protection against the autophagy-inhibitory and cytokeratin-disruptive effects of okadaic acid. Two other flavonoids, genistein (100 μM) and prunin (100 μM) as well as KN-62 (10 μM), a specific inhibitor of Ca2+/calmodulin-dependent kinase II), likewise displayed a good ability to protect against the effect of okadaic acid upon cytokeratin organization, while no such protection was seen with H-89 (20 μM), an inhibitor of the cyclic nucleotide-dependent protein kinases, or with H-7 (100 μM), which in addition inhibits protein kinase C. The results suggest that the cytokeratin cytoskeleton of hepatocytes is subject to rapid control by phosphorylation and dephosphorylation and that cytokeratin filaments may somehow be involved in the autophagic process. 相似文献
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Structure and function of enzymes acting on chitin and chitosan 总被引:1,自引:0,他引:1
Ingunn A. Hoell Gustav Vaaje-Kolstad 《Biotechnology & genetic engineering reviews》2013,29(1):331-366
Enzymatic conversions of chitin and its soluble, partially deacetylated derivative chitosan are of great interest. Firstly, chitin metabolism is an important process in fungi, insects and crustaceans. Secondly, such enzymatic conversions may be used to transform an abundant biomass to useful products such as bioactive chito-oligosaccharides. Enzymes acting on chitin and chitosan are abundant in nature. Here we review current knowledge on the structure and function of enzymes involved in the conversion of these polymeric substrates: chitinases (glycoside hydrolase families 18 & 19), chitosanases (glycoside hydrolase families 8, 46, 75 & 80) and chitin deacetylases (carbohydrate esterase family 4). 相似文献
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Bente
vreb Tonje H. Stea Ingunn H. Bergh Elling Bere Pl Surn Per Magnus Petur B. Juliusson Andrew K. Wills 《PLoS medicine》2022,19(1)
BackgroundSchool free fruit and vegetable (FFV) policies are used to promote healthy dietary habits and tackle obesity; however, our understanding of their effects on weight outcomes is limited. We assess the effect of a nationwide FFV policy on childhood and adolescent weight status and explore heterogeneity by sex and socioeconomic position.Methods and findingsThis study used a quasi-natural experimental design. Between 2007 and 2014, Norwegian combined schools (grades 1–10, age 6 to 16 years) were obligated to provide FFVs while elementary schools (grades 1–7) were not. We used 4 nationwide studies (n = 11,215 children) from the Norwegian Growth Cohort with longitudinal or cross-sectional anthropometric data up to age 8.5 and 13 years to capture variation in FFV exposure. Outcomes were body mass index standard deviation score (BMISDS), overweight and obesity (OW/OB), waist circumference (WC), and weight to height ratio (WtHR) at age 8.5 years, and BMISDS and OW/OB at age 13 years. Analyses included longitudinal models of the pre- and post-exposure trajectories to estimate the policy effect. The participation rate in each cohort was >80%, and in most analyses <4% were excluded due to missing data. Estimates were adjusted for region, population density, and parental education. In pooled models additionally adjusted for pre-exposure BMISDS, there was little evidence of any benefit or unintended consequence from 1–2.5 years of exposure to the FFV policy on BMISDS, OW/OB, WC, or WtHR in either sex. For example, boys exposed to the FFV policy had a 0.05 higher BMISDS (95% CI: −0.04, 0.14), a 1.20-fold higher odds of OW/OB (95% CI: 0.86, 1.66) and a 0.3 cm bigger WC (95% CI: −0.3, 0.8); while exposed girls had a 0.04 higher BMISDS (95% CI: −0.04, 0.13), a 1.03 fold higher odds of OW/OB (95% CI: 0.75, 1.39), and a 0-cm difference in WC (95% CI: −0.6, 0.6). There was evidence of heterogeneity in the policy effect estimates at 8.5 years across cohorts and socioeconomic position; however, these results were inconsistent with other comparisons. Analysis at age 13 years, after 4 years of policy exposure, also showed little evidence of an effect on BMISDS or OW/OB. The main limitations of this study are the potential for residual confounding and exposure misclassification, despite efforts to minimize their impact on conclusions.ConclusionsIn this study we observed little evidence that the Norwegian nationwide FFV policy had any notable beneficial effect or unintended consequence on weight status among Norwegian children and adolescents.Bente Øvrebø and colleagues assess whether a nationwide free school fruit and vegetable policy was associated with weight outcomes in children and early adolescents in Norway. 相似文献
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This study investigated the possibility of producing pectin-based pellets by extrusion/spheronization. The study also identified factors influencing the process and the characteristics of the resulting product. Three types of pectin with different degrees of amid and methoxyl substitution were studied in combination with different granulation liquids (water, calcium chloride, citric acid, and ethanol) and/or microcrystalline cellulose. Pellets were prepared in a power-consumption-controlled, twinscrew extruder; then they were spheronized and dried. The products were characterized by image analysis, sieving analysis, and disintegration and dissolution tests. The results were evaluated by multivariate analysis. Different additives, either in the granulation liquid or in the powder mixture, influenced the ability of the extruded mass to form pellets (the processability) with this technique. However, the various pectin types responded to modifications to a different extent. Short, nearly spherical pellets are obtained with granulation liquids, such as ethanol, that reduce the swelling ability of pectin. Pellets produced with ethanol are, however, mechanically weak and tend to ditintegrate. Pectin molecules with a high degree of free carboxylic acid groups seem to be more sensitive to changes in the granulation liquid. Addition of microcrystalline cellulose as an extrusion aid generally resulted in improvements in shape and size. It was demonstrated that the processability of pectin as well as the characteristics of the products can be influenced in different ways during the process (eg, adding substances to the granulation liquid or to the powder mixture). 相似文献
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Purpose. The aim of this study was to improve the formation of spherical pectin pellets by investigating the effect of additive concentration in the granulation liquid on the shape and size of the products as well as by identifying an optimal additive concentration.Methods. High-methoxylated, low-methoxylated, and amidated low-methoxylated pectin types were evaluated in combination with different concentrations of methanol, ethanol, citric acid, lactic acid, and calcium chloride. Pellets were prepared in a power-consumption-controlled twin-screw extruder, then spheronized and dried. The moisture content of the extrudate was determined, and the final products were characterized by image analysis and sieving analysis. A cloud point test was employed for the identification of an optimal additive concentration.Results. The concentration of additive in the granulation liquid affected the moisture content of the extrudate and the shape, size, and mechanical stability of the pectin pellets. Improvements in the pellet characteristics are dependent on the pectin type employed. The 2 low-methoxylated pectins were more sensitive to concentration changes than was the high-methoxylated type. Above a certain threshold concentration, the quality of the pellets are improved. This additive concentration differs according to type of pectin and type of additive.Conclusion. It was demonstrated that there is a concentration-dependent interaction between pectin and substances added to the granulation liquid that can be utilized to improve the formation of spherical pectin pellets. 相似文献
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Lunde E Western KH Rasmussen IB Sandlie I Bogen B 《Journal of immunology (Baltimore, Md. : 1950)》2002,168(5):2154-2162
A major objective in vaccine development is the design of reagents that give strong, specific T cell responses. We have constructed a series of rAb with specificity for MHC class II (I-E). Each has one of four different class II-restricted T cell epitopes genetically introduced into the first C domain of the H chain. These four epitopes are: 91-101 lambda2(315), which is presented by I-E(d); 110-120 hemagglutinin (I-E(d)); 323-339 OVA (I-A(d)); and 46-61 hen egg lysozyme (I-A(k)). We denote such APC-specific, epitope-containing Ab "Troybodies." When mixed with APC, all four class II-specific Troybodies were approximately 1,000 times more efficient at inducing specific T cell activation in vitro compared with nontargeting peptide Ab. Furthermore, they were 1,000-10,000 times more efficient than synthetic peptide or native protein. Conventional intracellular processing of the Troybodies was required to load the epitopes onto MHC class II. Different types of professional APC, such as purified B cells, dendritic cells, and macrophages, were equally efficient at processing and presenting the Troybodies. In vivo, class II-specific Troybodies were at least 100 times more efficient at targeting APC and activating TCR-transgenic T cells than were the nontargeting peptide Ab. Furthermore, they were 100-100,000 times more efficient than synthetic peptide or native protein. The study shows that class II-specific Troybodies can deliver a variety of T cell epitopes to professional APC for efficient presentation, in vitro as well as in vivo. Thus, Troybodies may be useful as tools in vaccine development. 相似文献
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H?kon Dahle Ingeborg ?kland Ingunn H Thorseth Rolf B Pederesen Ida H Steen 《The ISME journal》2015,9(7):1593-1606
Methods developed in geochemical modelling combined with recent advances in molecular microbial ecology provide new opportunities to explore how microbial communities are shaped by their chemical surroundings. Here, we present a framework for analyses of how chemical energy availability shape chemotrophic microbial communities in hydrothermal systems through an investigation of two geochemically different basalt-hosted hydrothermal systems on the Arctic Mid-Ocean Ridge: the Soria Moria Vent field (SMVF) and the Loki''s Castle Vent Field (LCVF). Chemical energy landscapes were evaluated through modelling of the Gibbs energy from selected redox reactions under different mixing ratios between seawater and hydrothermal fluids. Our models indicate that the sediment-influenced LCVF has a much higher potential for both anaerobic and aerobic methane oxidation, as well as aerobic ammonium and hydrogen oxidation, than the SMVF. The modelled energy landscapes were used to develop microbial community composition models, which were compared with community compositions in environmental samples inside or on the exterior of hydrothermal chimneys, as assessed by pyrosequencing of partial 16S rRNA genes. We show that modelled microbial communities based solely on thermodynamic considerations can have a high predictive power and provide a framework for analyses of the link between energy availability and microbial community composition. 相似文献
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Lumbwe Chola Lars T. Fadnes Ingunn M. S. Engebretsen Lungiswa Nkonki Victoria Nankabirwa Halvor Sommerfelt James K. Tumwine Thorkild Tylleskar Bjarne Robberstad PROMISE-EBF Study Group 《PloS one》2015,10(11)