Intrinsic disorder: signaling via highly specific but short-lived association

Association between signaling proteins and their cellular targets is generally thought to be highly specific (implicating a high association constant, K(a)) and, at the same time, transient or short-lived (corresponding to a high dissociation rate constant, k(d)). However, a combination of high K(a) and high k(d) would lead to a high association rate constant (k(a) = K(a)k(d)), which poses a problem because there is a limit to which k(a) can be increased, set by the diffusional approach to form the complex. In this Opinion article, I propose that having the signaling protein disordered before binding to the target provides a way out of this quandary. The intrinsic disorder of the signaling protein would decrease K(a) without sacrificing the specificity of the complex, and thus would allow k(d) to be increased to a range appropriate for signaling.     

Roles of Lignin Peroxidase and Manganese Peroxidase from Phanerochaete chrysosporium in the Decolorization of Olive Mill Wastewaters

The relative contributions of lignin peroxidase (LiP) and manganese peroxidase (MnP) to the decolorization of olive mill wastewaters (OMW) by Phanerochaete chrysosporium were investigated. A relatively low level (25%) of OMW decolorization was found with P. chrysosporium which was grown in a medium with a high Mn(II) concentration and in which a high level of MnP (0.65 (mu)M) was produced. In contrast, a high degree of OMW decolorization (more than 70%) was observed with P. chrysosporium which was grown in a medium with a low Mn(II) concentration but which resulted in a high level of LiP activity (0.3 (mu)M). In this culture medium, increasing the Mn(II) concentration resulted in decreased levels of OMW decolorization and LiP activity. Decolorization by reconstituted cultures of P. chrysosporium was found to be more enhanced by the addition of isolated LiP than by the addition of isolated MnP. The highest OMW decolorization levels were obtained at low initial chemical oxygen demands combined with high levels of extracellular LiP. These data, plus the positive effect of veratryl alcohol on OMW decolorization and LiP activity, indicate that culture conditions which yield high levels of LiP activity lead to high levels of OMW decolorization.     

Frequent occurrence of familial aggregations of high lipoprotein(a) levels associated with small apolipoprotein(a) isoforms

School-age children with high lipoprotein(a) [Lp(a)] levels were screened and family studies were conducted to examine the relationship between high Lp(a) levels and apolipoprotein(a) [apo(a)] isoforms in families. All the probands from 17 families had one of the A2 to A12 apo(a) isoforms, which are the smaller apo(a) isoforms of the 25 different isoforms thus far detected. The ratio of subjects with high plasma Lp(a) levels was 0.47 among the first-degree relatives. All 15 relatives with high plasma Lp(a) levels shared one of the small apo(a) isoforms with the proband in each family, while 16 of 17 relatives with normal Lp(a) levels did not. These data indicate the frequent occurrence of familial aggregations of high Lp(a) levels associated with one of the small apo(a) isoforms.     

MHC class II expression identifies functionally distinct human regulatory T cells

It has been known for decades that circulating human CD4 cells can express functional MHC class II molecules that induce T cell nonresponsiveness with Ag presentation. Because there is significant expression of MHC class II (MHC-II) determinants (DR) on a subpopulation CD4+ CD25(high) regulatory T cells (Treg), we examined the function of CD4 cells expressing MHC-DR. We demonstrate that MHC-II expression on human CD4+ CD25(high) T cells identifies a functionally distinct population of Treg that induces early contact-dependent suppression that is associated with high Foxp3 expression. In striking contrast, MHC-II- CD4+ CD25(high) Treg induce early IL-4 and IL-10 secretion and a late Foxp3-associated contact-dependent suppression. The DR expressing CD25(high) Treg express higher levels of Foxp3 message and protein, compared with the DR- CD25(high) Treg population. Direct single-cell cloning of CD4+ CD25(high) Treg revealed that, regardless of initial DR expression, ex vivo expression of CD25(high), and not DR, predicted which clones would exhibit contact-dependent suppression, high levels of Foxp3 message, and an increased propensity to become constitutive for DR expression. Thus, the direct ex vivo expression of MHC-II in the context of CD25(high) identifies a mature, functionally distinct regulatory T cell population involved in contact-dependent in vitro suppression.     

Comparative study of nitrogen and oxygen metabolism enzymes in Yugoslav cultivars of alfalfa (Medicago sativa L.)

Four Yugoslav cultivars of alfalfa were investigated in order to determine nitrogen fixing (nitrogenase), nitrogen assimilation (nitrate reductase, glutamine synthetase, glutamate dehydrogenase) and antioxidant (Superoxide dismutase, catalase, peroxidase) enzymes activities. The level of lipid peroxidation and protein content were also investigated. On the basis of the results obtained a resistant cultivar with high nitrogen fixing and a cultivar with high nitrogen assimilation abilities were chosen. The cultivar with high nitrogen fixing ability had high activities of nitrogenase, Superoxide dismutase, peroxidase and catalase, and also a low level of lipid peroxidation. The cultivar with high assimilation ability had high activities of nitrate reductase, glutamine synthetase and glutamate dehydrogenase and high soluble protein content.     

Polyethylene glycol-modified GM-CSF expands CD11b(high)CD11c(high) but notCD11b(low)CD11c(high) murine dendritic cells in vivo: a comparative analysis with Flt3 ligand

Dendritic cells (DC) are potent APCs that can be characterized in the murine spleen as CD11b(high)CD11c(high) or CD11b(low)CD11c(high). Daily injection of mice of Flt3 ligand (FL) into mice transiently expands both subsets of DC in vivo, but the effect of administration of GM-CSF on the expansion of DC in vivo is not well defined. To gain further insight into the role of GM-CSF in DC development and function in vivo, we treated mice with polyethylene glycol-modified GM-CSF (pGM-CSF) which has an increased half-life in vivo. Administration of pGM-CSF to mice for 5 days led to a 5- to 10-fold expansion of CD11b(high)CD11c(high) but not CD11b(low)CD11c(high) DC. DC from pGM-CSF-treated mice captured and processed Ag more efficiently than DC from FL-treated mice. Although both FL- and pGM-CSF-generated CD11b(high)CD11c(high) DC were CD8alpha-, a greater proportion of these DC from pGM-CSF-treated mice were 33D1+ than from FL-treated mice. CD11b(low)CD11c(high) DC from FL-treated mice expressed high levels of intracellular MHC class II. DC from both pGM-CSF- and FL-treated mice expressed high levels of surface class II, low levels of the costimulatory molecules CD40, CD80, and CD86 and were equally efficient at stimulating allogeneic and Ag-specific T cell proliferation in vitro. The data demonstrate that treatment with pGM-CSF in vivo preferentially expands CD11b(high)CD11c(high) DC that share phenotypic and functional characteristics with FL-generated CD11b(high)CD11c(high) DC but can be distinguished from FL-generated DC on the basis of Ag capture and surface expression of 33D1.     

Ultrahigh‐Energy‐Density Lithium‐Ion Batteries Based on a High‐Capacity Anode and a High‐Voltage Cathode with an Electroconductive Nanoparticle Shell

The combination of high‐capacity anodes and high‐voltage cathodes has garnered a great deal of attention in the pursuit of high‐energy‐density lithium‐ion batteries. As a facile and scalable electrode‐architecture strategy to achieve this goal, a direct one‐pot decoration of high‐capacity silicon (Si) anode materials and of high‐voltage LiCoO₂ (LCO) cathode materials is demonstrated with colloidal nanoparticles composed of electroconductive antimony‐doped tin oxide (ATO). The unusual ATO nanoparticle shells enhance electronic conduction in the LCO and Si electrode materials and mitigate unwanted interfacial side reactions between the electrode materials and liquid electrolytes. The ATO‐coated LCO materials (ATO‐LCO) enable the construction of a high‐mass‐loading cathode and suppress the dissolution of cobalt and the generation of by‐products during high‐voltage cycling. In addition, the ATO‐coated Si (ATO‐Si) anodes exhibit highly stable capacity retention upon cycling. Integration of the high‐voltage ATO‐LCO cathode and high‐capacity ATO‐Si anode into a full cell configuration brings unprecedented improvements in the volumetric energy density and in the cycling performance compared to a commercialized cell system composed of LCO/graphite.     

Insulin and glucagon binding to hepatocytes in relation to circulating hormones and metabolites in goats maintained on different diets

Insulin and glucagon receptors were measured on hepatocytes in relation to circulating hormones (insulin, glucagon and growth hormone) and metabolites (non-esterified fatty acids, volatile fatty acids, glucose, total lipids, urea and alpha-amino nitrogen), in twelve, two-year old, castrated male goats, fed rations of different composition and dietary energy. The goats were separated into four groups; group 1 was fed a restricted ration of 600 g clover hay/day, group 2 a ration high in carbohydrate (rolled barley), group 3 a ration high in fat (protected tallow) and group 4 a ration high in protein (fish meal). Rations in groups 2 - 4 were fed at 1300 g/day supplemented with 600 g of clover hay. The binding of insulin to hepatocyte receptors was increased by restricting dietary intake when compared to the high energy intake groups (p less than 0.01). There was no significant difference between the insulin binding of groups 2 -4. Glucagon receptor binding was increased on the high protein diet in comparison with th ration high in carbohydrate (p less than 0.05) or in fat (p less than 0.01). The glucagon binding was reduced by restricting feed intake when compared wih feeding high protein (p less than 0.02), but slightly increased when compared with feeding diets high in both carbohydrate or fat (p less than 0.02). There was no significant difference between the high carbohydrate or high fat fed groups. These changes in hormone receptors were accompanied by inverse changes in plasma insulin and glucagon.     

Effect of high shear on proteins

Shear is present in almost all bioprocesses and high shear is associated with processes involving agitation and emulsification. The purpose of this study is to investigate the effect of high shear and high shear rate on proteins. Two concentric cylinder-based shear systems were used. One was a closed concentric-cylinder shear device (CCSD) and the other was a homogenizer with a rotor/stator assembly. Mathematical modeling of these systems allowed calculation of the shear rate and shear. The CCSD generated low shear rates (a few hundred s(-1)), whereas the homogenizer could generate very high shear rates (> 10(5) s(-1)). High shear could be achieved in both systems by increasing the processing time. Recombinant human growth hormone (rhGH) and recombinant human deoxyribonuclease (rhDNase) were used as the model proteins in this study. It was found that neither high shear nor high shear rate had a significant effect on protein aggregation. However, a lower melting temperature and enthalpy were detected for highly sheared rhGH by using scanning microcalorimetry, presumably due to some changes in protein's conformation. Also, SDS-PAGE indicated the presence of low molecular-weight fragments, suggesting that peptide bond breakage occurred due to high shear. rhDNase was relatively more stable than rhGH under high shear. No conformational changes and protein fragments were observed. (c) 1996 John Wiley & Sons, Inc.     

Examining Associations between Health Information Seeking Behavior and Adult Education Status in the U.S.: An Analysis of the 2012 PIAAC Data

This paper presents data from the Program for the International Assessment of Adult Competencies with a focus on the interrelationships among health information seeking behavior (HISB), and health status or use of preventive health measures for U.S. adults both with and without a high school diploma. Key results of ordinal and binary logistic regression analyses indicated that, after controlling for demographic factors, (1) adults with a high school diploma use more text-based health information sources while adults without a high school diploma use more oral sources, (2) using the Internet as a source of health information is more strongly related to reporting excellent/very good health status than having a high school diploma, (3) those without a high school diploma who use the Internet report the largest increase in health status over any other health information source, and (4) for those with learning disability or vision problem, a high facility in reading English is an important predictor of whether the Internet is used as a health information source. The Internet appears to play a key role in both enhancing health status and enabling use of preventive measures for those with and without a high school diploma; although, individuals without a high school diploma who use the Internet for health information derive substantial benefit in health status.     

Identification of a yolk sac cell population with hematopoietic activity in view of CD45/c-Kit expression

During murine embryonic development, primitive hematopoiesis occurs in the yolk sac (YS). Recent studies have shown that the YS also harbors definitive hematopoietic activity. However, the population of YS cells contributing to definitive hematopoiesis has not been identified. In this study, we characterized the hematopoietic cell populations in the YS of mouse embryos from E9.5 to E14.5 in view of the expression profiles of CD45 and c-Kit. The YS cells from E9.5 to E11.5 could be divided into six populations: CD45(-) c-Kit(-) , CD45(-) c-Kit(low) , CD45(-) c-Kit(high) , CD45(low) c-Kit(high) , CD45(high) c-Kit(high) and CD45(high) c-Kit(very low) . Among these populations, CD45(low) c-Kit(high) cells showed the highest multilineage hematopoietic colony-forming activity. Later in development, the YS cells from E12.5 to E14.5 lost the second and fourth populations (i.e., they retained CD45(-) c-Kit(-) , CD45(-) c-Kit(high) , CD45(high) c-Kit(high) and CD45(high) c-Kit(very low) cells), and concurrently with the disappearance of the CD45(low) c-Kit(high) population, no significant hematopoietic activity was found in any of the populations on and after E12.5. CD45(low) c-Kit(high) YS cells, which had a round morphology with a large nucleus, possessed the ability to differentiate into myeloid and B lymphoid cells when cultured with stromal cells. These findings suggest that CD45(low) c-Kit(high) YS cells include more undifferentiated cells than the other YS cell populations and possess in vitro potency to differentiate into multilineage hematopoietic cells. Furthermore, this cell population disappears from the YS at around E12.5, when the site of hematopoiesis has already shifted to the fetal liver and the placenta.     

The effect of high protein diet on the regulatory properties of AMP deaminase from chicken liver

Feeding high protein diet for 5 days caused a 3,5-fold and 2-fold increase of the activity of xanthine dehydrogenase (EC 1.2.1.37) and 5-nucleotidase (EC 3.1.3.31) respectively, in chicken liver. Six hours after feeding the high protein diet there was no change in either enzyme activity although a 3-fold increase in the level of serum uric acid was observed. High protein diet considerably decreased the activity of AMP deaminase at low, but not at high substrate concentration. The activity ratio, measured at 10.0 and 0.16 mM AMP increased from 14:1 (low protein diet) to 23:1 and 24:1 after 6 h and 5 days of high protein diet, respectively. It has been suggested that feeding birds a high protein diet may cause transformation of liver AMP deaminase (EC 3.5.4.6) from a low Km form toward a high Km form.     

CD45(low)c-Kit(high) cells have hematopoietic properties in the mouse aorta-gonad-mesonephros region

Long-term reconstituting hematopoietic stem cells first arise from the aorta of the aorta-gonad-mesonephros (AGM) region in a mouse embryo. We have previously reported that in cultures of the dispersed AGM region, CD45(low)c-Kit(+) cells possess the ability to reconstitute multilineage hematopoietic cells, but investigations are needed to show that this is not a cultured artifact and to clarify when and how this population is present. Based on the expression profile of CD45 and c-Kit in freshly dissociated AGM cells from embryonic day 9.5 (E9.5) to E12.5 and aorta cells in the AGM from E13.5 to E15.5, we defined six cell populations (CD45(-)c-Kit(-), CD45(-)c-Kit(low), CD45(-)c-Kit(high), CD45(low)c-Kit(high), CD45(high)c-Kit(high), and CD45(high)c-Kit(very low)). Among these six populations, CD45(low)c-Kit(high) cells were most able to form hematopoietic cell colonies, but their ability decreased after E11.5 and was undetectable at E13.5 and later. The CD45(low)c-Kit(high) cells showed multipotency in vitro. We demonstrated further enrichment of hematopoietic activity in the Hoechst dye-effluxing side population among the CD45(low)c-Kit(high) cells. Here, we determined that CD45(low)c-Kit(high) cells arise from the lateral plate mesoderm using embryonic stem cell-derived differentiation system. In conclusion, CD45(low)c-Kit(high) cells are the major hematopoietic cells of mouse AGM.     

Adaptive changes in enzyme activity and metabolic pathways in adipose tissue from meal-fed rats

A number of metabolic factors and the activity of a number of enzymes were determined in meal-fed (animals fed a single daily 2 hr meal) and nibbling (ad libitum-fed) rats. The dependency of the observed adaptive changes on the ingestion of carbohydrate was studied by feeding diets high in carbohydrate or fat. Glucose-6-phosphate dehydrogenase and NADP-malic dehydrogenase were more active in adipose tissue from high carbohydrate meal-fed rats than in tissue from ad libitum-fed rats. The activity in adipose tissue of isocitric dehydrogenase, 6-phosphogluconate dehydrogenase, and NAD-malic dehydrogenase did not increase significantly in response to meal-feeding the high carbohydrate diet. No increase in lipogenesis or enzyme activity could be demonstrated in adipose tissue from rats meal-fed a high fat diet. Lipase activity of adipose tissue was increased by high carbohydrate meal-feeding and decreased by feeding a high fat diet. The in vitro uptake of palmitate-1-(14)C by adipose tissue was depressed by a high fat diet and enhanced in rats meal-fed a high carbohydrate diet. Diaphragm or slices of liver from high fat-fed rats oxidized palmitate-1-(14)C more rapidly than did tissue from ad libitum-fed animals. Evidence is presented for the quantitative importance of citrate as a source of extramitochondrial acetyl CoA in adipose tissue of meal-eating and ad libitum-fed rats. The relationship of extramitochondrially formed citrate to the NAD-malic dehydrogenase-malic enzyme system in adipose tissue is discussed.     

Longitudinal Gradients in the Chemical and Microbial Composition of the Bottom Sediment in a Channel Reservoir (Saidenbach R., Saxony)

Saidenbach Reservoir is situated in the Erzgebirge Hills, Saxony, in a catchment with agriculture as the principal use and a high sensitivity to soil erosion. The high elimination of total phosphorus (ca. 70%) mainly results from a) the sedimentation flux of planktonic diatoms and b) the adsorption to and sedimentation with mineral particles rich in iron. At stations with a high sulfide concentration in the 0–5 cm sediment layer (about 0.2%), the P content was likewise high (about 0.3%), probably due to the high iron concentration (more than 2.5% of dry weight). A fractionation procedure showed that the major part of the sediment phosphorus was not sensitive to reductants (dithionite) but has been found only in the following extraction step (NaOH extract).     

Growth condition-dependent sensitivity, photodamage and stress response of Chlamydomonas reinhardtii exposed to high light conditions

Different substrate conditions, such as varying CO(2) concentrations or the presence of acetate, strongly influence the efficiency of photosynthesis in Chlamydomonas reinhardtii. Altered photosynthetic efficiencies affect the susceptibility of algae to the deleterious effects of high light stress, such as the production of reactive oxygen species (ROS) and PSII photodamage. In this study, we investigated the effect of high light on C. reinhardtii grown under photomixotrophy, i.e. in the presence of acetate, as well as under photoautotrophic growth conditions with either low or high CO(2) concentrations. Different parameters such as growth rate, chlorophyll bleaching, singlet oxygen generation, PSII photodamage and the total genomic stress response were analyzed. Although showing a similar degree of PSII photodamage, a much stronger singlet oxygen-specific response and a broader general stress response was observed in acetate and high CO(2)-supplemented cells compared with CO(2)-limited cells. These different photooxidative stress responses were correlated with the individual cellular PSII content and probably directly influenced the ROS production during exposure to high light. In addition, growth of high CO(2)-supplemented cells was more susceptible to high light stress compared with cells grown under CO(2) limitation. The growth of acetate-supplemented cultures, on the other hand, was less affected by high light treatment than cultures grown under high CO(2) concentrations, despite the similar cellular stress. This suggests that the production of ATP by mitochondrial acetate respiration protects the cells from the deleterious effects of high light stress, presumably by providing energy for an effective defense.     

Mouse strain differences in plasmacytoid dendritic cell frequency and function revealed by a novel monoclonal antibody

We report in this study the generation of a novel rat mAb that recognizes mouse plasmacytoid dendritic cells (pDC). This Ab, named 120G8, stains a small subset of CD11c(low) spleen cell with high specificity. This population produces high amounts of IFN-alpha upon in vitro viral stimulation. Both ex vivo- and in vitro-derived 120G8(+) cells display a phenotype identical with that of the previously described mouse pDC (B220(high)Ly6C(high)Gr1(low)CD11b(-)CD11c(low)). Mice treated with 120G8 mAb are depleted of B220(high)Ly6C(high)CD11c(low) cells and have a much-reduced ability to produce IFN-alpha in response to in vivo CpG stimulation. The mAb 120G8 stains all and only B220(high)Ly6C(high)CD11c(low) pDC in all lymphoid organs. Immunohistochemical studies performed with this mAb indicate that pDC are located in the T cell area of spleen, lymph nodes, and Peyer's patches. Although the Ag recognized by 120G8 is not yet known, we show that its expression is up-regulated by type I IFN on B cells and DC. Using this mAb in immunofluorescence studies demonstrates strain- and organ-specific differences in the frequency of pDC and other DC subsets. 129Sv mice have a much higher frequency of pDC, together with a lower frequency of conventional CD8alpha(+)CD11c(high) DC, compared with C57BL/6 mice, both in spleen and blood. The higher ability of 129Sv mice to produce IFN-alpha in vivo is related to a higher number of pDC, but also to a higher ability of pDC from 129Sv mice to produce IFN-alpha in vitro in response to viral stimulation.     

Metabolism of apoprotein B in selectively bred baboons with low and high levels of low density lipoproteins

Very low density lipoprotein (VLDL) and low density lipoprotein (LDL) apoprotein (apo)-B turnover rates were measured simultaneously by injecting 131I-labeled VLDL and 125I-labeled LDL into fasting baboons (Papio sp.) selectively bred for high serum cholesterol levels and having either low or high LDL levels. The radioactivities in VLDL, intermediate density lipoprotein (IDL), LDL apoB, and urine were measured at intervals between 5 min and 6 days. Kinetic parameters for apoB were calculated in each baboon fed a chow diet or a high cholesterol, high fat diet (HCHF). VLDL apoB residence times were similar in the two groups of animals fed chow; they were increased by HCHF feeding in high LDL animals, but not in low LDL animals. Production rates of VLDL apoB were decreased by the HCHF diet in both high and low LDL animals. Most of the radioactivity from VLDL apoB was transferred to IDL. However, a greater proportion of radioactivity was removed directly from IDL apoB in low LDL animals than in high LDL animals, and only about one-third appeared in LDL. In high LDL animals, a greater proportion of this radioactivity was converted to LDL (61.4 +/- 7.2% in chow-fed animals and 49.2 +/- 10.9% in animals fed the HCHF diet; mean +/- SEM, n = 5). Production rates for LDL apoB were higher in high LDL animals than those in low LDL animals on both diets. The HCHF diet increased residence times of LDL apoB without changing production rates in both groups. VLDL apoB production was not sufficient to account for LDL apoB production in high LDL animals, a finding that suggested that a large amount of LDL apoB was derived from a source other than VLDL apoB in these animals.     

Glucose homeostasis can be differentially modulated by varying individual components of a western diet

Chronic overconsumption of a Western diet has been identified as a major risk factor for diabetes, yet precisely how each individual component contributes to defects in glucose homeostasis independent of consumption of other macronutrients remains unclear. Eight-week-old male Sprague Dawley rats were randomized to feeding with one of six semi-pure diets: control, processed (high advanced glycation end products/AGE), high protein, high dextrose (glucose polymer), high in saturated fat (plant origin), or high in saturated fat (animal origin). After chronic feeding for 24 weeks, body composition was determined by bioelectrical impedance spectroscopy and glucose homeostasis was assessed. When compared to the control and high AGE diets, excess consumption of the diet high in saturated fat (animal source) increased body weight and adiposity, and decreased insulin sensitivity, as defined by HOMA IR, impaired skeletal muscle insulin signaling and insulin hypersecretion in the context of increased circulating glucagon-like peptide (GLP-1). Compared to the control diet, chronic consumption of the high AGE, protein or dextrose diet increased fasting plasma glucose, decreased fasting plasma insulin and insulin secretion. These diets also reduced circulating GLP-1 concentrations. These data suggest that individual components of a western diet have differential effects in modulating glucose homeostasis and adiposity. These data provide clear evidence of a link between over-consumption of a western diet and the development of diabetes.     

Phosphorus requirements of the wheat plant in various stages of its life cycle

Summary In pot experiments root growth and P uptake were found to precede shoot growth. The high rate of P uptake in the early stages of the life cycle is not an expression of luxury consumption but reflects a high P requirement in plants. Plants cultivated in nutrient solutions with different P concentrations during various stages of development showed that a high P supply (1 ppm) between Feekes stages 6 and 9 (30 days) caused a higher grain yield than the same P concentration between Feekes stages 11 and 17 (30 days). The early applied P caused a high number of fertile ears per area, a high number of grains per ear, and a high P pool in vegetative parts. The latter could be mobilized during the grain-filling period. Therefore, for high grain yields soil and fertilizers have to meet the high P requirement (about 20 g P/m root · day) in an early stage of plant growth. During the grain filling period the P supply can be much lower.