7,026 research outputs found

    14-3-3 proteins bind to histone and affect both histone phosphorylation and dephosphorylation

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    Abstract14-3-3 proteins appear to play a critical role in Ca2+-stimulated secretion in permeabilized chromaffin cells. 14-3-3 proteins have been reported to be both stimulators and inhibitors of protein kinase C (PKC). We have found that 14-3-3 proteins, isolated on the basis of their ability to enhance secretory activity, stimulated histone phosphorylation by PKC, but they had no effect on myosin light chain phosphorylation by PKC. 14-3-3 proteins were also found to inhibit the rate of [32P]histone dephosphorylation but not the rate of [32P]myosin light chain dephosphorylation. Cross-linking experiments and affinity chromatography demonstrated that 14-3-3 proteins bind to histones. These results suggest that at least some of the reported effects of 14-3-3 proteins on PKC activity may result from 14-3-3 proteins binding to histone

    Influences of land use changes on the dynamics of water quantity and quality in the German lowland catchment of the Stör

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    Understanding the impacts of land use changes (LUCCs) on the dynamics of water quantity and quality is necessary for the identification of mitigation measures favorable for sustainable watershed management. Lowland catchments are characterized by a strong interaction of streamflow and near-surface groundwater that intensifies the risk of nutrient pollution. In this study, we investigated the effects of long-term changes in individual land use classes on the water and nutrient balance in the lowland catchment of the upper Stör in northern Germany. To this end, the hydrological model SWAT (Soil and Water Assessment Tool) and partial least squares regression (PLSR) were used. The SWAT model runs for three different land use maps (1987, 2010, and 2019) were conducted, and the outputs were compared to derive changes in water quantity (i.e., evapotranspiration – ET; surface runoff – SQ; base flow – BF; water yield – WYLD) and quality variables (i.e., sediment yield – SED; load of total phosphorus – TP; load of total nitrogen – TN). These changes were related to land use changes at the subbasin scale using PLSR. The major land use changes that significantly affected water quantity and quality variables were related to a decrease in arable land and a respective increase in pasture and urban land during the period of 1987–2019. Changes in landscape indictors such as area size, shape, dominance, and aggregation of each land use class accounted for as much as 61 %–88 % (75 % on average) of the respective variations in water quantity and quality variables. [...] The cause–effect results of this study can provide a quantitative basis for targeting the most influential change in landscape composition and configuration to mitigate adverse impacts on water quality in the future

    Multichannel error correction code decoder

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    A brief overview of a processing satellite for a mesh very-small-aperture (VSAT) communications network is provided. The multichannel error correction code (ECC) decoder system, the uplink signal generation and link simulation equipment, and the time-shared decoder are described. The testing is discussed. Applications of the time-shared decoder are recommended

    Symmetric Rotating Wave Approximation for the Generalized Single-Mode Spin-Boson System

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    The single-mode spin-boson model exhibits behavior not included in the rotating wave approximation (RWA) in the ultra and deep-strong coupling regimes, where counter-rotating contributions become important. We introduce a symmetric rotating wave approximation that treats rotating and counter-rotating terms equally, preserves the invariances of the Hamiltonian with respect to its parameters, and reproduces several qualitative features of the spin-boson spectrum not present in the original rotating wave approximation both off-resonance and at deep strong coupling. The symmetric rotating wave approximation allows for the treatment of certain ultra and deep-strong coupling regimes with similar accuracy and mathematical simplicity as does the RWA in the weak coupling regime. Additionally, we symmetrize the generalized form of the rotating wave approximation to obtain the same qualitative correspondence with the addition of improved quantitative agreement with the exact numerical results. The method is readily extended to higher accuracy if needed. Finally, we introduce the two-photon parity operator for the two-photon Rabi Hamiltonian and obtain its generalized symmetric rotating wave approximation. The existence of this operator reveals a parity symmetry similar to that in the Rabi Hamiltonian as well as another symmetry that is unique to the two-photon case, providing insight into the mathematical structure of the two-photon spectrum, significantly simplifying the numerics, and revealing some interesting dynamical properties.Comment: 11 pages, 5 figure

    Comparison of water balance method and alternative evaporation methods applied to the Aswan High Dam Reservoir

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    Aswan High Dam Reservoir (AHDR) is a large human-made reservoir situated in southern Egypt and northern Sudan. The reservoir is located in a typical arid zone so that evaporation results in a significant water loss from the reservoir. To quantify these evaporation water losses, different methods can  be applied. The water balance method was used to estimate water losses of the AHDR during 43 open-water seasons. Compared to earlier publications, this study used longer time series data and more evaporation approaches. Moreover, we evaluated the deviation between evaporation rates as derived from the water balance method and as calculated using 16 evaporation/evapotranspiration formulas. Five approaches are not well suited for use at the AHDR because they underestimated evaporation rates (e.g. Stephens-Stewart model), or overestimated evaporation rates (e.g. de Bruin model). Annual evaporation rates obtained by the Bowen ratio energy balance method at the three floating stations Raft, Allaqi and Abu Simbel were estimated at 7.9, 6.9 and 6.7 mm d-1, respectively. The monthly water losses of the years 1978 to 1984, a period with reasonable evaporation rates, are used to estimate the evaporation losses. The results of the study show a systematic deviation between the monthly average values determined using the water balance method through the period 1978 to 1984 and the monthly mean values determined by the 16 evaporation calculation approaches at three floating stations. This deviation is particularly clear in the months of May, June and September (primarily lower estimates) as well as in July (primarily higher estimates). The deviation can be attributed to the simplicity of the water balance method as well as to its limited suitability for large reservoirs as the AHDR over short periods like a month. Among the 16 evaporation calculation approaches the mass transfer method provided the most reasonable results under the given site conditions

    Tn6188 - A Novel Transposon in Listeria monocytogenes Responsible for Tolerance to Benzalkonium Chloride

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    peer-reviewedControlling the food-borne pathogen Listeria (L.) monocytogenes is of great importance from a food safety perspective, and thus for human health. The consequences of failures in this regard have been exemplified by recent large listeriosis outbreaks in the USA and Europe. It is thus particularly notable that tolerance to quaternary ammonium compounds such as benzalkonium chloride (BC) has been observed in many L. monocytogenes strains. However, the molecular determinants and mechanisms of BC tolerance of L. monocytogenes are still largely unknown. Here we describe Tn6188, a novel transposon in L. monocytogenes conferring tolerance to BC. Tn6188 is related to Tn554 from Staphylococcus (S.) aureus and other Tn554-like transposons such as Tn558, Tn559 and Tn5406 found in various Firmicutes. Tn6188 comprises 5117 bp, is integrated chromosomally within the radC gene and consists of three transposase genes (tnpABC) as well as genes encoding a putative transcriptional regulator and QacH, a small multidrug resistance protein family (SMR) transporter putatively associated with export of BC that shows high amino acid identity to Smr/QacC from S. aureus and to EmrE from Escherichia coli. We screened 91 L. monocytogenes strains for the presence of Tn6188 by PCR and found Tn6188 in 10 of the analyzed strains. These isolates were from food and food processing environments and predominantly from serovar 1/2a. L. monocytogenes strains harboring Tn6188 had significantly higher BC minimum inhibitory concentrations (MICs) (28.5 ± 4.7 mg/l) than strains without Tn6188 (14 ± 3.2 mg/l). Using quantitative reverse transcriptase PCR we could show a significant increase in qacH expression in the presence of BC. QacH deletion mutants were generated in two L. monocytogenes strains and growth analysis revealed that ΔqacH strains had lower BC MICs than wildtype strains. In conclusion, our results provide evidence that Tn6188 is responsible for BC tolerance in various L. monocytogenes strains.This work was supported by a grant from the Austrian Science Fund (FWF, http://www.fwf.ac.at/) to SSE (grant no. P22703‐B17), by the European Union funded integrated project BIOTRACER (contract no. 036272) under the 6th RTD framework and by the EU grant FP7‐KBBE‐2010‐4 (FOODSEG)

    Nanoparticles Composed of Zn and ZnO Inhibit \u3cem\u3ePeronospora tabacina\u3c/em\u3e Spore Germination \u3cem\u3ein vitro\u3c/em\u3e and \u3cem\u3eP. tabacina\u3c/em\u3e Infectivity on Tobacco Leaves

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    Manufactured nanoparticles (NPs) are increasingly being used for commercial purposes and certain NP types have been shown to have broad spectrum antibacterial activity. In contrast, their activities against fungi and fungi-like oomycetes are less studied. Here, we examined the potential of two types of commercially available Zn NPs (Zn NPs and ZnO NPs) to inhibit spore germination and infectivity on tobacco leaves resulting from exposure to the fungi-like oomycete pathogen Peronospora tabacina (P. tabacina). Both types of NPs, as well as ZnCl2 and bulk ZnO control treatments, inhibited spore germination compared to a blank control. ZnO ENMs were shown to be a much more powerful suppressor of spore germination and infectivity than bulk ZnO. ZnO and Zn NPs significantly inhibited leaf infection at 8 and 10 mg·L−1, respectively. Both types of NPs were found to provide substantially higher concentration dependent inhibition of spore germination and infectivity than could be readily explained by the presence of dissolved Zn. These results suggest that both NP types have potential for use as economic, low-dose, potentially non-persistent anti-microbial agents against the oomycete P. tabacina

    Dynamic responses of phosphorus metabolism to acute and chronic dietary phosphorus-limitation in Daphnia

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    Food quality is highly dynamic within lake ecosystems and varies spatially and temporally over the growing season. Consumers may need to continuously adjust their metabolism in response to this variation in dietary nutrient content. However, the rates of metabolic responses to changes in food nutrient content has received little direct study. Here, we examine responses in two metabolic phosphorus (P) pools, ribonucleic acids (RNA) and adenosine triphosphate (ATP), along with body mass and body P content in Daphnia magna exposed to chronic and acute dietary P-limitation. First, we examined food quality effects on animals consuming different food carbon (C):P quality over a 14 day period. Then, we raised daphnids on one food quality for 4 days, switched them to contrasting dietary treatments, and measured changes in their metabolic responses at shorter time-scales (over 48 h). Animal P, RNA, and ATP content all changed through ontogeny with adults containing relatively less of these pools with increasing body mass. Irrespective of age, Daphnia consuming high C:P diets had lower body %P, %RNA, %ATP, and mass compared to animals eating low C:P diets. Diet switching experiments revealed diet dependent changes in body %P, %RNA, %ATP, and animal mass within 48 h. We found that Daphnia switched from low to high C:P diets had some metabolic buffering capacity with decreases in body %P occurring after 24 h but mass remaining similar to initial diet conditions for 36 h after the diet switch. Switching Daphnia from low to high C:P diets caused a decrease in the RNA:P ratio after 48 h. Daphnia switched from high to low C:P diets increased their body P, RNA, and ATP content within 8–24 h. This switch from high to low C:P diets also led to increased RNA:P ratios in animal bodies. Overall, our study revealed that consumer P metabolism reflects both current and past diet due to more dynamic and rapid changes in P biochemistry than total body mass. This metabolic flexibility is likely linked to resource integration in D. magna, which reduces the negative effects of short-term or variable exposure to nutrient-deficient foods

    Seasonal effects of food quality and temperature on body stoichiometry, biochemistry, and biomass production in Daphnia populations

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    Food quality and temperature can affect zooplankton production in lakes by altering organismal metabolism. However, the influence of these factors on consumer nutritional physiology and population biomass remains relatively understudied in natural populations. Here, we examined seasonal changes in body stoichiometry, biochemistry, and population biomass in two Daphnia species collected from two separate lakes differing in dietary phosphorus (P) supply. Food quality, measured as seston carbon:P (C:P) ratios, varied throughout the study in each lake, and water temperatures generally increased across the growing season. Daphnid elemental composition was correlated with food quality in both populations, but relationships between daphnid body stoichiometry and temperature were consistently stronger as Daphnia body C:P ratios and content of major biochemical pools declined simultaneously throughout the summer, which largely coincided with increased water temperatures. Warmer temperatures were associated with relaxed %P-RNA coupling as daphnid body RNA content declined and P content remained relatively high. These responses combined with temperature related decreases in Daphnia body %lipids and %C appeared to explain declines in daphnid body C:P ratios in both lakes over the growing season. Seasonal changes in population biomass were related to both food quality and water temperature in the lower nutrient lake. Biomass production under more eutrophic conditions however was unrelated to food quality and was instead associated with seasonal temperature changes in the higher nutrient lake. Overall, our study shows that seasonal changes in temperature and resource quality may differentially affect consumer stoichiometry and biomass production in lake ecosystems by altering consumer elemental metabolism
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