The yeast prion PSI+ is a self-propagating amyloid of the translation termination factor, Sup35p. For known pathogenic prions, such as PSI+, a single protein can form an array of different amyloid ...structures (prion variants) each stably inherited and with differing biological properties. The ribosome-associated chaperones, Ssb1/2p (Hsp70s), and RAC (Zuo1p (Hsp40) and Ssz1p (Hsp70)), enhance de novo protein folding by protecting nascent polypeptide chains from misfolding and maintain translational fidelity by involvement in translation termination. Ssb1/2p and RAC chaperones were previously found to inhibit PSI+ prion generation. We find that most PSI+ variants arising in the absence of each chaperone were cured by restoring normal levels of that protein. PSI+ variants hypersensitive to Ssb1/2p have distinguishable biological properties from those hypersensitive to Zuo1p or Ssz1p. The elevated PSI+ generation frequency in each deletion strain is not due to an altered PIN+, another prion that primes PSI+ generation. PSI+ prion generation/propagation may be inhibited by Ssb1/2/RAC chaperones by ensuring proper folding of nascent Sup35p, thus preventing its joining amyloid fibers. Alternatively, the effect of RAC/Ssb mutations on translation termination and the absence of an effect on the URE3 prion suggest an effect on the mature Sup35p such that it does not readily join amyloid filaments. Ssz1p is degraded in zuo1Δ psi- cells, but not if the cells carry any of several PSI+ variants. Our results imply that prions arise more frequently than had been thought but the cell has evolved exquisite antiprion systems that rapidly eliminate most variants.
Time-resolved fluorescence on oligomers of the main light-harvesting complex from higher plants indicate that in vitro oligomerization leads to the formation of a weakly coupled inter-trimer ...chlorophyll–chlorophyll (Chl) exciton state which converts in tens of ps into a state which is spectrally broad and has a strongly far-red enhanced fluorescence spectrum. Both its lifetime and spectrum show striking similarity with a 400
ps fluorescence component appearing in intact leaves of
Arabidopsis when non-photochemical quenching (NPQ) is induced. The fluorescence components with high far-red/red ratio are thus a characteristic marker for NPQ conditions in vivo. The far-red emitting state is shown to be an emissive Chl–Chl charge transfer state which plays a crucial part in the quenching.
In this research article, ceramic particulate (SiO2/SiC) reinforced AA2024 alloy composite material formulation has been prepared via semi-automatic stir casting technique following industrial ...standard practice. The samples specimens have been prepared as per ASTM standard dimensions and the physical, mechanical and wear performance test were performed. The obtained test results have higher confidence level (95%) and the same has been used to rank the composite materials of the formulation using Preference Selection Index (PSI) method (a Multi-Criteria-Decision-Making (MCDM) tool) which is simple to compute and understand. This enables a practicing engineer to rank the designed materials via optimizing material properties like tensile strength, flexural strength, impact strength, wear resistance, density etc. It has been observed that the aluminium alloy composite incorporated with an equal presence of both ceramics shows best properties and also ranked highest by PSI method. Hence, such techniques may be used for decision making successfully in the selection of materials.
Drought is one of the most important abiotic stress factors limiting maize production worldwide. The objective of this study was to investigate whether photoprotection of PSII was associated with the ...degree of drought tolerance and yield in three maize hybrids (30Y87, 31R88, P3939). To do this, three maize hybrids were subjected to three cycles of drought, and we measured the activities of photosystem II (PSII) and photosystem I (PSI). In a second field experiment, three maize hybrids were subjected to drought by withholding irrigation, and plant water status, yield and yield attributes were measured. Drought stress decreased leaf water potential (Ψ
) in three maize hybrids, and this reduction was more pronounced in hybrid P3939 (-40%) compared to that of 30Y87 (-30%). Yield and yield attributes of three maize hybrids were adversely affected by drought. The number of kernels and 100-kernel weight was the highest in maize hybrid 30Y87 (-56%, -6%), whereas these were lowest in hybrid P3939 (-88%, -23%). Drought stress reduced the quantum yield of PSII Y(II), photochemical quenching (qP), electron transport rate through PSII ETR(II) and NPQ, except in P3939. Among the components of NPQ, drought increased the Y(NPQ) with concomitant decrease in Y(NO) only in P3939, whereas Y(NO) increased in drought-stressed plants of hybrid 30Y87 and 31R88. However, an increase in cyclic electron flow (CEF) around PSI and Y(NPQ) in P3939 might have protected the photosynthetic machinery but it did not translate in yield. However, drought-stressed plants of 30Y87 might have sufficiently downregulated PSII to match the energy consumption in downstream biochemical processes. Thus, changes in PSII and PSI activity and development of NPQ through CEF are physiological mechanisms to protect the photosynthetic apparatus, but an appropriate balance between these physiological processes is required, without which plant productivity may decline.
Photosynthetic characteristics in rice (Oryza sativa L.) leaves were examined after treatment with low temperature (15 deg C) and high irradiance (1,500 mu mol quanta m(-2) s(-1)). Decreases in ...quantum efficiencies in PSII (phi PSII) and PSI (phi PSI) and in the rate of CO2 assimilation were observed with a decrease in the maximal quantum efficiency of PSII (Fv/Fm) by simultaneous measurements of Chl fluorescence, P700(+) absorbance and gas exchange. The decreases in phi PSII were most highly correlated with those in CO2 assimilation. Although the initial (the activity immediately measured upon extraction) and total (the activity following pre-incubation with CO2 and Mg(2+)) activities of ribulose-1,5-bisphosphate (RuBP) carboxylase/oxygenase (Rubisco) decreased slightly, the maximal activity (the activity following treatment with SO4(2-)) of Rubisco remained almost constant. These results indicate that the decrease in CO2 assimilation rate with the decreasing Fv/Fm was not caused by a decrease in Rubisco activity but rather by a decrease in RuBP regeneration capacity which resulted from the decrease in the rate of the linear electron transport. On the other hand, the decrease in (phi PSI was very small and the ratio of phi PSI to phi PSII increased. The de-epoxidation state of xanthophyll cycle pigments also increased. Thus, the cyclic electron transport around PSI occurred in photoinhibited leaves.
Background
Coronal alignment of the tibial component determines functional outcome and survival in total knee arthroplasty (TKA). Innovative techniques for tibial instrumentation have been developed ...to improve accuracy and reduce the rate of outliers.
Methods
In a prospective study, 300 patients were allocated to four different groups using a randomization process (two innovative and two conventional) techniques of tibial instrumentation (conventional: extramedullary, intramedullary; innovative: navigation and patient-specific instrumentation (PSI);
n
= 75 for each group). The aims were to reconstruct the medial proximal tibial angle (MPTA) to 90° and the mechanical tibio-femoral axis (mTFA) to 0°. Both angles were evaluated and compared between all groups three months after the surgery. Patients who presented with a postoperative mTFA > 3° were classified as outliers.
Results
The navigation and intramedullary technique both demonstrated that they were significantly more precise in reconstructing a neutral mTFA and MPTA compared to the other two techniques. The odd’s ratio (OR) for producing outliers was highest for the PSI method (PSI OR = 5.5,
p
< 0.05; extramedullary positioning OR = 3.7,
p
> 0.05; intramedullary positioning OR = 1.7,
p
> 0.05; navigation OR = 0.04,
p
< 0.05). We could only observe significant differences between pre- and postoperative MPTA in the navigation and intramedullary group. The MPTA showed a significant negative correlation with the mTFA in all groups preoperatively and in the extramedullary, intramedullary and PSI postoperatively.
Conclusion
The navigation and intramedullary instrumentation provided the precise positioning of the tibial component. Outliers were most common within the PSI and extramedullary technique. Optimal alignment is dependent on the technique of tibial instrumentation and tibial component positioning determines the accuracy in TKA since mTFA correlated with MPTA pre- and postoperatively.
•441 influenza virus infections from a Swiss Hospital were included.•During 4 influenza seasons, 238 infections due to influenza A virus; 203 due to b.•30-day mortality was 6.0% and independently ...associated with A virus.•qSOFA≥2 points showed a very good accuracy (0.89).•Hospital-acquired infection was a predictor of worst outcome.
Influenza infections have been associated with high morbidity. The aims were to determine predictors of mortality among patients with influenza infections and to ascertain the role of quick Sequential Organ Failure Assessment (qSOFA) in predicting poor outcomes.
All adult patients with influenza infection at the Hospital of Jura, Switzerland during four influenza seasons (2014/15 to 2017/18) were included. Cepheid Xpert Xpress Flu/RSV was used during the first three influenza seasons and Cobas Influenza A/B and RSV during the 2017/18 season.
Among 1684 influenza virus tests performed, 441 patients with influenza infections were included (238 for influenza A virus and 203 for B). The majority of infections were community onset (369; 83.7%). Thirty-day mortality was 6.0% (25 patients). Multivariate analysis revealed that infection due to A virus (P 0.035; OR 7.1; 95% CI 1.1–43.8), malnutrition (P < 0.001; OR 25.0; 95% CI 4.5–138.8), hospital-acquired infection (P 0.003; OR 12.2; 95% CI 2.3–65.1), respiratory insufficiency (PaO2/FiO2 < 300) (P < 0.001; OR 125.8; 95% CI 9.6–1648.7) and pulmonary infiltrate on X-ray (P 0.020; OR 6.0; 95% CI 1.3–27.0) were identified as predictors of mortality. qSOFA showed a very good accuracy (0.89) equivalent to other more specific and burdensome scores such as CURB-65 and Pneumonia Severity Index (PSI).
qSOFA performed similarly to specific severity scores (PSI, CURB-65) in predicting mortality. Infection by influenza A virus, respiratory insufficiency and malnutrition were associated with worse prognosis.
To fill the “green absorption gap”, a green absorbing proteorhodopsin was expressed in a PSI-deletion strain (ΔPSI) of Synechocystis sp. PCC6803. Growth-rate measurements, competition experiments and ...physiological characterization of the proteorhodopsin-expressing strains, relative to the ΔPSI control strain, allow us to conclude that proteorhodopsin can enhance the rate of photoheterotrophic growth of ΔPSI Synechocystis strain. The physiological characterization included measurement of the amount of residual glucose in the spent medium and analysis of oxygen uptake- and production rates. To explore the use of solar radiation beyond the PAR region, a red-shifted variant Proteorhodopsin-D212N/F234S was expressed in a retinal-deficient PSI-deletion strain (ΔPSI/ΔSynACO). Via exogenous addition of retinal analogue an infrared absorbing pigment (maximally at 740 nm) was reconstituted in vivo. However, upon illumination with 746 nm light, it did not significantly stimulate the growth (rate) of this mutant. The inability of the proteorhodopsin-expressing ΔPSI strain to grow photoautotrophically is most likely due to a kinetic rather than a thermodynamic limitation of its NADPH-dehydrogenase in NADP+-reduction.
•Proteorhodopsin expression increases growth rate of a ∆PSI Synechocystis strain with at least 16 %.•Proteorhodopsin contributes to proton motive force generation in vivo in Synechocystis.•A transgenic Synechocystis strain has been generated that can absorb infrared light.•‘Reversed electron transfer’ through NDH-1 could not be demonstrated in Synechocystis.
This article proposes a neighbors' similarity-based fuzzy community detection (FCD) method, which we call "NeSiFC." In the proposed NeSiFC approach, we compute the similarity between two neighbors by ...introducing a modified local random walk (mLRW). Basically, in a network, a node and its' neighbors with noticeable similarities among them construct a community. To measure this similarity, we introduce a new metric, called the peripheral similarity index (PSI). This PSI is used to construct the transition probability matrix for the mLRW. The mLRW is applied for each node until it meets a parameter called step coefficient. The mLRW gives better neighbors' similarity for community detection. Finally, a fuzzy membership function is used iteratively to compute the membership degrees for all nodes with reference to existing communities. The proposed NeSiFC has no dependence on the network characteristics, and no adjustment or fine tuning of more than one parameter is needed. To show the efficacy of the proposed NeSiFC approach, we provide a thorough comparative performance analysis considering a set of well-known FCD algorithms viz., the genetic algorithm for fuzzy community detection, membership degree propagation, center-based fuzzy graph clustering, FMM/H2, and FuzAg on a set of popular benchmarks, as well as real-world datasets. For both disjoint and overlapping community structures, results of various accuracy and quality metrics indicate the outstanding performance of our proposed NeSiFC approach. The asymptotic complexity of the proposed NeSiFC is found as O(n 2 ).
Environmental organic pollutants such as polycyclic aromatic hydrocarbons (PAHs) affect photosynthetic performance in plants. The photooxidation of PAHs in natural sunlight, especially UV radiation, ...enhances the toxicity of PAHs. However, it is unclear as how these compounds and their photoproducts affect the photosynthetic apparatus. In this study, measurements of PSI and PSII were simultaneously performed in wheat (Triticum aestivum L.) plants treated with fluoranthene (FLT) and photomodified fluoranthene (PFLT). The study aimed to investigate whether the phototoxicity of FLT has a different mechanism of toxicity on the two photosystems. With regard to PSII, FLT and PFLT produced a significant decrease in the quantum yield of PSII and a pronounced increase in the yield of nonregulated energy dissipation. A significant reduction was observed in the yield of nonphotochemical quenching. The toxic effects of the PFLT treatment on PSII's performance were more pronounced. Likewise, we noted severe disruption in the electron transport rate in PSII and a decline in Fm caused by FLT phototoxicity. A decline in the quantum yield of PSI and an increase in donor and acceptor side limitation were observed concomitantly. The impact of PFLT was more evident than that of FLT. The data demonstrated that PSI is more tolerant of FLT but for PFLT, particularly at higher concentrations, a pronounced inhibition was observed in the oxidation-reduction kinetics of P700. All these data suggest that increased cyclic electron flow can confer greater protection from FLT toxicity but not from toxicity induced by higher concentrations of PFLT.
PDF
