Two-Dimensional Lanthanide Metal-Organic Framework Heterostructures for Noninvasively Photoresponsive High-Security Photonic Barcodes.

Stimuli-responsive micro/nanoscale photonic barcodes show great capacity for encryption and anticounterfeiting technologies due to multiple authentications, yet their application is commonly restricted by invasive stimuli. Herein, we report noninvasive light-stimulated high-security photonic barcodes based on spatially assembled photoresponsive two-dimensional (2D) 1,3,5-benzenetribenzoate (BTB)@Ln-MOF host-guest heterostructures. The photoluminescence (PL) spectra information on BTB@Ln-MOF heterostructures could be precisely controlled by the different wavelengths of ultraviolet (UV) light trigger. By using the PL properties and 2D heterostructures as cryptographic primitives, spatially resolved smart photonic barcodes based on both spectral and graphical coding are realized in BTB@Ln-MOF host-guest materials. These results will pave an avenue for the development of smart stimuli-responsive photonic barcodes for anticounterfeiting applications.

Sustainability of in vitro light-dependent NADPH generation by the thylakoid membrane of Synechocystis sp. PCC6803.

BACKGROUND: NADPH is used as a reductant in various biosynthetic reactions. Cell-free bio-systems have gained considerable attention owing to their high energy utilization and time efficiency. Efforts have been made to continuously supply reducing power to the reaction mixture in a cyclical manner. The thylakoid membrane (TM) is a promising molecular energy generator, producing NADPH under light. Thus, TM sustainability is of major relevance for its in vitro utilization. RESULTS: Over 70% of TMs prepared from Synechocystis sp. PCC6803 existed in a sealed vesicular structure, with the F1 complex of ATP synthase facing outward (right-side-out), producing NADPH and ATP under light. The NADPH generation activity of TM increased approximately two-fold with the addition of carbonyl cyanide-p-(trifluoromethoxy) phenylhydrazone (FCCP) or removal of the F1 complex using EDTA. Thus, the uncoupling of proton translocation from the electron transport chain or proton leakage through the Fo complex resulted in greater NADPH generation. Biosilicified TM retained more than 80% of its NADPH generation activity after a week at 30°C in the dark. However, activity declined sharply to below 30% after two days in light. The introduction of engineered water-forming NADPH oxidase (Noxm) to keep the electron transport chain of TM working resulted in the improved sustainability of NADPH generation activity in a ratio (Noxm to TM)-dependent manner, which correlated with the decrease of singlet oxygen generation. Removal of reactive oxygen species (ROS) by catalase further highlighted the sustainable NADPH generation activity of up to 80% in two days under light. CONCLUSION: Reducing power generated by light energy has to be consumed for TM sustainability. Otherwise, TM can generate singlet oxygen, causing oxidative damage. Thus, TMs should be kept in the dark when not in use. Although NADPH generation activity by TM can be extended via silica encapsulation, further removal of hydrogen peroxide results in an improvement of TM sustainability. Therefore, as long as ROS formation by TM in light is properly handled, it can be used as a promising source of reducing power for in vitro biochemical reactions.

Reciprocal regulation of phosphatidylcholine synthesis and H3K36 methylation programs metabolic adaptation.

Phospholipid biosynthesis plays a role in mediating membrane-to-histone communication that influences metabolic decisions. Upon nutrient deprivation, phospholipid methylation generates a starvation signal in the form of S-adenosylmethionine (SAM) depletion, leading to dynamic changes in histone methylation. Here we show that the SAM-responsive methylation of H3K36 is critical for metabolic adaptation to nutrient starvation in the budding yeast Saccharomyces cerevisiae. We find that mutants deficient in H3K36 methylation exhibit defects in membrane integrity and pyrimidine metabolism and lose viability quickly under starvation. Adjusting the synthesis of phospholipids potently rewires metabolic pathways for nucleotide synthesis and boosts the production of antioxidants, ameliorating the defects resulting from the loss of H3K36 methylation. We further demonstrate that H3K36 methylation reciprocally regulates phospholipid synthesis by influencing redox balance. Our study illustrates an adaptive mechanism whereby phospholipid synthesis entails a histone modification to reprogram metabolism for adaptation in a eukaryotic model organism.

Production of long-chain free fatty acids from metabolically engineered Rhodobacter sphaeroides heterologously producing periplasmic phospholipase A2 in dodecane-overlaid two-phase culture.

BACKGROUND: Long-chain free fatty acids (FFAs) are a type of backbone molecule that can react with alcohol to produce biodiesels. Various microorganisms have become potent producers of FFAs. Efforts have focused on increasing metabolic flux to the synthesis of either neutral fat or fatty acyl intermediates attached to acyl carrier protein (ACP), which are the source of FFAs. Membrane lipids are also a source of FFAs. As an alternative way of producing FFAs, exogenous phospholipase may be used after heterologous production and localization in the periplasmic space. In this work, we examined whether Rhodobacter sphaeroides, which forms an intracytoplasmic membrane, can be used for long-chain FFA production using phospholipase. RESULTS: The recombinant R. sphaeroides strain Rs-A2, which heterologously produces Arabidopsis thaliana phospholipase A2 (PLA2) in the periplasm, excretes FFAs during growth. FFA productivity under photoheterotrophic conditions is higher than that observed under aerobic or semiaerobic conditions. When the biosynthetic enzymes for FA (ß-ketoacyl-ACP synthase, FabH) and phosphatidate (1-acyl-sn-glycerol-3-phosphate acyltransferase, PlsC) were overproduced in Rs-A2, the FFA productivity of the resulting strain Rs-HCA2 was elevated, and the FFAs produced mainly consisted of long-chain FAs of cis-vaccenate, stearate, and palmitate in an approximately equimolar ratio. The high-cell-density culture of Rs-HCA2 with DMSO in two-phase culture with dodecane resulted in an increase of overall carbon substrate consumption, which subsequently leads to a large increase in FFA productivity of up to 2.0 g L-1 day-1. Overexpression of the genes encoding phosphate acyltransferase (PlsX) and glycerol-3-phosphate acyltransferase (PlsY), which catalyze the biosynthetic steps immediately upstream from PlsC, in Rs-HCA2 generated Rs-HXYCA2, which grew faster than Rs-HCA2 and showed an FFA productivity of 2.8 g L-1 day-1 with an FFA titer of 8.5 g L-1. CONCLUSION: We showed that long-chain FFAs can be produced from metabolically engineered R. sphaeroides heterologously producing PLA2 in the periplasm. The FFA productivity was greatly increased by high-cell-density culture in two-phase culture with dodecane. This approach provides highly competitive productivity of long-chain FFAs by R. sphaeroides compared with other bacteria. This method may be applied to FFA production by other photosynthetic bacteria with similar differentiated membrane systems.

Characterization of ATPase Activity of Free and Immobilized Chromatophore Membrane Vesicles of Rhodobacter sphaeroides.

The intracytoplasmic membrane of Rhodobacter sphaeroides readily vesiculates when cells are lysed. The resulting chromatophore membrane vesicle (CMV) contains the photosynthetic machineries to synthesize ATP by ATPase. The light-dependent ATPase activity of CMV was lowered in the presence of O2, but the activity increased to the level observed under anaerobic condition when the reaction mixture was supplemented with ascorbic acid (≥0.5 mM). Cell lysis in the presence of biotinyl cap phospholipid (bcp) resulted in the incorporation of bcp into the membrane to form biotinylated CMV (bCMV), which binds to streptavidin resin at a ratio of approximately 24 µg bacteriochlorophyll a/ml resin. The ATPase activity of CMV was not affected by biotinylation, but approximately 30% of the activity was lost by immobilization to resin. Interestingly, the remaining 70% of ATPase activity stayed constant during 7-day storage at 4°C. On the contrary, the ATPase activity of bCMV without immobilization gradually decreased to approximately 40% of the initial level in the same comparison. Thus, the ATPase activity of CMV is sustainable after immobilization, and the immobilized bCMV can be used repeatedly as an ATP generator.

Diagnostic value of interferon-γ-induced protein of 10kDa for tuberculous pleurisy: A meta-analysis.

BACKGROUND: The accurate diagnosis of tuberculous pleurisy is still a clinical challenge. Many studies reported that interferon-γ-induced protein of 10kDa (IP-10) plays a role in diagnosing tuberculous pleurisy, but with considerable variance of results. This meta-analysis aimed to evaluate the overall diagnostic accuracy of IP-10 for tuberculous pleurisy. METHODS: PubMed, EMBASE, and other databases were searched for studies examining accuracy of pleural IP-10 for diagnosing tuberculous pleurisy. Related data were extracted and sensitivity/specificity, positive/negative likelihood ratio (PLR/NLR), and diagnostic odds ratio (DOR) were pooled. Summary receiver operating characteristic curve and area under the curve (AUC) were performed and calculated to summarize the overall test performance. RESULTS: Fourteen studies involving 1382 subjects met inclusion criteria, including 715 cases of tuberculous pleurisy and 667 controls. Summary estimates of the diagnostic performance of the IP-10 for tuberculous pleurisy were listed as follows: sensitivity, 0.84 (95%CI 0.81 to 0.87); specificity, 0.90 (95% CI 0.88 to 0.92); PLR, 7.96 (95% CI 5.59 to 11.32); NLR, 0.19 (95% CI 0.15 to 0.24); DOR, 49.82 (95% CI 28.08 to 88.38); and AUC 0.94. No publication bias was detected. CONCLUSION: Pleural IP-10 is a useful diagnostic marker for tuberculous pleurisy. Nevertheless, its result should be interpreted together with the results of conventional test and clinical information of patients.

Presepsin as a diagnostic marker for sepsis: evidence from a bivariate meta-analysis.

BACKGROUND: The diagnosis of sepsis remains a clinical challenge. Many studies suggest that presepsin plays a role in diagnosing sepsis, but the results remain controversial. This study aimed to identify the overall diagnostic accuracy of presepsin for sepsis through meta-analysis. METHODS: A systematic literature search was performed in PubMed and EMBASE to identify studies evaluating the diagnostic accuracy of presepsin in sepsis patients. Data were retrieved and the pooled sensitivity, specificity, positive likelihood ratio, negative likelihood ratio, and diagnostic odds ratio (DOR) were calculated. A summary receiver operating characteristic curve and area under curve (AUC) were used to evaluate the overall diagnostic performance. The statistical analysis was performed using Stata 12.0 and Meta-DiSc 1.4 software. RESULTS: Eleven publications with 3,106 subjects were included in the meta-analysis. The pooled sensitivity, specificity, positive likelihood ratio, negative likelihood ratio, and DOR were 0.83 (95% confidence interval [CI] 0.77-0.88), 0.81 (95% CI 0.74-0.87), 4.43 (95% CI 3.05-6.43), 0.21 (95% CI 0.14-0.30), and 21.56 (95% CI 10.59-43.88), respectively. The area under the curve was 0.89 (95% CI 0.86-0.92). Estimated positive and negative post-probability values for a sepsis prevalence of 20% were 53% and 5%, respectively. No publication bias was identified. CONCLUSION: Based on currently available evidence, presepsin may have a valuable role in the diagnosis of sepsis, and its results should be interpreted carefully in the context of clinical condition and traditional markers.