Quantitative assessment whole-rock iron content in magnetite protolith based on terahertz time-domain spectroscopy: publisher's note.

This publisher's note serves to correct errors in Appl. Opt.63, 2528 (2024)APOPAI0003-693510.1364/AO.517400.

Quantitative assessment whole-rock iron content in magnetite protolith based on terahertz time-domain spectroscopy.

Terahertz time-domain spectroscopy was first used to establish a correlation with the whole-rock iron (TFe) content in different depths of the Bayan Obo protolith. Compared with element content obtained by the traditional method of X-ray fluorescence spectroscopy (XRF), a similar tendency of the absorption coefficient and refractive index is presented. Furthermore, three machine learning algorithms, namely, partial least squares regression (PLSR), random forest (RF), and multi-layer perceptron (MLP), were used to develop a quantitative analytical model for TFe content of the protolith minerals. Among the three algorithms, MLP has the highest detection accuracy, with a model coefficient of determination R 2 reaching up to 0.945. These findings demonstrate that terahertz time-domain spectroscopy can be used to rapidly quantify the TFe elemental content of protolith, providing a method of detecting the content of mineral components.

Systematic genetic modifications of cell wall biosynthesis enhanced the secretion and surface-display of polysaccharide degrading enzymes in Saccharomyces cerevisiae.

Saccharomyces cerevisiae is a robust cell factory to secrete or surface-display cellulase and amylase for the conversion of agricultural residues into valuable chemicals. Engineering the secretory pathway is a well-known strategy for overproducing these enzymes. Although cell wall biosynthesis can be tightly linked to the secretory pathway by regulation of all involved processes, the effect of its modifications on protein production has not been extensively studied. In this study, we systematically studied the effect of engineering cell wall biosynthesis on the activity of cellulolytic enzyme ß-glucosidase (BGL1) by comparing seventy-nine gene knockout S. cerevisiae strains and newly identified that inactivation of DFG5, YPK1, FYV5, CCW12 and KRE1 obviously improved BGL1 secretion and surface-display. Combinatorial modifications of these genes, particularly double deletion of FVY5 and CCW12, along with the use of rich medium, increased the activity of secreted and surface-displayed BGL1 by 6.13-fold and 7.99-fold, respectively. Additionally, we applied this strategy to improve the activity of the cellulolytic cellobiohydrolase and amylolytic α-amylase. Through proteomic analysis coupled with reverse engineering, we found that in addition to the secretory pathway, regulation of translation processes may also involve in improving enzyme activity by engineering cell wall biosynthesis. Our work provides new insight into the construction of a yeast cell factory for efficient production of polysaccharide degrading enzymes.

Development of an efficient yeast platform for cannabigerolic acid biosynthesis.

Cannabinoids are important therapeutical molecules for human ailments, cancer treatment, and SARS-CoV-2. The central cannabinoid, cannabigerolic acid (CBGA), is generated from geranyl pyrophosphate and olivetolic acid by Cannabis sativa prenyltransferase (CsPT4). Despite efforts to engineer microorganisms such as Saccharomyces cerevisiae (S. cerevisiae) for CBGA production, their titers remain suboptimal because of the low conversion of hexanoate into olivetolic acid and the limited activity and stability of the CsPT4. To address the low hexanoate conversion, we eliminated hexanoate consumption by the beta-oxidation pathway and reduced its incorporation into fatty acids. To address CsPT4 limitations, we expanded the endoplasmic reticulum and fused an auxiliary protein to CsPT4. Consequently, the engineered S. cerevisiae chassis showed a marked improvement of 78.64-fold in CBGA production, reaching a titer of 510.32 ± 10.70 mg l-1 from glucose and hexanoate.

Dynamic upregulation of the rate-limiting enzyme for valerolactam biosynthesis in Corynebacterium glutamicum.

Valerolactam is a monomer used to manufacture high-value nylon-5 and nylon-6,5. However, the biological production of valerolactam has been limited by the inadequate efficiency of enzymes to cyclize 5-aminovaleric acid to produce valerolactam. In this study, we engineered Corynebacterium glutamicum with a valerolactam biosynthetic pathway consisting of DavAB from Pseudomonas putida to convert L-lysine to 5-aminovaleric acid and ß-alanine CoA transferase (Act) from Clostridium propionicum to produce valerolactam from 5-aminovaleric acid. Most of the L-lysine was converted into 5-aminovaleric acid, but promoter optimization and increasing the copy number of Act were insufficient to significantly improve the titer of valerolactam. To eliminate the bottleneck at Act, we designed a dynamic upregulation system (a positive feedback loop based on the valerolactam biosensor ChnR/Pb). We used laboratory evolution to engineer ChnR/Pb to have higher sensitivity and a higher dynamic output range, and the engineered ChnR-B1/Pb-E1 system was used to overexpress the rate-limiting enzymes (Act/ORF26/CaiC) that cyclize 5-aminovaleric acid into valerolactam. In glucose fed-batch culture, we obtained 12.33 g/L valerolactam from the dynamic upregulation of Act, 11.88 g/L using ORF26, and 12.15 g/L using CaiC. Our engineered biosensor (ChnR-B1/Pb-E1 system) was also sensitive to 0.01-100 mM caprolactam, which suggests that this dynamic upregulation system can be used to enhance caprolactam biosynthesis in the future.

Isolation of the Anti-Inflammatory Agent Myceliostatin from a Methionine-Enriched Culture of Myceliophthora thermophila ATCC 42464.

Safe and effective nonsteroidal anti-inflammatory drugs are needed. Meanwhile, addition of amino acids to cultures of microorganisms is likely to increase the possibility of novel secondary metabolite isolation. In the course of screening for anti-inflammatory agents using cellular lipopolysaccharide (LPS)-induced nitric oxide (NO) production, two new related compounds with the myceliothermophin structure from a methionine-enriched culture of Myceliophthora thermophila ATCC 42464 were isolated. The new compounds have an additional methylthio group on the myceliothermophin structure and were named myceliostatins A and B. Both compounds inhibited LPS-induced NO production at nontoxic concentrations in macrophage-like mouse monocytic leukemia RAW264.7 cells. Myceliostatin B inhibited the expression of LPS-induced iNOS, IL-6, and IL-1ß and the upstream NF-κB activity in situ and in vitro. Finally, it was found to inhibit NF-κB binding to DNA in the reconstruction system with purified p65. Myceliostatin B also inhibited LPS-induced reactive oxygen species (ROS) production. Thus, myceliostatin B, a novel compound derived from M. thermophila, was found to be a new anti-inflammatory and antioxidant compound directly inhibiting NF-κB.

Influencing Factors on the Physicochemical Characteristics of Tea Polysaccharides.

Tea polysaccharides (TPSs) are one of the main bioactive constituents of tea with various biological activities such as hypoglycemic effect, antioxidant, antitumor, and immunomodulatory. The bioactivities of TPSs are directly associated with their structures such as chemical composition, molecular weight, glycosidic linkages, and conformation among others. To study the relationship between the structures of TPSs and their bioactivities, it is essential to elucidate the structure of TPSs, particularly the fine structures. Due to the vast variation nature of monosaccharide units and their connections, the structure of TPSs is extremely complex, which is also affected by several major factors including tea species, processing technologies of tea and isolation methods of TPSs. As a result of the complexity, there are few studies on their fine structures and chain conformation. In the present review, we aim to provide a detailed summary of the multiple factors influencing the characteristics of TPS chemical structures such as variations of tea species, degree of fermentation, and preparation methods among others as well as their applications. The main aspects of understanding the structural difference of TPSs and influencing factors are to assist the study of the structure and bioactivity relationship and ultimately, to control the production of the targeted TPSs with the most desired biological activity.

Graphene-based ultrasensitive optical microfluidic sensor for the real-time and label-free monitoring of simulated arterial blood flow.

Highly sensitive, real-time and label-free sensing of liquid flow in microfluidic environments remains challenging. Here, by growing high-quality graphene directly on a glass substrate, we designed a microfluidic-integrated graphene-based flow sensor (GFS) capable of detecting complex, weak, and transient flow velocity and pressure signals in a microfluidic environment. This device was used to study weak and transient liquid flows, especially blood flow, which is closely related to heart and artery functions. By simulating cardiac peristalsis and arterial flow using peristaltic pumps and microfluidic systems, we monitored simulated arterial blood flow. This ultrasensitive graphene-based flow sensor accurately detected a flow velocity limit as low as 0.7 mm/s, a pumping frequency range of 0.04 Hz to 2.5 Hz, and a pressure range from 0.6 kPa to 14 kPa. By measuring the blood flow velocities and pressures, pathological blood flow signals were distinguished and captured by the corresponding flow velocities or pressures, which can reflect vascular occlusion and heart functions. This sensor may be used for the real-time and label-free monitoring of patients' basic vital signs using their blood flow and provide a possible new method for the care of critically ill patients.

Nonlinearity-Induced Multiplexed Optical Trapping and Manipulation with Femtosecond Vector Beams.

Optical trapping and manipulation of atoms, nanoparticles, and biological entities are widely employed in quantum technology, biophysics, and sensing. Single traps are typically achieved with linearly polarized light, while vortex beams form rotationally unstable symmetric traps. Here we demonstrate multiplexed optical traps reconfigurable with intensity and polarization of the trapping beam using intensity-dependent polarizability of nanoparticles. Nonlinearity combined with a longitudinal field of focused femtosecond vortex beams results in a stable optical force potential with multiple traps, in striking contrast to a linear trapping regime. The number of traps and their orientation can be controlled by the cylindrical vector beam order, polarization, and intensity. The nonlinear trapping demonstrated here on the example of plasmonic nanoparticles opens up opportunities for deterministic trapping and polarization-controlled manipulation of multiple dielectric and semiconductor particles, atoms, and biological objects since most of them exhibit a required intensity-dependent refractive index.

Study on mechanism of release oxygen by photo-excited hemoglobin in low-level laser therapy.

According to the calculated results on the charge distribution of oxygenated heme and deoxygenated heme, and based on the theory of electron excitations in photo-acceptor molecules and the absorption spectra of hemoglobin, it is found that low-level laser within the waveband of about 800-1060 nm can promote the release of oxygen from oxyhemoglobin and improve the oxygen supply of capillaries to surrounding tissues. Furthermore, the reasons have been explained that why the low-level laser at a wavelength of 830 nm is better in the treatment on burn injury and stimulation of hair growth. We also explained why the near-infrared laser of 1064 nm is applied to the forehead to improve cerebral oxygenation in healthy humans. Finally, according to comparison of atomic charge distribution in heme before and after bound to small molecule of carbon monoxide or nitric oxide, it could be inferred that the low-level laser with an appropriate wavelength can promote the carbon monoxide hemoglobin and nitric oxide hemoglobin to dissociate the carbon monoxide molecules and the nitric oxide molecules. This may be used for adjuvant therapy of carbon monoxide poisoning or nitric oxide poisoning.

Plasmonic hybridization induced trapping and manipulation of a single Au nanowire on a metallic surface.

Hybridization in the narrow gaps between the surface plasmon polaritons (SPPs) along a metal surface and the localized surface plasmons on metallic nano-objects strongly enhance the electromagnetic field. Here, we employ plasmonic hybridization to achieve dynamic trapping and manipulation of a single metallic nanowire on a flat metal surface. We reveal that the plasmonic hybridization achieved by exciting plasmonic tweezers with a linearly polarized laser beam could induce strong trapping forces and large rotational torques on a single metallic nanowire. The position and orientation of the nanowire could dynamically be controlled by the hybridization-enhanced nonisotropic electric field in the gap. Experimental results further verify that a single Au nanowire could robustly be trapped at the center of an excited SPP field by the induced forces and then rotated by the torques. Finally, a plasmonic swallow tail structure is built to demonstrate its potential in the fabrication of lab-on-a-chip plasmonic devices.

A Self-Assembled MOF-Escherichia Coli Hybrid System for Light-Driven Fuels and Valuable Chemicals Synthesis.

The development of semi-artificial photosynthetic systems, which integrate metal-organic frameworks (MOFs) with industrial microbial cell factories for light-driven synthesis of fuels and valuable chemicals, represents a highly promising avenue for both research advancements and practical applications. In this study, an MOF (PCN-222) utilizing racemic-(4-carboxyphenyl) porphyrin and zirconium chloride (ZrCl4) as primary constituents is synthesized. Employing a self-assembly process, a hybrid system is constructed, integrating engineered Escherichia coli (E. coli) to investigate light-driven hydrogen and lysine production. These results demonstrate that the light-irradiated biohybrid system efficiently produce H2 with a quantum efficiency of 0.75% under full spectrum illumination, the elevated intracellular reducing power NADPH is also observed. By optimizing the conditions, the biohybrid system achieves a maximum lysine production of 18.25 mg L-1, surpassing that of pure bacteria by 332%. Further investigations into interfacial electron transfer mechanisms reveals that PCN-222 efficiently captures light and facilitates the transfer of photo-generated electrons into E. coli cells. It is proposed that the interfacial energy transfer process is mediated by riboflavin, with facilitation by secreted small organic acids acting as hole scavengers for PCN-222. This study establishes a crucial foundation for future research into the light-driven biomanufacturing using E. coli-based hybrid systems.

Nicotine rebalances NAD+ homeostasis and improves aging-related symptoms in male mice by enhancing NAMPT activity.

Imbalances in NAD+ homeostasis have been linked to aging and various diseases. Nicotine, a metabolite of the NAD+ metabolic pathway, has been found to possess anti-inflammatory and neuroprotective properties, yet the underlying molecular mechanisms remained unknown. Here we find that, independent of nicotinic acetylcholine receptors, low-dose nicotine can restore the age-related decline of NAMPT activity through SIRT1 binding and subsequent deacetylation of NAMPT, thus increasing NAD+ synthesis. 18F-FDG PET imaging revealed that nicotine is also capable of efficiently inhibiting glucose hypermetabolism in aging male mice. Additionally, nicotine ameliorated cellular energy metabolism disorders and deferred age-related deterioration and cognitive decline by stimulating neurogenesis, inhibiting neuroinflammation, and protecting organs from oxidative stress and telomere shortening. Collectively, these findings provide evidence for a mechanism by which low-dose nicotine can activate NAD+ salvage pathways and improve age-related symptoms.

Engineering Cell Polarization Improves Protein Production in Saccharomyces cerevisiae.

Saccharomyces cerevisiae has been widely used as a microbial cell factory to produce recombinant proteins. Therefore, enhancing the protein production efficiency of yeast cell factories to expand the market demand for protein products is necessary. Recombinant proteins are often retained in the secretory pathway because of the limited protein transport performed by vesicle trafficking. Cell polarization describes the asymmetric organization of the plasma membrane cytoskeleton and organelles and tightly regulates vesicle trafficking for protein transport. Engineering vesicle trafficking has broadly been studied by the overexpression or deletion of key genes involved but not by modifying cell polarization. Here, we used α-amylase as a reporter protein, and its secretion and surface-display were first improved by promoter optimization. To study the effect of engineering cell polarization on protein production, fourteen genes related to cell polarization were overexpressed. BUD1, CDC42, AXL1, and BUD10 overexpression increased the activity of surface-displayed α-amylase, and BUD1, BUD3, BUD4, BUD7, and BUD10 overexpression enhanced secreted α-amylase activity. Furthermore, BUD1 overexpression increased the surface-displayed and secreted α-amylase expression by 56% and 49%, respectively. We also observed that the combinatorial modification and regulation of gene expression improved α-amylase production in a dose-dependent manner. BUD1 and CDC42 co-overexpression increased the α-amylase surface display by 100%, and two genomic copies of BUD1 improved α-amylase secretion by 92%. Furthermore, these modifications were used to improve the surface display and secretion of the recombinant ß-glucosidase protein. Our study affords a novel insight for improving the surface display and secretion of recombinant proteins.

Protective Effect of Tangeretin and 5-Hydroxy-6,7,8,3',4'-Pentamethoxyflavone on Collagen-Induced Arthritis by Inhibiting Autophagy via Activation of the ROS-AKT/mTOR Signaling Pathway.

Rheumatoid arthritis (RA) is an autoimmune disease characterized by long duration and repeated relapse. This study explored the preventive effect of tangeretin (TAN) and 5-hydroxy-6,7,8,3',4'-pentamethoxyflavone (5-HPMF) on RA, and the underlying molecular mechanism based on a rat model stimulated by bovine type II collagen (BIIC). After the intervention of TAN or 5-HPMF (TAN/5-HPMF) for 5 weeks, the RA lesions and autophagy levels of the synovial tissue were significantly reduced, and the ROS content and HO-1 expression level were down-regulated simultaneously. The relative expression levels of p-AKT and p-mTOR were down-regulated after TAN/5-HPMF feeding. Meanwhile, the relative expression level of p62 increased by more than two-fold for TAN/5-HPMF treated rats at 200 mg/kg BW comparing with those in BIIC group. Results of immunofluorescence staining and Western blotting further confirmed that TAN/5-HPMF treatment reduced BIIC-induced conversion from LC3I to LC3II. Observations under transmission electron microscope also demonstrated that the autophagy level was reduced upon TAN/5-HPMF intervention. Collectively, these results revealed that TAN and 5-HPMF prevented the pathological process of BIIC-stimulated arthritis through inhibiting the autophagy of synovial cells, achieved via the ROS-AKT/mTOR signal axis. Thus, our findings confirmed the protective potential of TAN and 5-HPMF for RA disease.

Efficient Preparation of Black Tea Extract (BTE) with the High Content of Theaflavin Mono- and Digallates and the Protective Effects of BTE on CCl4-Induced Rat Liver and Renal Injury.

Theaflavins (TFs), formed by the dimerization of green tea catechins during "fermentation" to prepare black tea, possess antioxidant and anti-inflammatory effects. Reported efficacious effects of black tea (∼2% of TFs) or related products come from catechins unless TFs are assayed. The present study aimed to target the preparation of black tea extract (BTE) enriched with theaflavin mono- and digallates majorly from dry tea leaves in aqueous media versus traditional fermentation of fresh leaves. We further investigated the protective function of the produced BTE on rat liver and kidney injury induced by CCl4 and its underlying molecular mechanisms. The results showed that BTE suppressed the activation level of hepatic stellate cells (HSCs), and the secretion of collagen was induced by CCl4. The relative expression levels of TGF-ß, p-ERK1/ERK1, p-ERK2/ERK2, p-Smad1/Smad1, and p-Smad2/Smad2 were reduced to 56, 68, 56, 44, and 32%, respectively, compared with those of CCl4-treated rats. Therefore, BTE enriched with TFs prevented rat hepatic fibrosis through the TGF-ß/Smad/ERK signaling pathway and kidney injury by inhibiting the expression of TGF-ß and proinflammatory cytokines in rats. We predict the broad application of TFs and related products because of their strong antioxidant and inhibitory effects on chronic inflammation.

Stabilization of soil arsenic by natural limonite after mechanical activation and the associated mechanisms.

Arsenic (As) is an environmentally hazardous contaminant which have a serious threat to human health. In recent years, sustainability has drawn increasing attention in the environmental remediation field. Application of natural minerals as a class of iron-containing materials for soil As remediation is meaningful and challenging. In this paper the As sorption ability and soil stabilization of mechanical activated limonite has been studied. Mechanical activation can effectively enhance the adsorption performance of natural limonite. The positive effect of mechanical activation on limonite mainly include: (1) particle size reduction and specific surface area increase; (2) reduction of limonite crystallinity and increase of surface active sites; (3) mineral phase transformation to amorphous iron oxides substances. The average grain size of limonite reduces from 16.8 µm to 0.214 µm after activation while the specific surface area increases from 10.26 m2/g to 56.74 m2/g. The maximum adsorption capacities of mechanically activated limonite (Lm) for As (III) and As (V) were 9.14 mg/g and 8.26 mg/g, respectively at pH 7.0, higher than untreated limonite (L0). Mechanically activated limonite can effectively stabilize As in soils. When Lm dosage was 10%, the stabilization effects could reach about 78%. Limonite could transform the soil As from non-specifically and specifically sorbed fraction to amorphous iron hydrous oxides bounded fractions. Mechanically activated limonite (Lm) exhibited good adsorption and stabilization performance advantages for As in soils.

[Mineral Characteristics of Arsenic in the Active Area of the Banbishan Gold Mine and Its Effect on Arsenic Accumulation in Farmland Soil].

To explore the source and pollution characteristics of soil arsenic, mineralogy and chemical analysis methods were used to analyze the ore, waste rock, sediment, and river and soil samples around the mining area. Under a polarized light microscope, As-bearing mineral-arsenopyrite was found in the soil, ore, and waste rock around the Banbishan gold mine. Moreover, arsenopyrite in the waste rock has already experienced weathering and oxidation, and the oxidized arsenopyrite easily migrates and is released in the soil, which is potentially harmful. Because of the effect of mining transportation activities and indigenous smelting, arsenic was mainly distributed in the topsoil, at a depth of 0-20 cm, in the farmland on both sides of the road and in the places where villagers were gathered. The soil arsenic content in Xiaowulan Village and Gaozhangzi Village ranged from 7.2 to 196.2 mg·kg-1 and exceeded the rate of arsenic by 45.9% and 82.1%. According to the assessment by the RAC method, the farmland soil in Xiaowulan Village and Gaozhangzi Village were mainly at low to medium risk, although some soil points in Xiaowulan Village were at high risk. In general, the effects of the mining activities of the surrounding environment were not optimistic. As-bearing minerals in the oxidation of long-term weathering can cause much arsenic to be activated, which in turn, affects the local crops and long-term residents living around the mining area. It is suggested to carry out risk assessments for arsenic in the soil-crop-atmospheric-human system, and further study the conversion rules and mechanisms of arsenopyrite during weathering, to provide scientific guidance for the environmental protection of cultivated land.

[Adsorption and Mechanism of Arsenic by Natural Iron-containing Minerals].

Natural iron-containing minerals present in the geosphere in the form of crystalline minerals can be used as adsorption material for removal of arsenic from wastewater and remediation of arsenic-contaminated soils. In this paper, the adsorption and desorption of arsenic onto different iron-containing materials including hematite, limonite, siderite, ilmenite, magnetite, Fe2O3, Fe3O4, and Fe-Mn binary oxide (FMBO) were studied in laboratory experiments. The mechanism of arsenic adsorption was analyzed by scanning electron microscopy (SEM), X-ray diffraction (XRD), and fourier transform infrared spectroscopy (FTIR). The results showed that arsenic adsorption is fitted by pseudo-second-order kinetics and the Langmuir isotherm model for almost all adsorbents, suggesting monolayer adsorption of arsenic onto the minerals. The sorption efficiency and capacity of arsenic by FMBO are much higher than those of other materials. Furthermore, limonite has high sorption efficiencies for both As(Ⅲ) and As(Ⅴ) among the natural iron-containing minerals, and their adsorption capacities are 3.96 mg·g-1 and 2.99 mg·g-1, respectively. The XRD results showed that natural limonite contains a large number of weak crystalline mineral components such as goethite, which can provide relatively abundant arsenic adsorption sites. Thus, limonite appears to be the most suitable natural mineral for arsenic adsorption.

Microheterogeneous structure of 1-octanol in neat and water-saturated state.

The conformational and dynamic properties of 1-octanol in neat and in water-saturated states have been investigated by 1H NMR. It has been proved that neat 1-octanol is microheterogeneous in nature comprising regions enriched in either hydrocarbons or hydroxyl groups. A reversed micelle-like cluster model was proposed, where the octanol cluster has an inner polar core of hydrogen-bonded octanol hydroxyls and an outer shell of nonpolar alkyl chains radiating outside. It was also observed that the cluster structure of octanol experiences minor changes with the presence of water. In water-saturated octanol, water molecules associate via hydrogen bonding and reside in the innermost center of the polar region with restricted motion, whereas the octanol cluster structure is modified by loosening the compact structure. Moreover, the preferential solvations of both systems were tested and compared. It not only gives some clues about the microheterogeneity of the alcohol system and the structure of the cluster but also helps in advancing our understanding on the behavior and properties of the amphiphilic molecules system such as phospholipids.