Combined strategies for improving the heterologous expression of a novel xylanase from Fusarium oxysporum Fo47 in Pichia pastoris

Xylanase, an enzyme capable of hydrolyzing non-starch polysaccharides found in grain structures like wheat, has been found to improve the organizational structure of dough and thus increase its volume. In our past work, one promising xylanase FXYL derived from Fusarium oxysporum Fo47 and first expressed 779.64 U/mL activity in P. pastoris. It has shown significant potential in improving the quality of whole wheat bread, making it become a candidate for development as a new flour improver. After optimization of expression elements and gene dose, the xylanase activity of FXYL strain carrying three-copies reached 4240.92 U/mL in P. pastoris. In addition, 12 factors associated with the three stages of protein expression pathway were co-expressed individually in order in three-copies strain, and the translation factor Pab1 co-expression increased FXYL activity to 8893.53 U/mL. Nevertheless, combining the most effective or synergistic factors from three stages did not exhibit better results than co-expressing them alone. To further evaluate the industrial potential, the xylanase activity and protein concentration reached 81184.51 U/mL and 11.8 g/L in a 5 L fed-batch fermenter. These engineering strategies improved the expression of xylanase FXYL by more than 104-fold, providing valuable insights for the cost-effective industrial application of FXYL in the baking field.

Metabolic engineering of Saccharomyces cerevisiae for the synthesis of valuable chemicals

In the twenty first century, biotechnology offers great opportunities and solutions to climate change mitigation, energy and food security and resource efficiency. The use of metabolic engineering to modify microorganisms for producing industrially significant chemicals is developing and becoming a trend. As a famous, generally recognized as a safe (GRAS) model microorganism, Saccharomyces cerevisiae is widely used due to its excellent operational convenience and high fermentation efficiency. This review summarizes recent advancements in the field of using metabolic engineering strategies to construct engineered S. cerevisiae over the past ten years. Five different types of compounds are classified by their metabolites, and the modified metabolic pathways and strategies are summarized and discussed independently. This review may provide guidance for future metabolic engineering efforts toward such compounds and analogues. Additionally, the limitations of S. cerevisiae as a cell factory and its future trends are comprehensively discussed.

Improving statins production: From non-genetic strategies to genetic strategies

Statins are lipid-lowering drugs that selectively inhibit 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase, effectively reducing cholesterol synthesis. With improved nutritional conditions, the demand for statins is increasing in the global market. The use of microbial cell factories for statin biosynthesis has become advantageous due to the rapid advancements in biotechnology. These approaches offer simple operation and easy separation of products. This review provides an overview the strategies for statins production via microbial cell factories, including both traditional fermentation culture (non-genetic) and modern synthetic biology manufacture (genetic). Firstly, the complex fermentation parameters and process control technology on submerged fermentation (SmF) and solid-state fermentation (SSF) are introduced in detail. The potential use of recoverable agricultural wastes/(biomass) as a fermentation substrate in SSF for statin production is emphasized. Additionally, metabolic engineering strategies for constructing robust engineering strains and directed evolution are also discussed. The review highlights the potential and challenges of using microbial cell factories for statin production, and aims to promote greener production modes for statins.

Characterization of the enzyme kinetics of EMP and HMP pathway in Corynebacterium glutamicum: reference for modeling metabolic networks

The model of intracellular metabolic network based on enzyme kinetics parameters plays an important role in understanding the intracellular metabolic process of Corynebacterium glutamicum, and constructing such a model requires a large number of enzymological parameters. In this work, the genes encoding the relevant enzymes of the EMP and HMP metabolic pathways from Corynebacterium glutamicum ATCC 13032 were cloned, and engineered strains for protein expression with E.coli BL21 and P.pastoris X33 as hosts were constructed. The twelve enzymes (GLK, GPI, TPI, GAPDH, PGK, PMGA, ENO, ZWF, RPI, RPE, TKT, and TAL) were successfully expressed and purified by Ni2+ chelate affinity chromatography in their active forms. In addition, the kinetic parameters (V max, K m, and K cat) of these enzymes were measured and calculated at the same pH and temperature. The kinetic parameters of enzymes associated with EMP and the HMP pathway were determined systematically and completely for the first time in C.glutamicum. These kinetic parameters enable the prediction of key enzymes and rate-limiting steps within the metabolic pathway, and support the construction of a metabolic network model for important metabolic pathways in C.glutamicum. Such analyses and models aid in understanding the metabolic behavior of the organism and can guide the efficient production of high-value chemicals using C.glutamicum as a host.

Improving the Microstructural and Rheological Properties of Frozen Unfermented Wheat Dough with Laccase and Ferulic Acid

The quality deterioration that is induced by freezing treatment limits the development of frozen dough technology for standardized and delayed baking. In this study, laccase (LAC) and ferulic acid (FA) were employed to improve the rheological properties and microstructure of frozen unfermented dough. The results showed that the dough with LAC + FA had a lower softening degree than the dough with FA alone. Correspondingly, LAC + FA incorporation enhanced the viscoelastic behavior of frozen unfermented dough with better stability. Furthermore, a more uniform and homogeneous gluten network was observed in the LAC + FA-supplemented dough after 21 d of storage. The structural stability of the frozen gluten sample increased after LAC + FA treatment, possibly owing to an increase in the oxidation degree of FA. Moreover, LAC + FA treatment promoted the oxidation of the sulfhydryl groups to some extent, resulting in more extensive cross-linking. LAC + FA treatment hindered the protein conformational changes typically induced by frozen storage compared with LAC alone. Overall, LAC + FA treatment has a synergistic effect on enhancing the viscoelastic behaviors of frozen unfermented dough and inhibiting the conformational variation in frozen gluten; thus, it shows promise for improving frozen dough.

Label-Free Electrochemical Aptasensor for Sensitive Detection of Malachite Green Based on AuNPs/MWCNTs@TiO2 Nanocomposites

This study proposes a label-free aptamer biosensor for the sensitive detection of malachite green(MG) using gold nanoparticles/multi-walled carbon nanotubes @ titanium dioxide(AuNPs/MWCNTs@TiO₂). The nanocomposite provides a large surface area and good electrical conductivity, improving current transfer and acting as a platform for aptamer immobilization. The aptamer and the complementary chain(cDNA) are paired by base complementary to form the recognition element and fixed on the AuNPs by sulfhydryl group, which was modified on the cDNA. Since DNA is negatively charged, the redox probe in the electrolyte is less exposed to the electrode surface under the repulsion of the negative charge, resulting in a low-electrical signal level. When MG is present, the aptamer is detached from the cDNA and binds to MG, the DNA on the electrode surface is reduced, and the rejection of the redox probe is weakened, which leads to an enhanced electrical signal and enables the detection of MG concentration by measuring the change in the electrical signal. Under the best experimental conditions, the sensor demonstrates a good linear relationship for the detection of MG from 0.01 to 1000 ng/mL, the limit of detection (LOD)is 8.68 pg/mL. This sensor is stable, specific, and reproducible, allowing for the detection of various small-molecule pollutants by changing the aptamer, providing an effective method for detecting small-molecule pollutants.

Measurement of Direct-Photon Cross Section and Double-Helicity Asymmetry at sqrt[s]=510 GeV in p[over →]+p[over →] Collisions

We present measurements of the cross section and double-helicity asymmetry A_{LL} of direct-photon production in p[over →]+p[over →] collisions at sqrt[s]=510  GeV. The measurements have been performed at midrapidity (|η|<0.25) with the PHENIX detector at the Relativistic Heavy Ion Collider. At relativistic energies, direct photons are dominantly produced from the initial quark-gluon hard scattering and do not interact via the strong force at leading order. Therefore, at sqrt[s]=510  GeV, where leading-order-effects dominate, these measurements provide clean and direct access to the gluon helicity in the polarized proton in the gluon-momentum-fraction range 0.02<x<0.08, with direct sensitivity to the sign of the gluon contribution.

Disruption of phosphate metabolism and sterol transport-related genes conferring yeast resistance to vanillin and rapid ethanol production

Vanillin is a potent growth-inhibiting factor in Saccharomyces cerevisiae during lignocellulose biorefineries. Here, a haploid gene-deletion library was screened to search for vanillin-tolerant mutants and explain the possible tolerance mechanisms. Twenty-two deletion mutants were identified. The deleted genes in these mutants were involved in phosphate and inositol polyphosphate metabolism and intracellular sterol transport. Activation of the phosphate signaling pathway is not conducive to yeast against the pressure of vanillin. Furthermore, the findings indicate the role of inositol polyphosphates in altering vanillin tolerance by regulating phosphate metabolism. Meanwhile, reducing the transport of sterols from the plasma membrane enhanced tolerance to vanillin. In the presence of vanillin, the representative yeast deletions, pho84Δ and lam3Δ, showed good growth performance and promoted rapid ethanol production. Overall, this study identifies robust yeast strain alternatives for ethanol fermentation of cellulose and provides guidance for further genomic reconstruction of yeast strains.

Association of human gut microbiota composition and metabolic functions with Ficus hirta Vahl dietary supplementation

Ficus hirta Vahl (FHV), a traditional herbal ingredient of the tonic diet, receives increasing popularity in southern China. However, it is largely unknown that how a FHV diet (FHVD) affects the human gut microbiome. In this exploratory study, a total of 43 healthy individuals were randomized into the FHVD (n = 25) and Control (n = 18) groups to receive diet intervention for 8 weeks. 16S rRNA gene sequencing, metagenomic sequencing and metabolic profile of participants were measured to assess the association between FHV diet and gut microbiome. A preservation effect of Faecalibacterium and enrichment of Dialister, Veillonella, Clostridium, and Lachnospiraceae were found during the FHVD. Accordingly, the pathway of amino acid synthesis, citrate cycle, coenzyme synthesis, and partial B vitamin synthesis were found to be more abundant in the FHVD. In addition, serine, glutamine, gamma-aminobutyric acid, tryptamine, and short-chain fatty acids (SCFAs) were higher after the FHVD. The conjoint analysis of FHV components and in-vitro fermentation confirmed that the improved SCFAs concentration was collectively contributed by the increasing abundance of key enzyme genes and available substrates. In conclusion, the muti-omics analysis showed that the FHVD optimized the structure of the gut microbial community and its metabolic profile, leading to a healthy tendency, with a small cluster of bacteria driving the variation rather than a single taxon.

Characterization and application of a novel xylanase from Halolactibacillus miurensis in wholewheat bread making

The presence of arabinoxylan in wholewheat flour affects its quality significantly. Here, an efficient arabinoxylan hydrolytic enzyme, Hmxyn, from Halolactibacillus miurensis was identified and heterologously expressed in pichia pastoris. Moreover, its relevant properties, including potential application in the wholewheat bread were evaluated. Recombinant Hmxyn exhibited maximal activity at 45°C and pH 6.5, and was stable at mid-range temperature (&lt;55°C) and pH (5.5–8.0) conditions. Hmxyn had a clear hydrolysis effect on wheat arabinoxylan in dough and caused the degradation of the water-unextractable arabinoxylan, which increased the content of wheat soluble arabinoxylan of dough. The fermentation characteristics results and microstructure analysis revealed that Hmxyn improved the organizational structure and air holding capacity of fermented dough, thus promoting the dough expansion. Baking experiments further showed that Hmxyn significantly increased specific volume- and texture-linked properties of wholewheat breads. This study indicates the application potential of Hmxyn in the preparation of wholewheat bread.

Acute and Chronic Toxicity of Binary Mixtures of Bisphenol A and Heavy Metals

Bisphenol A (BPA) and heavy metals are widespread contaminants in the environment. However, the combined toxicities of these contaminants are still unknown. In this study, the bioluminescent bacteria Vibrio qinghaiensis Q67 was used to detect the single and combined toxicities of BPA and heavy metals, then the joint effects of these contaminants were evaluated. The results show that chronic toxicities of chromium (Cr), cadmium (Cd), lead (Pb), arsenic (As), mercury (Hg), nickel (Ni), and BPA were time−dependent; in fact, the acute toxicities of these contaminants were stronger than the chronic toxicities. Furthermore, the combined toxicities of BPA and heavy metals displayed BPA + Hg > BPA + Cr > BPA + As > BPA + Ni > BPA + Pb > BPA + Cd in the acute test and BPA + Hg > BPA + Cd > BPA + As > BPA + Cd in the chronic test, which suggested that the combined toxicity of BPA and Hg was stronger than that of other mixtures in acute as well as chronic tests. Additionally, both CA and IA models underestimated the toxicities of mixtures at low concentrations but overestimated them at high concentrations, which indicates that CA and IA models were not suitable to predict the toxicities of mixtures of BPA and heavy metals. Moreover, the joint effects of BPA and heavy metals mainly showed antagonism and additive in the context of acute exposure but synergism and additive in the context of chronic exposure. Indeed, the difference in the joint effects on acute and chronic exposure can be explained by the possibility that mixtures inhibited cell growth and luminescence in chronic cultivation. The chronic toxicity of the mixture should be considered if the mixture results in the inhibition of the growth of cells.

Comparative transcriptome and metabolome analyses reveal the methanol dissimilation pathway of Pichia pastoris

BACKGROUND

Pichia pastoris (Komagataella phaffii) is a model organism widely used for the recombinant expression of eukaryotic proteins, and it can metabolize methanol as its sole carbon and energy source. Methanol is oxidized to formaldehyde by alcohol oxidase (AOX). In the dissimilation pathway, formaldehyde is oxidized to CO₂ by formaldehyde dehydrogenase (FLD), S-hydroxymethyl glutathione hydrolase (FGH) and formate dehydrogenase (FDH).

RESULTS

The transcriptome and metabolome of P. pastoris were determined under methanol cultivation when its dissimilation pathway cut off. Firstly, Δfld and Δfgh were significantly different compared to the wild type (GS115), with a 60.98% and 23.66% reduction in biomass, respectively. The differential metabolites between GS115 and Δfld were mainly enriched in ABC transporters, amino acid biosynthesis, and protein digestion and absorption. Secondly, comparative transcriptome between knockout and wild type strains showed that oxidative phosphorylation, glycolysis and the TCA cycle were downregulated, while alcohol metabolism, proteasomes, autophagy and peroxisomes were upregulated. Interestingly, the down-regulation of the oxidative phosphorylation pathway was positively correlated with the gene order of dissimilation pathway knockdown. In addition, there were significant differences in amino acid metabolism and glutathione redox cycling that raised our concerns about formaldehyde sorption in cells.

CONCLUSIONS

This is the first time that integrity of dissimilation pathway analysis based on transcriptomics and metabolomics was carried out in Pichia pastoris. The blockage of dissimilation pathway significantly down-regulates the level of oxidative phosphorylation and weakens the methanol assimilation pathway to the point where deficiencies in energy supply and carbon fixation result in inefficient biomass accumulation and genetic replication. In addition, transcriptional upregulation of the proteasome and autophagy may be a stress response to resolve formaldehyde-induced DNA-protein crosslinking.

Application of Nanomaterial Modified Aptamer-Based Electrochemical Sensor in Detection of Heavy Metal Ions

Heavy metal pollution resulting from significant heavy metal waste discharge is increasingly serious. Traditional methods for the detection of heavy metal ions have high requirements on external conditions, so developing a sensitive, simple, and reproducible detection method is becoming an urgent need. The aptamer, as a new kind of artificial probe, has received more attention in recent years for its high sensitivity, easy acquisition, wide target range, and wide use in the detection of various harmful substances. The detection platform that an aptamer-based electrochemical biosensor (E-apt sensor) provides is a new approach for the detection of heavy metal ions. Nanomaterials are particularly important in the construction of E-apt sensors, as they can be used as aptamer carriers or sensitizers to stimulate or inhibit electrochemical signals, thus significantly improving the detection sensitivity. This review summarizes the application of different types of nanomaterials in E-apt sensors. The construction methods and research progress of the E-apt sensor based on different working principles are systematically introduced. Moreover, the advantages and challenges of the E-apt sensor in heavy metal ion detection are summarized.

A piecewise constitutive model for collagen fiber tissues

Inspired by Meyers et al. (Science, 2013), a piecewise model is established so as to individually predict both the heel region and the linear region of stress-strain curve. When the piecewise model satisfactorily predicts the experimental data, the constitutive parameters are precisely identified with definite physical significances. Along with this piecewise guideline, a complete constitutive model can be established for the whole stress-strain curve of collagen fiber tissues with the failure region as well. Graphical abstract.

Improving Thermostability and Catalytic Activity of Glycosyltransferase From Panax ginseng by Semi-Rational Design for Rebaudioside D Synthesis

As a natural sweetener and sucrose substitute, the biosynthesis and application of steviol glycosides containing the component rebaudioside D have attracted worldwide attention. Here, a glycosyltransferase PgUGT from Panax ginseng was first reported for the biosynthesis of rebaudioside D. With the three-dimensional structures built by homology modeling and deep-learning–based modeling, PgUGT was semi-rationally designed by FireProt. After detecting 16 site-directed variants, eight of them were combined in a mutant Mut8 with both improved enzyme activity and thermostability. The enzyme activity of Mut8 was 3.2-fold higher than that of the wild type, with an increased optimum reaction temperature from 35 to 40°C. The activity of this mutant remained over 93% when incubated at 35°C for 2 h, which was 2.42 times higher than that of the wild type. Meanwhile, when the enzymes were incubated at 40°C, where the wild type was completely inactivated after 1 h, the residual activity of Mut8 retained 59.0% after 2 h. This study would provide a novel glycosyltransferase with great potential for the industrial production of rebaudioside D and other steviol glycosides.

Characterization of D-Allulose-3-Epimerase From Ruminiclostridium papyrosolvens and Immobilization Within Metal-Organic Frameworks

D-allulose is one sort of C-3 epimer of D-fructose with the low calorie (0.4 kcal/g) and high sweetness (70% of the relative sweetness of sucrose), which can be biosynthesized by D-allulose-3-epimerase (DAE). In this work, we report the characterization of a novel DAE from Ruminiclostridium papyrosolvens (RpDAE) by genome mining approach. The activity of RpDAE reached maximum at pH 7.5 and 60°C, supplemented with 1 mM Co²⁺. Using D-fructose (500 g/L) as the substrate for epimerization reaction, RpDAE produced D-allulose (149.5 g/L). In addition, RpDAE was immobilized within the microporous zeolite imidazolate framework, ZIF67, by in situ encapsulation at room temperature. The synthesized bio-composites were characterized by powder X-ray diffraction and Fourier transform infrared spectroscopy. RpDAE-ZIF67 maintained 56% of residual activity after five reaction cycles. This study provides helpful guidance for further engineering applications and industrial production of D-allulose.

Selection and Application of ssDNA Aptamers for Fluorescence Biosensing Detection of Malachite Green

Malachite green oxalate (MG) is a kind of veterinary drug, which is freely soluble in water and hazardous to aquatic products, resulting in food toxicity and human health problems. The demand for effective and sensitive detection of MG residues is increasing in food safety. In this work, three DNA aptamers MG-36-12/16/17 targeting MG with good affinity (Kd values were 169.78, 71.94, and 102.46 μM, respectively) were obtained by Capture-SELEX. Furthermore, MG-36-12, MG-76-16-6A, and MG-36-17 were found to perform sensitively and specifically to detect MG as a sensing probe in a FRET fluorescent aptasensor, where the FAM-labeled aptamer and GO were employed as efficient energy donor–acceptor pair. The linear range of this aptasensor using aptamer MG-36-12 was from 4 to 1200 ng/mL and the LOD was as low as 1.82 ng/mL. Additionally, the fluorescent assay using aptamer MG-36-17 to detect MG exhibited a linear relationship from 4 to 2000 ng/mL and a LOD of 5.05 ng/mL. Meanwhile, the aptasensor showed high specificity to MG with no cross-reactivity to other veterinary drugs and had a mean recovery of 82.77% to 102.48% in actual water samples from the aquatic product market.

Transcriptional Regulation of the Creatine Utilization Genes of Corynebacterium glutamicum ATCC 14067 by AmtR, a Central Nitrogen Regulator

In the genus Corynebacterium, AmtR is a key component of the nitrogen regulatory system, and it belongs to the TetR family of transcription regulators. There has been much research on AmtR structure, functions, and regulons in the type strain C. glutamicum ATCC 13032, but little research in other C. glutamicum strains. In this study, chromatin immunoprecipitation and massively parallel DNA sequencing (ChIP-seq) was performed to identify the AmtR regulon in C. glutamicum ATCC 14067. Ten peaks were obtained in the C. glutamicum ATCC 14067 genome including two new peaks related to three operons (RS_01910-RS_01915, RS_15995, and RS_16000). The interactions between AmtR and the promoter regions of the three operons were confirmed by electrophoretic mobility shift assays (EMSAs). The RS_01910, RS_01915, RS_15995, and RS_16000 are not present in the type strain C. glutamicum ATCC 13032. Sequence analysis indicates that RS_01910, RS_01915, RS_15995, and RS_16000, are related to the degradation of creatine and creatinine; RS_01910 may encode a protein related to creatine transport. The genes RS_01910, RS_01915, RS_15995, and RS_16000 were given the names crnA, creT, cshA, and hyuB, respectively. Real-time quantitative PCR (RT-qPCR) analysis and sfGFP (superfolder green fluorescent protein) analysis reveal that AmtR directly and negatively regulates the transcription and expression of crnA, creT, cshA, and hyuB. A growth test shows that C. glutamicum ATCC 14067 can use creatine or creatinine as a sole nitrogen source. In comparison, a creT deletion mutant strain is able to grow on creatinine but loses the ability to grow on creatine. This study provides the first genome-wide captures of the dynamics of in vivo AmtR binding events and the regulatory network they define. These elements provide more options for synthetic biology by extending the scope of the AmtR regulon.

[Optimization of CRISPR/Cas9-based multiplex base editing in Corynebacterium glutamicum]

As a new CRISPR/Cas-derived genome engineering technology, base editing combines the target specificity of CRISPR/Cas and the catalytic activity of nucleobase deaminase to install point mutations at target loci without generating DSBs, requiring exogenous template, or depending on homologous recombination. Recently, researchers have developed a variety of base editing tools in the important industrial strain Corynebacterium glutamicum, and achieved simultaneous editing of two and three genes. However, the multiplex base editing based on CRISPR/Cas9 is still limited by the complexity of multiple sgRNAs, interference of repeated sequence and difficulty of target loci replacement. In this study, multiplex base editing in C. glutamicum was optimized by the following strategies. Firstly, the multiple sgRNA expression cassettes based on individual promoters/terminators was optimized. The target loci can be introduced and replaced rapidly by using a template plasmid and Golden Gate method, which also avoids the interference of repeated sequence. Although the multiple sgRNAs structure is still complicated, the editing efficiency of this strategy is the highest. Then, the multiple gRNA expression cassettes based on Type Ⅱ CRISPR crRNA arrays and tRNA processing were developed. The two strategies only require one single promoter and terminator, and greatly simplify the structure of the expression cassette. Although the editing efficiency has decreased, both methods are still applicable. Taken together, this study provides a powerful addition to the genome editing toolbox of C. glutamicum and facilitates genetic modification of this strain.

Genome-Scale Mining of Novel Anchor Proteins of Corynebacterium glutamicum

The display of recombinant proteins on the surfaces of bacteria is a research topic with many possible biotechnology applications—among which, the choice of host cell and anchoring motif is the key for efficient display. Corynebacterium glutamicum is a promising host for surface display due to its natural advantages, while single screening methods and fewer anchor proteins restrict its application. In this study, the subcellular localization (SCL) predictor LocateP and tied-mixture hidden Markov models were used to analyze all five known endogenous anchor proteins of C. glutamicum and test the accuracy of the predictions. Using these two tools, the SCLs of all proteins encoded by the genome of C. glutamicum 13032 were predicted, and 14 potential anchor proteins were screened. Compared with the positive controls NCgl1221 and NCgl1337, three anchoring proteins—NCgl1307, NCgl2775, and NCgl0717—performed better. This study also discussed the applicability of the anchor protein screening method used in this experiment to other bacteria.

Application of Corynebacterium glutamicum engineering display system in three generations of biorefinery

The fermentation production of platform chemicals in biorefineries is a sustainable alternative to the current petroleum refining process. The natural advantages of Corynebacterium glutamicum in carbon metabolism have led to C. glutamicum being used as a microbial cell factory that can use various biomass to produce value-added platform chemicals and polymers. In this review, we discussed the use of C. glutamicum surface display engineering bacteria in the three generations of biorefinery resources, and analyzed the C. glutamicum engineering display system in degradation, transport, and metabolic network reconstruction models. These engineering modifications show that the C. glutamicum engineering display system has great potential to become a cell refining factory based on sustainable biomass, and further optimizes the inherent properties of C. glutamicum as a whole-cell biocatalyst. This review will also provide a reference for the direction of future engineering transformation.

Unstable Non-isthmic Spondylolisthesis Following Unilateral Biportal Endoscopy Assisted Unilateral Laminotomy for Bilateral Decompression: A Case Report

Lumbar decompressive laminectomy is a standard treatment for degenerative lumbar spinal stenosis, but in some cases, can lead to iatrogenic spondylolysis and delayed segmental instability. Iatrogenic spondylolysis occurs in most cases in pars interarticularis, but rare cases have also been reported, pediculolysis in pedicle and laminolysis in lamina. Minimally invasive spine surgery (MIS) is known to have a low risk of developing these iatrogenic spondylolyses, and unilateral biportal endoscopy is the MIS that has been drawing attention. We present a case of a 72-year-old female who was diagnosed with L4-5 unstable non-isthmic spondylolisthesis and severe right central disc extrusion 10 weeks after UBE assisted unilateral laminotomy for bilateral decompression (ULBD) at the consecutive segments of L3-4 and L4-5. Pre-operative imaging studies revealed severe central stenosis without spondylolisthesis at L3-L4 and L4-L5 along with L4-L5 facet tropism. She was managed by anterior lumbar interbody fusion and cement augmented pedicle screw fixation, which resulted in the complete resolution of her clinical and neurologic symptoms.

[The influence of cachexia on the immunotherapy efficacy of Sintilimab for non-small cell lung cancer]

Objective: To investigate whether cachexia affects the treatment effect of immune checkpoint inhibitors for non-small cell lung cancer (NSCLC). Methods: The prognosis of 62 patients with advanced NSCLC who received anti-programmed cell death-1 (PD-1) in Henan Provincial People's Hospital from 2019 to 2021 were retrospectively analyzed. The cachexia was evaluated before and after the second course of immunotherapy. Kaplan-Meier and Log rank methods were used for survival analysis, Cox regression model was used for multivariate analysis, and Spearman's correlation analysis was used for correlation analysis. Results: After the second course of immunotherapy, psoas major muscle area (PMMA) values of the cachexia group and the control group were (14.10±4.09) and (11.66±3.22) cm(2) respectively, with statistics significance (P=0.001). The level of Prealbumin and body weight were correlated with cachexia (P<0.05). The 6-month and 1-year survival rates of 62 cases in the whole group were 58.6% and 42.5%, respectively. The progression-free survival (PFS) in the control group (7.6 months) was higher than that in the cachexia group (3.8 months, P=0.006). The PFS in patients with high expression of PD-L1 (7.1 months) was longer than that of patients with low expression (3.8 months, P=0.009). The overall survival (OS) in the cachexia group (6.3 months) was lower than that in the control group (18.2 months, P=0.006). The OS in patients with high expression of PD-L1 (14.5 months) was longer than that of patients with low expression (1 months, P=0.038). The level of Prealbumin, the level of PD-L1 expression and the change rate of PMMA were related to the OS of the patients (P<0.05). The level of Prealbumin and the change rate of PMMA were the independent influencing factors of the OS (P<0.05). The PMMA and the level of Prealbumin were negatively correlated (r=-0.003 8, P<0.05). Conclusion: Cachexia has a negative impact on the outcomes of patients who received anti-PD-1 immune checkpoint inhibitor therapy.

Development of a Transcription Factor-Based Diamine Biosensor in Corynebacterium glutamicum

Diamines serve as major platform chemicals that can be employed to a variety of industrial scenarios, particularly as monomers for polymer synthesis. High-throughput sensors for diamine biosynthesis can greatly improve the biological production of diamines. Here, we identified and characterized a transcription factor-driven biosensor for putrescine and cadaverine in Corynebacterium glutamicum. The transcriptional TetR-family regulatory protein CgmR (CGL2612) is used for the specific detection of diamine compounds. This study also improved the dynamic range and the sensitivity to putrescine by systematically optimizing genetic components of pSenPut. By a single cell-based screening strategy for a library of CgmR with random mutations, this study obtained the most sensitive variant CgmR_I152T, which possessed an experimentally determined limit of detection (LoD) of ≤0.2 mM, a K of 11.4 mM, and a utility of 720. Using this highly sensitive putrescine biosensor pSenPut_I152T, we demonstrated that CgmRI_152T can be used as a sensor to detect putrescine produced biologically in a C. glutamicum system. This high sensitivity and the range of CgmR will be an influential tool for rewiring metabolic circuits and facilitating the directed evolution of recombinant strains toward the biological synthesis of diamine compounds.

Probing Gluon Spin-Momentum Correlations in Transversely Polarized Protons through Midrapidity Isolated Direct Photons in p^{↑}+p Collisions at sqrt[s]=200 GeV

Studying spin-momentum correlations in hadronic collisions offers a glimpse into a three-dimensional picture of proton structure. The transverse single-spin asymmetry for midrapidity isolated direct photons in p^{↑}+p collisions at sqrt[s]=200  GeV is measured with the PHENIX detector at the Relativistic Heavy Ion Collider (RHIC). Because direct photons in particular are produced from the hard scattering and do not interact via the strong force, this measurement is a clean probe of initial-state spin-momentum correlations inside the proton and is in particular sensitive to gluon interference effects within the proton. This is the first time direct photons have been used as a probe of spin-momentum correlations at RHIC. The uncertainties on the results are a 50-fold improvement with respect to those of the one prior measurement for the same observable, from the Fermilab E704 experiment. These results constrain gluon spin-momentum correlations in transversely polarized protons.

Cell-Free Biosynthesis System: Methodology and Perspective of in Vitro Efficient Platform for Pyruvate Biosynthesis and Transformation

The modification of intracellular metabolic pathways by metabolic engineering has generated many engineered strains with relatively high yields of various target products in the past few decades. However, the unpredictable accumulation of toxic products, the cell membrane barrier, and competition between the carbon flux of cell growth and product synthesis have severely retarded progress toward the industrial-scale production of many essential chemicals. On the basis of an in-depth understanding of intracellular metabolic pathways, scientists intend to explore more sustainable methods and construct a cell-free biosynthesis system in vitro. In this review, the synthesis and application of pyruvate as a platform compound is used as an example to introduce cell-free biosynthesis systems. We systematically summarize a proposed methodology workflow of cell-free biosynthesis systems, including pathway design, enzyme mining, enzyme modification, multienzyme assembly, and pathway optimization. Some new methods, such as machine learning, are also mentioned in this review.

Modulation of Gut Microbiota Composition and Short-Chain Fatty Acid Synthesis by Mogroside V in an In Vitro Incubation System

Mogroside V (MV), a sweetener, is one of the major components inSiraitia grosvenorii. In our research, after in vitro incubation with MV for 24 h, the human gut microbiota diversity changed, with an enrichment of the genera Bacteroides, Lactobacillus, Prevotella, Megasphaera, and Olsenella and the inhibition of Clostridium XlVa, Dorea, and Desulfovibrio. Moreover, the synthesis of short-chain fatty acids, such as acetate, propionate, and butyrate, was increased by gut microbiota. According to ultraperformance liquid chromatography-mass spectrometry (UPLC-MS) analysis, MV was decomposed into secondary mogrosides, such as mogroside II/I and mogrol, by gut microbiota. Enhanced antioxidant abilities of the metabolites were found in the broth. The results suggested that MV, as a potential prebiotic, could benefit human health through its interaction with gut microbiota.

Hypocomplementemia (C3) as an independent predictor for children with acute post-streptococcal glomerulonephritis: a long-term observation

OBJECTIVE

The aim of this study was to examine the altering patterns in clinical characteristics and severity of acute post-streptococcal glomerulonephritis (APSGN) in children.

PATIENTS AND METHODS

We analyzed the medical records of 119 children who were diagnosed with APSGN from 1987 to 2018, retrospectively. The patients were divided into two groups: Group I (n=72, before 1998) and Group II (n=47, after 1998). Clinical, radiologic, and laboratory findings were compared between the two groups.

RESULTS

The clinical manifestations, including vomiting (20.8% vs. 4.3%, p=0.014), oliguria (40.3% vs. 19.1%, p=0.016), and generalized edema (86.1% vs. 63.8%, p=0.005), were statistically less frequent since 1998. Pulmonary edema on chest X-ray (22.7% vs. 4.4%, p=0.014) was less frequent in Group II than in Group I. The level of BUN (23.3±19.3 vs. 18.8±11.2, p=0.009) was lower in Group II than in Group I, while that of creatinine was not significantly different between the two groups. C3 level was an independent factor for predicting the development of edema (odds ratio [OR]: 1.034, 95% CI: 1.010-1.060, p=0.006) and acute nephritic symptoms (≥2) (OR: 0.974, 95% CI: 0.952-0996, p=0.020). It was also negatively correlated with an increasing number of acute nephritic symptoms, including oliguria and edema, in patients with APSGN (R=-0.182, p=0.048).

CONCLUSIONS

This study demonstrated that APSGN had favorable clinical manifestations and severity over the past 30 years. The monitoring of C3 levels can be used to assess the disease severity and risk of complications, including edema and oliguria, which are decreasing in South Korean children.

Development of a Hyperosmotic Stress Inducible Gene Expression System by Engineering the MtrA/MtrB-Dependent NCgl1418 Promoter in Corynebacterium glutamicum

Corynebacterium glutamicum is an important workhorse for industrial production of diversiform bioproducts. Precise regulation of gene expression is crucial for metabolic balance and enhancing production of target molecules. Auto-inducible promoters, which can be activated without expensive inducers, are ideal regulatory tools for industrial-scale application. However, few auto-inducible promoters have been identified and applied in C. glutamicum. Here, a hyperosmotic stress inducible gene expression system was developed and used for metabolic engineering of C. glutamicum. The promoter of NCgl1418 (P _NCgl1418 ) that was activated by the two-component signal transduction system MtrA/MtrB was found to exhibit a high inducibility under hyperosmotic stress conditions. A synthetic promoter library was then constructed by randomizing the flanking and space regions of P _NCgl1418 , and mutant promoters exhibiting high strength were isolated via fluorescence activated cell sorting (FACS)-based high-throughput screening. The hyperosmotic stress inducible gene expression system was applied to regulate the expression of lysE encoding a lysine exporter and repress four genes involved in lysine biosynthesis (gltA, pck, pgi, and hom) by CRISPR interference, which increased the lysine titer by 64.7% (from 17.0 to 28.0 g/L) in bioreactors. The hyperosmotic stress inducible gene expression system developed here is a simple and effective tool for gene auto-regulation in C. glutamicum and holds promise for metabolic engineering of C. glutamicum to produce valuable chemicals and fuels.

[A new analysis method for 24-hour intraocular pressure data]

The study aimed to introduce a new analysis method of 24-hour intraocular pressure (IOP) and to propose the concept of overall IOP. Data of 24-hour IOP of a patient with a confirmed diagnosis of normal tension glaucoma was selected. Based on the present indexes including peak IOP, trough IOP, maximum difference, and mean IOP, new indexes were proposed, which included main IOP, duration of main IOP, and rate of IOP increase. A radar chart was drawn, and overall IOP was calculated. Overall IOP value = IOP distribution (sum of IOP value multiplied by the corresponding duration) × IOP fluctuation (standard deviation) × rate of IOP increase/100. By comparing two series of IOP data, the advantages of the new IOP indexes were demonstrated. The introduction of the concept of overall IOP expands the description of IOP from a single static state to a comprehensive dynamic state, which enables us to analyze the results of 24-hour IOP monitoring more thoroughly. (Chin J Ophthalmol, 2021, 57: 228-231).

[Association between serum vitamin D level and immune imbalance in advanced schistosomiasis patients with liver fibrosis]

OBJECTIVE

To examine the relationship between serum vitamin D level and immune imbalance in advanced schistosomiasis patients with liver fibrosis.

METHODS

A total of 120 advanced schistosomiasis patients with liver fibrosis that were admitted to the Department of Schistosomiasis of The First Hospital of Jiaxing City from May 2016 to September 2018 were recruited as the observation group, and 50 healthy volunteers randomly sampled from the hospital during the same period served as the control group. The serum IgG antibody, IgA antibody, C3 complement, C4 complement, CD4⁺ cell proportion, CD8⁺ cell proportion, 25-hydroxyvitamin D [25(OH)D] levels were compared between the two groups. Liver fibrosis was classified into grade I, II and III according to the classification criteria of liver fibrosis by ultrasonography, and the serum IgG antibody, IgA antibody, C3 complement, C4 complement, CD4⁺ proportion, CD8⁺ proportion, 25(OH)D levels were compared among patients with grade I, II and III liver fibrosis. In addition, all patients were classified into the sufficient group, the insufficient group and the deficient group according to the serum vitamin D level, and the serum IgG antibody, IgA antibody, C3 complement, C4 complement, CD4⁺ proportion, CD8⁺ proportion, 25(OH)D levels were compared among these three groups. Moreover, the associations of the serum vitamin D level with these immune indicators were examined.

RESULTS

The 120 advanced schistosomiasis patients with liver fibrosis included 58 men and 62 women, and had a mean age of (72.00 ± 3.00) years. There were 32 cases with grade I liver fibrosis, 46 cases with grade II liver fibrosis, and 42 cases with grade III liver fibrosis. There were no significant differences between the observation group and the control group in terms of serum D-dimer, total cholesterol (TC), triglyceride (TG), C3 complement or C4 complement levels (t = 2.467, 0.322, 0.790, -2.432 and -2.630, all P values > 0.05); however, there were significant differences seen in alanine aminotransferase (ALT), aspartate aminotransferase (AST), blood calcium, blood phosphorus, IgG antibody, IgA antibody, CD4⁺ proportion, CD8⁺ proportion, and 25(OH)D levels (t = 5.130, 6.382, -1.341, 2.361, 8.708, 11.783, -2.995, -6.543 and -3.022, all P values < 0.05). In addition, there were significant differences in AST, ALT, blood phosphorus, IgA antibody, C3 complement, CD8⁺ cell proportion and 25(OH)D levels among patients with grades I, II and III liver fibrosis (F = 19.704, 16.254, 62.669, 49.347, 5.430, 5.434 and 5.783, all P values < 0.05). There were significant differences in ALT, blood phosphorus, IgA antibody, CD8⁺ cell proportion and 25(OH)D levels between patients with grades I and III liver fibrosis (all P values < 0.05), and significant differences were seen between patients with grades II and III liver fibrosis in terms of blood phosphorus, IgA antibody and CD8⁺ cell proportion (all P values < 0.05), while there was a significant difference in the CD8⁺ cell proportion between patients with grades I and II liver fibrosis (P < 0.05). Moreover, there were significant differences among the sufficient, insufficient and deficient groups in terms of IgG antibody, IgA antibody, C3 complement, CD4⁺ cell proportion and CD8⁺ cell proportion (F = 13.303, 59.623, 8.698, 9.969 and 12.805, all P values < 0.05), and there was a significant difference in the CD8⁺ cell proportion between the insufficient and deficient groups (P < 0.05). Pearson correlation analysis revealed that serum 25(OH)D level were negatively associated with IgG and IgA antibody levels (r = -0.754 and -0.773, both P values < 0.05), and positively associated with C3 complement, CD4⁺ cell proportion and CD8⁺ cell proportion in advanced schistosomiasis patients with liver fibrosis (r = 0.827, 0.850 and 0.830, all P values < 0.05).

CONCLUSIONS

Immune imbalance occurs in advanced schistosomiasis patients with liver fibrosis, and serum vitamin D level may correlate with immune imbalance in advanced schistosomiasis patients with liver fibrosis.

Cell Surface Display of Thermomyces lanuginosus Lipase in Pichia pastoris

A cell surface displayed system in Pichia pastoris GS115 was developed by using GCW61, a glycosylphosphatidylinositol-modified cell wall protein from P. pastoris, as the anchor protein. Thermomyces lanuginosus lipase (TLL) was successfully displayed on the P. pastoris cell wall by fusing GCW61 gene with TLL2 gene (NCBI Accession: O59952) that was optimized with codon bias and synthesized. Cell surface displayed TLL2 was confirmed by the immunofluorescence microscopy. Flask fermentation was performed for 144 h with lipase activity up to 1964.76 U/g. Enzymatic properties of cell surface displayed TLL2 were also investigated. Displayed TLL2 occurred the maximum activity at pH 9 and 55°C and demonstrated characteristics of wide thermal adaptability and alkaline pH resistance. The optimum substrate was p-nitrophenyl hexanoate. Bivalent metal ions Ca²⁺, Mn²⁺, and Zn²⁺ had the activation effect on displayed TLL2, while Cu²⁺, Fe²⁺, Fe³⁺, K⁺, Li⁺, Na⁺, and Co²⁺ ions had the inhibitory effect on it. Since cell surface displayed TLL2 required less purification steps compared with free enzyme and showed high enzyme activities, it would be able to be further applied in various potential applications.

Construction and screening of a glycosylphosphatidylinositol protein deletion library in Pichia pastoris

Background

Glycosylphosphatidylinositol (GPI)-anchored glycoproteins have diverse intrinsic functions in yeasts, and they also have different uses in vitro. In this study, the functions of potential GPI proteins in Pichia pastoris were explored by gene knockout approaches.

Results

Through an extensive knockout of GPI proteins in P. pastoris, a single-gene deletion library was constructed for 45 predicted GPI proteins. The knockout of proteins may lead to the activation of a cellular response named the ‘compensatory mechanism’, which is characterized by changes in the content and relationship between cell wall polysaccharides and surface proteins. Among the 45 deletion strains, five showed obvious methanol tolerance, four owned high content of cell wall polysaccharides, and four had a high surface hydrophobicity. Some advantages of these strains as production hosts were revealed. Furthermore, the deletion strains with high surface hydrophobicity were used as hosts to display Candida antarctica lipase B (CALB). The strain gcw22Δ/CALB-GCW61 showed excellent fermentation characteristics, including a faster growth rate and higher hydrolytic activity.

Conclusions

This GPI deletion library has some potential applications for production strains and offers a valuable resource for studying the precise functions of GPI proteins, especially their putative functions.

Nuclear Dependence of the Transverse Single-Spin Asymmetry in the Production of Charged Hadrons at Forward Rapidity in Polarized p+p, p+Al, and p+Au Collisions at sqrt[s_{NN}]=200 GeV

We report on the nuclear dependence of transverse single-spin asymmetries (TSSAs) in the production of positively charged hadrons in polarized p^{↑}+p, p^{↑}+Al, and p^{↑}+Au collisions at sqrt[s_{NN}]=200  GeV. The measurements have been performed at forward rapidity (1.4<η<2.4) over the range of transverse momentum (1.8<p_{T}<7.0  GeV/c) and Feynman x (0.1<x_{F}<0.2). We observed positive asymmetries for positively charged hadrons in p^{↑}+p collisions, and significantly reduced asymmetries in p^{↑}+A collisions. These results reveal a nuclear dependence of TSSAs for charged-hadron production in a regime where perturbative techniques are applicable. These results provide new opportunities to use p^{↑}+A collisions as a tool to investigate the rich phenomena behind TSSAs in hadronic collisions and to use TSSAs as a new handle in studying small-system collisions.

Genome-wide screening of Saccharomyces cerevisiae deletion mutants reveals cellular processes required for tolerance to the cell wall antagonist calcofluor white

We screened a haploid library of Saccharomyces cerevisiae single-gene deletion mutants to identify nonessential genes associated with increased sensitivity to or resistance against the cell wall antagonist calcofluor white. Through a genome-wide screen, we isolated 537 strains that had an altered growth rate relative to wild type, of which 485 showed increased sensitivity and 52 showed increased resistance to calcofluor white. The MAPK signaling pathway, N-glycan biosynthesis, endocytosis, vacuole acidification, autophagy, and the sulfur relay system were identified as being associated with calcofluor white sensitivity. Resistance genes were mainly involved in chitin metabolism and the RIM101 pathway or encoded several components of the ESCRT complexes or related to cysteine and methionine metabolism and RNA degradation. Further investigation indicated a clear global response network that S. cerevisiae relies on in the presence of the cell wall antagonist calcofluor white, which may help us to understand fungal cell wall remodeling and the mechanisms of toxicity of calcofluor white with respect to eukaryotic cells.

Improved Efficiency of the Desulfurization of Oil Sulfur Compounds in Escherichia coli Using a Combination of Desensitization Engineering and DszC Overexpression

The 4S pathway of biodesulfurization, which can specifically desulfurize aromatic S-heterocyclic compounds without destroying their combustion value, is a low-cost and environmentally friendly technology that is complementary to hydrodesulfurization. The four Dsz enzymes convert the model compound dibenzothiophene (DBT) into the sulfur-free compound 2-hydroxybiphenyl (HBP). Of these four enzymes, DszC, the first enzyme in the 4S pathway, is the most severely affected by the feedback inhibition caused by HBP. This study is the first attempt to directly modify DszC to decrease its inhibition by HBP, with the results showing that the modified protein is insensitive to HBP. On the basis of the principle that the final HBP product could show a blue color with Gibbs reagent, a high-throughput screening method for its rapid detection was established. The screening method and the combinatorial mutagenesis generated the mutant AKWC (A101K/W327C) of DszC. After the IC₅₀ was calculated, the feedback inhibition of the AKWC mutant was observed to have been substantially reduced. Interestingly, the substrate inhibition of DszC had also been reduced as a result of directed evolution. Finally, the recombinant BL21(DE3)/BADC*+C* (C* represents AKWC) strain exhibited a specific conversion rate of 214.84 μmol_HBP/g_DCW/h, which was 13.8-fold greater than that of the wild-type strain. Desensitization engineering and the overexpression of the desensitized DszC protein resulted in the elimination of the feedback inhibition bottleneck in the 4S pathway, which is practical and effective progress toward the production of sulfur-free fuel oil. The results of this study demonstrate the utility of desensitization of feedback inhibition regulation in metabolic pathways by protein engineering.

Pseudorapidity Dependence of Particle Production and Elliptic Flow in Asymmetric Nuclear Collisions of p+Al, p+Au, d+Au, and ^{3}He+Au at sqrt[s_{NN}]=200 GeV

Asymmetric nuclear collisions of p+Al, p+Au, d+Au, and ^{3}He+Au at sqrt[s_{NN}]=200  GeV provide an excellent laboratory for understanding particle production, as well as exploring interactions among these particles after their initial creation in the collision. We present measurements of charged hadron production dN_{ch}/dη in all such collision systems over a broad pseudorapidity range and as a function of collision multiplicity. A simple wounded quark model is remarkably successful at describing the full data set. We also measure the elliptic flow v_{2} over a similarly broad pseudorapidity range. These measurements provide key constraints on models of particle emission and their translation into flow.

RNA-Seq analysis of global transcriptomic changes suggests a roles for the MAPK pathway and carbon metabolism in cell wall maintenance in a Saccharomyces cerevisiae FKS1 mutant

FKS1 encodes a β-1,3-glucan synthase, which is a key player in cell wall assembly in Saccharomyces cerevisiae. Here we analyzed the global transcriptomic changes in the FKS1 mutant to establish a correlation between the changes in the cell wall of the FKS1 mutant and the molecular mechanism of cell wall maintenance. These transcriptomic profiles showed that there are 1151 differentially expressed genes (DEGs) in the FKS1 mutant. Through KEGG pathway analysis of the DEGs, the MAPK pathway and seven pathways involved in carbon metabolism were significantly enriched. We found that the MAPK pathway is activated for FKS1 mutant survival and the synthesis of cell wall components are reinforced in the FKS1 mutant. Our results confirm that the FKS1 mutant has a β-1,3-glucan defect that affects the cell wall and partly elucidate the molecular mechanism responsible for cell wall synthesis. Our greater understanding of these mechanisms helps to explain how the FKS1 mutant survives, has useful implications for the study of similar pathways in other fungi, and increases the theoretical foundation for the regulation of the cell wall in S. cerevisiae.

[Genetic Polymorphisms of 19 STR Loci in Populations of Three Culture Region in Shandong]

OBJECTIVES

To analyse the genetic polymorphisms of 19 autosomal STR loci in Han population of east, middle-northwest and southwest-south Shandong and to explore its genetic relationships among the population of these three regions.

METHODS

STR loci of 1 044 unrelated Han individuals in three Shandong regions were typed with a Goldeneye® DNA ID System 20A kit. The allele frequency and population genetics parameters of 19 autosomal STR loci were statistically analysed by Modified-Powerstates software. The genetic distances among the population in three regions were calculated by Arlequin v3.5 software. The phylogenetic tree was conducted using MEGA v4.0 software.

RESULTS

Fifteen of 19 autosomal STR loci were detected with the H values greater than 0.7, PIC values greater than 0.7, and DP values greater than 0.9 in the populations of all three Shandong regions. Among the populations in these three regions, the genetic distance between the populations in middle-northwest and southwest-south Shandong was closest （F_st=0.000 16）, followed by east and southwest-south Shandong （F_st=0.0003 6）. The genetic distance between the populations in east and middle-northwest Shandong was the farthest （F_st=0.000 66, P<0.05）.

CONCLUSIONS

The 19 autosomal STR loci show good genetic polymorphisms in Han population of three Shandong regions, and 15 of them are high. There are genetic differences between the populations in east and middle-northwest Shandong.

Improved production and characterization of Volvariella volvacea Endoglucanase 1 expressed in Pichia pastoris

Endoglucanase 1 (EG1) isolated from the straw mushroom has great potential in the textile and paper industries. Improving EG1 expression level will add to its value for industrial applications. In this study, we employed two combined strategies to enhance the expression quantity of EG1, which are increase the copy number of EG1 and enhance the folding and secretion efficiency of EG1 in the endoplasmic reticulum by overexpress HAC1. Multiple plasmids, which contains four copies of EG1, were constructed by isocaudamers, resulted a recombinant strain with EG1 activity up to 39.6 U/mL, 262% higher than that measured in the strain containing only a single copy. A significant increase in activity (151%) was found when eight copies of EG1 was introduced into a different host, compared with a host harboring four copies. Further overexpression of the HAC1 transcription factor in the host harboring eight EG1 copies led to activity of 91.9 U/mL, which is 619% higher than that measured in the original strain. Finally, EG1 activity of 650.1 U/mL was achieved in a 3-L scaled-up fed-batch fermenter and the protein yield was 4.05 g/L. The characteristics of recombinant EG1 were also investigated, the optimal values for enzyme activity were 60 °C and pH 5.0, which yielded a catalytic efficiency of 312.9 mL mg^-1min^-1 using carboxymethyl cellulose(CMC) as the substrate.

Measurements of Multiparticle Correlations in d+Au Collisions at 200, 62.4, 39, and 19.6 GeV and p+Au Collisions at 200 GeV and Implications for Collective Behavior

Recently, multiparticle-correlation measurements of relativistic p/d/^{3}He+Au, p+Pb, and even p+p collisions show surprising collective signatures. Here, we present beam-energy-scan measurements of two-, four-, and six-particle angular correlations in d+Au collisions at sqrt[s_{NN}]=200, 62.4, 39, and 19.6 GeV. We also present measurements of two- and four-particle angular correlations in p+Au collisions at sqrt[s_{NN}]=200  GeV. We find the four-particle cumulant to be real valued for d+Au collisions at all four energies. We also find that the four-particle cumulant in p+Au has the opposite sign as that in d+Au. Further, we find that the six-particle cumulant agrees with the four-particle cumulant in d+Au collisions at 200 GeV, indicating that nonflow effects are subdominant. These observations provide strong evidence that the correlations originate from the initial geometric configuration, which is then translated into the momentum distribution for all particles, commonly referred to as collectivity.

Nuclear Dependence of the Transverse-Single-Spin Asymmetry for Forward Neutron Production in Polarized p+A Collisions at sqrt[s_{NN}]=200 GeV

During 2015, the Relativistic Heavy Ion Collider (RHIC) provided collisions of transversely polarized protons with Au and Al nuclei for the first time, enabling the exploration of transverse-single-spin asymmetries with heavy nuclei. Large single-spin asymmetries in very forward neutron production have been previously observed in transversely polarized p+p collisions at RHIC, and the existing theoretical framework that was successful in describing the single-spin asymmetry in p+p collisions predicts only a moderate atomic-mass-number (A) dependence. In contrast, the asymmetries observed at RHIC in p+A collisions showed a surprisingly strong A dependence in inclusive forward neutron production. The observed asymmetry in p+Al collisions is much smaller, while the asymmetry in p+Au collisions is a factor of 3 larger in absolute value and of opposite sign. The interplay of different neutron production mechanisms is discussed as a possible explanation of the observed A dependence.

Expression of bovine rotavirus VP8 and preparation of IgY antibodies against recombinant VP8

Group A rotavirus is the leading cause of acute gastroenteritis in cattle and swine. Although, vaccination against this virus is an effective strategy for prevention, additional strategy to control disease is necessary. Egg yolk immunoglobulin (IgY)-based passive immunization could be a better option in preventing this disease. Bovine rotavirus (BRV) is group A rotavirus and possesses a genome of 11 segments of double-stranded RNA. The outer layer of capsid is composed of two proteins (VP7 and VP4), which induce virus neutralizing antibodies. Trypsin cleavage of VP4 produces VP8 (28 kDa) and VP5 (60 kDa) fragments. Since a number of studies have demonstrated the induction of neutralizing antibodies using VP8 subunit vaccines, we have produced IgY against the recombinant VP8. The cDNA spanning the VP8 subunit was amplified from bovine rotavirus-infected cells and cloned into pET21d(+) expression vector to generate recombinant VP8. The resulting carboxy-terminal His-tagged VP8 proteins were expressed in Escherichia coli strain BL21(DE3) by isopropyl β-D-1-thiogalactopyranoside (IPTG) induction. The recombinant proteins were purified using Ni-NTA agarose beads, and the purified protein was used as the immunizing agent to produce polyclonal antibodies in chicken. The resulting polyclonal antisera specifically recognized VP8 in Western blot assay and were able to neutralize BRV replication in cell cultures. These results demonstrate that IgY can be used in immunological assays and, in addition, in passive immunization of newborn calves against BRV.

Recombineering using RecET in Corynebacterium glutamicum ATCC14067 via a self-excisable cassette

Gene manipulation is essential for metabolic engineering and synthetic biology, but the current general gene manipulation methods are not applicable to the non-model strain Corynebacterium glutamicum (C. glutamicum) ATCC14067, which is used for amino acid production. Here, we report an effective and sequential deletion method for C. glutamicum ATCC14067 using the exonuclease-recombinase pair RecE + RecT (RecET) for recombineering via a designed self-excisable linear double-strand DNA (dsDNA) cassette, which contains the Cre/loxP system, to accomplish markerless deletion. To the best of our knowledge, this is the first effective and simple strategy for recombination with markerless deletion in C. glutamicum ATCC14067. This strategy provides a simple markerless deletion strategy for C. glutamicum and builds a solid basis for producer construction.