Economical one-pot synthesis of isoquercetin and D-allulose from quercetin and sucrose using whole-cell biocatalyst

Isoquercetin and D-allulose have diverse applications and significant value in antioxidant, antibacterial, antiviral, and lipid metabolism. Isoquercetin can be synthesized from quercetin, while D-allulose is converted from D-fructose. However, their production scale and overall quality are relatively low, leading to high production costs. In this study, we have devised a cost-effective one-pot method for biosynthesizing isoquercetin and D-allulose using a whole-cell biocatalyst derived from quercetin and sucrose. To achieve this, the optimized isoquercetin synthase and D-allulose-3-epimerase were initially identified through isofunctional gene screening. In order to reduce the cost of uridine diphosphate glucose (UDPG) during isoquercetin synthesis and ensure a continuous supply of UDPG, sucrose synthase is introduced to enable the self-circulation of UDPG. At the same time, the inclusion of sucrose permease was utilized to successfully facilitate the catalytic production of D-allulose in whole cells. Finally, the recombinant strain BL21/UGT-SUS+DAE-SUP, which overexpresses MiF3GTMUT, GmSUS, EcSUP, and DAEase, was obtained. This strain co-produced 41±2.4 mg/L of isoquercetin and 5.7±0.8 g/L of D-allulose using 120 mg/L of quercetin and 20 g/L of sucrose as substrates for 5 h after optimization. This is the first green synthesis method that can simultaneously produce flavonoid compounds and rare sugars. These findings provide valuable insights and potential for future industrial production, as well as practical applications in factories.

HyCas9-12aGEP: an efficient genome editing platform for Corynebacterium glutamicum

Corynebacterium glutamicum plays a crucial role as a significant industrial producer of metabolites. Despite the successful development of CRISPR-Cas9 and CRISPR-Cas12a-assisted genome editing technologies in C. glutamicum, their editing resolution and efficiency are hampered by the diverse on-target activities of guide RNAs (gRNAs). To address this problem, a hybrid CRISPR-Cas9-Cas12a genome editing platform (HyCas9-12aGEP) was developed in C. glutamicum in this study to co-express sgRNA (corresponding to SpCas9 guide RNA), crRNA (corresponding to FnCas12a guide RNA), or hfgRNA (formed by the fusion of sgRNA and crRNA). HyCas9-12aGEP improves the efficiency of mapping active gRNAs and outperforms both CRISPR-Cas9 and CRISPR-Cas12a in genome editing resolution and efficiency. In the experiment involving the deletion of the cg0697-0740 gene segment, an unexpected phenotype was observed, and HyCas9-12aGEP efficiently identified the responsible genotype from more than 40 genes. Here, HyCas9-12aGEP greatly improve our capability in terms of genome reprogramming in C. glutamicum.

Engineering of human tryptophan hydroxylase 2 for efficient synthesis of 5-hydroxytryptophan

L-Tryptophan hydroxylation catalyzed by tryptophan hydroxylase (TPH) presents a promising method for synthesizing 5-hydroxytryptophan (5-HTP), yet the limited activity of wild-type human TPH2 restricts its application. A high-activity mutant, MT10 (H318E/H323E), was developed through semi-rational active site saturation testing (CAST) of wild-type TPH2, exhibiting a 2.85-fold increase in kcat/Km over the wild type, thus enhancing catalytic efficiency. Two biotransformation systems were developed, including an in vitro one-pot system and a Whole-Cell Catalysis System (WCCS). In the WCCS, MT10 achieved a conversion rate of only 31.5 % within 32 h. In the one-pot reaction, MT10 converted 50 mM L-tryptophan to 44.5 mM 5-HTP within 8 h, achieving an 89 % conversion rate, outperforming the M1 (NΔ143/CΔ26) variant. Molecular dynamics simulations indicated enhanced interactions of MT10 with the substrate, suggesting improved binding affinity and system stability. This study offers an effective approach for the efficient production of 5-HTP.

Correlation between changes in flavor compounds and microbial community ecological succession in the liquid fermentation of rice wine

Microorganisms play an important role in regulating flavor compounds in rice wine, whereas we often don't understand how did they affect flavor compounds. Here, the relations between flavor compounds and microbial community ecological succession were investigated by monitoring flavor compounds and microbial community throughout the fermentation stage of rice wine. The composition of microbial community showed a dynamic change, but 13 dominant bacterial genera and 4 dominant fungal genera were detected throughout the fermentation stages. Saccharomyces presented a strong negative correlation with fungi genera but had positive associations with bacteria genera. Similarly, flavor compounds in rice wine were also showed the dynamic change, and 112 volatile compounds and 17 free amino acids were identified in the whole stages. The alcohol-ester ratio was decreased in the LTF stage, indicating that low temperature boosts ester formation. The potential correlation between flavor compounds and microbial community indicated that Delftia, Chryseobacterium, Rhizopus and Wickerhamomyces were the core functional microorganisms in rice wine. These findings clarified the correlation between changes in flavor compounds and in microbial community in the liquid fermentation of rice wine, and these results have some reference value for the quality improvement and technological optimization in liquid fermentation of rice wine.

L-lysine production by systems metabolic engineering of an NADPH auto-regulated Corynebacterium glutamicum

Here, the systems metabolic engineering of L-lysine-overproducing Corynebacterium glutamicum is described to create a highly efficient microorganism producer. The key chromosomal mutations associated with L-lysine synthesis were identified based on whole-genome sequencing. The carbon flux was subsequently redirected into the L-lysine synthesis pathway and increased the availability of energy and product transport systems required for L-lysine synthesis. In addition, a promoter library sensitive to intracellular L-lysine concentration was constructed and applied to regulate the NADPH pool dynamically. In the fed-batch fermentation experiment, the L-lysine titer of the final engineered strain was 223.4 ± 6.5 g/L. This study is the first to improve L-lysine production by enhancing ATP supply and NADPH self-regulation to improve the intracellular environment.

[Chinese expert guidance on overall application of lenvatinib in hepatocellular carcinoma]

Lenvatinib mesylate is an oral receptor tyrosine kinase inhibitor against targets of vascular endothelial growth factor receptors 1-3, fibroblast growth factor receptors 1-4, platelet-derived growth factor receptor α, stem cell growth factor receptor, and rearranged during transfection, et al. Lenvatinib has been approved by the National Medical Products Administration of China on September 4, 2018, for the first-line treatment of patients with unresectable hepatocellular carcinoma who have not received systematic treatment before. Up to February 2023, Lenvatinib has been listed in China for more than 4 years, accumulating a series of post-marketing clinical research evidences. Based on the clinical practice before and after the launch of lenvatinib and referring to the clinical experience of other anti-angiogenesis inhibitors, domestic multidisciplinary experts and scholars adopt the Delphi method to formulate the Chinese Expert Guidance on Overall Application of Lenvatinib in Hepatocellular Carcinoma after repeated discussions and revisions, in order to provide reference for reasonable and effective clinical application of lenvatinib for clinicians.

[Alteration and significance of serum lipid levels and nutritional status during BCMA-CAR-T-cell therapy in patients with refractory or relapsed multiple myeloma: a retrospective study based on LEGEND-2]

Objective: To explore the dynamic changes in serum lipid levels and nutritional status during BCMA-CAR-T-cell therapy in patients with refractory or relapsed multiple myeloma (R/R MM) based on LEGEND-2. Methods: The data of patients with R/R MM who underwent BCMA-CAR-T therapy at our hospital between March 30, 2016, and February 6, 2018, were retrospectively collected. Serum lipid levels, controlled nutritional status (CONUT) score, and other clinical indicators at different time points before and after CAR-T-cell infusion were compared and analyzed. The best cut-off value was determined by using the receiver operator characteristic (ROC) curve. The patients were divided into high-CONUT score (>6.5 points, malnutrition group) and low-CONUT score groups (≤6.5 points, good nutrition group), comparing the progression-free survival (PFS) and total survival (OS) of the two groups using Kaplan-Meier survival analysis. Results: Before the infusion of CAR-T-cells, excluding triglycerides (TG), patients' serum lipid levels were lower than normal on average. At 8-14 d after CAR-T-cell infusion, serum albumin (ALB), total cholesterol (TC), high-density lipoprotein (HDL), low-density lipoprotein (LDL), and apolipoprotein A1 (Apo A1) levels dropped to the minimum, whereas CONUT scores reached the maximum. In addition to TG, apolipoprotein B (Apo B) levels increased compared with baseline. After CAR-T-cell therapy, the patients' serum lipid levels significantly increased with well-improved nutritional status. Spearman's related analysis showed that TC, HDL, and ApoA1 levels after CAR-T-cell injection were significantly negatively correlated with the grade of cytokine-release syndrome (CRS) (r=-0.548, P=0.003; r=-0.444, P=0.020; r=-0.589, P=0.001). Furthermore, survival analysis indicated that the CONUT score was unrelated to PFS, and the median OS of patients with R/R MM in the high-CONUT score group was shorter than that in the low-CONUT score group (P=0.046) . Conclusions: During CAR-T-cell therapy, hypolipidemia and poor nutritional status were aggravated, which is possibly related to CRS. The patients' serum lipid levels and nutritional status were significantly improved after CAR-T-cell treatment. The CONUT score affected the median OS in patients treated with CAR-T-cells. Therefore, specific screening and intervention for nutritional status in patients receiving CAR-T-cell therapy are required.

Engineering of Shikimate Pathway and Terminal Branch for Efficient Production of L-Tryptophan in Escherichia coli

L-tryptophan (L-trp), produced through bio-manufacturing, is widely used in the pharmaceutical and food industries. Based on the previously developed L-trp-producing strain, this study significantly improved the titer and yield of L-trp, through metabolic engineering of the shikimate pathway and the L-tryptophan branch. First, the rate-limiting steps in the shikimate pathway were investigated and deciphered, revealing that the combined overexpression of the genes aroE and aroD increased L-trp production. Then, L-trp synthesis was further enhanced at the shaking flask level by improving the intracellular availability of L-glutamine (L-gln) and L-serine (L-ser). In addition, the transport system and the competing pathway of L-trp were also modified, indicating that elimination of the gene TnaB contributed to the extracellular accumulation of L-trp. Through optimizing formulas, the robustness and production efficiency of engineered strains were enhanced at the level of the 30 L fermenter. After 42 h of fed-batch fermentation, the resultant strain produced 53.65 g/L of L-trp, with a yield of 0.238 g/g glucose. In this study, the high-efficiency L-trp-producing strains were created in order to establish a basis for further development of more strains for the production of other highly valuable aromatic compounds or their derivatives.

Reduction of acetate synthesis, enhanced arginine export, and supply of precursors, cofactors, and energy for improved synthesis of L-arginine by Escherichia coli

L-arginine (L-Arg) is a semi-essential amino acid with many important physiological functions. However, achieving efficient manufacture of L-Arg on an industrial scale using Escherichia coli (E. coli) remains a major challenge. In previous studies, we constructed a strain of E. coli A7, which had good L-Arg production capacity. In this study, E. coli A7 was further modified, and E. coli A21 with more efficient L-Arg production capacity was obtained. Firstly, we reduced the acetate accumulation of strain A7 by weakening the poxB gene and overexpressing acs gene. Secondly, we improved the L-Arg transport efficiency of strains by overexpressing the lysE gene from Corynebacterium glutamicum (C. glutamicum). Finally, we enhanced the supplies of precursors for the synthesis of L-Arg and optimized the supplies of cofactor NADPH and energy ATP in strain. After fermentation in a 5-L bioreactor, the L-Arg titer of strain A21 was found to be 89.7 g/L. The productivity was 1.495 g/(L·h) and the glucose yield was 0.377 g/g. Our study further narrowed the titer gap between E. coli and C. glutamicum in the synthesis of L-Arg. In all recent studies on the L-Arg production by E. coli, this was the highest titer recorded. In conclusion, our study further promotes the efficient mass synthesis of L-Arg by E. coli. KEY POINTS: • The acetate accumulation of starting strain A7 was decreased. • Overexpression of gene lysE of C. glutamicum enhanced L-Arg transport in strain A10. • Enhance the supplies of precursors for the synthesis of L-Arg and optimize the supplies of cofactor NADPH and energy ATP. Finally, Strain A21 was detected to have an L-Arg titer of 89.7 g/L in a 5-L bioreactor.

Field ponding water exacerbates the dissemination of manure-derived antibiotic resistance genes from paddy soil to surrounding waterbodies

Farmlands fertilized with livestock manure-derived amendments have become a hot topic in the dissemination of antibiotic resistance genes (ARGs). Field ponding water connects rice paddies with surrounding water bodies, such as reservoirs, rivers, and lakes. However, there is a knowledge gap in understanding whether and how manure-borne ARGs can be transferred from paddy soil into field ponding water. Our studies suggest that the manure-derived ARGs aadA1, bla1, catA1, cmlA1-01, cmx(A), ermB, mepA and tetPB-01 can easily be transferred into field ponding water from paddy soil. The bacterial phyla Crenarchaeota, Verrucomicrobia, Cyanobacteria, Choloroflexi, Acidobacteria, Firmicutes, Bacteroidetes, and Actinobacteria are potential hosts of ARGs. Opportunistic pathogens detected in both paddy soil and field ponding water showed robust correlations with ARGs. Network co-occurrence analysis showed that mobile genetic elements (MGEs) were strongly correlated with ARGs. Our findings highlight that manure-borne ARGs and antibiotic-resistant bacteria in paddy fields can conveniently disseminate to the surrounding waterbodies through field ponding water, posing a threat to public health. This study provides a new perspective for comprehensively assessing the risk posed by ARGs in paddy ecosystems.

[Pelvic autonomic nerve preservation in rectal cancer: anatomical concept and clinical significance]

Colorectal cancer is one of the most common cancers in the world, and surgery is the mainstage treatment. Urogenital and sexual dysfunction after radical resection of rectal cancer has become an important problem for patients, which seriously affects the quality of life. Some patients give up radical surgery for rectal cancer because of the concerns about sexual and urinary dysfunction. The cause of this problem is intraoperative of injury pelvic autonomic nerve. The preservation of the hypogastric nerve during the surgery is important for the male ejaculation. Pelvic splanchnic nerves are mainly responsible for the male erection. The anatomical origin, distribution, and urogenital function of these two nerves are detailed described in this article. At the same time, this article introduces the classification, key points of the operation and the evaluation of autonomic nerve preservation surgery. With the rapid development of minimally invasive surgery, performing radical surgery for rectal cancer is important, we also need to fully understand the anatomical concept of pelvic autonomic nerves, and apply modern minimally invasive surgical techniques to preserve the patient's pelvic autonomic nerves as well. It is an compulsory course and an important manifestation for the standardization of rectal cancer surgery.

Cofactor Engineering for Efficient Production of α-Farnesene by Rational Modification of NADPH and ATP Regeneration Pathway in Pichia pastoris

α-Farnesene, an acyclic volatile sesquiterpene, plays important roles in aircraft fuel, food flavoring, agriculture, pharmaceutical and chemical industries. Here, by re-creating the NADPH and ATP biosynthetic pathways in Pichia pastoris, we increased the production of α-farnesene. First, the native oxiPPP was recreated by overexpressing its essential enzymes or by inactivating glucose-6-phosphate isomerase (PGI). This revealed that the combined over-expression of ZWF1 and SOL3 increases α-farnesene production by improving NADPH supply, whereas inactivating PGI did not do so because it caused a reduction in cell growth. The next step was to introduce heterologous cPOS5 at various expression levels into P. pastoris. It was discovered that a low intensity expression of cPOS5 aided in the production of α-farnesene. Finally, ATP was increased by the overexpression of APRT and inactivation of GPD1. The resultant strain P. pastoris X33-38 produced 3.09 ± 0.37 g/L of α-farnesene in shake flask fermentation, which was 41.7% higher than that of the parent strain. These findings open a new avenue for the development of an industrial-strength α-farnesene producer by rationally modifying the NADPH and ATP regeneration pathways in P. pastoris.

Environmentally relevant concentrations of mercury facilitate the horizontal transfer of plasmid-mediated antibiotic resistance genes

Abundant antibiotic resistance genes (ARGs) are typically found in mercury (Hg)-contaminated aquatic environments. This phenomenon is partly attributed to the co-resistance, cross-resistance, and shared regulatory responses to Hg and antibiotics. However, it remains unclear whether and how Hg influences the conjugative transfer of ARGs mediated by mobilizable plasmids. In the present study, we found that Hg²⁺ at the environmentally relevant concentrations (0.001-0.5 mg L^-1) facilitated the conjugative transfer of ARGs through the mobilizable plasmid RP4 from the donor Escherichia coli HB101 to the recipient E. coli K12. Exposure to Hg²⁺ significantly increases the formation of reactive oxygen species, malondialdehyde production, antioxidant enzyme activities, and cell membrane permeability, while decreasing the concentration of glutathione. Scanning electron microscopy and transmission electron microscopy showed that the cell membrane suffered from oxidative damage, which is beneficial for conjugative transfer. The expression of global regulatory genes (korA, korB, and trbA) negatively regulating conjugative transfer was restrained by Hg²⁺, while promoting the expression of positive regulatory genes involved in the mating pair formation system (trbBp and traF) and the DNA transfer and replication systems (trfAp and traJ). Although a high Hg²⁺ concentration (1.0 mg L^-1) suppressed ARGs conjugative transfer, our results suggest that Hg²⁺ facilitates the dissemination of ARGs in aquatic environments at environmentally relevant concentrations. This study improves our understanding of ARGs dissemination in Hg-contaminated aquatic environments.

An enzymatic colorimetric whole-cell biosensor for high-throughput identification of lysine overproducers

L-lysine is a crucial nutrient for both humans and animals, and its main commercial use is as a supplement in animal feed to promote chicken and other animal growth. Fluorescence biosensors based on the transcriptional regulator have been developed for high-throughput screening of L-lysine producers. However, due to its inability to specifically detect lysine, this fluorescent biosensor cannot be employed to screen high-yielding strains. Here, we present a novel technique for observing L-lysine concentrations within individual Corynebacterium glutamicum cells. The transcriptional regulator LysG and its binding site, as well as the phytoene desaturase that catalyzes the synthesis of the red pigment, make up the functional core of the biosensor. The lysine-sensitive mutant LysG^{(E123Y, E125A)}, which improved the sensitivity of biosensors, was generated by site-directed saturation mutagenesis. In addition, we increased the lysine-induced chromogenic biosensor response to 320 mM by optimizing the L-lysine export mechanism and the pathway for the synthesis of lycopene precursors. The direct identification of producers with elevated L-lysine accumulation is thus made straightforward by colorimetric screening. Lys-8, a lysine producer with a maximum lysine titer of 316.2 mM, was sorted out based on the biosensor. The enzymatic colorimetric biosensor constructed here is a simple tool with great potential for the development of high-level lysine-producing C. glutamicum.

Review of DNA repair enzymes in bacteria: With a major focus on AddAB and RecBCD

DNA recombination repair systems are essential for organisms to maintain genomic stability. In recent years, we have improved our understanding of the mechanisms of RecBCD/AddAB family-mediated DNA double-strand break repair. In E. coli, it is RecBCD that plays a central role, and in Firmicute Bacillus subtilis it is the AddAB complex that functions. However, there are open questions about the mechanism of DNA repair in bacteria. For example, how bacteria containing crossover hotspot instigator (Chi) sites regulate the activity of proteins. In addition, we still do not know the exact process by which the RecB nuclease or AddA nuclease structural domains load RecA onto DNA. We also know little about the mechanism of DNA repair in the industrially important production bacterium Corynebacterium glutamicum (C. glutamicum). Therefore, exploring DNA repair mechanisms in bacteria may not only deepen our understanding of the DNA repair process in this species but also guide us in the targeted treatment of diseases associated with recombination defects, such as cancer. In this paper, we firstly review the classical proteins RecBCD and AddAB involved in DNA recombination repair, secondly focus on the novel helical nuclease AdnAB found in the genus Mycobacterium.

Metabolic engineering of Escherichia coli for efficient production of L-arginine

As an important semi-essential amino acid, L-arginine (L-Arg) has important application prospects in medicine and health care. However, it remains a challenge to efficiently produce L-Arg by Escherichia coli (E. coli). In the present study, we obtained an E. coli A1 with L-Arg accumulation ability, and carried out a series of metabolic engineering on it, and finally obtained an E. coli strain A7 with high L-Arg production ability. First, genome analysis of strain A1 was performed to explore the related genes affecting L-Arg accumulation. We found that gene speC and gene speF played an important role in the accumulation of L-Arg. Second, we used two strategies to solve the feedback inhibition of the L-Arg pathway in E. coli. One was the combination of a mutation of the gene argA and the deletion of the gene argR, and the other was the combination of a heterologous insertion of the gene argJ and the deletion of the gene argR. The combination of exogenous argJ gene insertion and argR gene deletion achieved higher titer accumulation with less impact on strain growth. Finally, we inserted the gene cluster argCJBDF of Corynebacterium glutamicum (C. glutamicum) to enhance the metabolic flux of the L-Arg pathway in E. coli. The final strain obtained 70.1 g/L L-Arg in a 5-L bioreactor, with a yield of 0.326 g/g glucose and a productivity of 1.17 g/(L· h). This was the highest level of L-Arg production by E. coli ever reported. Collectively, our findings provided valuable insights into the possibility of the industrial production of L-Arg by E. coli. KEY POINTS: • Genetic background of E. coli A1 genome analysis. • Heterologous argJ substitution of argA mutation promoted excessive accumulation of L-Arg in E. coli A1. • The overexpression of L-Arg synthesis gene cluster argCJBDF of Corynebacterium glutamicum (C. glutamate) promoted the accumulation of L-Arg, and 70.1 g/L L-Arg was finally obtained in fed-batch fermentation.

[A new insights of mesorectum]

Total mesorectal excision (TME) represents the gold standard for radical resection in rectal cancer. The development in radiology and laparoscopic surgical equipment and the advancement in technology have led to a deepened understanding of the mesorectum and its surrounding structures. Both the accuracy of preoperative staging and the preciseness of the planes of TME surgical dissection have been enhanced. The postoperative local recurrence rate is reduced and the long-term survival of rectal cancer patients is improved. The preservation of the pelvic autonomic nervous system maintains the patient's urinary and sexual functions to the greatest extent possible, which in turn improves the patient's postoperative quality of life. A thorough understanding of the anatomy of the mesorectum and its surrounding structures is a prerequisite for successful TME. Herein, we review the basic concepts and the anatomy of the mesorectum in the current literature. Some important clinical issues are also discussed systematically in terms of imaging, surgery, and pathology.

Enhancement of l-Pipecolic Acid Production by Dynamic Control of Substrates and Multiple Copies of the pipA Gene in the Escherichia coli Genome

l-Pipecolic acid is an important rigid cyclic nonprotein amino acid, which is obtained through the conversion of l-lysine catalyzed by l-lysine cyclodeaminase (LCD). To directly produce l-pipecolic acid from glucose by microbial fermentation, in this study, a recombinant Escherichia coli strain with high efficiency of l-pipecolic acid production was constructed. This study involves the dynamic regulation of the substrate concentration and the expression level of the l-lysine cyclodeaminase-coding gene pipA. In terms of substrate concentration, we adopted the l-lysine riboswitch to dynamically regulate the expression of lysP and lysO genes. As a result, the l-pipecolic acid yield was increased about 1.8-fold as compared with the control. In addition, we used chemically inducible chromosomal evolution (CIChE) to realize the presence of multiple copies of the pipA gene on the genome. The resultant E. coli strain XQ-11-4 produced 61 ± 3.4 g/L l-pipecolic acid with a productivity of 1.02 ± 0.06 g/(L·h) and a glucose conversion efficiency (α) of 29.6% in fermentation. This is the first report that discovered multiple copies of pipA gene expression on the genome that improves the efficiency of l-pipecolic acid production in an l-lysine high-producing strain, and these results give us new insight for constructing the other valuable biochemicals derived from l-lysine.

[Expression of METTL14 in epithelial ovarian cancer and the effect on cell proliferation, invasion and migration of A2780 and SKOV3 cells]

Objective: To study the expression of methyltransferase-like protein 14 (METTL14) in epithelial ovarian cancer and its clinical significance, and to explore the effect of METTL14 expression on the proliferation, invasion and migration of ovarian cancer cells. Methods: Immunohistochemistry (IHC) was used to detect METTL14 expression in tumor tissue samples, and analyze the relationships among METTL14 expression, clinicopathological factors, and prognosis in ovarian cancer. Lentiviral vectors and small interfering RNA (siRNA) were used to up-regulate and down-regulate the METTL14 expression in ovarian cancer cell lines A2780 and SKOV3, respectively. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was used to detect the N6-methyladenosine (m6A) content in ovarian cancer cells. Cell counting kit-8 (CCK-8), wound healing assay, and transwell assay were used to examine the function of METTL14 expression in the cells. Results: (1) The IHC score of METTL14 protein was 6.2±3.7 in 20 samples of ovarian cancer tissues and 3.3±2.5 in 15 samples of normal ovarian tissues, and the difference was statistically significant (t=-2.64, P=0.012). Among the patients who suffered from ovarian cancer, there were 69 cases with high expression of METTL14 protein (IHC score≥6), accounting for 57.0% (69/121), and the cases with low expression of METTL14 protein (IHC score<6) accounting for 43.0% (52/121). Compared with the patients with low expression of METTL14, the patients with high expression of METTL14 had later stages, higher rates of lymph node metastasis, abdominal metastasis, and more ascite amount. The differences were statistically significant (all P<0.05). The overall survival rate was significantly lower in patients with high METTL14 expression than the low expression (P=0.009). (2) LC-MS/MS data showed that the relative expression of m6A in A2780 and SKOV3 cells in the lentivirus (LV)-METTL14 group were 0.213±0.024 and 0.181±0.018, which were significantly higher than those in the LV-normal control (NC) group (0.109±0.022 and 0.128±0.020; all P<0.05). While the relative expression of m6A in A2780 and SKOV3 cells in the si-METTL14 group were 0.063±0.012 and 0.069±0.015, which were significantly lower than the expression in si-NC group of 0.108±0.014 and 0.121±0.014 (all P<0.05). CCK-8 assay showed that the absorbance values were significantly lower in the si-METTL14 group compared with the si-NC group at 36, 48, 60 hours (all P<0.05); while were significantly increased in the LV-METTL14 group compared with the LV-NC group at 48, 60 hours (all P<0.01). Scratch wound assays showed that the migration rate of the si-METTL14 group was lower than those of the si-NC group, while the LV-METTL14 group were higher than the LV-NC group by 24 hours, the differences were statistically significant (all P<0.01). Cell migration and invasion were detected by transwell migration and invasion assays. After cultivated for 24 hours, the invasion cell number and the migration cell number in the si-METTL14 group were less than those in the si-NC group. While the invasion cell number and the migration cell number in the LV-METTL14 group were more than those in the LV-NC group, respectively. The differences were statistically significant (all P<0.01). Conclusion: Patients with high METTL14 expression have a worse prognosis in ovarian cancer, which may increase the m6A modification of ovarian cancer cells and promote cells proliferation, invasion and migration.

Advances and prospects in metabolic engineering of Escherichia coli for L-tryptophan production

As an important raw material for pharmaceutical, food and feed industry, highly efficient production of L-tryptophan by Escherichia coli has attracted a considerable attention. However, there are complicated and multiple layers of regulation networks in L-tryptophan biosynthetic pathway and thus have difficulty to rewrite the biosynthetic pathway for producing L-tryptophan with high efficiency in E. coli. This review summarizes the biosynthetic pathway of L-tryptophan and highlights the main regulatory mechanisms in E. coli. In addition, we discussed the latest metabolic engineering strategies achieved in E. coli to reconstruct the L-tryptophan biosynthetic pathway. Moreover, we also review a few strategies that can be used in E. coli to improve robustness and streamline of L-tryptophan high-producing strains. Lastly, we also propose the potential strategies to further increase L-tryptophan production by systematic metabolic engineering and synthetic biology techniques.

Rational reformation of Corynebacterium glutamicum for producing L-lysine by one-step fermentation from raw corn starch

This article focuses on engineering Corynebacterium glutamicum to produce L-lysine efficiently from starch using combined method of "classical breeding" and "genome breeding." Firstly, a thermo-tolerable L-lysine-producing C. glutamicum strain KT_45-6 was obtained after multi-round of acclimatization at high temperature. Then, amylolytic enzymes were introduced into strain KT_45-6, and the resultant strains could use starch for cell growth and L-lysine production except the strain with expression of isoamylase. In addition, co-expression of amylolytic enzymes showed a good performance in starch degradation, cell growth and L-lysine production, especially co-expression of α-amylase (AA) and glucoamylase (GA). Moreover, L-lysine yield was increased by introducing AA-GA fusion protein (i.e., strain KT_45-6S-5), and finally reached to 23.9 ± 2.3 g/L in CgXII^IPM-medium. It is the first report of an engineered L-lysine-producing strain with maximum starch utilization that may be used as workhorse for producing amino acid using starch as the main feedstock. KEY POINTS: • Thermo-tolerable C. glutamicum was obtained by temperature-induced adaptive evolution. • The fusion order between AA and GA affects the utilization efficiency of starch. • C. glutamicum with starch utilization was constructed by optimizing amylases expression.

CD8αα+T cells exert a pro-inflammatory role in patients with psoriasis

Background

Psoriasis is a common chronic inflammatory disease caused by excessive activation of CD4⁺T cells, including Th17, Th1 and Th22. The role of CD8⁺T cells in psoriasis pathogenesis remains poorly understood.

Aim

To identify the phenotype of CD8⁺T cells in patients with psoriasis and to investigate its role in the formation of lesions.

Methods

The phenotype of CD8⁺T cells in psoriatic lesions was detected by immunofluorescence staining. Flow cytometry was performed to detect their phenotype in peripheral blood. Thereafter, coculture of CD8αα⁺T cells with autogenous CD4⁺T cells was performed to investigate the function of CD8αα⁺T cells in patients with psoriasis. Finally, pro‐inflammatory factors produced by CD8αα⁺T cells were examined by immunofluorescence staining and flow cytometry.

Results

Compared to the CD8αβ⁺T cells, CD8αα⁺T cell infiltration in psoriatic lesions markedly increased. Moreover, epidermal CD8αα⁺T cells exhibited tissue‐resident memory T cells (T_RM) phenotypes and dermal CD8αα⁺T cells exhibited effector memory (T_EM) phenotypes in psoriatic lesions. Additionally, we found that CD8αα⁺T cells from patients with psoriasis did not express the markers of regulatory T cells and could promote the proliferation of CD4⁺T effector cells and produce interleukin‐17 and interferon‐γ.

Conclusions

Our findings demonstrate that CD8αα⁺T cells contribute to the pathogenesis of psoriasis by producing pro‐inflammatory factors.

Enhancing β-alanine production from glucose in genetically modified Corynebacterium glutamicum by metabolic pathway engineering

To directly produce β-alanine from glucose by microbial fermentation, a recombinant Corynebacterium glutamicum strain with high efficiency of β-alanine production was constructed in this study. To do this, the biosynthetic pathway of β-alanine in an L-lysine-producing strain XQ-5 was modified by enhancing carbon flux in biosynthetic pathway and limiting carbon flux in competitive pathway. This study showed that replacement of L-aspartate kinase (AK) with wild-type AK and disruption of lactate dehydrogenase and alanine/valine aminotransferases increase β-alanine production because of decreasing the by-products accumulation. Moreover, L-aspartate-α-decarboxylase (ADC) from Bacillus subtilis was designed as the best enzyme for increasing β-alanine production, and its variant (BsADC^E56S/I88M) showed the highest activity for catalyzing L-aspartate to generate β-alanine. To further increase β-alanine production, expression level of BsADC^E56S/I88M was controlled by optimizing promoter and RBS, indicating that P_gro plus ThirRBS is the best combination for BsADC^E56S/I88M expression and β-alanine production. The resultant strain XQ-5.5 produced 30.7 ± 2.3 g/L of β-alanine with a low accumulation of lactate (from 5.2 ± 0.14 to 0.2 ± 0.09 g/L) and L-alanine (from 7.6 ± 0.22 to 3.8 ± 0. 32 g/L) in shake-flask fermentation and produced 56.5 ± 3.2 g/L of β-alanine with a productivity of 0.79 g/(L·h) and the glucose conversion efficiency (α) of 39.5% in feed-batch fermentation. This is the first report of genetically modifying the biosynthetic pathway of β-alanine that improves the efficiency of β-alanine production in an L-lysine-producing strain, and these results give us a new insight for constructing the other valuable biochemical. KEY POINTS: • Optimization and overexpression of the key enzyme BsADC increased the accumulation of β-alanine. • The AK was replaced with wild-type AK to increase the conversion of aspartic acid to β-alanine. • A 56.5-g/L β-alanine production in fed-batch fermentation was achieved.

[Focusing the role of surgery in the treatment of liver cirrhotic portal hypertension]

Portal hypertension treatment has always been regarded as complex and diverse. With the innovation of concepts and technologies, its treatment model has been transformed from a single-disciplinary diagnosis and treatment model to a multidisciplinary collaborative diagnosis and treatment model. In the multidisciplinary diagnosis and treatment model, the surgical treatment of portal hypertension is not a treatment that is about to disappear soon, but one of the indispensable treatment methods under the multidisciplinary diagnosis and treatment model, and it will play an increasingly important role. Surgeons should formulate individualized, standardized, and minimally invasive treatment methods under the input of new concepts, master the surgical indications and individualized surgical methods for different populations, and maximize the optimization surgical treatment methods for portal hypertension. Therefore, it is necessary to re-examine the role of surgical treatment in the diagnosis and treatment of liver cirrhotic portal hypertension.

Agricultural land-use change exacerbates the dissemination of antibiotic resistance genes via surface runoffs in Lake Tai Basin, China

Agricultural runoff is an important antibiotic resistance genes (ARGs) dissemination pathway from farmlands to water environment, however few studies have focused on the influence of agricultural land-use change on the pattern of ARGs in runoff and assess the health risk to public. Lake Tai Basin which experiences agricultural land-use change was selected to elucidate this concern. Our findings revealed that the pattern of ARGs was more diverse and the gene abundance was higher in orchard runoffs by comparison with conventional cropland runoffs. Co-occurrence network analysis between mobile genetic elements and ARGs demonstrated that after agricultural land-use change, ARG dissemination via runoffs became more threatened. In addition, this study illustrated the correlations between the antibiotic resistome and microbiome in runoffs, finding that non-dominant microbial taxa were the limiting factor which determined the pattern of ARGs in surface runoffs. In summary, the pattern and dissemination risk of ARGs in the surface runoff after agricultural land-use change in Lake Tai Basin were clarified via this study.

Reconstruction of the Diaminopimelic Acid Pathway to Promote L-lysine Production in Corynebacterium glutamicum

The dehydrogenase pathway and the succinylase pathway are involved in the synthesis of L-lysine in Corynebacterium glutamicum. Despite the low contribution rate to L-lysine production, the dehydrogenase pathway is favorable for its simple steps and potential to increase the production of L-lysine. The effect of ammonium (NH4+) concentration on L-lysine biosynthesis was investigated, and the results indicated that the biosynthesis of L-lysine can be promoted in a high NH4+ environment. In order to reduce the requirement of NH4+, the nitrogen source regulatory protein AmtR was knocked out, resulting in an 8.5% increase in L-lysine production (i.e., 52.3 ± 4.31 g/L). Subsequently, the dehydrogenase pathway was upregulated by blocking or weakening the tetrahydrodipicolinate succinylase (DapD)-coding gene dapD and overexpressing the ddh gene to further enhance L-lysine biosynthesis. The final strain XQ-5-W4 could produce 189 ± 8.7 g/L L-lysine with the maximum specific rate (qLys,max.) of 0.35 ± 0.05 g/(g·h) in a 5-L jar fermenter. The L-lysine titer and qLys,max achieved in this study is about 25.2% and 59.1% higher than that of the original strain without enhancement of dehydrogenase pathway, respectively. The results indicated that the dehydrogenase pathway could serve as a breakthrough point to reconstruct the diaminopimelic acid (DAP) pathway and promote L-lysine production.

Dual Regulation of Cytoplasm and Peroxisomes for Improved Α-Farnesene Production in Recombinant Pichia pastoris

Microbial production of α-farnesene from renewable raw materials is a feasible alternative to traditional petroleum craft. Recently, the research on improving α-farnesene production in Pichia pastoris mainly focused on cytoplasmic engineering, while comprehensive engineering of multiple subcellular compartments is rarely reported. Here, we first sought to confirm that the isopentenol utilization pathway (IUP) could act as a two-step shortcut for IPP synthesis in P. pastoris peroxisomes. In addition, we proposed dual regulation of cytoplasm and peroxisomes to boost α-farnesene synthesis in P. pastoris X33, thus the resultant strain produced 2.18 ± 0.04 g/L, which was 1.3 times and 2.1 times than that of the strain only with peroxisomal or cytoplasmic engineering, respectively. The α-farnesene production achieved 2.56 ± 0.04 g/L in shake flasks after carbon source cofeeding, which was the highest reported production in worldwide literatures to the best of my knowledge. Therefore, we propose these strategies as efficient approaches to enhancing α-farnesene production in P. pastoris, which might bring new ideas for the biosynthesis of high-value compounds.

Agricultural land-use change and rotation system exert considerable influences on the soil antibiotic resistome in Lake Tai Basin

In this study, we use high-throughput quantitative polymerase chain reaction approaches to comprehensively assess the effects of agricultural land-use change on the antibiotic resistome of agricultural runoffs after rainfalls in Lake Tai Basin. For the first time in this region, our findings show that orchard runoffs harbored more diverse and abundant antibiotic resistance genes (ARGs) than traditional cropland runoffs. Network analysis demonstrated that orchard runoffs possessed a strong ability for ARG dissemination via horizontal gene transfer. These results suggest that residents might be exposed to a higher public health threat than before. Moreover, the present study confirmed that the rice-wheat rotation system plays a key role in regulating the soil antibiotic resistome profile. Using 16S rRNA high-throughput sequencing technology, this study clarified the relationships between the antibiotic resistome and soil microbiome composition. Finally, we discuss the key environmental factors driving changes in the soil antibiotic resistome. In summary, this study gives insight into the dissemination of environmental ARGs to the people living in the Lake Tai Basin.

Effects of the Sn100 kVp Tube Voltage Mode on the Radiation Dose and Image Quality of Dual-Source Computed Tomography Pulmonary Angiography

OBJECTIVE

This study aimed to investigate the effects of the Sn100 kVp tube voltage mode on the image quality and radiation dose of computed tomography pulmonary angiography (CTPA).

METHODS

A total of 145 patients who underwent CTPA were randomly divided into five groups: control group (120 kVp, 150 mAs), test group A (Sn100 kVp, 270 mAs), test group B (120 kVp, 30 mAs), test group C (70 kVp, 150 mAs), and test group D (80 kVp, 70 mAs). After image post-processing, the image quality and radiation dose of each group were analyzed.

RESULTS

The computed tomography values of images in the four test groups were more than 250 HU, which met the criteria for diagnosis. The signal-to-noise ratio and contrast-to-noise ratio of the images in the four test groups were lower than those in the control group. The radiation dose in each test group was lower than in the control group. The radiation dose was lowest in test group A.

CONCLUSION

The Sn100 kVp energy spectrum purification protocol can meet the requirements for clinical diagnosis, ensure image quality, and reduce the dose of radiation that patients receive.

Atypical presentation of shoulder brucellosis misdiagnosed as subacromial bursitis: A case report

BACKGROUND

Brucella infections in the shoulder joint are uncommon, and few have been reported in the literature.

CASE SUMMARY

A 26-year-old male was admitted to our hospital with complaint of recurrent pain and limited movement of the right shoulder. The patient reported the pain to have first occurred as an isolated event 6 mo previously and to have reoccurred 5 mo later, when it was accompanied by limited movement of the shoulder. Findings from physical examination and magnetic resonance imaging (referred to as MRI) suggested the diagnosis of subacromial bursitis, and diagnostic paracentesis and arthroscopic debridement were performed. Surprisingly, synovial fluid culture detected brucella, and the finding was confirmed by mass spectrometry of a colony sample. The diagnosis was corrected to brucellosis of the shoulder joint, and antibiotic drug treatment (oral rifampicin and doxycycline) was administrated for 6 wk. The 4-mo postoperative follow-up examination (MRI) yielded normal findings. The 2-year follow-up showed no signs of recurrence.

CONCLUSION

This rare case of brucellosis infection in shoulder highlights the importance of increasing awareness to help avoid misdiagnosis.

Separation of nasopharyngeal epithelial cells from carcinoma cells on 3D scaffold platforms

Scaffold microstructures were developed to mimic a three-dimensional extracellular matrix in studying cell migration and invasion. The multiple-layer scaffold platforms were designed to investigate cell migration and separation from top to bottom layer. Two cell lines including immortalized nasopharyngeal epithelial (NP460) cells and nasopharyngeal carcinoma (NPC43) cells with Epstein-Barr virus were compared in this study. On one-layer platforms with trench depth of 15 µm, both NP460 and NPC43 cells were guided to migrate along the 18-µm-wide trenches, and exhibited random migration directions when the trench width was 10 or 50 µm. Nearly no cell was found to migrate in the 10-µm-wide trenches on one-layer platforms. However, the NP460 and NPC43 cells showed very different probability in the narrow trenches on two-layer platforms, making it possible to separate the nasopharyngeal epithelial cells from the carcinoma cells. Moreover, 1-µm deep grating topography on the top layer inhibited NP460 cells to migrate from top ridges to the 10-µm-wide trenches, but promoted such behavior for NPC43 cells. The results demonstrated in This study suggest that the engineered multiple-layer scaffold platforms could be used to separate carcinoma cells in NPC tumor as a potential treatment of NPC.

[Research progress of Rehmanniae Radix in prevention and treatment of osteoporosis]

Osteoporosis fracture with high disability and mortality is a difficult problem that seriously affects the life quality of individuals. At present, there is still a lack of anti-osteoporosis drugs with clear target and significant efficacy in the clinical practice. Rehmanniae Radix and its prescriptions have significant clinical effects. In this regard, more and more studies have reported the effects and mechanisms of Rehmanniae Radix and its active components, and the certain research outputs have been achieved. In this article, the PubMed, Web of science, China National Knowledge Infrastructure, and Wanfang database were searched to collect and organize the latest research progress of Rehmanniae Radix treatment of osteoporosis in the recent 10 years. We summarized the research dynamics as well as the function indexes and mechanisms of the raw and processed Rehmanniae Radix, active ingredients such as catalpol, aucubin, acteoside and Rehmanniae Radix polysaccharide, and their formulating prescriptions, and then excavated the potential active ingredients, targets and signaling pathways, including the effect on bone marrow mesenchymal stem cells, promoting the osteoblast proliferation and promoting osteogenesis differentiation(increasing alkaline phosphatase, typeⅠ collagen, osteoprotegerin, and osteocalcin and promoting calcium deposits), increasing the bone density, inhibiting the osteoclast quantity and differentiation, promoting the osteoclast apoptosis, and reducing tartrate resistant acid phosphatase and bone resorption pit area to provide the reference and develop new ideas for developing Rehmanniae Radix prescriptions for treatment of osteoporosis and exploring its mechanism.

Rational modification of the carbon metabolism of Corynebacterium glutamicum to enhance l-leucine production

l-Leucine is an essential amino acid that has wide and expanding applications in the industry. It is currently fast-growing market demand that provides a powerful impetus to further increase its bioconversion productivity and production stability. In this study, we rationally engineered the metabolic flux from pyruvate to l-leucine synthesis in Corynebacterium glutamicum to enhance both pyruvate availability and l-leucine synthesis. First, the pyc (encoding pyruvate carboxylase) and avtA (encoding alanine-valine aminotransferase) genes were deleted to weaken the metabolic flux of the tricarboxylic acid cycle and reduce the competitive consumption of pyruvate. Next, the transcriptional level of the alaT gene (encoding alanine aminotransferase) was down regulated by inserting a terminator to balance l-leucine production and cell growth. Subsequently, the genes involved in l-leucine biosynthesis were overexpressed by replacing the native promoters PleuA and PilvBNC of the leuA gene and ilvBNC operon, respectively, with the promoter Ptuf of eftu (encoding elongation factor Tu) and using a shuttle expression vector. The resulting strain WL-14 produced 28.47 ± 0.36 g/L l-leucine in shake flask fermentation.

Imported dengue serotype 1 outbreak in a non-endemic region, China, 2017: A molecular and seroepidemiological study

OBJECTIVES

Beginning in June 2017, numerous dengue virus (DENV) infections occurred in the Jining City of Shandong Province, formerly a dengue-free region in East China. We sought to describe the clinical and epidemiological features of this outbreak.

METHODS

We reviewed the clinical records and epidemiological data regarding a case series of patients diagnosed with DENV in Jining City, from June 30 to September 14, 2017. Diagnosis was confirmed by molecular method, culture, or rapid diagnostic tests. Sequencing of the DENV envelope gene or the whole viral genome was performed for 11 patients. Additionally, neutralizing antibodies against DENV was measured among patients and residents from their same villages.

RESULTS

Data from 150 patients were evaluated in this outbreak. None were diagnosed with dengue hemorrhagic fever or dengue shock syndrome. The patients' ages ranged between 2-88 years (median 51 years, [IQR=37.5-64.3]), and 100 (66.7%) were female. Epidemiological analyses implicated a man who had visited Saudi Arabia as the likely source of the outbreak. Phylogenetic studies identified DENV serotype 1. Most of the patients demonstrated increases of neutralizing antibody titers one year after infection compared with titers three months after infection. The residents living in dengue-affected villages had a significant higher seroprevalence of 21.2% (95%CI 16.9-25.5) than residents (3.2%, 95%CI-0.36-6.7) living in a non-dengue-affected village.

CONCLUSIONS

This report documents the first dengue outbreak in Shandong Province, China, in more than 60 years. It underscores the need for medical providers to record patients' travel histories and to consider dengue in their differential diagnoses.

Effect of oral L-citrulline on brachial and aortic blood pressure defined by resting status: evidence from randomized controlled trials

Background

Experimental evidence indicates that oral L-citrulline (L-Cit) may reduce resting blood pressure (BP) as well as BP responses to exercise and cold exposure (non-resting). However, results from human intervention trials are inconsistent. This study aims to summarize the clinical evidence regarding the effects of L-Cit supplementation on brachial systolic blood pressure (SBP), brachial diastolic blood pressure (DBP), in addition to aortic SBP and aortic DBP at rest and non-resting conditions.

Methods

Multiple databases including PubMed, Embase, Cochrane library, Web of Science, and Clinical Trials were searched systematically. Randomized controlled trials of human participants were quantitatively meta-analyzed.

Results

Fourteen trials contained in eight studies were available for quantitative syntheses for brachial BP. Results showed that L-Cit supplementation significantly reduced both brachial SBP (− 4.490 mmHg, 95% CI: − 7.332 to − 1.648, P = 0.002) and brachial DBP (− 3.629 mmHg, 95% CI: − 5.825 to − 1.434, P = 0.001). Nine of the trials were meta-analyzed for aortic BP which showed that L-Cit intervention significantly reduced aortic SBP (− 6.763 mmHg, 95% CI: − 10.991 to − 2.534, P = 0.002), but not aortic DBP (− 3.396 mmHg, 95% CI: − 7.418 to 0.627, P = 0.098). The observed reducing effects of L-Cit appeared stronger for non-resting than for resting brachial SBP (P for difference = 0.044).

Conclusion

L-Cit supplementation significantly decreased non-resting brachial and aortic SBP. Brachial DBP was significantly lowered by L-Cit regardless of resting status. Given the relatively small number of available trials in the stratified analyses and the potential limitations of these trials, the present findings should be interpreted cautiously and need to be confirmed in future well-designed trials with a larger sample size.

Metabolic engineering of glucose uptake systems in Corynebacterium glutamicum for improving the efficiency of l-lysine production

Traditional amino acid producers typically exhibit the low glucose uptake rate and growth deficiency, resulting in a long fermentation time because of the accumulation of side mutations in breeding of strains. In this study, we demonstrate that the efficiency of l-lysine production in traditional l-lysine producer Corynebacterium glutamicum ZL-9 can be improved by rationally engineering glucose uptake systems. To do this, different bypasses for glucose uptake were investigated to reveal the best glucose uptake system for l-lysine production in traditional l-lysine producer. This study showed that overexpression of the key genes in PTSGlc or non-PTSGlc increased the glucose consumption, growth rate, and l-lysine production. However, increasing the function of PTSGlc in glucose uptake led to the increase of by-products, especially for plasmid-mediated expression system. Increasing the participation of non-PTSGlc in glucose utilization showed the best glucose uptake system for l-lysine production. The final strain ZL-92 with increasing the expression level of iolT1, iolT2 and ppgK could produce 201.6 ± 13.8 g/L of l-lysine with a productivity of 5.04 g/L/h and carbon yield of 0.65 g/(g glucose) in fed-batch culture. This is the first report of a rational modification of glucose uptake systems that improve the efficiency of l-lysine production through increasing the participation of non-PTSGlc in glucose utilization in traditional l-lysine producer. Similar strategies can be also used for producing other amino acids or their derivatives.

Accurate method of generating infrared imaging features by the angular disturbance of an airborne platform

The imaging quality of an airborne infrared (IR) system is limited by the angular disturbance of the airborne platform. Based on the full-chain (IR scene-atmosphere-optical system-detector-airborne platform) signal transmission process, this study focused on the low-frequency sinusoidal angular disturbance features of the airborne platform and accurately calculated the point spread function caused by the angular disturbance and the IR imaging features when the IR system's different locations were dynamically simulated in a three-dimensional scene. First, the degradation mechanism of the IR imaging features resulting from the angular disturbance was analyzed from the viewpoint of scene radiation signal transmission and detector sampling. Then, the dynamic simulation in the three-dimensional scene resulting from the angular disturbance was realized by considering the geometric transformation of the spatial imaging, scale registration of the spatial sampling, radiation coupling, and angular disturbance caused by the airborne platform. Finally, the distances detected under different disturbance conditions were predicted using the established model. The obtained results provide data supporting the demonstration, verification, and optimization of the IR imaging system's design scheme.

Metabolic engineering of l-leucine production in Escherichia coli and Corynebacterium glutamicum: a review

l-Leucine, as an essential branched-chain amino acid for humans and animals, has recently been attracting much attention because of its potential for a fast-growing market demand. The applicability ranges from flavor enhancers, animal feed additives and ingredients in cosmetic to specialty nutrients in pharmaceutical and medical fields. Microbial fermentation is the major method for producing l-leucine by using Escherichia coli and Corynebacterium glutamicum as host bacteria. This review gives an overview of the metabolic pathway of l-leucine (i.e. production, import and export systems) and highlights the main regulatory mechanisms of operons in E. coli and C. glutamicum l-leucine biosynthesis. We summarize here the current trends in metabolic engineering techniques and strategies for manipulating l-leucine producing strains. Finally, future perspectives to construct industrially advantageous strains are considered with respect to recent advances in biology.

A Quantitative Study of the Dimensional Change of Inferior Vena Cava on Computed Tomography During Acute Hemorrhage Shock in Swine

Background: The purpose of this study was to examine the dimensional change of IVC during acute hemorrhage through a volume-controlled acute hemorrhagic shock model in swine. Methods: Volume-controlled hemorrhage was performed in 10 adult Bama mini pigs. Enhanced CT scan and hemodynamic monitoring were performed when the cumulative blood loss volume reached 0%, 10%, 20%, 30%, and 40%. The transverse diameter (T) and anteroposterior diameter (AP) of IVC were measured in axial images. Hemodynamic parameters were obtained with Pulse Contour Cardiac Output (PiCCO) hemodynamic monitor device. Arterial blood samples were also collected for artery blood gas analysis at each time point. Results: As the blood loss volume increased, the collapsibility (T/AP) and cross section area (CSA) of IVC significantly changed first in hepatic level and pre-renal level. The significant decrease of the CSA of IVC (shrink) occurred early when the blood loss volume reached only 10%, but the collapse of IVC occurred until the blood loss volume reached 30%. Conclusions: IVC shrank early but collapsed late during the acute hemorrhage in swine. The finding of collapsed IVC on CT scans suggested severe hypovolemic shock. Evaluation of the IVC at the CT scans can be an adjunctive test of the hemodynamic status in trauma patients.

Performance analysis of the infrared imaging system for aircraft plume detection from geostationary orbit

In view of the optical detection requirements of wide-area and continuous surveillance of air targets, the detection ability of an infrared imaging system in geostationary orbit for aircraft plumes is studied. The point spread model of the subpixel imaging of the full chain, including the aircraft plume, the sea surface, the environmental atmosphere, the optical system, and the imaging detector is established. The detection ability of the typical imaging system in geostationary orbit is analyzed from the signal-to-noise ratio (SNR) and the detection range in combination with the effect of the point spread function (PSF) of the optical system. Meanwhile, the optimal coupling condition of the PSF to the spatial resolution is discussed. The imaging characteristics of the aircraft target on the focal plane of the infrared imaging system under different spatial sampling rates are simulated and verified. Research shows that the SNR of the system first increases, and then decreases gradually with an increase of the spatial sampling rate. The detectable range covered by the pixel footprint decreases as the detector size increases. When the detector size is 15, 20, and 30 μm, the target can be detected with a spatial resolution of 200-700, 300-700, and 400-600 m, respectively.

Overexpression of thermostable meso-diaminopimelate dehydrogenase to redirect diaminopimelate pathway for increasing L-lysine production in Escherichia coli

Dehydrogenase pathway, one of diaminopimelate pathway, is important to the biosynthesis of L-lysine and peptidoglycan via one single reaction catalyzed by meso-diaminopimelate dehydrogenase (DapDH). In this study, the thermostable DapDH was introduced into diaminopimelate pathway that increased the final titer (from 71.8 to 119.5 g/L), carbon yield (from 35.3% to 49.1%) and productivity (from 1.80 to 2.99 g/(L∙h)) of L-lysine by LATR12-2∆rpiB::ddh_St in fed-batch fermentation. To do this, the kinetic properties and the effects of different DapDHs on L-lysine production were investigated, and the results indicated that overexpression of StDapDH in LATR12-2 was beneficial to construct an L-lysine producer with good productive performance because it exhibited the best of kinetic characteristics and optimal temperature as well as thermostability in reductive amination. Furthermore, ammonium availability was optimized, and found that 20 g/L of (NH₄)₂SO₄ was the optimal ammonium concentration for improving the efficiency of L-lysine production by LATR12-2∆rpiB::ddh_St. Metabolomics analysis showed that introducing the StDapDH significantly enhanced carbon flux into pentose phosphate pathway and L-lysine biosynthetic pathway, thus increasing the levels of NADPH and precursors for L-lysine biosynthesis. This is the first report of a rational modification of diaminopimelate pathway that improves the efficiency of L-lysine production through overexpression of thermostable DapDH in E. coli.

Accurate deduction of infrared imaging features of subpixel targets based on the conversion of radiation fields of measured area targets

The accurate generation of infrared (IR) imaging features of subpixel targets plays a very important role in the demonstration, verification, and optimization of system design schemes as well as in research into detection algorithms for small targets in the development of remote IR early warning systems. Based on the generation mechanism of target full-link IR imaging features, this study theoretically considers target radiation characteristics, the working environment, and the spatial response and energy-conversion characteristics of IR sensors, and an accurate deduction model of IR imaging features of subpixel targets is proposed and established. First, the surface-radiation field distribution of the target and background are inverted based on the measured data and the model of radiation calibration; then, the accurate simulation of IR imaging features of subpixel targets is realized by considering the geometric transformation of the spatial imaging, the aperiodic transfer function, scale registration of spatial sampling, and radiation coupling. Finally, the accuracy of the proposed model is verified by using the outfield experiment data. The experimental results show that the IR imaging-diffusion features of subpixel targets with different duty cycles are in good agreement with the prediction results of the model. The results obtained provide data support for the demonstration, verification, and optimization of the system design scheme, as well as for research into detection algorithms of small targets in the development of remote IR early warning systems.

Bidirectional reflectance characteristics of the sea surface based on midinfrared measured data

In order to establish a more realistic radiation model of the sea surface, the effects of solar radiation, sky radiation, and atmospheric thermal radiation on sea surface radiation are taken into consideration, on the basis of which the infrared radiative transfer equation of the sea surface is deduced in this paper. A method for calculating the bidirectional reflection characteristics of the sea surface based on measured data is proposed according to the projection imaging of beam propagation. Based on the measurements of sea surface temperature, incident sky radiation, incident solar radiation, and radiance of sea crests at different times, the radiative transfer equation is used to retrieve the bidirectional reflectance of a midwave infrared sea surface. Meanwhile, the results of the method mentioned above are compared with the calculated results of Cox-Munk, Mermelstein, Wu, and Beckmann bidirectional reflection characteristics models. Research shows that the bidirectional reflectance at the wave crest of a sea surface increases gradually, when the solar incident zenith angle changes from 56.39° to 76.02° as well as the direction of observation remaining constant (θ_r=80.0°; ϕ_r=73.0°). The reflection ability at the wave crest of the sea surface is strongest when the incident direction of the sun is close to the observation direction, which is in accordance with the law of reflection. The Cox-Munk model and Wu model are closer to our values when the solar incidence zenith angle is small (θ_i≤65.93°). On the other hand, the calculated values of the Mermelstein and Wu models are closer to the values in this paper when the solar incidence zenith angle is large (θ_i≤65.93°). In general, the error of the Beckmann model is a little greater than that of the other three models.