O-acetyl-L-homoserine (OAH) is a promising platform compound for the production of L-methionine and other valuable compounds, while its low yield and low conversion rate limit the industrial application. To solve these problems, we constructed a strain for high OAH production with the previously constructed L-homoserine producer Escherichia coli HS33 as the chassis by systematic metabolic engineering. Firstly, PEP accumulation, pyruvate utilization, and OAH synthesis pathway (overexpressing aspB, aspA, and thrA^C1034T) were enhanced to obtain an initial strain accumulating 13.37 g/L OAH. Subsequently, the co-factor synthesis genes were integrated to supply reducing power and energy, which increased the yield to 15.79 g/L. The OAH yield of the engineered strain OAH28 was further increased to 17.49 g/L by strengthening the acetic acid reuse pathway, improving the supply of acetyl-CoA, and regulating the expression of MetX from different sources. Finally, in a 5 L fermenter, OAH28 achieved an OAH titer of 47.12 g/L, with a glucose conversion rate of 32% and productivity of 0.59 g/(L·h). The results lay a foundation for increasing the OAH production by metabolic engineering and give insights into the industrial production of OAH.
Metabolic Engineering/methods* ; Escherichia coli/genetics* ; Homoserine/biosynthesis* ; Fermentation

Echinocandin B (ECB) is a key precursor of the antifungal drug anidulafungin. It is a secondary metabolite of Aspergillus nidulans, and its titer in fermentation is significantly affected by the ECB synthesis pathway and cell morphology. In this study, the key genes related to the transcription activation, hydroxylation, and cell morphology during ECB biosynthesis were investigated to increase the fermentation titer of ECB and to change the cell morphology of Aspergillus nidulans to reduce the viscosity of the fermentation broth. The results indicated that after overexpression of ecdB and ecdK, the ECB titer increased by 25.8% and 23.7%, respectively, compared with that of the wild-type strain, reaching (2 030.5±99.2) mg/L and (1 996.4±151.4) mg/L. However, the deletion of fksA associated with cell wall synthesis resulted in damage to the cell wall, affecting strain growth and product synthesis. The engineered strain overexpressing ecdB was fermented in a 50-L bioreactor, in which the ECB titer reached 2 234.5 mg/L. The findings laid a research foundation for the subsequent metabolic engineering of this strain.
Fermentation ; Aspergillus nidulans/genetics* ; Echinocandins/genetics* ; Bioreactors/microbiology* ; Fungal Proteins/biosynthesis* ; Metabolic Engineering

Synthetic biology is a crucial tool for the development of the bio-industry and bio-economy, representing a significant aspect of new quality productive forces. As a core course for graduate students in bioengineering, Synthetic Biology plays a vital role in ensuring the supply of essential talents for the development of the bio-industry in the new era. To better serve regional economic development and provide high-level talents for China's progress in the bio-industry, we analyzed typical issues encountered in the past teaching activities, set up a multi-disciplinary teaching team, optimized the course contents, adjusted the teaching mode, and mobilized students' learning interest. With the application of scientific research project as the starting point, we guided students to think and discuss deeply through the simulation of application writing and project defense, which improved students' critical thinking and innovative thinking. With industrialization as a focus, we explored a new training model combining production, education, and research through the joint practice base of the university and enterprises introduced typical cases of biomanufacturing to encourage students to engage in scientific research. The teaching reform significantly enhances the comprehensive abilities and national sentiments of graduate students. This paper hopes to serve as a reference for colleagues engaged in teaching in this field.
Synthetic Biology/education* ; Teaching ; China ; Humans

AIM: To evaluate the changes in corneal epithelial thickness(CET)and corneal optical density(CD)after smart pulse technology(SPT)-assisted transepithelial photorefractive keratectomy(TPRK)and analyze their correlation.METHODS: The prospective study included 60 patients(120 eyes)with myopia and myopic astigmatism who underwent SPT-TPRK in the ophthalmology department at the First Affiliated Hospital of Xinxiang Medical University between February and August 2023. Changes in CET and CD were evaluated preoperatively and at 1 wk, 1 and 3 mo postoperatively.RESULTS: A total of 14 cases(28 eyes)were lost to follow-up, and 3 patients(6 eyes)with postoperative haze were excluded from this study, resulting in a final inclusion of 43 patients(86 eyes). At 1 wk after SPT-TPRK, CET had statistically significantly thickened compared to preoperative levels(P<0.05), particularly in the CET at 0-2 mm central corneal area(P<0.05). At 1 mo after SPT-TPRK, the CET at 0-2 mm area had statistically significantly decreased(P<0.05). At 3 mo after SPT-TPRK, the CET at 0-2 mm had essentially reached preoperative levels. Postoperative CD values increased, with a positive correlation between CET in the 0-2 mm area and CD in the whole 0-2 mm area(r=0.256, P<0.05), and a positive correlation between CET in the 2-5 mm area and CD in the anterior 2-6 mm area(r=0.319, P<0.05).CONCLUSION: Corneal epithelial remodeling takes 3 mo in areas within 2 mm of the central cornea; areas with thinner CET have faster postoperative corneal epithelial remodeling and greater thickening in the early postoperative period; CD increases in the early postoperative period compared to the preoperative value, and in some areas, there is a positive correlation between CET and CD value.

【Objective】 To statistically analyze the relationship between homologous recombination repair deficiency (HRD) score and clinicopathological characteristics, genomic mutations in patients with high-risk and metastatic hormone-sensitive prostate cancer (mHSPC) and the prognostic predictive value in mHSPC. 【Methods】 A total of 127 patients diagnosed with high-risk prostate cancer and mHSPC, treated at the Department of Urology of Chinese PLA General Hospital during Dec.2021 and Nov.2023 were enrolled.Homologous recombination repair (HRR) gene sequencing was performed, and the genomic scar score (GSS) algorithm were conducted to calculate the HRD score.The relationship between HRD scores and clinicopathological features, genomic alterations, and prognosis were analyzed. 【Results】 The median HRD score was 1.6(0.8, 5.2), 30(23.6%) patients’ HRD scores ≥10, and 11(8.7%) patients’ HRD scores ≥20.Clinicopathological features, including ISUP classification ≥4 (P=0.044) and metastatic status (P=0.008) were associated with high HRD score.Patients with mutations in the BRCA, TP53 and MYC systems had significantly higher HRD score than those with wild-type genes (P<0.05).In mHSPC, the risk of biochemical recurrence was 12.836 times higher in patients with HRD score ≥20 than in those with <20 [OR:12.836 (1.332-124.623), P=0.028]. 【Conclusion】 Baseline HRD score was lower in patients with high-risk prostate cancer and mHSPC.Patients with high HRD score may have higher histological grading (ISUP≥4) and later clinical stage.Further investigation is needed to determine the threshold of HRD scores as biochemical markers suggestive of a poor prognosis.

Objective:To evaluate the effect of intermittent fasting on postoperative cognitive function in aged rats and the role of Janus kinase 2/signal transducer and activator of transcription 3 (JAK2/STAT3) signaling pathway in it.Methods:Eighty SPF healthy male Sprague-Dawley rats, aged 20 months, weighing 600-650 g, were divided into 4 groups ( n=20 each) using a random number table method: control group (group C), postoperative cognitive dysfuction (POCD) group (group P), intermittent fasting + POCD group (group IF+ P), and intermittent fasting+ JAK2/STAT3 signaling pathway agonist C-A1+ POCD group (group IF+ A+ P). IF+ P group and IF+ A+ P group underwent a 4-week intermittent fasting procedure: fasting for 24 h followed by free eating for 24 h, without limiting water intake throughout the entire process, in addition C-A1 100 μg/kg was intraperitoneally injected daily during intermittent fasting in IF+ A+ P group. Rats underwent exploratory laparotomy under sevoflurane anesthesia to prepare POCD models in P group, IF+ P group and IF+ A+ P group. Three days after surgery, open field tests were conducted to evaluate the autonomous motor function of rats, and Morris water maze tests were conducted to evaluate the cognitive function of rats on 3-7 days after surgery. After the Morris water maze tests, the rats were sacrificed and the hippocampal CA1 area was removed for determination of the expression of JAK2, phosphorylated JAK2 (p-JAK2), STAT3, and phosphorylated STAT3 (p-STAT3) (by Western blot) and contents of interleukin-6 (IL-6), IL-1β and tumor necrosis factor-alpha (TNF-α) (by enzyme-linked immunosorbent assay) and for microscopic examination of pathological changes of hippocampal CA1 region (using HE staining). Results:There was no statistically significant difference in the speed, distance and duration of stay at the center of the open field test among the four groups ( P>0.05). Compared with group C, the escape latency was significantly prolonged, the number of crossing the original platform was reduced, and the p-JAK2/JAK2 ratio, p-STAT3/STAT3 ratio and contents of IL-6, IL-1β and TNF-α in the hippocampal CA1 region were increased ( P<0.05), and the pathological damage occurred in the hippocampal CA1 region in group P. Compared with P group, the escape latency was significantly shortened, the number of crossing the original platform was increased, and the p-JAK2/JAK2 ratio, p-STAT3/STAT3 ratio and contents of IL-6, IL-1β and TNF-α in the hippocampal CA1 region were decreased ( P<0.05), and the pathological damage in the hippocampal CA1 area was significantly alleviated in IF+ P group. Compared with IF+ P group, the escape latency was significantly prolonged, the number of crossing the original platform was reduced, and the p-JAK2/JAK2 ratio, p-STAT3/STAT3 ratio and contents of IL-6, IL-1β and TNF-α in the hippocampal CA1 region were increased ( P<0.05), and the pathological damage in the hippocampal CA1 area was aggravated in group IF+ A+ P. Conclusions:Intermittent fasting can improve postoperative cognitive function in aged rats, and the mechanism may be related to inhibiting the JAK2/STAT3 signaling pathway and reducing the neuroinflammatory responses in the hippocampal CA1 region.

Objective:To evaluate the role of nuclear factor kappa B (NF-κB)/NOD-like receptor thermoprotein structural domain-associated protein 3 (NLRP3) signaling pathway in hippocampal microglia in dexmedetomidine-induced improvement in long-term cognitive function after multiple sevoflurane anesthesia in newborn mice.Methods:One hundred SPF healthy male C57BL/6 mice, aged 6 days, weighing 3-5 g, were divided into 5 groups ( n=20 each) by a random number table method: control group (group C), multiple sevoflurane anesthesia group (group S), multiple sevoflurane anesthesia+ NF-κB inhibitor pyrrolidine dithiocarboxylate group (group SP), multiple sevoflurane anesthesia + dexmedetomidine group (group SD), and multiple sevoflurane anesthesia + NF-κB agonist phorbol 12-myristate 13-acetate (PMA) + dexmedetomidine group (group SPD). Anesthesia was induced by inhalation of 3% sevoflurane and maintained by inhalation of 60% oxygen and 3% sevoflurane for 2 h for 3 consecutive days in S, SP, SD and SPD groups. At 30 min before each sevoflurane inhalation, pyrrolidine dithiocarbamate 100 mg/kg was intraperitoneally injected in group SP, and dexmedetomidine 20 μg/kg was intraperitoneally injected in group SD. NF-κB agonist PMA 15 μg/kg was intraperitoneally injected at 1 h before each sevoflurane inhalation, and 30 min later dexmedetomidine 20 μg/kg was intraperitoneally injected in group SPD. The mice were sacrificed at the age of 11 days, and the hippocampal tissues were isolated for determination of the expression of phosphorylated NF-κB p65 (p-NF-κB p65) and NLRP3 (by Western blot). The co-staining area of NLRP3 and microglia-specific ionized calcium binding adaptor molecule 1 (Iba-1) double positive cells (NLRP3 + -Iba-1 + cells) was calculated by immunofluorescence. The open field test and novel object recognition test were performed at 29 days of age, and the Morris water maze test was performed at 30-34 days of age. Results:There were no significant differences in each parameter of the open field test among the five groups ( P>0.05). Compared with group C, the expression of p-NF-κB p65 and NLRP3 in hippocampal tissues was significantly up-regulated, the co-staining area of NLRP3 + -Iba-1 + cells was increased, the percentage of novel object exploration and discrimination index were decreased, the escape latency was prolonged, and the frequency of crossing the original platform was reduced in group S ( P<0.05). Compared with group S, the expression of p-NF-κB p65 and NLRP3 in hippocampal tissues was significantly down-regulated, the co-staining area of NLRP3 + -Iba-1 + cells was reduced, the percentage of novel object exploration and discrimination index were increased, the escape latency was shortened, and the frequency of crossing the original platform was increased in SP, SD and SPD groups ( P<0.05). Compared with SD group, the expression of p-NF-κB p65 and NLRP3 was significantly up-regulated, the co-staining area of NLRP3 + -Iba-1 + cells was increased, the percentage of novel object exploration and discrimination index were decreased, the escape latency was prolonged, and the number of crossing the original platform location was decreased in SPD group ( P<0.05). Conclusions:The mechanism by which dexmedetomidine improves long-term cognitive function after multiple sevoflurane anesthesia may be related to inhibiting the activation of NF-κB/NLRP3 signaling pathway in the hippocampal microglia of newborn mice.

Objective:To evaluate the effect of preoperative mild cognitive impairment (MCI) on the potency of sevoflurane in inhibiting body movement responses during skin incision in aged female patients.Methods:This was a prospective study. Female American Society of Anesthesiologists Physical Status classification Ⅰ or Ⅱ patients, aged 60-75 yr, with body mass index of 18.5-23.9 kg/m 2, scheduled to undergo radical mastectomy between January 2022 and March 2023 in our hospital, were selected. The patient′s cognitive function was assessed using Mini-Mental State Examination and Montreal Cognitive Assessment. The patients were divided into 2 groups based on whether they had MCI or not before operation: normal group (group N) and MCI group (group M). General anesthesia was induced by inhaling 8% sevoflurane, and the laryngeal mask airway was inserted after they lost consciousness and their jaws relaxed. According to the Dixon′s up-and-down method, the end-tidal concentration of sevoflurane in the first patient was set at 2%. If the body movement response occurred, the concentration was increased by 2% in the next patient, otherwise the concentration was decreased by 2% in the next patient. The MAC and 95% confidence interval ( CI) of sevoflurane were calculated using the probability regression method. Results:The minimum alveolar concentration of sevoflurane was 1.60% (95% CI 1.48% -1.70%) in group N and 1.38% (95% CI 1.25%-1.49%) in group M, and there was statistically significant difference ( P<0.05). Conclusions:Preoperative MCI can increase the potency of sevoflurane in inhibiting body movement responses during skin incision in aged female patients.

Objective To determine the optimal conditions for CXCR4 upregulation by comparing the expression levels of chemokine(C-X-C motif)receptor 4(CXCR4)in MSCs cultured with varying concentrations of oxygen and hydrogen peroxide(H2O2).Methods MSCs were cultured with 0.1％,1％,or 3％O2 and 50 μmol/L H2O2 for different lengths of time(3,6,12,and 24 h).The mRNA and protein expressions of CXCR4 in MSCs were measured by real-time quantitative PCR(qPCR),Western blotting,and immunofluorescence staining.The viability and chemotactic ability of MSCs were measured using CCK-8,wound-healing and Transwell migration assays.Results Both hypoxia and H2O2 treatment were found to upregulate MSC expressions of CXCR4 to some extent.The mRNA and protein levels of CXCR4 were higher after 6-12 h of culture of MSCs with 3％O2,and significantly higher when treated with H2O2 for 6 h.Cell viability was significantly increased after culture with 3％O2 compared with the control group and both 3％O2 and H2O2 pretreatment could enhance chemotactic migration in MSCs.Conclusion Culture with 3％O2 and H2O2 pretreatment can upregulate CXCR4 expressions in MSCs and enhance migration in cells,with superior effects observed with 3％O2.Therefore,treatment with 3％O2 represents the best choice for upregulating the chemotactic ability of MSCs.

L-methionine, also known as L-aminomethane, is one of the eight essential amino acids required by the human body and has important applications in the fields of feed, medicine, and food. In this study, an L-methionine high-yielding strain was constructed using a modular metabolic engineering strategy based on the M2 strain (Escherichia coli W3110 ΔIJAHFEBC/PAM) previously constructed in our laboratory. Firstly, the production of one-carbon module methyl donors was enhanced by overexpression of methylenetetrahydrofolate reductase (methylenetetrahydrofolate reductase, MetF) and screening of hydroxymethyltransferase (GlyA) from different sources, optimizing the one-carbon module. Subsequently, cysteamine lyase (hydroxymethyltransferase, MalY) and cysteine internal transporter gene (fliY) were overexpressed to improve the supply of L-homocysteine and L-cysteine, two precursors of the one-carbon module. The production of L-methionine in shake flask fermentation was increased from 2.8 g/L to 4.05 g/L, and up to 18.26 g/L in a 5 L fermenter. The results indicate that the one carbon module has a significant impact on the biosynthesis of L-methionine, and efficient biosynthesis of L-methionine can be achieved through optimizing the one carbon module. This study may facilitate further improvement of microbial fermentation production of L-methionine.
Humans ; Methionine ; Methylenetetrahydrofolate Reductase (NADPH2) ; Carbon ; Cysteine ; Escherichia coli/genetics* ; Hydroxymethyl and Formyl Transferases ; Carrier Proteins ; Escherichia coli Proteins