Knockout of a PLD gene in Schizochytrium limacinum SR21 enhances docosahexaenoic acid accumulation by modulation of the phospholipid profile

BACKGROUND

The hydrolysis and transphosphatidylation of phospholipase D (PLD) play important roles in the interconversion of phospholipids (PLs), which has been shown to profoundly impact lipid metabolism in plants. In this study, the effect of the PLD1 gene of Schizochytrium limacinum SR21 (S. limacinum SR21) on lipid metabolism was investigated.

RESULTS

PLD1 knockout had little impact on cell growth and lipid production, but it significantly improved the percentage of polyunsaturated fatty acids in lipids, of which docosahexaenoic acid (DHA) content increased by 13.3% compared to the wild-type strain. Phospholipomics and real-time quantitative PCR analysis revealed the knockout of PLD1 reduced the interexchange and increased de novo synthesis of PLs, which altered the composition of PLs, accompanied by a final decrease in phosphatidylcholine (PC) and an increase in phosphatidylinositol, lysophosphatidylcholine, and phosphatidic acid levels. PLD1 knockout also increased DHA content in triglycerides (TAGs) and decreased it in PLs.

CONCLUSIONS

These results indicate that PLD1 mainly performs the transphosphatidylation activity in S. limacinum SR21, and its knockout promotes the migration of DHA from PLs to TAGs, which is conducive to DHA accumulation and storage in TAGs via an acyl CoA-independent pathway. This study provides a novel approach for identifying the mechanism of DHA accumulation and metabolic regulation strategies for DHA production in S. limacinum SR21.

Strategies for high cell density cultivation of Akkermansia muciniphila and its potential metabolism

IMPORTANCE

Currently, there is significant interest in Akkermansia muciniphila as a promising next-generation probiotic, making it a hot topic in scientific research. However, to achieve efficient industrial production, there is an urgent need to develop an in vitro culture method to achieve high biomass using low-cost carbon sources such as glucose. This study aims to explore the high-density fermentation strategy of A. muciniphila by optimizing the culture process. This study also employs techniques such as LC-MS and RNA-Seq to explain the possible regulatory mechanism of high-density cell growth and increased cell surface hydrophobicity facilitating cell colonization of the gut in vitro culture. Overall, this research sheds light on the potential of A. muciniphila as a probiotic and provides valuable insights for future industrial production.

A Bifidobacterium animalis subsp. lactis strain that can suppress Helicobacter pylori: isolation, in vitro and in vivo validation

The administration of probiotics is an effective approach for treatment of Helicobacter pylori, which is associated with human gastrointestinal diseases and cancers. To explore more effective probiotics for H. pylori infection elimination, bacteria from infant feces were screened in this study. We successfully isolated the Bifidobacterium animalis subsp. lactis strains and evaluated its efficacy to inhibit H. pylori growth in vitro and in vivo. The results showed that a B. animalis strain (named BB18) sustained a high survival rate after incubation in gastric juice. The rapid urease test suggested that B. animalis BB18 reduced pathogen loads in H. pylori-infected Mongolian gerbils. Alleviation of H. pylori infection-induced gastric mucosa damage and decreased levels inflammatory cytokines were observed after the B. animalis BB18 administration. These findings demonstrated that B. animalis BB18 can inhibit H. pylori infection both in vitro and in vivo, suggesting its potential application for the prevention and eradication therapy of H. pylori infection.

A Pilot Study of an Interactive Virtual Tour Tool for Patient Education Prior to Undergoing High-Dose Rate Brachytherapy for Prostate Cancer

PURPOSE/OBJECTIVE(S)

High-dose rate (HDR) brachytherapy for treatment of prostate cancer is an invasive procedure that can be associated with patient anxiety. Patient education regarding the procedure can allow for better informed decision-making while also decreasing anxiety. We sought to develop and assess the utility of an interactive virtual tour tool that portrays a 360-degree view of the HDR brachytherapy patient experience, with the goals of providing patient education, decreasing patient anxiety, and assisting in wayfinding on the procedure day.

MATERIALS/METHODS

Using a 360-degree camera, we captured multiple photographs that depicted the various hospital locations that a patient would navigate through on the day of their HDR brachytherapy procedure, including the medical center lobby, pre-operative/post-operative units, and the brachytherapy suite. We then compiled these 360-degree photographs using virtual tour software, to allow users to navigate throughout the locations. We added informational text, spoken audio, and videos associated with key staff, objects, and the brachytherapy procedure that allow the users to interact with and learn about these various components within the virtual tour. This tool was accessible via a website link on a computer, tablet, or smartphone and was provided at the time of consult to patients who were planning to undergo HDR brachytherapy for prostate cancer. A questionnaire assessing the tool's ease of use, educational value, wayfinding utility, and ability to improve anxiety and treatment decision-making was conducted prior to and after their procedure.

RESULTS

Preliminary feedback from healthy volunteers is highly positive, with users finding that the tool is easily accessible, user-friendly, improves understanding of HDR brachytherapy, simulates the treatment experience accurately, helps with wayfinding, and has the potential to decrease patient anxiety and increase comfort with the treatment decision. Data from the patient questionnaires are being collected and will be analyzed.

CONCLUSION

A 360-degree virtual tour tool allows for an easily accessible, immersive, and interactive method of patient education on an invasive, anxiety-associated procedure. This has the potential to decrease patient anxiety and improve comfort regarding treatment decision-making. This tool may be applied toward other relatively involved radiotherapy modalities, including gynecologic HDR brachytherapy, respiratory-gated treatments, and CyberKnife stereotactic radiosurgery.

Transesterification of phosphatidylcholine with DHA-rich algal oil using immobilized Candida antarctica lipase B to produce DHA-phosphatidylcholine

Docosahexaenoic acid (DHA) enriched with phospholipids (PLs) (DHA-PLs) is a type of structured PL with good physicochemical and nutritional properties. Compared to PLs and DHA, DHA-PLs has higher bioavailability and structural stability and many nutritional benefits. To improve the enzymatic synthesis of DHA-PLs, this study investigated the preparation of phosphatidylcholine (PC) enriched with DHA (DHA-PC) via enzymatic transesterification of algal oil, which is rich in DHA-triglycerides, using immobilized Candida antarctica lipase B (CALB). The optimized reaction system incorporated 31.2% DHA into the acyl chain of PC and converted 43.6% PC to DHA-PC within 72 h at 50 °C, 1:8 PC: algal oil mass ratio, 25% enzyme load (based on total substrate mass), and 0.02 g/mL molecular sieve concentration. Consequently, the side reactions of PC hydrolysis were effectively suppressed and products with high PC content (74.8%) were produced. Molecular structure analysis showed that exogenous DHA was specifically incorporated into the sn-1 site of the PC by immobilized CALB. Furthermore, the evaluation of reusability with eight cycles showed that the immobilized CALB had good operational stability in the present reaction system. Collectively, this study demonstrated the applicability of immobilized CALB as a biocatalyst for synthesizing DHA-PC and provided an improved enzyme-catalyzed method for future DHA-PL synthesis.

Metabolic mechanism of astaxanthin biosynthesis in Xanthophyllomyces dendrorhous in response to sodium citrate treatment

Astaxanthin is an important ketocarotenoid widely used in industries. However, its application is limited because of its low yield. Sodium citrate (Na-citrate), one of the major carbon sources for microorganisms, can promote cell growth and product accumulation. The basidiomycetous red yeast Xanthophyllomyces dendrorhous was thus used to study the effect of Na-citrate on cell growth and astaxanthin synthesis. The highest biomass and astaxanthin yield (6.0 g/L and 22.5 mg/L) were obtained in shake-flask when 3 g/L Na-citrate was added at 24 h and were 1.8 and 2.0 times higher than those of the control group, respectively. Furthermore, metabolomics and real-time reverse transcription PCR (qRT-PCR) analysis were conducted to study the metabolic pathways of X. dendrorhous in response to Na-citrate. The qRT-PCR assay revealed that Na-citrate facilitated glucose consumption, promoted the metabolic flux from glycolysis, and regulated the tricarboxylic acid (TCA) cycle, providing more energy and substrates for the synthesis of astaxanthin. The gene analysis revealed that adding Na-citrate significantly upregulated the expression of six key genes (ICL, HMGS, crtE, crtYB, crtI, and crtS) involved in pathways related to astaxanthin biosynthesis. These results suggest that exogenous Na-citrate treatment is a potentially valuable strategy to stimulate astaxanthin production in X. dendrorhous.

A Novel Bioflocculant Produced by Cobetia marina MCCC1113: Optimization of Fermentation Conditions by Response Surface Methodology and Evaluation of Flocculation Performance when Harvesting Microalgae

A preliminary study was carried out to optimize the culture medium conditions for producing a novel microbial flocculant from the marine bacterial species Cobetia marina. The optimal glucose, yeast extract, and glutamate contents were 30, 10, and 2 g/l, respectively, while the optimal initial pH of the culture medium was determined to be 8. Following response surface optimization, the maximum bioflocculant production level of 1.36 g/l was achieved, which was 43.40% higher than the original culture medium. Within 5 min, a 20.0% (v/v) dosage of the yielded bioflocculant applied to algal cultures resulted in the highest flocculating efficiency of 93.9% with Spirulina platensis. The bioflocculant from C. marina MCCC1113 may have promising application potential for highly productive microalgae collection, according to the findings of this study.

Total bone mineral density is inversely associated with stroke: a family osteoporosis cohort study in rural China

BACKGROUND

The relationship of osteoporosis and stroke is still not fully clarified. Apart from the well-known risk factors for stroke, bone mineral density (BMD) has gained more interest in recent years.

AIM

To further elucidate the relationship between BMD and stroke risk, a prospective cohort study in the Chinese rural population was conducted.

DESIGN

Retrospective analysis of a family osteoporosis cohort.

METHODS

Our subjects were selected from an osteoporosis cohort conducted in Anqing, China. All participants underwent a questionnaire assessment, clinical examinations and laboratory assessments. During the follow-up period, the number of people who had a stroke was recorded. Generalized estimating equation regression analysis was performed to determine the significance of the association between BMD and stroke.

RESULTS

A total of 17868 people were included. A two-way interaction test of sex and BMD on stroke was significant (P = 0.002). There was a significant difference in BMD and stroke morbidity in the male group (P = 0.003). When BMD was assessed as quartiles and the lowest quartile was used as reference, a significantly lower risk for stroke was observed in Q2-4. Notably, no significant difference was observed in female participants with adjusted odds ratio (P > 0.05). The P-value for interaction was calculated. The body mass index (P = 0.014) and waist-to-hip ratio (P = 0.027) were found to be significantly associated with BMD and stroke risk in female participants.

CONCLUSIONS

In Chinese rural areas, total BMD may negatively correlated with stroke, especially in men.

Study on the mechanism of efficient extracellular expression of toxic streptomyces phospholipase D in Brevibacillus choshinensis under Mg2+ stress

Background

Phospholipase D (PLD) has significant advantages in the food and medicine industries due to its unique transphosphatidylation. However, the high heterologous expression of PLD is limited by its cytotoxicity. The present study sought to develop an efficient and extracellular expression system of PLD in the non-pathogenic Brevibacillus choshinensis (B. choshinensis).

Results

The extracellular PLD was effectively expressed by the strong promoter (P2) under Mg2+ stress, with the highest activity of 10 U/mL. The inductively coupled plasma–mass spectrometry (ICP-MS) results elucidated that the over-expression of PLD by P2 promoter without Mg2+ stress induced the ionic homeostasis perturbation caused by the highly enhanced Ca2+ influx, leading to cell injury or death. Under Mg2+ stress, Ca2+ influx was significantly inhibited, and the strengths of P2 promoter and HWP gene expression were weakened. The study results revealed that the mechanism of Mg2+ induced cell growth protection and PLD expression might be related to the lowered strength of PLD expression by P2 promoter repression to meet with the secretion efficiency of B. choshinensis, and the redistribution of intracellular ions accompanied by decreased Ca2+ influx.

Conclusions

The PLD production was highly improved under Mg2+ stress. By ICP-MS and qPCR analysis combined with other results, the mechanism of the efficient extracellular PLD expression under Mg2+ stress was demonstrated. The relatively low-speed PLD expression during cell growth alleviated cell growth inhibition and profoundly improved PLD production. These results provided a potential approach for the large-scale production of extracellular PLD and novel insights into PLD function.

Safety and efficacy of dendritic cell-based immunotherapy (DCVAC/LuCa) combined with carboplatin/pemetrexed for patients with advanced non-squamous non-small-cell lung cancer without oncogenic drivers

Background

Our prospective, open-label, single-arm phase II study investigated the safety and efficacy of DCVAC/LuCa (dendritic cell vaccines for lung cancer) combined with standard carboplatin/pemetrexed in advanced non-squamous (nsq) non-small-cell lung cancer (NSCLC).

Patients and methods

Eligible patients had stage IV nsq NSCLC without oncogenic drivers and had not received prior systemic cancer therapy. Treatment consisted of carboplatin/pemetrexed for up to 6 cycles followed by 21 cycles of pemetrexed maintenance or until progression or intolerance. Non-progression patients after two cycles of chemotherapy started to receive DCVAC/LuCa subcutaneously (s.c.) on day 15 of cycle 3, and thereafter q3w (day 15 of chemotherapy cycles) for up to 15 doses. Dosing of DCVAC/LuCa s.c. varied among patients depending on the baseline number of leucocytes but remained constant for each single patient. Safety was assessed by adverse events (AEs), treatment-related adverse events (TRAEs), serious adverse events (SAEs), and adverse events of special interest (AESIs). Efficacy was measured by overall survival (OS), progression-free survival (PFS), time to progression (TTP), and objective response rate (ORR).

Results

Sixty-one patients were enrolled. In the safety population (n = 60), eight patients (13.33%) had grade 3 or greater TRAEs, and six patients (10.0%) showed SAEs which were not related to leukapheresis or DC vaccination. Six grade 1 AEs were considered to be related to leukapheresis. No AESIs or DCVAC/LuCa-induced AEs were observed. The 2-year survival rate in the modified intention-to-treat population (n = 44) was 52.57%. Median OS was not reached. Median PFS was 8.0 months, median TTP was 10.2 months, and the ORR was 31.82%.

Conclusion

In treatment-naïve stage IV nsq NSCLC patients without oncogenic drivers, the combination of carboplatin/pemetrexed and DCVAC/LuCa was well tolerated and showed promising efficacy. Therefore, a study to prove our immunotherapeutic concept in a randomized phase III trial is planned.

•

We investigated the safety and efficacy of DCVAC/LuCa combined with standard carboplatin/pemetrexed in nsq NSCLC.

•

The combination therapy showed a favorable tolerability profile in a selected Chinese population.

•

The 2-year survival rate in the modified intention-to-treat population (n = 44) was 52.57%.

Response of nutrient resorption of Leymus chinensis to nitrogen and phosphorus addition in a meadow steppe of northeast China

Nutrient resorption, one of the most important strategies for plant nutrient conservation, is significantly affected by soil fertility. However, the effects of experimentally altered soil fertility on plant N and P resorption are poorly understood. The potential nutrient resorption response mechanisms of the dominant species Leymus chinensis to six N addition levels (0, 2.5, 5, 10, 20 and 40 g·N·m^-2 ·year^-1 ), two P addition levels (0 and 10 g P·m^-2 ·year^-1 ) and their interactions were studied after 3 years of treatments in a temperate meadow steppe. In both green leaves and culms, N and P addition significantly increased N and P concentrations, respectively. Nitrogen addition led to a decrease in the N resorption efficiency (NRE) of both leaves and culms. Within each N treatment, P addition decreased the P resorption efficiency (PRE) of both leaves and culms and the NRE of leaves, except in the N2.5 treatment. Both NRE and PRE in leaves were higher than those in culms under N and P addition conditions. The nutrient concentrations and resorption efficiency were significantly correlated with the soil nutrient availability. Our results suggest that plants rely more on nutrient absorption from the soil, reducing the proportion of elements obtained through nutrient resorption in nutrient-rich environments.

Enhancing astaxanthin accumulation in Xanthophyllomyces dendrorhous by a phytohormone: metabolomic and gene expression profiles

Xanthophyllomyces dendrorhous is a promising source of natural astaxanthin due to its ability to accumulate high amounts of astaxanthin. This study showed that 6‐benzylaminopurine (6‐BAP) is an effective substrate that enhances cell biomass and astaxanthin accumulation in X. dendrorhous. In the current study, the biomass and astaxanthin content in X. dendrorhous were determined to be improved by 21.98% and 24.20%, respectively, induced by 6‐BAP treatments. To further understand the metabolic responses of X. dendrorhous to 6‐BAP, time‐course metabolomics and gene expression levels of X. dendrorhous cultures with and without 6‐BAP feeding were investigated. Metabolome analysis revealed that 6‐BAP facilitated glucose consumption, promoted the glycolysis, suppressed the TCA cycle, drove carbon flux of acetyl‐CoA into fatty acid and mevalonate biosynthesis, and finally facilitated the formation of astaxanthin. ROS analysis suggested that the antioxidant mechanism in X. dendrorhous can be induced by 6‐BAP. Additionally, the process of 6‐BAP significantly upregulated the expression of six key genes involved in pathways related to astaxanthin biosynthesis. This research demonstrates the metabolomic mechanism of phytohormone stimulation of astaxanthin production iNn X. dendrorhous and presents a new strategy to improve astaxanthin production to prevent the dilemma of choosing between accumulation of astaxanthin and cell biomass.

Development of a fourth-order compact finite difference scheme for simulation of simulated-moving-bed process

A fourth-order compact finite difference scheme was developed to solve the model equation of simulated moving bed, which has a boundary condition that is updated along the calculation process and cannot be described as an explicit function of time. Two different methods, direct method and pseudo grid point method, were proposed to deal with the boundary condition. The high accuracy of the two methods was confirmed by a case study of solving an advection-diffusion equation with exact solution. The developed compact finite difference scheme was then used to simulate the SMB processes for glucose-fructose separation and enantioseparation of 1,1′-bi-2-naphtol. It was found that the simulated results fit well with the experimental data. Furthermore, the developed method was further combined with the continuous prediction method to shorten the computational time and the results showed that, the computational time can be saved about 45%.

Role of miR-214-5p in the migration and invasion of pancreatic cancer cells

OBJECTIVE

To analyze the role of miR-214-5p in proliferation and metastasis of pancreatic cancer (PC) cells, as well as its underlying mechanism.

PATIENTS AND METHODS

30 pairs of PC tissues and adjacent normal tissues were collected in our Department. The expression level of miR-214-5p was detected by quantitative Real-time-polymerase chain reaction (qRT-PCR). Biological information analysis and luciferase report gene assay were used to verify potential target genes of miR-214-5p. Cell counting kit-8 (CCK-8) and transwell methods were applied to observe the interference of miR-214-5p on invasion and migration of PC cells. Western blot (WB) assay was applied to determine the expression changes of Jagged 1 (JAG1) and epithelial-mesenchymal transition (EMT)-related genes in PC cells.

RESULTS

QRT-PCR results showed that the expression level of miR-214-5p is significantly down-regulated in PC tissues and cells. Bioinformatics software and luciferase report gene assay identified that JAG1 is a target gene of miR-214-5p. The negative correlation between protein expressions of miR-214-5p and JAG1 was assessed by Western Blot assay. Furthermore, miR-214-5p could suppress cell proliferation, invasion and migration, and it also blocked the EMT in PC cells in vitro. Meanwhile, JAG1 overexpression reversed the inhibitory effects of miR-214-5p on proliferation, invasion and migration of PC cells.

CONCLUSIONS

Overexpressing miR-214-5p could significantly inhibit malignant behavior of PC cells through targeted regulation of JAG1. Thus, miR-214-5p might be a potential therapeutic target for treatment of PC.

Low expression of microRNA-1266 promotes colorectal cancer progression via targeting FTO

OBJECTIVE

To explore the role of microRNA-1266 in colorectal cancer (CRC) and its underlying mechanism.

PATIENTS AND METHODS

The expression level of microRNA-1266 in 48 CRC tissues and paracancerous tissues was detected by quantitative Real-time-polymerase chain reaction (qRT-PCR). The relationship between microRNA-1266 expression and basic characteristics of CRC patients was analyzed. The effect of microRNA-1266 on the viability of CRC cells was detected by cell counting kit-8 (CCK-8) assay. Subsequently, a potential target gene for microRNA-1266 was predicted through bioinformatics. Finally, the binding condition between microRNA-1266 and the target gene was verified by RNA binding protein immunoprecipitation (RIP) and luciferase reporter gene assay, respectively.

RESULTS

MicroRNA-1266 was lowly expressed in 48 cases of CRC tissues than that of paracancerous tissues. Clinical data demonstrated that microRNA-1266 expression was correlated to tumor size and TNM of CRC patients. Knockdown of microRNA-1266 promoted proliferation of CRC cells. FTO was predicted to be the target gene for microRNA-1266, which was negatively regulated by microRNA-1266.

CONCLUSIONS

MicroRNA-1266 is lowly expressed in CRC tissues than that of paracancerous tissues. Lowly expressed microRNA-1266 promotes the occurrence and progression of CRC by directly targeting FTO.

The role of fluconazole in the regulation of fatty acid and unsaponifiable matter biosynthesis in Schizochytrium sp. MYA 1381

Background

Schizochytrium has been widely used in industry for synthesizing polyunsaturated fatty acids (PUFAs), especially docosahexaenoic acid (DHA). However, unclear biosynthesis pathway of PUFAs inhibits further production of the Schizochytrium. Unsaponifiable matter (UM) from mevalonate pathway is crucial to cell growth and intracellular metabolism in all higher eukaryotes and microalgae. Therefore, regulation of UM biosynthesis in Schizochytrium may have important effects on fatty acids synthesis. Moreover, it is well known that UMs, such as squalene and β-carotene, are of great commercial value. Thus, regulating UM biosynthesis may also allow for an increased valuation of Schizochytrium.

Results

To investigate the correlation of UM biosynthesis with fatty acids accumulation in Schizochytrium, fluconazole was used to block the sterols pathway. The addition of 60 mg/L fluconazole at 48 h increased the total lipids (TLs) at 96 h by 16% without affecting cell growth, which was accompanied by remarkable changes in UMs and NADPH. Cholesterol content was reduced by 8%, and the squalene content improved by 45% at 72 h, which demonstrated fluconazole’s role in inhibiting squalene flow to cholesterol. As another typical UM with antioxidant capacity, the β-carotene production was increased by 53% at 96 h. The increase of squalene and β-carotene could boost intracellular oxidation resistance to protect fatty acids from oxidation. The NADPH was found to be 33% higher than that of the control at 96 h, which meant that the cells had more reducing power for fatty acid synthesis. Metabolic analysis further confirmed that regulation of sterols was closely related to glucose absorption, pigment biosynthesis and fatty acid production in Schizochytrium.

Conclusion

This work first reported the effect of UM biosynthesis on fatty acid accumulation in Schizochytrium. The UM was found to affect fatty acid biosynthesis by changing cell membrane function, intracellular antioxidation and reducing power. We believe that this work provides valuable insights in improving PUFA and other valuable matters in microalgae.

Changes to the tropomyosin structure alter the angiotensin-converting enzyme inhibitory activity and texture profiles of eel balls under high hydrostatic pressure

Changes in the structure of tropomyosin (TM) altered the texture profiles of eel balls and the inhibitory activity of the angiotensin-converting enzyme (ACE). The secondary and tertiary structure of TM was determined after high hydrostatic pressure (HHP) treatment. The correlation between the spatial structure of TM and the texture profiles of eel balls was developed and discussed. The β-sheet was converted to a β-turn and a random coil when treated at HHP (200-400 MPa), meanwhile the α-helix unfolded and was converted into a β-sheet, β-turn and a random coil with treatment at 500 and 600 MPa. The surface hydrophobicity (H0) was increased and the sulfhydryl (SH) content decreased with an increase in the pressure. The results indicated that the texture profiles of eel balls showed a negative relationship with the α-helix, β-sheet and SH content. The texture profiles of eel balls were greatly enhanced after treatment at 500 and 600 MPa, leading to the improved surface network of the eel ball products. The ACE inhibitory activity of TM after HHP treatment exhibited a positive relationship with the β-sheet content in the protein. The ACE inhibitory activity was preserved under 600 MPa.

Experimental determination of the dispersion of ions from a point source in the environment

The dispersion of ions from a point source has been extensively modelled but there have been very few attempts to experimentally verify the theoretical findings. The main reason for this has been the difficulty of discriminating between cluster ion and charged particle concentrations in the air. In this paper, we describe a novel technique for the experimental determination of the dispersion of ions from a point source in air. Laboratory experiments showed that the lifetime of cluster ions in an aerosol cloud was of the order of minutes. However, once they attached to aerosols, the particles retained the charge for at least 30 min, suggesting that they may be carried long distances in natural winds. A negative air ionizer was used to produce ions and charged particles in an open field in the presence of a steady horizontal wind. A neutral cluster and air ion spectrometer was used to measure cluster ion and charged particle concentrations as a function of downwind distance from the source. The results are broadly consistent with the Gaussian dispersion model for a continuous point source. We estimate that cluster ions can be carried up to a distance of several hundred metres before they fully attach to particles which can then be carried as far as 3-4 km. Therefore, these observations have important bearing on exposure to cluster ions and charged particles downwind of ion sources such as high voltage power lines and busy roads.

Screening chemical modulators of benzoic acid derivatives to improve lipid accumulation in Schizochytrium limacinum SR21 with metabolomics analysis

BACKGROUND

Schizochytrium sp. is a marine fungus with great potential as an alternative commercial source of lipids rich in polyunsaturated fatty acids (PUFAs). To further increase lipid accumulation in Schizochytrium sp., the effect of exogenous additives has become one of the hotspots of current research. Although benzoic acid derivatives showed positive effects on lipid accumulation in Schizochytrium, the biochemical mechanism needs further investigation.

RESULTS

Four benzoic acid derivatives (sodium benzoate, p-aminobenzoic acid, p-methyl benzoic acid and folic acid) were screened and evaluated for their effect on lipid accumulation in Schizochytrium limacinum SR21. The lipid yield was increased by 56.84% with p-aminobenzoic acid (p-ABA) at a concentration of 200 mg/L among the four tested chemical modulators. The metabolomics analysis showed that 200 mg/L p-ABA was optimal for promoting glucose catabolism in glycolysis with an increase in the mevalonate pathway and a weakening of the tricarboxylic acid (TCA) cycle. Moreover, p-ABA increased NADPH generation by enhancing the pentose phosphate pathway (PPP), ultimately redirecting the metabolic flux to lipid synthesis. Fed-batch fermentation further proved that p-ABA could significantly increase the yield of lipid by 30.01%, reaching 99.67 g/L, and the lipid content was increased by 35.03%, reaching 71.12%. More importantly, the yields of docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) were increased by 33.28% and 42.0%, respectively.

CONCLUSION

The addition of p-ABA could promote the synthesis of tetrahydrofolate, enhancing NADPH, which ultimately promoted the flow of carbon flux to lipid synthesis. These findings provide a valuable strategy for improving the lipid accumulation in Schizochytrium by additives.

Functions of PKS Genes in Lipid Synthesis of Schizochytrium sp. by Gene Disruption and Metabolomics Analysis

Schizochytrium sp. is a kind of marine microalgae with great potential as promising sustainable source of polyunsaturated fatty acids (PUFAs). Polyketide synthase-like (PKS synthase) is supposed to be one of the main ways to synthesize PUFAs in Schizochytrium sp. In order to study the exact relationship between PKS and PUFA biosynthesis, chain length factor (CLF) and dehydrogenase (DH) were cloned from the PKS gene cluster in Schizochytrium sp., then disrupted by homologous recombination. The results showed that DH- and CLF-disrupted strains had significant decreases (65.85 and 84.24%) in PUFA yield, while the saturated fatty acid (SFA) proportion in lipids was slightly increased. Meanwhile, the disruption of CLF decreased the C-22 PUFA proportion by 57.51% without effect on C-20 PUFA accumulation while DH-disrupted mutant decreased the production of each PUFA. Combined with analysis of protein prediction, it indicated that CLF gene exerted an enormous function on the carbon chain elongation in PUFA synthesis, especially for the final elongation from C-20 to C-22 PUFAs. Metabolomics analysis also suggested that the disruption of both genes resulted in the decrease of PUFAs but increase of SFAs, thus weakening glycolysis and tricarboxylic acid (TCA) cycle pathways. This study offers a broad new vision to research the mechanism of PUFA synthesis in Schizochytrium sp.

Using a trait-based approach to optimize mixotrophic growth of the red microalga Porphyridium purpureum towards fatty acid production

BACKGROUND

Organic carbon sources have been reported to simultaneously increase the growth and lipid accumulation in microalgae. However, there have been no studies of the mixotrophic growth of Porphyridium purpureum in organic carbon media. In this study, three organic carbon sources, glucose, sodium acetate, and glycerol were used as substrates for the mixotrophic growth of P. purpureum. Moreover, a novel trait-based approach combined with Generalized Additive Modeling was conducted to determine the dosage of each organic carbon source that optimized the concentration of cell biomass or fatty acid.

RESULTS

A 0.50% (w/v) dosage of glucose was optimum for the enhancement of the cell growth of P. purpureum, whereas sodium acetate performed well in enhancing cell growth, arachidonic acid (ARA) and eicosapentaenoic acid (EPA) content, and glycerol was characterized by its best performance in promoting both cell growth and ARA/EPA ratio. The optimum dosages of sodium acetate and glycerol for the ARA concentration were 0.25% (w/v) and 0.38% (v/v), respectively. An ARA concentration of 211.47 mg L-1 was obtained at the optimum dosage of glycerol, which is the highest ever reported.

CONCLUSIONS

The results suggested that a comprehensive consider of several traits offers an effective strategy to select an optimum dosage for economic and safe microalgae cultivation. This study represents the first attempt of mixotrophic growth of P. purpureum and proved that both biomass and ARA accumulation could be enhanced under supplements of organic carbon sources, which brightens the commercial cultivation of microalgae for ARA production.

Expression and clinical significance of long-non-coding RNA GHET1 in pancreatic cancer

OBJECTIVE

To investigate the expression level and biological function of long non-coding RNA gastric carcinoma high expressed transcript 1 (lncRNA-GHET1) in pancreatic ductal adenocarcinoma (pancreatic cancer for short), to analyze the correlation between the expression of GHET1 and clinicopathological features and to explore the role and clinical significance of GHET1 in the development and progression of pancreatic cancer.

PATIENTS AND METHODS

The relative expression of GHET1 in 5 human pancreatic cancer cell lines was detected by quantitative Real-time polymerase chain reaction (qRT-PCR). The specific interference sequence of GHET1 was designed and transiently transfected into pancreatic cancer cells. qRT-PCR assay was used to detect the interference efficiency. Cell counting kit-8 (CCK-8) assay was used to detect the effect of the interference with GHET1 on the proliferation of pancreatic cancer cells. Flow cytometry was used to detect the effect of the interference with GHET1 on the cycle distribution and apoptosis. qRT-PCR was used to detect the relative expression of GHET1 in pancreatic cancer tissues compared with that in cancer-adjacent tissues. The correlation between the expression of GHET1 and the pathological features of pancreatic cancer patients was analyzed.

RESULTS

The expression of GHET1 in human pancreatic cancer cells was relatively high. The results of CCK-8 showed that the proliferation of tumor cells was inhibited after the interference with GHET1 expression. The results of flow cytometry showed that the expression of GHET1 was blocked at G1/G0 phase, and the apoptosis rate was increased. The results of qRT-PCR showed that the expression of GHET1 was upregulated in pancreatic cancer tissues of 49 out of 64 patients compared with that in cancer-adjacent tissues, and the highly expressed GHET1 was positively correlated with the tumor, node and metastasis (TNM) staging of pancreatic cancer.

CONCLUSIONS

Highly expressed GHET1 promotes the proliferation of pancreatic cancer, inhibits apoptosis and is related to TNM staging. The expression of GHET1 can be used as a potential molecular marker for the prognosis and therapeutic target of pancreatic cancer.

Overexpression of Malonyl-CoA: ACP Transacylase in Schizochytrium sp. to Improve Polyunsaturated Fatty Acid Production

Polyunsaturated fatty acids (PUFAs) have been widely applied in the food and medical industry. In this study, malonyl-CoA: ACP transacylase (MAT) was overexpressed through homologous recombination to improve PUFA production in Schizochytrium. The results showed that the lipid and PUFA concentration were increased by 10.1 and 24.5% with MAT overexpression, respectively. Metabolomics analysis revealed that the intracellular tricarboxylic acid cycle was weakened and glucose absorption was accelerated in the engineered strain. In the mevalonate pathway, intracellular carotene content was decreased, and the carbon flux was then redirected toward PUFA synthesis. Furthermore, a glucose fed-batch fermentation was finally performed with the engineered Schizochytrium. The total lipid yield was further increased to 110.5 g/L, 39.6% higher than the wild strain. Docosahexaenoic acid and eicosapentaenoic acid yield were enhanced to 47.39 g/L and 1.65 g/L with an increase of 81.5 and 172.5%, respectively. This study provided an effective metabolic engineering strategy for industrial PUFA production.

Enhancement of cell growth and phycocyanin production in Arthrospira (Spirulina) platensis by metabolic stress and nitrate fed-batch

Arthrospira (Spirulina) platensis is known to have high-quality proteins content and phycocyanin as one of the major pigment constituents of the cells, and the most challenging problem associated with phycocyanin production in Arthrospira is to optimize its intracellular accumulation. The present study evaluated the metabolic stress conditions (by nutrient enrichment) of Arthrospira platensis FACHB-314 for boosting biomass growth and high content phycocyanin accumulation. Experimental results showed that 5 mM sodium glutamate and 7.5 mM succinic acid could enhance biomass yield as well as phycocyanin accumulation compared with that of the control groups. The present study demonstrates that the biomass growth and phycocyanin accumulation were significantly enhanced in fed-batch cultivation of Arthrospira platensis by applying the substrates as metabolic stress agents combined with nitrate feeding strategy. cobA/hemD, hemG and ho genes presented the over-expression level with adding sodium glutamate and succinic acid in cultures, respectively, compared to the control groups.

Scale-up cultivation enhanced arachidonic acid accumulation by red microalgae Porphyridium purpureum

The present study attempts to cultivate Porphyridium purpureum under different scale-up conditions for further development and commercialization of microalgae-derived PUFAs such as ARA and EPA. Different temperatures (25, 30, and 35 °C) and light intensities (70, 165, and 280 μmol/m²s) were applied to the 50 L pilot-scale cultivation of P. purpureum in ASW. The cultivation under the light intensity of 280 μmol/m²s at 35 °C obtained biomass concentration up to 9.52 g/L, total fatty acid content to 56.82 mg/g, and ARA content to 22.29 mg/g. While the maximum EPA content of 7.00 mg/g was achieved under the light intensity of 280 μmol/m²s at 25 °C and the highest ratio of UFAs to TFAs of 74.66% was also obtained in this trial. Both biomass concentration and TFAs content were improved by increasing light intensity and temperature. Moreover, the ratio of ARA to EPA was enhanced by increasing cultivation temperature under the light intensity of 280 μmol/m²s. In contrast with flask culture, the conversion of linoleic acid (C18:2) to ARA was enhanced in scale-up culture, leading to more ARA content. Phosphate limitation enhanced the synthesis of lipid and LPUFAs. Moreover, the biomass concentration and biosynthesis of palmitic acid were preferred by sufficient C (NaHCO₃).

[Recombinant human tumor necrosis factor receptor type Ⅱ-IgG Fc fusion protein for treatment of occupational medicamentosa-like dermatitis induced by trichloroethylene]

Objective: To investigate the efficacy and safety of the recombinant human tumor necrosis factor receptor Ⅱ-IgG Fc fusion protein (rhTNFR: Fc, etanercept) for the treatment of occupational medicamentosa-like dermatitis induced by trichloroethylene (OMLDT) . Methods: In September 2011 to February 2016, 12 patients with OMLDT were treated with etanercept 25 mg, subcutaneous injection, twice per week, doubling of first dose. The course of treatment was 6 weeks. The drug eruption area and severity index (DASI) score, the proportion of patients achieving a 50%, 75% and 90% reduction in DASI (DASI50, DASI75, DASI90) and the serum level of TNF-α were used to assess the efficacy at different times. Adverse reactions were also recorded and evaluated. The results were statistically analyzed by nonparametric Friedman test and repetitive measurement ANOVA using the software SPSS19.0. Results: After 4 weeks treatment, the DASI score decreased form 56.33±7.02 to 0.50±0.91 (P<0.01) . The DASI50, DASI75 and DASI90 were all increased to 12 (100%) . The serum level of TNF-α decreased form (43.74±41.62) pg/ml to (3.03±0.47) pg/ml (P<0.01) . Statistically significant difference was observed from the above indexes. There were no adverse reactions in clinical application. Conclusion: Recombinant human tumor necrosis factor receptor Ⅱ-IgG Fc fusion protein may be a safe and effective drug in the treatment of OMLDT.

Biocatalytic synthesis of vitamin A palmitate using immobilized lipase produced by recombinant Pichia pastoris

In this work, the Candida antarctica lipase B (CALB), produced by recombinant Pichia pastoris, was immobilized and used to synthesize vitamin A palmitate by transesterification of vitamin A acetate and palmitic acid in organic solvent. The reaction conditions including the type of solvent, temperature, rotation speed, particle size, and molar ratio between the two substrates were investigated. It turned out that the macroporous resin HPD826 serving as a carrier showed the highest activity (ca. 9200 U g^-1) among all the screened carriers. It was found that the transesterification kinetic of the immobilized CALB followed the ping pong Bi-Bi mechanism and the reaction product acetic acid inhibited the enzymatic reaction with an inhibition factor of 2.823 mmol L^-1. The conversion ability of the immobilized CALB was 54.3% after 15 cycles. In conclusion, the present work provides a green route for vitamin A palmitate production using immobilized CALB to catalyze the transesterification of vitamin A acetate and palmitic acid.

Raman spectroscopy of transition metal dichalcogenides

Raman spectroscopy of transition metal dichalcogenides (TMDs) is reviewed based on our recent theoretical and experimental works. First, we discuss the semi-classical and quantum mechanical description for the polarization dependence of Raman spectra of TMDs in which the optical dipole transition matrix elements as a function of laser excitation energy are important for understanding the polarization dependence of the Raman intensity and Raman tensor. Overviewing the symmetry of TMDs, we discuss the dependence of the Raman spectra of TMDs on layer thickness, polarization, laser energy and the structural phase. Furthermore, we discuss the Raman spectra of twisted bilayer and heterostructures of TMDs. Finally, we give our perspectives on the Raman spectroscopy of TMDs.

Determining the need for rescue intracytoplasmic sperm injection in partial fertilisation failure during a conventional IVF cycle

To explore the need for rescue intracytoplasmic sperm injection (ICSI) in cases of partial fertilisation failure during a conventional in vitro fertilisation cycle, rescue ICSI was performed for cycles with a fertilisation rate of <50%. The data were divided into three groups based on the fertilisation rate: group 1 (0%), group 2 (<25%) and group 3 (>25%). The impact of rescue ICSI on each group was then analysed in terms of ovum fertilisation, embryo development, embryo utilisation and selection of embryos for transfer. Rescue ICSI was performed on 1831 unfertilised oocytes from 313 cycles. The fertilisation rates for group 1, group 2 and group 3 were 74.66, 68.35 and 65.46%, and the rate of polyploidy in the three groups was 8.55, 11.33, and 14.47%. The percentage of embryos that can be transferred from rescue ICSI for group 2 was 38.33%, and this value was higher than those of the other two groups. It is concluded that rescue ICSI is not recommended for patients with an IVF rate of >25% as the procedure is associated with a greater risk and low returns. However, it is feasible to perform rescue ICSI for patients with IVF rates of <25%.

Targeting RING domains of Mdm2-MdmX E3 complex activates apoptotic arm of the p53 pathway in leukemia/lymphoma cells

Reactivation of tumor-suppressor p53 for targeted cancer therapy is an attractive strategy for cancers bearing wild-type (WT) p53. Targeting the Mdm2–p53 interface or MdmX ((MDM4), mouse double minute 4)–p53 interface or both has been a focus in the field. However, targeting the E3 ligase activity of Mdm2–MdmX really interesting new gene (RING)–RING interaction as a novel anticancer strategy has never been explored. In this report, we describe the identification and characterization of small molecule inhibitors targeting Mdm2–MdmX RING–RING interaction as a new class of E3 ligase inhibitors. With a fluorescence resonance energy transfer-based E3 activity assay in high-throughput screening of a chemical library, we identified inhibitors (designated as MMRis (Mdm2–MdmX RING domain inhibitors)) that specifically inhibit Mdm2–MdmX E3 ligase activity toward Mdm2 and p53 substrates. MMRi6 and its analog MMRi64 are capable of disrupting Mdm2–MdmX interactions in vitro and activating p53 in cells. In leukemia cells, MMRi64 potently induces downregulation of Mdm2 and MdmX. In contrast to Nutlin3a, MMRi64 only induces the expression of pro-apoptotic gene PUMA (p53 upregulated modulator of apoptosis) with minimal induction of growth-arresting gene p21. Consequently, MMRi64 selectively induces the apoptotic arm of the p53 pathway in leukemia/lymphoma cells. Owing to the distinct mechanisms of action of MMRi64 and Nutlin3a, their combination synergistically induces p53 and apoptosis. Taken together, this study reveals that Mdm2–MdmX has a critical role in apoptotic response of the p53 pathway and MMRi64 may serve as a new pharmacological tool for p53 studies and a platform for cancer drug development.

Comparison of charged nanoparticle concentrations near busy roads and overhead high-voltage power lines

Overhead high-voltage power lines are known sources of corona ions. These ions rapidly attach to aerosols to form charged particles in the environment. Although the effect of ions and charged particles on human health is largely unknown, much attention has focused on the increasing exposure as a result of the expanding power network in urban residential areas. However, it is not widely known that a large number of charged particles in urban environments originate from motor vehicle emissions. In this study, for the first time, we compare the concentrations of charged nanoparticles near busy roads and overhead power lines. We show that large concentrations of both positive and negative charged nanoparticles are present near busy roadways and that these concentrations commonly exceed those under high-voltage power lines. We estimate that the concentration of charged nanoparticles found near two freeways carrying around 120 vehicles per minute exceeded the corresponding maximum concentrations under two corona-emitting overhead power lines by as much as a factor of 5. The difference was most pronounced when a significant fraction of traffic consisted of heavy-duty diesel vehicles which typically have high particle and charge emission rates.

Impact of carbon and nitrogen feeding strategy on high production of biomass and docosahexaenoic acid (DHA) by Schizochytrium sp. LU310

A new isolated Schizochytrium sp. LU310 from the mangrove forest of Wenzhou, China, was found as a high producing microalga of docosahexaenoic acid (DHA). In this study, the significant improvements for DHA fermentation by the batch mode in the baffled flasks (i.e. higher oxygen supply) were achieved. By applied the nitrogen-feeding strategy in 1000 mL baffled flasks, the biomass, DHA concentration and DHA productivity were increased by 110.4%, 117.9% and 110.4%, respectively. Moreover, DHA concentration of 21.06 g/L was obtained by feeding 15 g/L of glucose intermittently, which was an increase of 41.25% over that of the batch mode. Finally, an innovative strategy was carried out by intermittent feeding carbon and simultaneously feeding nitrogen. The maximum DHA concentration and DHA productivity in the fed-batch cultivation reached to 24.74 g/L and 241.5 mg/L/h, respectively.

Trion-induced negative photoconductivity in monolayer MoS2

Optical excitation typically enhances electrical conduction and low-frequency radiation absorption in semiconductors. We, however, observe a pronounced transient decrease of conductivity in doped monolayer molybdenum disulfide (MoS(2)), a two-dimensional (2D) semiconductor, using ultrafast optical-pump terahertz-probe spectroscopy. In particular, the conductivity is reduced to only 30% of its equilibrium value at high pump fluence. This anomalous phenomenon arises from the strong many-body interactions in the 2D system, where photoexcited electron-hole pairs join the doping-induced charges to form trions, bound states of two electrons and one hole. The resultant increase of the carrier effective mass substantially diminishes the conductivity.

A review of phytotherapy of gout: perspective of new pharmacological treatments

The purpose of this review article is to outline plants currently used and those with high promise for the development of anti-gout products. All relevant literature databases were searched up to 25 March 2013. The search terms were 'gout', 'gouty arthritis', 'hyperuricemia', 'uric acid', 'xanthine oxidase (XO) inhibitor', 'uricosuric', 'urate transporter 1(URAT1)' and 'glucose transporter 9 (GLUT9)'. Herbal keywords included 'herbal medicine', 'medicinal plant', 'natural products', 'phytomedicine' and 'phytotherapy'. 'antiinflammatory effect' combined with the words 'interleukin-6 (IL-6)', 'interleukin-8 (IL-8)', 'interleukin-1beta (IL-1beta)', and 'tumor necrosis factor alpha (TNF-alpha)'. XO inhibitory effect, uricosuric action, and anti-inflammatory effects were the key outcomes. Numerous agents derived from plants have anti-gout potential. In in vitro studies, flavonoids, alkaloids, essential oils, phenolic compounds, tannins, iridoid glucosides, and coumarins show the potential of anti-gout effects by their XO inhibitory action, while lignans, triterpenoids and xanthophyll are acting through their anti-inflammatory effects. In animal studies, essential oils, lignans, and tannins show dual effects including reduction of uric acid generation and uricosuric action. Alkaloids reveal inhibit uric acid generation, show anti-inflammatory effects, or a combination of the two. Phenolic compounds and flavonoids inhibit uric acid production, show uricosuric anti-inflammatory effects. In the rare human studies, colchicine from Colchicum autumnale showed anti-inflammatory effects while for other plant extracts, although revealing anti-gout potential, further phytochemical investigations are needed to identify their active constituents. Besides, the plants which give antioxidant activities are much potent in the management of gout and need to be further investigated. The current review is a detailed discussion of the potential of medicinal plants for treatment of gout.