Engineering yeast mitochondrial metabolism for 3-hydroxypropionate production.

BACKGROUND: With unique physiochemical environments in subcellular organelles, there has been growing interest in harnessing yeast organelles for bioproduct synthesis. Among these organelles, the yeast mitochondrion has been found to be an attractive compartment for production of terpenoids and branched-chain alcohols, which could be credited to the abundant supply of acetyl-CoA, ATP and cofactors. In this study we explored the mitochondrial potential for production of 3-hydroxypropionate (3-HP) and performed the cofactor engineering and flux control at the acetyl-CoA node to maximize 3-HP synthesis. RESULTS: Metabolic modeling suggested that the mitochondrion serves as a more suitable compartment for 3-HP synthesis via the malonyl-CoA pathway than the cytosol, due to the opportunity to obtain a higher maximum yield and a lower oxygen consumption. With the malonyl-CoA reductase (MCR) targeted into the mitochondria, the 3-HP production increased to 0.27 g/L compared with 0.09 g/L with MCR expressed in the cytosol. With enhanced expression of dissected MCR enzymes, the titer reached to 4.42 g/L, comparable to the highest titer achieved in the cytosol so far. Then, the mitochondrial NADPH supply was optimized by overexpressing POS5 and IDP1, which resulted in an increase in the 3-HP titer to 5.11 g/L. Furthermore, with induced expression of an ACC1 mutant in the mitochondria, the final 3-HP production reached 6.16 g/L in shake flask fermentations. The constructed strain was then evaluated in fed-batch fermentations, and produced 71.09 g/L 3-HP with a productivity of 0.71 g/L/h and a yield on glucose of 0.23 g/g. CONCLUSIONS: In this study, the yeast mitochondrion is reported as an attractive compartment for 3-HP production. The final 3-HP titer of 71.09 g/L with a productivity of 0.71 g/L/h was achieved in fed-batch fermentations, representing the highest titer reported for Saccharomyces cerevisiae so far, that demonstrated the potential of recruiting the yeast mitochondria for further development of cell factories.

Human expansion into Asian highlands in the 21st Century and its effects.

Most intensive human activities occur in lowlands. However, sporadic reports indicate that human activities are expanding in some Asian highlands. Here we investigate the expansions of human activities in highlands and their effects over Asia from 2000 to 2020 by combining earth observation data and socioeconomic data. We find that ∼23% of human activity expansions occur in Asian highlands and ∼76% of these expansions in highlands comes from ecological lands, reaching 95% in Southeast Asia. The expansions of human activities in highlands intensify habitat fragmentation and result in large ecological costs in low and lower-middle income countries, and they also support Asian developments. We estimate that cultivated land net growth in the Asian highlands contributed approximately 54% in preventing the net loss of the total cultivated land. Moreover, the growth of highland artificial surfaces may provide living and working spaces for ∼40 million people. Our findings suggest that highland developments hold dual effects and provide new insight for regional sustainable developments.

Rewiring regulation on respiro-fermentative metabolism relieved Crabtree effects in Saccharomyces cerevisiae.

The respiro-fermentative metabolism in the yeast Saccharomyces cerevisiae, also called the Crabtree effect, results in lower energy efficiency and biomass yield which can impact yields of chemicals to be produced using this cell factory. Although it can be engineered to become Crabtree negative, the slow growth and glucose consumption rate limit its industrial application. Here the Crabtree effect in yeast can be alleviated by engineering the transcription factor Mth1 involved in glucose signaling and a subunit of the RNA polymerase II mediator complex Med2. It was found that the mutant with the MTH1 A81D&MED2*432Y allele could grow in glucose rich medium with a specific growth rate of 0.30 h-1, an ethanol yield of 0.10 g g-1, and a biomass yield of 0.21 g g-1, compared with a specific growth rate of 0.40 h-1, an ethanol yield of 0.46 g g-1, and a biomass yield of 0.11 g g-1 in the wild-type strain CEN.PK 113-5D. Transcriptome analysis revealed significant downregulation of the glycolytic process, as well as the upregulation of the TCA cycle and the electron transfer chain. Significant expression changes of several reporter transcription factors were also identified, which might explain the higher energy efficiencies in the engineered strain. We further demonstrated the potential of the engineered strain with the production of 3-hydroxypropionic acid at a titer of 2.04 g L-1, i.e., 5.4-fold higher than that of a reference strain, indicating that the alleviated glucose repression could enhance the supply of mitochondrial acetyl-CoA. These results suggested that the engineered strain could be used as an efficient cell factory for mitochondrial production of acetyl-CoA derived chemicals.

Share Rose, Get Fun: The Influence of Donation on Happiness.

There is little literature on the impact of donation on individual wellbeing in China. This study examines individual donations in China to answer the question of whether helping others makes us happier and to provide policy implications for in Chinese context. Based on the 2012 Chinese General Social Survey (CGSS) data and using ordered logit and OLS as benchmark models, this study finds that donation can significantly increase individual happiness. After using propensity score matching (PSM) to eliminate the possible impact of self-selection, the above conclusion remains robust. After a sub-sample discussion, it is found that this effect is more pronounced under completely voluntary donation behavior, and is not affected by economic factors, indicating that the happiness effect of donation does not vary significantly depending on the individual's economic status. This study contributes to the literature on donation behavior by examining the impact of donation behavior on donors' subjective happiness in China, and further identifies subjective happiness differences, as between voluntary and involuntary donations, thereby providing theoretical and empirical support for the formulation of policies for the development of donation institutions in China.

MicroRNA 452 regulates GTF2E1 expression in colorectal cancer cells.

MicroRNAs play important roles in the pathogenesis of human diseases by regulating target gene expression in specific cells or tissues. Previously, we identified microRNA 452 (MIR452), which was specifically upregulated in early stage of human colorectal cancer (CRC) tissues. Here, we show the biological role of MIR452 and general transcription factor IIE subunit 1 (GTF2E1) in colorectal cancer. A luciferase reporter system was used to confirm the effect of MIR452 on GTF2E1 expression. The expression levels of MIR452 and the target genes were evaluated by quantitative RT-PCR (qRT-PCR) and western blotting. We verified the association between MIR452 and the GTF2E1 expression and found that GTF2E1 transcripts were directly downregulated by MIR452. The mRNA and protein levels of GTF2E1 were also downregulated in CRC cells upon transfection with MIR452. GTF2E1 protein expression was decreased in CRC tissues compared to adjacent nontumour tissues. These results suggest that MIR452 might directly or indirectly regulate the genes transcription related to CRC by downregulating GTF2E1 expression.

Using Internet Search Queries to Assess Public Awareness of the Healthy Cities Approach: A Case Study in Shenzhen, China.

Cities around the globe are embracing the Healthy Cities approach to address urban health challenges. Public awareness is vital for successfully deploying this approach but is rarely assessed. In this study, we used internet search queries to evaluate the public awareness of the Healthy Cities approach applied in Shenzhen, China. The overall situation at the city level and the intercity variations were both analyzed. Additionally, we explored the factors that might affect the internet search queries of the Healthy Cities approach. Our results showed that the public awareness of the approach in Shenzhen was low. There was a high intercity heterogeneity in terms of interest in the various components of the Healthy Cities approach. However, we did not find a significant effect of the selected demographic, environmental, and health factors on the search queries. Based on our findings, we recommend that the city raise public awareness of healthy cities and take actions tailored to health concerns in different city zones. Our study showed that internet search queries can be a valuable data source for assessing the public awareness of the Healthy Cities approach.

Expressing a cytosolic pyruvate dehydrogenase complex to increase free fatty acid production in Saccharomyces cerevisiae.

BACKGROUND: Saccharomyces cerevisiae is being exploited as a cell factory to produce fatty acids and their derivatives as biofuels. Previous studies found that both precursor supply and fatty acid metabolism deregulation are essential for enhanced fatty acid synthesis. A bacterial pyruvate dehydrogenase (PDH) complex expressed in the yeast cytosol was reported to enable production of cytosolic acetyl-CoA with lower energy cost and no toxic intermediate. RESULTS: Overexpression of the PDH complex significantly increased cell growth, ethanol consumption and reduced glycerol accumulation. Furthermore, to optimize the redox imbalance in production of fatty acids from glucose, two endogenous NAD+-dependent glycerol-3-phosphate dehydrogenases were deleted, and a heterologous NADP+-dependent glyceraldehyde-3-phosphate dehydrogenase was introduced. The best fatty acid producing strain PDH7 with engineering of precursor and co-factor metabolism could produce 840.5 mg/L free fatty acids (FFAs) in shake flask, which was 83.2% higher than the control strain YJZ08. Profile analysis of free fatty acid suggested the cytosolic PDH complex mainly resulted in the increases of unsaturated fatty acids (C16:1 and C18:1). CONCLUSIONS: We demonstrated that cytosolic PDH pathway enabled more efficient acetyl-CoA provision with the lower ATP cost, and improved FFA production. Together with engineering of the redox factor rebalance, the cytosolic PDH pathway could achieve high level of FFA production at similar levels of other best acetyl-CoA producing pathways.

Comparing the Use of Spatially Explicit Indicators and Conventional Indicators in the Evaluation of Healthy Cities: A Case Study in Shenzhen, China.

Various indicator systems have been developed to monitor and assess healthy cities. However, few of them contain spatially explicit indicators. In this study, we assessed four health determinants in Shenzhen, China, using both indicators commonly included in healthy city indicator systems and spatially explicit indicators. The spatially explicit indicators were developed using detailed building information or social media data. Our results showed that the evaluation results of districts and sub-districts in Shenzhen based on spatially explicit indicators could be positively, negatively, or not associated with the evaluation results based on conventional indicators. The discrepancy may be caused by the different information contained in the two types of indicators. The spatially explicit indicators measure the quantity of the determinants and the spatial accessibility of these determinants, while the conventional indicators only measure the quantity. Our results also showed that social media data have great potential to represent the high-resolution population distribution required to estimate spatially explicit indicators. Based on our findings, we recommend that spatially explicit indicators should be included in healthy city indicator systems to allow for a more comprehensive assessment of healthy cities.

Spatial Inequity of Multi-Level Healthcare Services in a Rapid Expanding Immigrant City of China: A Case Study of Shenzhen.

Since the onset of reform and opening up in China, large cities in the nation have been experiencing problems related to limited medical resources. These resource limitations are due to rapid population growth and urban expansion. As the country's fastest growing city, Shenzhen has experienced a substantial misalignment between the supply and the demand of healthcare services. Numerous researchers have analyzed spatial inequity in healthcare services by focusing on the spatial accessibility of medical facilities, such as hospitals, clinics, and community health service centers (CHSCs). However, the issue of inequity in healthcare services for vulnerable groups has largely been ignored. We chose general hospitals (GHs) and CHSCs, which provide direct healthcare services to residents, as the study objects. By performing spatial accessibility analysis using the gravity model and the two-step floating catchment area method, we investigated healthcare services inequity for vulnerable groups based on four dimensions: residential type, age, education level, and occupation. We found that the services provided by GHs cannot meet the demand in Shenzhen. This inadequacy is characterized by spatial centralization and neglect of those who reside in urban villages, who have low education levels, and who are employed in the manufacturing industry. In contrast, CHSCs generally serve a relatively broad population. This phenomenon is related to differences in the land and capital needs between GHs and CHSCs. Our study reveals that an appropriate adjustment of GH location could significantly improve healthcare services inequity. Therefore, to alleviate this inequity, it is particularly necessary to increase the number of GHs in the peripheral circle and in areas with large vulnerable populations, accelerate the implementation of the hierarchical medical system, and promote the transfer of medical resources to grassroot institutes through CHSCs. This study helps improve our understanding of healthcare services inequity in rapid expanding cities, which is of substantial significance for improving the planning and construction of medical facilities, facilitating scientific decision-making, and promoting social equity.

Construction of a three-dimensionaI finite eIement modeI of puIp-exposed maxiIIary premoIar with wedge-shaped defect restored by fiber post / 中国组织工程研究

BACKGROUND: To date, there is no report on the successful construction of a three-dimensional finite element model of maxillary premolar with wedge-shaped defect restored by fiber post.OBJECTIVE: To establish the three-dimensional finite element model of maxillary premolar with wedge-shaped defect restored by fiber post. METHODS: Micro-CT was used to obtain imaging information of the human maxillary first premolar sample. Then Mimics, Geomagic and Hypermesh were used to establish a clear-structured three-dimensional finite element model of pulp-exposed maxillary premolar with wedge-shaped defect restored by fiber post. RESULTS AND CONCLUSION: The three-dimensional finite element model of normal maxillary premolar had 180 119 units and 33 289 nodes. Compared with the real subject, the three-dimensional finite element model of maxillary premolar with wedge-shaped defect restored by fiber post had vivid appearance, good image quality and accurate grid partitioning with 237 496 units and 43 965 nodes in total, which could obtain good results in the aspects of geometry, boundary constraint and mechanical compatibility. Moreover, it could better simulate the mechanical stress distribution of diseased teeth under occlusion to further confirm the magnitude and distribution of forces, thereby providing a better basis for future biomechanical studies.

Anti-cariogenic Properties of α-Pinene, a Monoterpene in Plant Essential Oil

Dental caries is the most common chronic disease in the dental field. Streptococcus mutans (S. mutans) is the most important bacteria in the formation of dental plaque and dental caries. In a previous study, we confirmed that the essential oil of Chrysanthemum boreale has antibacterial activity against S. mutans. Alpha-pinene is one of the major chemical components of Chrysanthemum boreale essential oil. In the present study, we investigated the inhibitory effects of α-pinene on cariogenic properties such as growth, acid production, biofilm formation, and bactericidal activity on S. mutans. Alpha-pinene at a concentration range of 0.25-0.5 mg/mL significantly inhibited the growth of S. mutans and acid production of S. mutans. Biofilm formation was significantly inhibited at < 0.0625 mg/mL α-pinene, similar to the data from scanning electronic microscopy. Under confocal laser scanning microscopy, the bacterial viability was decreased by α-pinene in a dose-dependent manner. These results suggested that α-pinene may be a useful agent for inhibiting the cariogenic properties of S. mutans.

The complexity of bladder cancer: long noncoding RNAs are on the stage.

The mammalian genome encodes thousands of long noncoding RNAs (lncRNAs) and it is increasingly clear that lncRNAs are key regulators of cellular function and development. Gain and/or loss of function studies in cell culture indicate that lncRNAs can regulate gene transcription indirectly through the targeting and recruitment of chromatin-modifying complexes as well as directly at the transcriptional or posttranscriptional levels. LncRNA biology is attracting great attention in cancer research because dysregulated lncRNAs occur in a variety of cancers, placing lncRNAs on the stage of cancer genome research. We briefly describe the latest lncRNA biology and discuss the oncogenic lncRNAs involved in core pathways in bladder cancer and the application of lncRNAs to its diagnosis and targeted treatment. LncRNAs are becoming essential components of the gene regulatory circuitry in the complexity of bladder cancer.

Mesenchymal stem cells transplantation ameliorates glomerular injury in streptozotocin-induced diabetic nephropathy in rats via inhibiting macrophage infiltration.

Mesenchymal stem cells (MSCs) treatment has been shown to be effective in diabetic nephropathy (DN). However, the mechanisms involved in the renoprotective effects of MSCs have not been clearly demonstrated. Especially, there was no study on the relationship of MSCs and macrophages in diabetic kidney. To explore the effect of MSCs on macrophages in DN, streptozotocin-induced diabetes animals received no treatment or treatment with MSCs (2×10(6), via tail vein) for two continuous weeks. Eight weeks after treatment, physical, biochemical and morphological parameters were measured. Immunohistochemistry for fibronectin (FN), CollagenI, ED-1, monocyte chemoattractant protein-1 (MCP-1) was performed. Expressions of pro-inflammatory cytokines and hepatocyte growth factor (HGF) at gene level and protein level were determined by real-time reverse transcription-polymerase chain reaction and enzyme-linked immunosorbent assay, respectively. Blood glucose, urinary albumin excretion, creatinine clearance were significantly reduced after MSCs treatment. The glomerulosclerosis as revealed by periodic acid Schiff stain and expression of FN and CollagenI was also dramatically attenuated. Most importantly, the expression of MCP-1 and the number of infiltrated macrophages in kidney were effectively suppressed by MSCs treatment. The expression of HGF in MSCs group was up-regulated. Meanwhile, the expressions of IL-1ß, IL-6 and TNFα were significantly down-regulated by MSCs treatment. Our study suggest that MSCs treatment ameliorates DN via inhibition of MCP-1 expression by secreting HGF, thus reducing macrophages infiltration, down-regulating IL-1ß, IL-6, TNFα expression in renal tissue in diabetic rats.