Complete pathway elucidation and heterologous reconstitution of (+)-nootkatone biosynthesis from Alpinia oxyphylla

(+)-Nootkatone is a natural sesquiterpene ketone widely used in food, cosmetics, pharmaceuticals, and agriculture. It is also regarded as one of the most valuable terpenes used commercially. However, plants contain trace amounts of (+)-nootkatone, and extraction from plants is insufficient to meet market demand. Alpinia oxyphylla is a well-known medicinal plant in China, and (+)-nootkatone is one of the main components within the fruits. By transcriptome mining and functional screening using a precursor-providing yeast chassis, the complete (+)-nootkatone biosynthetic pathway in Alpinia oxyphylla was identified. A (+)-valencene synthase (AoVS) was identified as a novel monocot-derived valencene synthase; three (+)-valencene oxidases AoCYP6 (CYP71BB2), AoCYP9 (CYP71CX8), and AoCYP18 (CYP701A170) were identified by constructing a valencene-providing yeast strain. With further characterisation of a cytochrome P450 reductase (AoCPR1) and three dehydrogenases (AoSDR1/2/3), we successfully reconstructed the (+)-nootkatone biosynthetic pathway in Saccharomyces cerevisiae, representing a basis for its biotechnological production. Identifying the biosynthetic pathway of (+)-nootkatone in A. oxyphylla unravelled the molecular mechanism underlying its formation in planta and also supported the bioengineering production of (+)-nootkatone. The highly efficient yeast chassis screening method could be used to elucidate the complete biosynthetic pathway of other valuable plant natural products in future.

[Expression profile of circular RNA in inflammatory response in human bronchial epithelial cells induced by carbon black nanoparticles]

Objective: To explore the toxic effect of carbon black nanoparticles on human bronchial epithelial cells, and identify the differentially expressed circular RNA based on the full transcriptome high-throughput sequencing, so as to provide evidence for the development of biomarkers exposed to carbon black nanoparticles and their application on epigenetic toxicology. Methods: In June 2020, 16 HBE cells were treated with carbon black nanoparticles at concentrations of 20, 40 and 80 μg/ml, and 16 HBE cells without any intervention were used as the control group. The cytotoxicity of carbon black nanoparticles was detected by CCK8 and LDH experiments. Real-time quantitative fluorescent PCR (qRT-PCR) and ELISA were used to detect the changes of interleukin-6 (IL-6) and interleukin-8 (IL-6, IL-8) mRNA and protein levels of carbon black nanoparticles with concentration gradient after 72 h exposure. Western blot analysis was conducted to detect the expression levels of toll-like receptor 4 (TLR4), phosphorylated nuclear factor-κB (P-NF-κB), apoptosis-related speckled protein (ASC) and Caspase-1 associated with nuclear factor-κB. According to high-throughput sequencing results, differentially expressed Circrnas were screened and identified by qRT-PCR, and those with stable differentially expressed circrnas and the strongest association with the NF-κB pathway were selected for ring performance identification. Results: After being exposed to carbon black nanoparticles for 72 h, the activity of 16HBE cells decreased significantly (P<0.05), and the release of lactate dehydrogenase increased significantly (P<0.05). Compared with control group, mRNA expression levels of IL-6 and IL-8, protein levels of IL-6 and IL-8 were increased, and protein levels of TLR4, p-NF-κB, ASC and Caspase-1 were significantly up-regulated in 16 HBE cells of different concentrations, with statistical significance (P<0.05). Compared with the control group, a total of 492 differentially expressed circular Rnas (|log2 FC|>1) were detected. Among the 5 differentially expressed (P<0.05) circular Rnas, circ_002642 was selected as the object of subsequent research on circular Rnas, affter 72 hours of exposure to 80 μg/ml CBNPs, 16HBE cells showed signlficantly higher expression of circ_002642 (P<0.05) . Conclusion: Carbon black nanoparticles can induce differentially expressed circular RNAs associated with inflammatory response in human bronchial epithelial cells.

Revolution of vitamin E production by starting from microbial fermented farnesene to isophytol

Vitamin E is one of the most widely used vitamins. In the classical commercial synthesis of vitamin E (α-tocopherol), the chemical synthesis of isophytol is the key technical barrier. Here, we establish a new process for isophytol synthesis from microbial fermented farnesene. To achieve an efficient pathway for farnesene production, Saccharomyces cerevisiae was selected as the host strain. First, β-farnesene synthase genes from different sources were screened, and through protein engineering and system metabolic engineering, a high production of β-farnesene in S. cerevisiae was achieved (55.4 g/L). This farnesene can be chemically converted into isophytol in three steps with approximately 92% yield, which is economically equal to that from the best total chemical synthesis. Furthermore, we co-produced lycopene and farnesene to reduce the cost of farnesene. A factory based on this new process was successfully operated in Hubei Province, China, in 2017, with an annual output of 30,000 tons of vitamin E. This new process has completely changed the vitamin E market due to its low cost and safety.

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The traditional chemical synthesis of vitamin E is complex and could be explosive

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An innovative way to synthesize isophytol from biofermented farnesene is established

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This process is safer and cheaper, changing the production and marketing of vitamin E

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Co-production of β-farnesene and lycopene improves the competitiveness of this process

Systematic identification of Ocimum sanctum sesquiterpenoid synthases and (-)-eremophilene overproduction in engineered yeast

Plant-derived natural active products have attracted increasing attention for use in flavors and perfumes. These compounds also have applications in insect pest control because of their environment-friendly properties. Holy basil (Ocimum sanctum), a famous herb used in Ayurveda in India, is a natural source of medical healing agents and insecticidal repellents. Despite the available genomic sequences and genome-wide bioinformatic analysis of terpene synthase genes, the functionality of the sesquiterpene genes involved in the unique fragrance and insecticidal activities of Holy basil are largely unknown. In this study, we systematically screened the sesquiterpenoid biosynthesis genes in this plant using a precursor-providing yeast system. The enzymes that synthesize β-caryophyllene and its close isomer α-humulene were successfully identified. The enzymatic product of OsaTPS07 was characterized by in vivo mining, in vitro reaction, and NMR detection. This product was revealed as (-)-eremophilene. We created a mutant yeast strain that can achieve a high-yield titer by adjusting the gene copy number and FPP precursor enhancement. An optimized two-stage fed-batch fermentation method achieved high biosynthetic capacity, with a titer of 34.6 g/L cyclic sesquiterpene bioproduction in a 15-L bioreactor. Further insect-repelling assays demonstrated that (-)-eremophilene repelled the insect pest, fall leafworm, suggesting the potential of (-)-eremophilene as an alternative to synthetic chemicals for agricultural pest control. This study highlights the potential of our microbial platform for the bulk mining of plant-derived ingredients and provides an impressive cornerstone for their industrial utilization.

Parathyroid hormone independently predicts fracture, vascular events, and death in patients with stage 3 and 4 chronic kidney disease

Doctors do not know whether treatment of high parathyroid hormone levels is linked to better outcomes in their patients with kidney disease. In this study, lower parathyroid hormone levels at baseline were linked to lower risk of fracture, vascular events, and death in people with kidney disease.

PURPOSE

Chronic kidney disease (CKD) affects ~ 20% of older adults, and secondary hyperparathyroidism (HPT) is a common condition in these patients. To what degree HPT predicts fractures, vascular events, and mortality in pre-dialysis CKD patients is debated. In stage 3 and 4 CKD patients, we assessed relationships between baseline serum PTH levels and subsequent 10-year probabilities of clinical fractures, vascular events, and death.

METHODS

We used Marshfield Clinic Health System electronic health records to analyze data from adult CKD patients receiving care between 1985 and 2013, and whose PTH was measured using a second-generation assay. Covariates included PTH, age, gender, tobacco use, vascular disease, diabetes, hypertension, hyperlipidemia, obesity, GFR, and use of osteoporosis medications.

RESULTS

Five thousand one hundred eight subjects had a mean age of 68 ± 17 years, 48% were men, and mean follow-up was 23 ± 10 years. Fractures, vascular events, and death occurred in 18%, 71%, and 56% of the cohort, respectively. In univariate and multivariate models, PTH was an independent predictor of fracture, vascular events, and death. The hazards of fracture, vascular events and death were minimized at a baseline PTH of 0, 69, and 58 pg/mL, respectively.

CONCLUSIONS

We found that among individuals with stage 3 and 4 CKD, PTH was an independent predictor of fractures, vascular events, and death. Additional epidemiologic studies are needed to confirm these findings. If a target PTH range can be confirmed, then randomized placebo-controlled trials will be needed to confirm that treating HPT reduces the risk of fracture, vascular events, and death.

[Prevalence and risk factors of nonalcoholic fatty liver disease in patients with chronic hepatitis B receiving antiviral therapy]

Objective: To investigate the prevalence and risk factors of non-alcoholic fatty liver disease(NAFLD) in patients with chronic hepatitis B(CHB) receiving antiviral treatment. Methods: The cross-sectional study included 3 477 cases with CHB who received antiviral therapy. The prevalence of NAFLD was investigated, and then the risk factors were screened and analyzed by stepwise regression method in CHB patients with NAFLD as the dependent variable and the related influencing factors as independent variables. Results: The prevalence of NAFLD was 24.1% in CHB patients who received antiviral therapy. After adjusting for age and gender, central obesity (OR: 7.44, 95%CI: 6.06 ~ 9.14), hypertension (OR: 1.74, 95%CI: 1.51 ~ 2.20), and triglyceride (OR: 1.52, 95%CI: 1.18 ~ 1.96) were positively associated with NAFLD, and cirrhosis was negatively associated with NAFLD (OR: 0.42, 95%CI: 0.34 ~ 0.53). Patients with long-term antiviral therapy had increased risk of NAFLD. Conclusion: A significant proportion of CHB patients receiving antiviral therapy have suffered from NAFLD. Therefore, CHB patients receiving long-term antiviral treatment should pay more attention to the prevalence of NAFLD.

Enhanced upper tropical tropospheric COS: impact on the stratospheric aerosol layer

Carbonyl sulfide (COS) is considered to be a major source of the stratospheric sulfate aerosol during periods of volcanic quiescence. We measured COS at the tropical tropopause and find mixing ratios to be 20 to 50% larger than are assumed in models. The enhanced COS levels are correlated with high concentrations of biomass-burning pollutants like carbon monoxide (CO) and hydrogen cyanide (HCN). The analysis of backward trajectories and global maps of fire statistics suggest that biomass-burning emissions transported upward by deep convection are the source of the enhanced COS in the upper tropical troposphere.

Screening for CRX gene mutations in Chinese patients with Leber congenital amaurosis and mutational phenotype

PURPOSE

To screen for possible disease-causing mutations in the CRX gene in Chinese patients with Leber congenital amaurosis (LCA) and to enrich the understanding of its mutational phenotype.

METHODS

Genomic DNA was collected from 27 patients with LCA. The coding sequences of the CRX gene were analyzed using the PCR-heteroduplex-SSCP method. Mutations were confirmed by DNA sequencing.

RESULTS

We identified two heterozygous variations in the CRX gene in two patients with LCA. One was a deletion (GCC-->-CC, A181D1bp) leading to a frameshift and protein truncation. This mutation was present in a patient with LCA, but not in his healthy parents. The ocular manifestations of this A181Delta1bp mutation are described. An intronic variation (IVS1-13G-->C) was found in a patient with LCA as well as in his healthy father.

CONCLUSION

A heterozygous A181D1bp mutation in the CRX gene caused an LCA phenotype in a Chinese patient.

[Cloning the differentially expressed genes in the retina of rds mouse during the development of retinitis pigmentosa]

OBJECTIVE

To clone the differentially expressed genes in the retina of rds mouse (the animal model of congenital retinitis pigmentosa) during the disease development.

METHODS

The retinal mRNA of rds mouse during the development of retinitis pigmentosa was analyzed by the mRNA differential display. The differentially expressed mRNA fragments were cloned and sequenced.

RESULTS

There was obvious difference of gene expression between rds mouse and the control during the development of retinitis pigmentosa. Five differentially expressed bands were cloned and sequenced. One of those had 86% identity (132/154) with the sequence of the human cDNA DKFZp434D1227 from adult testis in GenBank, which was submitted lately (15-Oct-1999) and without much information. The other had lower identity with the sequences in GenBank. A highly expressed clone in the rds mouse on postnatal day 25 had the same length as another clone in the normal on postnatal day 37, which was not expressed in the rds mouse on day 37. The sequences of the two clones were identical in all but two base pairs.

CONCLUSION

These results indicate that there are a lot of novel differentially expressed genes in the chronic processing diseases, such as retinitis pigmentosa.

[Changes in blood constitutive equation parameters during shock in rabbits]

Based on the method which can more precisely obtain the constitutive parameters, we studied the changes of hemorphelogical characteristics of rabbits during shock and the effect of MN9200, a king of calcium channel anatogist injected into the veins of the rabbits. The results showed that shock induced a significant change in hemorheological index and NM9202 improved the condition.

[Finite element analysis of human tibia in vitro]

This investigation was aimed at the fatigue fracture of tibia that often occurs in soldiers, as well as in dancers and athletes. The data of ground reaction force(GRF) of soldiers were measured using a force platform in three common gaits: marching, parading and running. The stress distribution in tibia under these GRFs were analyzed with a FE model. The results showed that the smallest GRF(744.8N) is in quick marching, the next (1156.4N) in parading and the largest (1391.6N) in running. The stress distribution under GRF was mot uniform in the tibia. The maximum stresses occurred at a site 1/3 tibia length below the knee where tibia fracture is often seen clinically. The maximum stresses were 110 MPa and 115 MPa in parading and running respectively. This means that the tibial tractures in soldiers are mostly associated with stress, i.e. the greater the stress is, the higher the incidence of stress fracture comes about.