Optimization of isoprene production using a metabolically engineered Escherichia Coli

The volatile C5 hydrocarbon, isoprene is an important platform chemical, which has been used in the manufacture of synthetic rubber for tires and also has the potential for various other applications such as elastomers and adhesives. Moreover, isoprene is convertible to biofuel blend stocks such as C10 gasoline, C15 diesel, and jet fuels because of its higher energy content than other biofuels. Although isoprene is currently derived from petroleum, its sustainable supply has been suffered from price fluctuation of crude oil, high refining cost and energy consumption, and low recovery yield of pure isoprene. As an alternative, the biologically produced isoprene (bio-isoprene) has been developed rapidly for the last decade. Bio-isoprene is synthesized from dimethylallyl diphosphate (DMAPP), which is derived from mevalonate (MVA) pathway or the methylerythritol phosphate (MEP) pathway, by isoprene synthase. In this study, metabolic engineering for enhanced production of bio-isoprene was performed by deletion of relevant genes and optimization of culture condition. In comparison of isoprene production between E.coli DH5α and MG1655, lower isoprene production was observed in MG1655. The lower isoprene production in E. coli MG1655 was ascribed to the presence of recA gene which is absent in the DH5α strain. The deletion of recA gene in E.coli MG1655 allows higher isoprene production than E. coli DH5α. Moreover, the optimized expression of isoprene synthesis pathway with 0.03mM IPTG induction enhanced the isoprene production up to 2,850 mg/L. Overall, isoprene production through the optimization was improved by 28.5-fold compared to the initial production of MG1655 strain. Please click Additional Files below to see the full abstract

MetaMix: Meta-state Precision Searcher for Mixed-precision Activation Quantization

Mixed-precision quantization of efficient networks often suffer from activation instability encountered in the exploration of bit selections. To address this problem, we propose a novel method called MetaMix which consists of bit selection and weight training phases. The bit selection phase iterates two steps, (1) the mixed-precision-aware weight update, and (2) the bit-search training with the fixed mixed-precision-aware weights, both of which combined reduce activation instability in mixed-precision quantization and contribute to fast and high-quality bit selection. The weight training phase exploits the weights and step sizes trained in the bit selection phase and fine-tunes them thereby offering fast training. Our experiments with efficient and hard-to-quantize networks, i.e., MobileNet v2 and v3, and ResNet-18 on ImageNet show that our proposed method pushes the boundary of mixed-precision quantization, in terms of accuracy vs. operations, by outperforming both mixed- and single-precision SOTA methods

The first Irish genome and ways of improving sequence accuracy

Whole-genome sequencing of an Irish person reveals hundreds of thousands of novel genomic variants. Imputation using previous known information improves the accuracy of low-read-depth sequencing

A case of primary psoas abscess presenting as buttock abscess

Buttock abscess is a rare clinical manifestation from unusual extrapelvic extension of psoas abscess. A 48-year-old woman presented with painful swelling of the buttock with a sense of local heat. Magnetic resonance imaging revealed a large subfascial abscess over the glutei muscles and was traced into the intraabdominal cavity over the iliac wing to the psoas muscle. Both the psoas abscess and the buttock abscess were evacuated via separate approaches. Empirical antibiotic therapy was delivered for 3 weeks. After 6 months, no evidence of recurrence was found. Psoas abscess could be included in the differential diagnosis of buttock abscess

Sex-specific Association Between Asthma and Hypertension in Nationally Representative Young Korean Adults

It has been reported that people with asthma have an increased risk of hypertension. However, little is known about the specific relationship between asthma and hypertension in young adults. Among subjects who participated in the Korea National Health and Nutrition Examination Survey conducted in 2008-2013, a total of 10,138 young adults (4,226 men and 5,912 women) aged 19-39 years were analyzed. Multiple logistic regression analysis was used to estimate adjusted odds ratios (ORs) and 95% confidence intervals (CIs). The prevalence of ever asthma was 11.1% in men and 8.4% in women. The mean diastolic blood pressure (DBP) was lower in men with asthma than in men without asthma (p = 0.03), whereas the mean DBP was higher in women with asthma than in women without asthma (p = 0.04). Having asthma was inversely associated with hypertension in men (OR: 0.62, 95% CI: 0.41-0.91). In contrast, having asthma was positively associated with hypertension in women (OR: 2.19, 95% CI: 1.19-4.02). Our results suggest that asthma pathophysiology might be differentially associated with hypertension in young adults depending on sex

New microbial ecosystem created by artificak floating island

To scrutinize the microbial ecosystem and processing of water quality improvement under the artificial floating island, water quality parameteres, bacterial numbers and extracellular enzyme activities were measured biweekly flom 3, November 2001 to 20,April 2002 in Lake Paldang, Korea. Most of the mean encironmental parameters were not different from artificially floating island (AFI) site and control site. But,zooplankton numbers were about 100 times higher at AFI site than those of control site, even though the chlorophyll α concentrations were not so different. During winter, the rations of respiratory active bacteria to total bacterial number were two fold higher and enzyme activities of β-glucosidase and phosphatase were extremely higher at AFI site than those of contrl site. With these high densities of zooplankton, active bacteria and high rates of degradation under the AFI, the organic materials are eliminated at inside of lake with newly created ecosystem.Article信州大学山地水環境教育研究センター研究報告 2: 5-9(2004)departmental bulletin pape