Tailored biosynthesis of plant-derived ginsenoside Rh2 in yeast via repurposing a key promiscuous microbial enzyme

With the development of synthetic biology, substantial progress has been made in the low-cost production of plant natural products in microbes. Ginsenoside Rh2 is a potential anticancer drug isolated from medicinal plant ginseng. Fermentative production of ginsenoside Rh2 in yeast has recently been investigated as an alternative strategy compared to extraction from plants. However, the titer was quite low due to low catalytic capability of the key ginseng glycosyltransferase in microorganisms. Please click on the link below for full content

Measuring compactness of the urban landscape within a city territory for environmental capabilities: the case of 50 cities in eastern China

[EN] When a compact city is pursued as the strategy for urban sustainability the understanding of compactness is varied from the developed countries to the developing countries. In China the historical cities are characterized with high density and mixed land use. After a short time of motorization they still show compact forms in the central city. A large amount of newly developed areas are distributed in clusters near or far from the center. The crop land and natural habitat are encroached to different degrees. This paper developed an approach to measure the structural compactness of urban landscape patches within a city territory. It included six spatial metrics to measure the shape and density of the central agglomeration, the area configuration and distant relationship between the central agglomeration and the other clusters, and the distribution of all urban patches. By this approach the 50 cities in eastern China were categorized into five classes of forms: one center, multi-centers, centralized groups, cluster groups and scatter. Then the vegetation biomass loss with urban expansion was calculated based on remote sensing data, and used to assess the environmental capability of the five types of urban form. The suggestions of urban form optimization could be put forward for the five categories of cities.Shuang, CS.; Tong, Z.; Guangyu, L.; Yue, Y. (2018). Measuring compactness of the urban landscape within a city territory for environmental capabilities: the case of 50 cities in eastern China. En 24th ISUF International Conference. Book of Papers. Editorial Universitat Politècnica de València. 13-20. https://doi.org/10.4995/ISUF2017.2017.5094OCS132

Directed evolution of glycosyltransferase for the artificial biosynthesis of natural product glycosides

Over one fifth natural product drugs (including protein biopharmaceuticals), cosmetics, and nutraceuticals have a diverse set of sugars in their structures. These glycosylations dramatically influence the physicochemical and pharmacological properties of these compounds. Glycosyltransferases (GTs) offer very attractive approaches to the biosynthesis of complex glycosylated natural products. However, the limited number of available GTs, together with their instability and strict substrate specificity, have severely hampered the broad application of these enzymes. In the past few years, we have used directed evolution as a tool to tailor the GTs with desired substrate specificity and higher catalytic activity. Here I will introduce some of our efforts in 1) the semi-rational design of a glucosyltransferase UGT51 from S. cerevisiae to repurposing its promiscuous activity towards the biosynthesis of rare ginsenoside Rh2; and 2) the directed evolution of an α1,3-fucosyltransferase using a single-cell ultrahigh-throughput screening method. I will also discuss the development of new tools for the high-throughput screening method for GTs and the mechanistic insight we found during the evolution of these enzymes

Three-dimensional echo-shifted EPI with simultaneous blip-up and blip-down acquisitions for correcting geometric distortion

Purpose: Echo-planar imaging (EPI) with blip-up/down acquisition (BUDA) can provide high-quality images with minimal distortions by using two readout trains with opposing phase-encoding gradients. Because of the need for two separate acquisitions, BUDA doubles the scan time and degrades the temporal resolution when compared to single-shot EPI, presenting a major challenge for many applications, particularly functional MRI (fMRI). This study aims at overcoming this challenge by developing an echo-shifted EPI BUDA (esEPI-BUDA) technique to acquire both blip-up and blip-down datasets in a single shot. Methods: A three-dimensional (3D) esEPI-BUDA pulse sequence was designed by using an echo-shifting strategy to produce two EPI readout trains. These readout trains produced a pair of k-space datasets whose k-space trajectories were interleaved with opposite phase-encoding gradient directions. The two k-space datasets were separately reconstructed using a 3D SENSE algorithm, from which time-resolved B0-field maps were derived using TOPUP in FSL and then input into a forward model of joint parallel imaging reconstruction to correct for geometric distortion. In addition, Hankel structured low-rank constraint was incorporated into the reconstruction framework to improve image quality by mitigating the phase errors between the two interleaved k-space datasets. Results: The 3D esEPI-BUDA technique was demonstrated in a phantom and an fMRI study on healthy human subjects. Geometric distortions were effectively corrected in both phantom and human brain images. In the fMRI study, the visual activation volumes and their BOLD responses were comparable to those from conventional 3D echo-planar images. Conclusion: The improved imaging efficiency and dynamic distortion correction capability afforded by 3D esEPI-BUDA are expected to benefit many EPI applications.Comment: 8 figures, peer-reviewed journal pape

Robust image analysis with sparse representation on quantized visual features

10.1109/TIP.2012.2219543IEEE Transactions on Image Processing223860-871IIPR

Age-related sensitivity and pathological differences in infections by 2009 pandemic influenza A (H1N1) virus

<p>Abstract</p> <p>Background</p> <p>The highly pandemic 2009 influenza A H1N1 virus infection showed distinguished skewed age distribution with majority of infection and death in children and young adults. Although previous exposure to related antigen has been proposed as an explanation, the mechanism of age protection is still unknown.</p> <p>Methods</p> <p>In this study, murine model of different ages were inoculated intranasally with H1N1 (A/Beijing/501/09) virus and the susceptibility and pathological response to 2009 H1N1 infection were investigated.</p> <p>Results</p> <p>Our results showed that the younger mice had higher mortality rate when infected with the same dose of virus and the lethal dose increased with age. Immunohistochemical staining of H1N1 antigens in mice lung indicated infection was in the lower respiratory tract. Most bronchial and bronchiolar epithelial cells in 4-week mice were infected while only a minor percentage of those cells in 6-month and 1-year old mice did. The young mice developed much more severe lung lesions and had higher virus load in lung than the two older groups of mice while older mice formed more inducible bronchus-associated lymphoid tissue in their lungs and more severe damage in spleen.</p> <p>Conclusions</p> <p>These results suggest that young individuals are more sensitive to H1N1 infection and have less protective immune responses than older adults. The age factor should be considered when studying the pathogenesis and transmission of influenza virus and formulating strategies on vaccination and treatment.</p