The Conversion of UDP-Glc to UDP-Man: In Silico and Biochemical Exploration To Improve the Catalytic Efficiency of CDP-Tyvelose C2-Epimerases

A promiscuous CDP-tyvelose 2-epimerase (TyvE) from Thermodesulfatator atlanticus (TaTyvE) belonging to the nucleotide sugar active short-chain dehydrogenase/reductase superfamily (NS-SDRs) was recently discovered. TaTyvE performs the slow conversion of NDP-glucose (NDP-Glc) to NDP-mannose (NDP-Man). Here, we present the sequence fingerprints that are indicative of the conversion of UDP-Glc to UDP-Man in TyvE-like enzymes based on the heptagonal box motifs. Our data-mining approach led to the identification of 11 additional TyvE-like enzymes for the conversion of UDP-Glc to UDP-Man. We characterized the top two wild-type candidates, which show a 15- and 20-fold improved catalytic efficiency, respectively, on UDP-Glc compared to TaTyvE. In addition, we present a quadruple variant of one of the identified enzymes with a 70-fold improved catalytic efficiency on UDP-Glc compared to TaTyvE. These findings could help the design of new nucleotide production pathways starting from a cheap sugar substrate like glucose or sucrose.     

Eigenschaften von Gießfilmen aus nativen und chemisch modifizierten Stärken

Properties of Casting Films from Native and Chemically Modified Starches. Starch acetates and hexanoates were prepared from potato, wrinkled pea, and amylomaize starch of low and high degrees of substitution (DS=0.1-2.8). These products were used as raw materials for film casting in a laboratory scale. The objective of this work was to study the influence of starch types and derivatisations on film properties, i.e. tensile strength and elongation as well as water absorption and solubility. After the addition of softeners transparent, flexible, and water soluble films were obtained from unsubstituted and partially substituted starches, while totally substituted starch derivatives (triacetates and hexanoates) resulted in films insoluble in water. The well-known amylose advantage of film casting was found only after derivatisation. In the case of wrinkled pea and amylomaize starch considerable improvements of mechanical film properties, both tensile strength and elongation, were achieved even at low degrees of substitution.     

Sea transport of bananas in containers – Parameter identification for a temperature model

Losses of product quality during the sea transport of bananas in containers are related to the emergence of hot spots. In order to analyze critical conditions, a spatial temperature profile was recorded ashore in a container loaded with banana pallets. The identification of a structured system model showed that it is possible to reduce the information on the measured temperature curves to a set of only two index values. These can be interpreted as factors for coupling to the air stream and for the amount of heat generated by biological processes per banana box. The width of gaps between pallets was identified as the major influence on the spatial temperature profile. Boxes from which the unwanted banana ripening heat cannot be channeled away by the cooling unit can be detected by the quotient of the index values.     

Diffusion Analysis of NAnoscopic Ensembles: A Tracking-Free Diffusivity Analysis for NAnoscopic Ensembles in Biological Samples and Nanotechnology (Small 16/2023)

The rapid development of microscopic techniques over the past decades enables the establishment of single molecule fluorescence imaging as a powerful tool in biological and biomedical sciences. Single molecule fluorescence imaging allows to study the chemical, physicochemical, and biological properties of target molecules or particles by tracking their molecular position in the biological environment and determining their dynamic behavior. However, the precise determination of particle distribution and diffusivities is often challenging due to high molecule/particle densities, fast diffusion, and photobleaching/blinking of the fluorophore. A novel, accurate, and fast statistical analysis tool, Diffusion Analysis of NAnoscopic Ensembles (DANAE), that solves all these obstacles is introduced. DANAE requires no approximations or any a priori input regarding unknown system-inherent parameters, such as background distributions; a requirement that is vitally important when studying the behavior of molecules/particles in living cells. The superiority of DANAE with various data from simulations is demonstrated. As experimental applications of DANAE, membrane receptor diffusion in its natural membrane environment, and cargo mobility/distribution within nanostructured lipid nanoparticles are presented. Finally, the method is extended to two-color channel fluorescence microscopy.     

A Tensor-based Regression Approach for Human Motion Prediction

Collaborative robotic systems will be a key enabling technology for current and future industrial applications. The main aspect of such applications is to guarantee safety for humans. To detect hazardous situations, current commercially available robotic systems rely on direct physical contact to the co-working person. To further advance this technology, there are multiple efforts to develop predictive capabilities for such systems. Using motion tracking sensors and pose estimation systems combined with adequate predictive models, potential episodes of hazardous collisions between humans and robots can be predicted. Based on the provided predictive information, the robotic system can avoid physical contact by adjusting speed or position. A potential approach for such systems is to perform human motion prediction with machine learning methods like artificial neural networks (NNs). In our approach, the motion patterns of past seconds are used to predict future ones by applying a linear Tensor-on-Tensor Regression model, selected according to a similarity measure between motion sequences obtained by dynamic time warping (DTW). For test and validation of our proposed approach, industrial pseudo assembly tasks were recorded with a motion capture system, providing unique traceable Cartesian coordinates $(x,y,z)$ for each human joint. The prediction of repetitive human motions associated with assembly tasks, whose data vary significantly in length and have highly correlated variables, has been achieved in real time.     

Improving In Vitro Detection of Sensitization to Lipid Transfer Proteins: A New Molecular Multiplex IgE Assay

Scope

LTP-syndrome is characterized by sensitization (IgE) to multiple non-specific lipid transfer proteins (nsLTPs) with a variable clinical outcome. The treatment is primarily based on offending food avoidance. However, the determination of Pru p 3-specific IgE is currently the main diagnostic tool to assess sensitization to nsLTPs. Herein, the study evaluates improvement of LTP-syndrome diagnosis and clinical management using a new IgE multiplex-immunoblot assay with a high diversity of food nsLTPs.

Methods and results

An EUROLINE-LTP strip with 28 recombinant nsLTPs from 18 allergenic sources is designed. In total the study investigates 38 patients with LTP-syndrome and compares results from the nsLTPs (LTP-strip) with the respective food extracts of Prick-by-prick (PbP) testing. The agreement exceeds 70% for most nsLTPs, e.g., Pru p 3 (100%), Mal d 3 (97%), Pru av 3 (89%), Pha v 3 isoforms (87%/84%), Ara h 9 (82%), Cor a 8 (82%), and Jug r 3 (82%). The functionality and allergenic relevance of nine recombinant nsLTPs are proven by Basophil activation testing (BAT).

Conclusions

The new IgE multiplex-immunoblot nsLTP assay shows a good diagnostic performance allowing culprit food assessment. Negative results from LTP-strip may indicate potentially tolerable foods, improving diet intervention and patients’ quality of life.     

Conversion of a polysilazane-modified cellulose-based paper into a C/SiFe(N,C)O ceramic paper via thermal ammonolysis

Cellulose-based paper samples were surface-modified by a polymeric single-source precursor prepared from perhydropolysilazane (PHPS) and iron(III)acetylacetonate (Fe(acac)₃) and ammonolyzed at 500°C, 700°C, 900°C, and 1000°C, leading to C/SiFe(N,C)O-based ceramic papers with in situ-generated hierarchical micro/nano-morphology. As reference, cellulose-free samples were prepared under the same conditions. Upon thermal treatment, the microstructure evolutions of the resulting ceramic paper and the reference sample were comparatively investigated. Scanning electron microscopy (SEM) showed that for all temperatures, the ceramic papers exhibit the same morphology as the template, however, with noticeable shrinkage and curling, particularly evident at higher temperatures. X-ray diffraction (XRD) measurements of the reference samples and the ceramic papers showed a similar crystallization behavior and phase evolution in both materials. In the ceramic paper, the crystallization process seems to occur at a later time. The results provide a comprehensive understanding of the investigated C/SiFe(N,C)O-based ceramic system. It was shown that use of the cellulose-based paper template has the benefit of retaining the microstructure and furthermore, apart from transforming the cellulose fibers into turbostratic carbon, does not change the phase evolution during the polymer-to-ceramic transformation, allowing at the same time the manufacturing of novel morphologically complex parts by a convenient one-pot synthesis approach.     

X-Ray Tomoscopy Reveals the Dynamics of Ice Templating

Little experimentally explored and understood are the complex dynamics of microstructure formation by ice-templating when aqueous solutions or slurries are directionally solidified (freeze cast) into cellular solids. With synchrotron-based, time-resolved X-ray tomoscopy it is possible to study in situ under well-defined conditions the anisotropic, partially faceted growth of ice crystals in aqueous systems. Obtaining one full tomogram per second for ≈270 s with a spatial resolution of 6 µm, it is possible to capture with minimal X-ray absorption, the freezing front in a 3% weight/volume (w/v) sucrose-in-water solution, which typically progresses at 5–30 µm s⁻¹ for applied cooling rates of $\dot{C}$ = 1–10 °C min⁻¹. These time and length scales render X-ray tomoscopy ideally suited to quantify in 3D ice crystal growth and templating phenomena that determine the performance-defining hierarchical architecture of freeze-cast materials: a complex pore morphology and “ridges”, “jellyfish cap”, and “tentacle”-like secondary features, which decorate the cell walls.     

Formation and Etching of the Insulating Sr-Rich V5+ Phase at the Metallic SrVO3 Surface Revealed by Operando XAS Spectroscopy Characterizations

In the search of low cost and more efficient electronic devices, here the properties of SrVO₃ transparent conductor oxide (TCO) thin film are investigated, both visible-range optically transparent and highly conductive, it stands as a promising candidate to substitute the standard indium-tin-oxide (ITO) in applications. Its surface stability under water (both liquid and vapor) and other gaseous atmospheres is especially addressed. Through the use of spectroscopy characterizations, X-ray photoemission and operando X-ray absorption measurements, the formation of a thin Sr-rich V⁵⁺ layer located at the surface of the polycrystalline SrVO₃ film with aging is observed, and for the first time how it can be removed from the surface by solvating in water atmosphere. The surface recovery is associated to an etching process, here spectroscopically characterized in operando conditions, allowing to follow the stoichiometric modification under reaction. Once exposed in oxygen atmosphere, the Sr-rich V⁵⁺ layer forms again. The findings improve the understanding of aging effects in perovskite oxides, allowing for the development of functionalized films in which it is possible to control or to avoid an insulating surface layer. This constitutes an important step towards the large-scale use of V-based TCOs, with possible implementations in oxide-based electronics.