Heterologous expression of a thermophilic diacylglycerol acyltransferase triggers triglyceride accumulation in Escherichia coli

Triglycerides (TAGs), the major storage molecules of metabolic energy and source of fatty acids, are produced as single cell oil by some oleogenic microorganisms. However, these microorganisms require strict culture conditions, show low carbon source flexibilities, lack efficient genetic modification tools and in some cases pose safety concerns. TAGs have essential applications such as behaving as a source for added-value fatty acids or giving rise to the production of biodiesel. Hence, new alternative methods are urgently required for obtaining these oils. In this work we describe TAG accumulation in the industrially appropriate microorganism Escherichia coli expressing the heterologous enzyme tDGAT, a wax ester synthase/triacylglycerol:acylCoA acyltranferase (WS/DGAT). With this purpose, we introduce a codon-optimized gene from the thermophilic actinomycete Thermomonospora curvata coding for a WS/DGAT into different E. coli strains, describe the metabolic effects associated to the expression of this protein and evaluate neutral lipid accumulation. We observe a direct relation between the expression of this WS/DGAT and TAG production within a wide range of culture conditions. More than 30% TAGs were detected within the bacterial neutral lipids in 90 minutes after induction. TAGs were observed to be associated with the hydrophobic enzyme while forming round intracytoplasmic bodies, which could represent a bottleneck for lipid accumulation in E. coli. We detected an increase of almost 3- fold in the monounsaturated fatty acids (MUFA) occurring in the recombinant strains. These MUFA were predominant in the accumulated TAGs achieving 46% of the TAG fatty acids. These results set the basis for further research on the achievement of a suitable method towards the sustainable production of these neutral lipids

Triglyceride Blisters in Lipid Bilayers: Implications for Lipid Droplet Biogenesis and the Mobile Lipid Signal in Cancer Cell Membranes

Triglycerides have a limited solubility, around 3%, in phosphatidylcholine lipid bilayers. Using millisecond-scale course grained molecular dynamics simulations, we show that the model lipid bilayer can accommodate a higher concentration of triolein (TO) than earlier anticipated, by sequestering triolein molecules to the bilayer center in the form of a disordered, isotropic, mobile neutral lipid aggregate, at least 17 nm in diameter, which forms spontaneously, and remains stable on at least the microsecond time scale. The results give credence to the hotly debated existence of mobile neutral lipid aggregates of unknown function present in malignant cells, and to the early biogenesis of lipid droplets accommodated between the two leaflets of the endoplasmic reticulum membrane. The TO aggregates give the bilayer a blister-like appearance, and will hinder the formation of multi-lamellar phases in model, and possibly living membranes. The blisters will result in anomalous membrane probe partitioning, which should be accounted for in the interpretation of probe-related measurements

Lipid droplets: a classic organelle with new outfits

Lipid droplets are depots of neutral lipids that exist virtually in any kind of cell. Recent studies have revealed that the lipid droplet is not a mere lipid blob, but a major contributor not only to lipid homeostasis but also to diverse cellular functions. Because of the unique structure as well as the functional importance in relation to obesity, steatosis, and other prevailing diseases, the lipid droplet is now reborn as a brand new organelle, attracting interests from researchers of many disciplines

Integration of fiber optical shape sensing with medical visualization for minimal-invasive interventions

We present a fiber optical shape sensing system that allows to track the shape of a standard telecom fiber with fiber Bragg grating. The shape sensing information is combined with a medical visualization platform to visualize the shape sensing information together with medical images and post-processing results like 3D models, vessel graphs, or segmentation results. The framework has a modular nature to use it for various medical applications like catheter or needle based interventions. The technology has potential in the medical area as it is MR-compatible and can easily be integrated in catheters and needles due to its small size

Oekobilanz fuer den Baustoff Kalksandstein und Kalksandstein-Wandkonstruktionen

Die Arbeit beschreibt Wandkonstruktionen, bei denen der Baustoff Kalksandstein Verwendung findet. Es wird eine Oekobilanz erstellt. Im Rahmen der Datenerfassung sind Kalksandsteinwerte in die Analyse einbezogen. (HW)The work describes wall constructions made using calcareous sandstone. An ecological balance is prepared. Data acquisition for the analysis includes eight calcareous sandstone works. (HW)SIGLEAvailable from TIB Hannover: RA 2242(82) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Bow-tie nano-antenna assisted generation of extreme ultraviolet radiation

Pfullmann N, Waltermann C, Noack M, et al. Bow-tie nano-antenna assisted generation of extreme ultraviolet radiation. New Journal Of Physics. 2013;15(9): 93027.We report on the generation of extreme ultraviolet radiation utilizing the plasmonic field enhancement in arrays of bow-tie gold optical antennae. Furthermore, their suitability to support high-order harmonic generation is examined by means of finite-difference time-domain calculations and experiments. Particular emphasis is paid to the thermal properties, which become significant at the employed peak intensities. A damage threshold depending on the antenna length is predicted and confirmed by our experimental findings. Moreover, the gas density in the vicinity of the antennae is characterized experimentally to determine the number of atoms contributing to the measured radiation, which is almost an order of magnitude larger than previously reported