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Quantitative detection of pseudouridine in RNA by mass spectrometry
(2024-11-11) Hermon, Shanice Jessica; Sennikova, Anastasia; Becker, Sidney
Pseudouridine (Ψ) is one of the most prevalent and dynamic modification in RNA, and was shown to evade the host immune response in mRNA vaccines. Despite its significance, the biological role of Ψ remains poorly understood as certain key limitations and challenges in the detection of Ψ are yet to be overcome. In account of this, we report the usage of a chemical labelling strategy for the first quantitative detection of Ψ by mass spectrometry. We demonstrate a labelling efficiency exceeding 99% in isolated yeast tRNAs hosting multiple Ψs. LC-MS/MS analysis enables precise mapping of Ψ at single-base resolution, while simultaneously capturing a wide array of additional post-transcriptional modifications, which is not achieved with current sequencing technologies. This advancement may help unravel the dynamics and biological implications of Ψ, shedding light on its interplay with other modifications and deepening our understanding of its functional role.
Optimizing hexanoic acid biosynthesis in Saccharomyces cerevisiae for the de novo production of olivetolic acid
(2024-12-04) Schäfer, Kilan J.; Aras, Marco; Boles, Eckhard; Kayser, Oliver
Medium chain fatty acids (MCFAs) are valuable platform compounds for the production of biotechnologically relevant chemicals such as biofuels and biochemicals. Two distinct pathways have been implemented in the yeast Saccharomyces cerevisiae for the biosynthetic production of MCFAs: (i) the mutant fatty acid biosynthesis (FAB) pathway in which the fatty acid synthase (FAS) complex is mutated and (ii) a heterologous multispecies-derived reverse β-oxidation (rBOX) pathway. Hexanoic acid has become of great interest as its acyl-CoA ester, hexanoyl-CoA, is required for the biosynthesis of olivetolic acid (OA), a cannabinoid precursor. Due to insufficient endogenous synthesis of hexanoyl-CoA, recombinant microbial systems to date require exogenous supplementation of cultures with hexanoate along with the overexpression of an acyl-CoA ligase to allow cannabinoid biosynthesis. Here, we engineer a recombinant S. cerevisiae strain which was metabolically optimized for the production of hexanoic acid via the FAB and rBOX pathways and we combine both pathways in a single strain to achieve titers of up to 120 mg L−1. Moreover, we demonstrate the biosynthesis of up to 15 mg L−1 OA from glucose using hexanoyl-CoA derived from the rBOX pathway.
Human consciousness and the ‘anthropological turn’: theological perspectives on evolutionary anthropology
(2025-03-11) Breul, Martin
Recent discussions between evolutionary and theological anthropology have intensified, particularly through the work of Michael Tomasello. As a key figure in evolutionary anthropology, Tomasello synthesizes extensive empirical research into an accessible ‘natural history’ of core human abilities. He posits that a unique human trait distinguishing us from our closest relatives is the capacity for “collective intentionality”, a concept he adapts from the philosophy of action. In this article, I show that Tomasello’s insights carry significant implications for philosophical and theological debates. Philosophically, his evolutionary framework invites a new understanding of the mind–brain problem, promoting a non-reductive view of human consciousness which questions the basic metaphysical assumptions of the debate by taking a genealogical perspective. Theologically, his work supports a “practical metaphysics”, suggesting that although morality is autonomous, it can lead to theistic interpretations of human existence. This supports the Kantian idea that religion does not precede morality but that religious views of the world are interpretations of human moral life. At the same time, religion is not just an add-on to morality but an interpretation of a human form of life as such. Both discourses exemplify the importance of a genealogical perspective in philosophy and theology, especially reinforcing the necessity of considering the ‘natural history’ of consciousness, free will or religiosity in anthropology.
Barkhausen noise- and eddy current-based measurements for online detection of deformation-induced martensite during flow forming of metastable austenitic steel AISI 304L
(2024-12-07) Rozo Vasquez, Julian; Kanagarajah, Hanigah; Arian, Bahman; Kersting, Lukas; Homberg, Werner; Trächtler, Ansgar; Walther, Frank
This paper deals with micromagnetic measurements for online detection of strain-induced α′-martensite during plastic deformation of metastable austenitic steel AISI 304L. The operating principles of the sensors are magnetic Barkhausen noise (MBN) and eddy currents (EC), which are suitable for detection of microstructure evolution due to formation of ferromagnetic phases. The focus of this study was put on the qualification of different micromagnetic techniques and different measurement systems under conditions similar to the real ones during production, which is crucial for implementation of a property-controlled flow forming process. The investigation was carried out on tubular specimens produced by flow forming, which have different content of α′-martensite. To characterize the sensitivity of the sensors, different contact conditions between sensors and workpieces were reproduced. MBN sensors are suitable for detecting amount of α′-martensite, but the measurements are affected by the surface roughness. This entails that the calibration models for MBN sensors must take account of these effects. EC sensors show a closer match with the amount of α′-martensite without having major affectation by other effects.
Manipulating martensitic transformation and residual stress development in stress superposed incremental forming of SS304
(2025-03-18) Mamros, Elizabeth M.; Maaß, Fabian; Gnäupel-Herold, Thomas H.; Tekkaya, A. Erman; Kinsey, Brad L.; Ha, Jinjin
Stress superposition is one of the strategies used in metal deformation processes to increase the material formability, decrease the required forming forces, and create highly customized components. To investigate the effects of tensile and compressive stresses superposed to the single point incremental forming (SPIF) process, experiments and numerical simulations were conducted for a stainless steel 304 (SS304) truncated square pyramid geometry. Tensile stresses were superposed in-plane on the specimen blank by a custom hydraulic frame, and compressive stresses were incorporated via a polyurethane die. Identified parameters for a martensitic transformation kinetics model for SS304 were used in a two-step finite element approach to predict the ’-martensite volume fraction. These results were compared to experimental results measured by a Feritscope at four locations along each pyramid wall and validated by electron backscatter diffraction. The residual stresses were measured using x-ray diffraction. The parts from each incremental forming process revealed differences in the residual stresses, which impacted the final geometries, and the ’-martensite volume fraction at the four measurement locations. The evolution of the stress state, defined by the stress triaxiality and Lode angle parameter, for each process contributed to the phase transformation variance. It was found that superposing both tensile and compressive stresses to SPIF resulted in the greatest phase transformation and lowest magnitude of residual stresses near the base and the greatest overall geometrical accuracy. Stress-superposed incremental forming can be implemented to manipulate final part properties, which is ideal for applications requiring highly customized parts, e.g., biomedical trauma fixation hardware.