"What's (the) Matter?", A Show on Elementary Particle Physics with 28 Demonstration Experiments

We present the screenplay of a physics show on particle physics, by the Physikshow of Bonn University. The show is addressed at non-physicists aged 14+ and communicates basic concepts of elementary particle physics including the discovery of the Higgs boson in an entertaining fashion. It is also demonstrates a successful outreach activity heavily relying on the university physics students. This paper is addressed at anybody interested in particle physics and/or show physics. This paper is also addressed at fellow physicists working in outreach, maybe the experiments and our choice of simple explanations will be helpful. Furthermore, we are very interested in related activities elsewhere, in particular also demonstration experiments relevant to particle physics, as often little of this work is published. Our show involves 28 live demonstration experiments. These are presented in an extensive appendix, including photos and technical details. The show is set up as a quest, where 2 students from Bonn with the aid of a caretaker travel back in time to understand the fundamental nature of matter. They visit Rutherford and Geiger in Manchester around 1911, who recount their famous experiment on the nucleus and show how particle detectors work. They travel forward in time to meet Lawrence at Berkeley around 1950, teaching them about the how and why of accelerators. Next, they visit Wu at DESY, Hamburg, around 1980, who explains the strong force. They end up in the LHC tunnel at CERN, Geneva, Switzerland in 2012. Two experimentalists tell them about colliders and our heroes watch live as the Higgs boson is produced and decays. The show was presented in English at Oxford University and University College London, as well as Padua University and ICTP Trieste. It was 1st performed in German at the Deutsche Museum, Bonn (5/'14). The show has eleven speaking parts and involves in total 20 people.Comment: 113 pages, 88 figures. An up to date version of the paper with high resolution pictures can be found at http://www.th.physik.uni-bonn.de/People/dreiner/Downloads/. In v2 the acknowledgements and a citation are correcte

Strain and tool development for the production of industrially relevant compounds with Corynebacterium glutamicum\textit{Corynebacterium glutamicum}

$\textit{Corynebacterium glutamicum}$ is one of the most important model organisms in white biotechnology for the industrial production of numerous amino acids, most notably L-glutamate and L-lysine, but also of other metabolites and proteins. In order to further expand possible applications of this organism for the conversion of renewable feedstocks into industrially relevant compounds, two different approaches of strain engineering of $\textit{C. glutamicum}$ were addressed in the present thesis. In the first part of this work, a new expression system based on a chromosomally encoded T7 RNA polymerase and a plasmid-based T7 promoter was established and characterized in $\textit{C. glutamicum}$. For this purpose, the T7 RNA polymerase (gene 1) was integrated into the prophage-free strain $\textit{C. glutamicum}$ MB001 under the control of the IPTG-inducible lacUV5 promoter, resulting in strain MB001(DE3). In addition, the expression plasmids pMKEx1 and pMKEx2 were constructed into which a target gen can be cloned under control of the T7 promoter and, if necessary, can be fused to a polyhistidine-tag or a Strep-tag. The T7 expression system was evaluated with the reporter gene $\textit{eyfp}$ and compared to the well-established pEKEx2 system, which is based on the $\textit{tac}$ promotor. The basal expression of the T7 system was lower than that of the pEKEx2 system. The specific fluorescence of eYFP increased 450-fold after maximal induction of the T7 system with 250 μM IPTG and was 3.5-fold higher than the specific eYFP fluorescence obtained after maximal $\textit{eyfp}$ expression with the pEKEx2 system. Furthermore, it was shown that proteins such as pyruvate kinase or secretory GFP proteins can also be successfully produced in higher amounts with the T7 system than with the pEKEx2 system. In the second part of this work, a genetically encoded biosensor for the cytoplasmic lysine concentration was used to screen for mutated variants of pyruvate carboxylase (PCx), which enabled an improved Llysine production. PCx catalyzes the ATP-dependent carboxylation from pyruvate to oxaloacetate and plays an important role as anaplerotic enzyme. It replenishes the tricarboxylic acid cycle during growth on sugars when intermediates have been removed from the cycle by branching metabolic pathways. This reaction is for example of great importance for L-lysine production and it has already been shown that overexpression of the $\textit{pyc}$ gene as well as the mutation P458S in PCx lead to an increased L-lysine yield in $\textit{C. glutamicum}$. In order to find further advantageous mutations for lysine production, a plasmidbased library with mutated $\textit{pyc}$ variants was generated in this work using error-prone PCR. Out of this library, two PCx variants could be isolated with the help of the lysine biosensor pSenLys-Spec and FACS-based high-throughput screening, which showed an increased lysine formation compared to the strain with wild-type PCx. The variants PCx$^{T343A, I1012S}$ and PCx$^{T132A}$ enabled an increase of the lysine titer by 9% and 19%, respectively, after plasmid-based overexpression of the respective genes in the strain DM1868Δ$\textit{pyc}$/pSenLys-Spec. When the mutations were introduced one by one into the genome of the lysine-producing strain DM1868, the variant PCx$^{T132A}$ produced 7% more lysine and PCx$^{T343A}$ 15% more lysine compared to strain DM1868 encoding wild-type PCx. In previous studies, PCx activity of $\textit{C. glutamicum}$ could only be measured with permeabilized cells. For a more detailed characterization, conditions were established that enabled the measurement of PCx activity in cell-free extracts and the isolation of the enzyme in active form. For purified PCx, K$_{m}$ values of 3.8 mM for pyruvate, 0.6 mM for ATP, and 13.3 mM for bicarbonate were determined. ADP and aspartate inhibited PCx activity with $\textit{K}_{i}$ values of 1.5 mM and 9.3 mM, respectively. Initial characterization of the variants PCx$^{T132A}$ and PCx$^{T343A}$ revealed that their activity was not inhibited up to aspartate concentrations of approx. 7.5 mM. The $\textit{K}_{i}$ values of 13.2 mM for PCx$^{T132A}$ and 10.8 mM for PCx$^{T343A}$ were higher than for wild-type PCx and provide an explanation for the increased lysine production obtained with these variants in $\textit{C. glutamicum}$

Pyruvate carboxylase from Corynebacterium glutamicum : purification and characterization

Pyruvate carboxylase of Corynebacterium glutamicum serves as anaplerotic enzyme when cells are growing on carbohydrates and plays an important role in the industrial production of metabolites derived from the tricarboxylic acid cycle, such as l-glutamate or l-lysine. Previous studies suggested that the enzyme from C. glutamicum is very labile, as activity could only be measured in permeabilized cells, but not in cell-free extracts. In this study, we established conditions allowing activity measurements in cell-free extracts of C. glutamicum and purification of the enzyme by avidin affinity chromatography and gel filtration. Using a coupled enzymatic assay with malate dehydrogenase, Vmax values between 20 and 25 μmol min−1 mg−1 were measured for purified pyruvate carboxylase corresponding to turnover numbers of 160 – 200 s−1 for the tetrameric enzyme. The concentration dependency for pyruvate and ATP followed Michaelis-Menten kinetics with Km values of 3.76 ± 0.72 mM and 0.61 ± 0.13 mM, respectively. For bicarbonate, concentrations ≥5 mM were required to obtain activity and half-maximal rates were found at 13.25 ± 4.88 mM. ADP and aspartate inhibited PCx activity with apparent Ki values of 1.5 mM and 9.3 mM, respectively. Acetyl-CoA had a weak inhibitory effect, but only at low concentrations up to 50 μM. The results presented here enable further detailed biochemical and structural studies of this enzyme

Pyruvate Carboxylase Variants Enabling Improved Lysine Production from Glucose Identified by Biosensor-Based High-Throughput Fluorescence-Activated Cell Sorting Screening

Pyruvate carboxylase is an anaplerotic carbon dioxide-fixing enzyme replenishing the tricarboxylic acid cycle with oxaloacetate during growth on sugars. In this study, we applied a lysine biosensor to identify pyruvate carboxylase variants in Corynebacterium glutamicum that enable improved l-lysine production from glucose. A suitable reporter strain was transformed with a pyc gene library created by error-prone PCR and screened by fluorescence-activated cell sorting (FACS) for cells with increased fluorescence triggered by an elevated cytoplasmic lysine concentration. Two pyruvate carboxylase variants, PCxT343A,I1012S and PCxT132A were identified allowing 9% and 19% increased lysine titers upon plasmid-based expression. Chromosomal expression of PCxT132A and PCxT343A variants led to 6% and 14% higher l-lysine levels. The new PCx variants can be useful also for other microbial strains producing TCA cycle-derived metabolites. Our approach indicates that a biosensor such as pSenLys enables directed evolution of many enzymes involved in converting a carbon source into the target metabolite

Efficacy and safety of ruxolitinib in patients with newly-diagnosed polycythemia vera: futility analysis of the RuxoBEAT clinical trial of the GSG-MPN study group

Patients (pts) with polycythemia vera (PV) suffer from pruritus, night sweats, and other symptoms, as well as from thromboembolic complications and progression to post-PV myelofibrosis. Ruxolitinib (RUX) is approved for second-line therapy in high-risk PV pts with hydroxyurea intolerance or resistance. The RuxoBEAT trial (NCT02577926, registered on October 1, 2015, at clinicaltrials.gov) is a multicenter, open-label, two-arm phase-IIb trial with a target population of 380 pts with PV or ET, randomized to receive RUX or best available therapy. This pre-specified futility analysis assesses the early clinical benefit and tolerability of RUX in previously untreated PV pts (6-week cytoreduction was allowed). Twenty-eight patients were randomly assigned to receive RUX. Compared to baseline, after 6 months of treatment, there was a significant reduction of median hematocrit (46 to 41%), the median number of phlebotomies per year (4.0 to 0), and median patient-reported pruritus scores (2 to 1), and a trend for reduced night sweat scores (1.5 to 0). JAK2V617F allele burden, as part of the scientific research program, also significantly decreased. One hundred nine adverse events (AEs) occurred in 24/28 patients (all grade 1 to 3), and no pt permanently discontinued treatment because of AEs. Thus, treatment with ruxolitinib in untreated PV pts is feasible, well-tolerated, and efficient regarding the above-mentioned endpoints