Evaluation of the over-expression of a \u3ci\u3eMiscanthus\u3c/i\u3e x \u3ci\u3egiganteus\u3c/i\u3e PPDK (C4ppdk1) in switchgrass (\u3ci\u3ePanicum virgatum\u3c/i\u3e) for improved cold temperature C4 photosynthesis

Switchgrass (Panicum virgatum) has been proposed as a potential biofuel feedstock to aid in the displacement of petroleum-based combustible fuels over the course of the next several decades. Improving the yield potential of this perennial grass is therefore of economic interest. Increased net ethanol yields can be achieved in cellulosic feedstocks via two means: 1. Improved sugar release from digestible cell wall materials, 2. Increased overall biomass yield. The latter is the subject of this study. As a C4 photosynthetic plant, switchgrass is highly productive in the hot, humid climate of the southeastern United States. By bypassing the photorespiratory pathway, C4 plants have the ability to avoid as much as 25% yield losses due to the oxygenase activity of Rubisco. The utilization of this alternate pathway exposes the plant to cold temperature growth inhibition. Early spring and higher latitudinal temperatures do not provide optimal growth conditions for most C4 plants. One C4 plant, miscanthus (Miscanthus x giganteus), has been shown to avoid the inhibiting effects of cold temperatures through the upregulation of a particular C4 enzyme, pyruvate phosphate dikinase (PPDK). This enzyme, responsible for the rate limiting step in the C4 pathway, has been shown to increase cold temperature carbon fixation and growth in miscanthus when it is upregulated. For this reason, this enzyme is an interesting target for overexpression in transgenic switchgrass to increase cold temperature photosynthesis. The miscanthus PPDK cDNA was synthesized and ultimately overexpressed in transgenic switchgrass, which were characterized for photosynthesis and growth under both cold and warm temperatures. There were no statistically significant increases in biomass yields or in photosynthetic capacity between transformed plants and non-transformed control plants. These data suggest that the initial hypothesis was probably too simplistic; there is likely greater complexity to understand the relationship of cold temperature C4 photosynthesis and the role of PPDK. Future experiments are needed to evaluate the underlying regulation and complexities of the C4 pathway to further understand how to specifically target and influence gene expression to accomplish higher efficiencies

Auto-ignition of near-ambient temperature H2/air mixtures during flame-vortex interaction

International audienceThis paper demonstrates auto-ignition in reactants at approximately 350 K, upstream of curved H 2 /air flame surfaces during flame/vortex interaction. Temperature fields were measured using laser Rayleigh scattering during head-on interactions of toroidal-vortices with stagnation flames. Repeatable ignition occurred along the ring of the vortex-slightly towards the center-when it was approximately 1 mm upstream of the wrinkled flame surface. The resultant outwardly propagating toroidal flame led to approximately twice the volumetric heat release rate over the duration of the interaction. The ignition occurred in a region of low fluid dynamic strain rate that was farther from the flame than the region of maximum vorticity. Evidence of additional ignition pockets was found upstream of other flame wrinkles, preferentially near the highest magnitude flame curvatures. Different hypotheses for explaining this observation are discussed. The possibility of substantial heat release driven by auto-ignition and complicated diffusion has implications for reaction rate closure models and transport models used in turbulent combustion simulations

Experimental study on curvature effects and preferential diffusion for perturbed laminar premixed ammonia-air flames

Ammonia-air flames are known for low reactivity and have been posing as a huge hindrance in employing the chemical as a sustainable fuel of tomorrow. Curvature is a parameter that could influence the flame structure and so the position of the maximum heat release rate. Flame-acoustic interactions on a Bunsen burner are performed to study the local flame response to highly perturbed flows. NH2* chemiluminescence is used to study the reactivity of these flames. Non-perturbed flames are used as a reference to understand the inherent behaviour of Bunsen ammonia flames. A case study has been chosen for an equivalence ratio ranging between 1.0 and 1.4 at atmospheric conditions to study perturbed flames. The objective is to study the effect of curvature induced by the perturbations on the reactivity of the flame. It was seen that this given case study was quite complex as the flame response was to multiple factors like the effect of Lewis number, convective-diffusion velocities, decomposition of ammonia into hydrogen, thereby, promoting preferential diffusion of hydrogen in both large-scale and locally for certain cases apart from the generated acoustic perturbation which itself dictates the flow regime of the fresh gases, etc. Since the Damköhler number was around 1, the perturbation time scales and the reactivity time scales were comparable and so none of the effects could be ignored. It was concluded that for richer flames where Le>1, the negative curvature promoted the production of hydrogen leading to local enhancement in reactivity. A change in the local thickness due to the induced curvature was seen for all conditions

Lung tumour growth kinetics in SPC-c-Raf-1-BB transgenic mice assessed by longitudinal in-vivo micro-CT quantification

<p>Abstract</p> <p>Background</p> <p>SPC-c-Raf-1-BxB transgenic mice develop genetically induced disseminated lung adenocarcinoma allowing examination of carcinogenesis and evaluation of novel treatment strategies. We report on assessment of lung tumour growth kinetics using a semiautomated region growing segmentation algorithm.</p> <p>Methods</p> <p>156 non contrast-enhanced respiratory gated micro-CT of the lungs were obtained in 12 SPC-raf transgenic (n = 9) and normal (n = 3) mice at different time points. Region-growing segmentation of the aerated lung areas was obtained as an inverse surrogate for tumour burden. Time course of segmentation volumes was assessed to demonstrate the potential of the method for follow-up studies.</p> <p>Results</p> <p>Micro-CT allowed assessment of tumour growth kinetics and semiautomated region growing enabled quantitative analysis. Significant changes of the segmented lung volumes over time could be shown (<it>p </it>= 0.009). Significant group differences could be detected between transgenic and normal animals for time points 8 to 13 months (<it>p </it>= 0.043), when marked tumour progression occurred.</p> <p>Conclusion</p> <p>The presented region-growing segmentation algorithm allows in-vivo quantification of multifocal lung adenocarcinoma in SPC-raf transgenic mice. This enables the assessment of tumour load and progress for the study of carcinogenesis and the evaluation of novel treatment strategies.</p

Quantifying and Localizing the Mitochondrial Proteome Across Five Tissues in A Mouse Population.

We have used SWATH mass spectrometry to quantify 3648 proteins across 76 proteomes collected from genetically diverse BXD mouse strains in two fractions (mitochondria and total cell) from five tissues: liver, quadriceps, heart, brain, and brown adipose (BAT). Across tissues, expression covariation between genes' proteins and transcripts-measured in the same individuals-broadly aligned. Covariation was however far stronger in certain subsets than others: only 8% of transcripts in the lowest expression and variance quintile covaried with their protein, in contrast to 65% of transcripts in the highest quintiles. Key functional differences among the 3648 genes were also observed across tissues, with electron transport chain (ETC) genes particularly investigated. ETC complex proteins covary and form strong gene networks according to tissue, but their equivalent transcripts do not. Certain physiological consequences, such as the depletion of ATP synthase in BAT, are thus obscured in transcript data. Lastly, we compared the quantitative proteomic measurements between the total cell and mitochondrial fractions for the five tissues. The resulting enrichment score highlighted several hundred proteins which were strongly enriched in mitochondria, which included several dozen proteins were not reported in literature to be mitochondrially localized. Four of these candidates were selected for biochemical validation, where we found MTAP, SOAT2, and IMPDH2 to be localized inside the mitochondria, whereas ABCC6 was in the mitochondria-associated membrane. These findings demonstrate the synergies of a multi-omics approach to study complex metabolic processes, and this provides a resource for further discovery and analysis of proteoforms, modified proteins, and protein localization

Isolating strain and curvature effects in premixed flame/vortex interactions

This study focuses on the response of premixed flames to a transient hydrodynamic perturbation in an intermediate situation between laminar stretched flames and turbulent flames: an axisymmetric vortex interacting with a flame. The reasons motivating this choice are discussed in the framework of turbulent combustion models and flame response to the stretch rate. We experimentally quantify the dependence of the flame kinematic properties (displacement and consumption speeds) to geometrical scalars (stretch rate and curvature) in flames characterized by different effective Lewis numbers. Whilst the displacement speed can be readily measured using particle image velocimetry and tomographic diagnostics, providing a reliable estimate of the consumption speed from experiments remains particularly challenging. In the present work, a method based on a budget of fuel on a well chosen domain is proposed and validated both experimentally and numerically using two-dimensional direct numerical simulations of flame/vortex interactions. It is demonstrated that the Lewis number impact neither the geometrical nor the kinematic features of the flames, these quantities being much more influenced by the vortex intensity. While interacting with the vortex, the flame displacement (at an isotherm close to the leading edge) and consumption speeds are found to increase almost independently of the type of fuel. We show that the total stretch rate is not the only scalar quantity impacting the flame displacement and consumption speeds and that curvature has a significant influence. Experimental data are interpreted in the light of asymptotic theories revealing the existence of two distinct Markstein numbers, one characterizing the dependence of flame speed to curvature, the other to the total stretch rate. This theory appears to be well suited for representing the evolution of the displacement speed with respect to either the total stretch rate, curvature or strain rate. It also explains the limited dependence of the flame displacement speed to Lewis number and the strong correlation with curvature observed in the experiments. An explicit relationship between displacement and consumption speeds is also given, indicating that the fuel consumption rate is likely to be altered by both the total stretch rate and curvature

Case report: mRNA-1273 COVID-19 vaccine-associated myopericarditis: Successful treatment and re-exposure with colchicine

IntroductionVaccine-induced myocarditis is a rare complication of messenger RNA (mRNA) COVID-19 vaccines.Case presentationWe report a case of acute myopericarditis in a recipient of allogeneic hematopoietic cells following the first dose of the mRNA-1273 vaccine and the successful administration of a second and third dose while on prophylactic treatment with colchicine to successfully complete the vaccination.ConclusionTreatment and prevention of mRNA-vaccine-induced myopericarditis represent a clinical challenge. The use of colchicine is feasible and safe to potentially reduce the risk of this rare but severe complication and allows re-exposure to an mRNA vaccine

Quantifying and Localizing the Mitochondrial Proteome Across Five Tissues in A Mouse Population

We have used SWATH mass spectrometry to quantify 3648 proteins across 76 proteomes collected from genetically diverse BXD mouse strains in two fractions (mitochondria and total cell) from five tissues: liver, quadriceps, heart, brain, and brown adipose (BAT). Across tissues, expression covariation between genes' proteins and transcripts-measured in the same individuals-broadly aligned. Covariation was however far stronger in certain subsets than others: only 8% of transcripts in the lowest expression and variance quintile covaried with their protein, in contrast to 65% of transcripts in the highest quintiles. Key functional differences among the 3648 genes were also observed across tissues, with electron transport chain (ETC) genes particularly investigated. ETC complex proteins covary and form strong gene networks according to tissue, but their equivalent transcripts do not. Certain physiological consequences, such as the depletion of ATP synthase in BAT, are thus obscured in transcript data. Lastly, we compared the quantitative proteomic measurements between the total cell and mitochondrial fractions for the five tissues. The resulting enrichment score highlighted several hundred proteins which were strongly enriched in mitochondria, which included several dozen proteins were not reported in literature to be mitochondrially localized. Four of these candidates were selected for biochemical validation, where we found MTAP, SOAT2, and IMPDH2 to be localized inside the mitochondria, whereas ABCC6 was in the mitochondria-associated membrane. These findings demonstrate the synergies of a multi-omics approach to study complex metabolic processes, and this provides a resource for further discovery and analysis of proteoforms, modified proteins, and protein localization