We conclude that zebrafish embryos are particularly sensitive to potential disruptors of the RAR/RXR regulatory system. (C) 2013 Elsevier Ltd. All rights reserved.”
“Background: Purple nonsulfur bacteria (PNSB) are facultative photosynthetic bacteria and exhibit an extremely versatile metabolism. A central focus of research on PNSB dealt with the elucidation of mechanisms PP2 datasheet by which they manage to balance cellular redox under diverse conditions, in particular under photoheterotrophic growth.\n\nResults:

Given the complexity of the central metabolism of PNSB, metabolic modeling becomes crucial for an integrated analysis of the accumulated biological knowledge. We reconstructed a stoichiometric model capturing the central metabolism of three important representatives of PNSB (Rhodospirillum

rubrum, Rhodobacter sphaeroides and Rhodopseudomonas palustris). Using flux variability analysis, the model reveals key metabolic constraints related to redox homeostasis in these bacteria. With the help of the model we can (i) give quantitative explanations for non-intuitive, partially species-specific phenomena of photoheterotrophic growth of PNSB, (ii) reproduce various quantitative experimental data, and (iii) formulate several new hypotheses. For example, model analysis of photoheterotrophic growth reveals that – despite a large number of utilizable catabolic pathways – substrate-specific biomass and CO(2) yields are fixed constraints, irrespective of the assumption of optimal growth. Furthermore, our model explains quantitatively why a CO(2) fixing pathway such as the Calvin cycle is required Selleck GSK3326595 by PNSB for many substrates (even if CO(2) is released). We also analyze the role of other pathways potentially involved in redox metabolism and how

they affect quantitatively the required capacity of the Calvin cycle. Our model also selleck products enables us to discriminate between different acetate assimilation pathways that were proposed recently for R. sphaeroides and R. rubrum, both lacking the isocitrate lyase. Finally, we demonstrate the value of the metabolic model also for potential biotechnological applications: we examine the theoretical capabilities of PNSB for photoheterotrophic hydrogen production and identify suitable genetic interventions to increase the hydrogen yield.\n\nConclusions: Taken together, the metabolic model (i) explains various redox-related phenomena of the versatile metabolism of PNSB, (ii) delivers new hypotheses on the operation and relevance of several metabolic pathways, and (iii) holds significant potential as a tool for rational metabolic engineering of PNSB in biotechnological applications.”
“For the first time the rhodium-catalyzed 1,4-addition of organoboranes to hindered Baylis-Hillman adducts, trisubstituted alkenes, affording highly functionalized alkenes, via addition of the organoboranes and hydroxyelimination, is reported.