436 research outputs found
Visualisierung von Mutationen auf Einzelzellebene
No full textTäuber S, Dormeyer M, Commichau FM, Grünberger A. Visualisierung von Mutationen auf Einzelzellebene. BIOspektrum. 2020;26(4):388-390.Bacterial mutations have been investigated since many years, but they remain difficult to observe directly in single cells, which limits the analysis of the underlying molecular mechanism. However, for the investigation of mutations at the level of single cells, precise analytical tools are currently developed. This article describes a workflow for visualizing mutations in single cells and lays the foundation for the quantification of bacterial mutation rates in the future
Microbial cell factories for the sustainable manufacturing of B vitamins
No full textVitamins are essential compounds in human and animal diets. Their demand is increasing globally in food, feed, cosmetics, chemical and pharmaceutical industries. Most current production methods are unsustainable because they use non-renewable sources and often generate hazardous waste. Many microorganisms produce vitamins naturally, but their corresponding metabolic pathways are tightly regulated since vitamins are needed only in catalytic amounts. Metabolic engineering is accelerating the development of microbial cell factories for vitamins that could compete with chemical methods that have been optimized over decades, but scientific hurdles remain. Additional technological and regulatory issues need to be overcome for innovative bioprocesses to reach the market. Here, we review the current state of development and challenges for fermentative processes for the B vitamin group
Characterization of Bacillus subtilis mutants with carbon source-independent glutamate biosynthesis
No full textBacillus subtilis synthesizes glutamate from 2-oxoglutarate and glutamine using the glutamate synthase, encoded by the gltAB operon. Glutamate degradation involves the catabolic glutamate dehydrogenase (GDH) RocG. Expression of both gltAB and rocG is controlled by the carbon and nitrogen sources. In the absence of glucose or other well-metabolizable carbon sources, B. subtilis is unable to grow unless provided with external glutamate. In this work, we isolated mutations that suppressed this growth defect of B. subtilis on minimal media (sgd mutants). All mutations enabled the cells to express the gltAB operon even in the absence of glucose. The mutations were all identified in the rocG gene suggesting that the catabolic GDH is essential for controlling gltAB expression in response to the availability of sugars. Copyright (c) 2007 S. Karger AG, Basel
In vitro Phosphorylation of Key Metabolic Enzymes from Bacillus subtilis: PrkC Phosphorylates Enzymes from Different Branches of Basic Metabolism
No full textPhosphorylation is an important mechanism of protein modification. In the Gram-positive soil bacterium Bacillus subtilis, about 5% of all proteins are subject to phosphorylation, and a significant portion of these proteins is phosphorylated on serine or threonine residues. We were interested in the regulation of the basic metabolism in B. subtilis. Many enzymes of the central metabolic pathways are phosphorylated in this organism. In an attempt to identify the responsible protein kinase(s), we identified four candidate kinases, among them the previously studied kinase PrkC. We observed that PrkC is indeed able to phosphorylate several metabolic enzymes in vitro. Determination of the phosphorylation sites revealed a remarkable preference of PrkC for threonine residues. Moreover, PrkC often used several phosphorylation sites in one protein. This feature of PrkC-dependent protein phosphorylation resembles the multiple phosphorylations often observed in eukaryotic proteins. The HPr protein of the phosphotransferase system is one of the proteins phosphorylated by PrkC, and PrkC phosphorylates a site (Ser-12) that has recently been found to be phosphorylated in vivo. The agreement between in vivo and in vitro phosphorylation of HPr on Ser-12 suggests that our in vitro observations reflect the events that take place in the cell. Copyright (C) 2010 S. Karger AG, Base
Visualization of tandem repeat mutagenesis in Bacillus subtilis
No full textDormeyer M, Lentes S, Ballin P, et al. Visualization of tandem repeat mutagenesis in Bacillus subtilis. DNA REPAIR. 2018;63:10-15.Mutations are crucial for the emergence and evolution of proteins with novel functions, and thus for the diversity of life. Tandem repeats (TRs) are mutational hot spots that are present in the genomes of all organisms. Understanding the molecular mechanism underlying TR mutagenesis at the level of single cells requires the development of mutation reporter systems. Here, we present a mutation reporter system that is suitable to visualize mutagenesis of TRs occurring in single cells of the Gram-positive model bacterium Bacillus subtilis using microfluidic single-cell cultivation. The system allows measuring the elimination of TR units due to growth rate recovery. The cultivation of bacteria carrying the mutation reporter system in microfluidic chambers allowed us for the first time to visualize the emergence of a specific mutation at the level of single cells. The application of the mutation reporter system in combination with microfluidics might be helpful to elucidate the molecular mechanism underlying TR (in)stability in bacteria. Moreover, the mutation reporter system might be useful to assess whether mutations occur in response to nutrient starvation
Role of DNA Repair and Protective Components in Bacillus subtilis Spore Resistance to Inactivation by 400 nm Blue Light
No full textThe high intrinsic decontamination resistance of Firmicutes spores, is important medically (disease) and commercially (food spoilage). Effective methods of spore eradication would be of considerable interest in the health care and medical products industries; particularly if the decontamination method effectively killed spores while remaining benign to both humans and sensitive equipment. Intense blue light at ∼ 400 nm is one such treatment that has drawn significant interest. This work has determined the resistance of spores to blue light in an extensive panel of Bacillus subtilis strains, including wild-type strains and mutants that: i) lack protective components such as the spore coat and its pigment (s) or the DNA protective α/β-type small acid-soluble spore proteins (SASP); ii) have an elevated spore core water content; or iii) lack enzymes involved in DNA repair, including homologous recombination and non-homologous end joining (HR and NHEJ), apurinic/apyrimidinic endonucleases, nucleotide- and base excision repair (NER & BER), translesion synthesis (TLS) by Y-family DNA polymerases and spore photoproduct (SP) removal by SP lyase (SPL). The most important factors in spore blue light resistance were determined to be: spore coats/pigmentation, α/β-type SASP, NER, BER TLS and SP repair. A major conclusion from this work is that blue light kills spores by DNA-damage, and the results in this work indicate at least some of the specific DNA-damage. It appears that high-intensity blue light could be a significant addition to the agents used to kill bacterial spores in applied settings
INTELLEKTUELLE UND SCHULE
No full textOvaj se rad bavi ambivalentnim odnosom intelektualaca prema
instituciji škole i obrnuto. Na temelju specifi čnih samoopisa intelektualaca koji se mogu sažeti kroz pojmove istine, razuma i humanosti autor smatra da bi institucija škole trebala uložiti veći napor kako bi pridobila intelektualce kao partnere u dijalogu i kao savjetnike u institucionalnom i pedagoškom razvojnom
procesu. Preporuka je upućena i drugoj strani, odnosno intelektualcima, koji bi se (više) trebali pozabaviti temama škole i školske pedagogije, kao što je to bio slučaj sedamdesetih godina dvadesetog stoljeća. Autor razvija suprotstavljene tipove centripetalnih i centrifugalnih intelektualaca i predstavlja značajne intelektualce čije je djelovanje bilo od dalekosežnog pedagoškog značaja na međunarodnoj razini. Na kraju postaje jasno da je stalno kretanje od unutarnjeg ka vanjskom, od inkluzije prema ekskluziji i natrag, ono što intelektualce predodređuje da budu pedagoški inovativni. Ovo je vidljivo na primjerima školskih projekata
„Glocksee“ i „Laborschule Bielefeld“, koje je nemoguće zamisliti bez njihovih inicijatora i intelektualnih savjetnika Oskara Negta i Hartmuta von Hentiga.This paper addresses the ambivalent relationship between intellectuals and the institution of school. Based on the specific self-descriptions of intellectuals which can be summarized through the concepts of truth, reason and humanity, the author calls on the institution of school to make an increased effort into winning intellectuals as partners in dialogue and advisors for the institutional and pedagogical developmental process. On the other hand, intellectuals are encouraged to take a (more) active role in the topics related to school and school pedagogy, as was the case in the 70ies of the 20th century. The author develops the oppositeness of centripetal and centrifugal types of intellectuals and presents important intellectuals whose work had far-reaching benefi ts for education on an international level. Finally, it is clear that that the side-to-side pendulum motion between the inside and the outside and between inclusion and exclusion is what predetermines intellectuals to innovate. The examples of the two school projects - Glocksee and Laborschule Bielefeld – shows that they would be hard to imagine
without their initiators and scientific advisors Oskar Negt and Hartmund von Hentig.In dem Aufsatz geht es um das ambivalente Verhältnis von Intellektuellen zur Schule und vice versa. Basierend auf den spezifi schen Selbstbeschreibungen von Intellektuellen, die sich mit den Begriffen Wahrheit, Vernunft und Humanität überschreiben lassen, wird dafür plädiert, dass sich Schule verstärkt darum bemüht, Intellektuelle als Dialogpartner und Ratgeber für den institutionellen und pädagogischen Entwicklungsprozess zu gewinnen. Aber auch umgekehrt wird die Empfehlung artikuliert, dass sich Intellektuelle
(wieder) stärker mit Schule und schulpädagogischen Themen auseinandersetzen, wie das in den siebziger Jahren des zwanzigsten Jahrhunderts einmal der Fall war. Das Gegenüber von zentripetalen und zentrifugalen Intellektuellen-Typen wird entwickelt. Bedeutende Intellektuelle werden vorgestellt, deren Wirken international von weitreichender pädagogischer Bedeutung war. Letztlich wird deutlich, dass es das Pendeln zwischen Drinnen und Draußen, zwischen Inklusion und Exklusion ist, was den Intellektuellen prädestiniert,
pädagogisch innovativ zu sein. Exemplarisch kann das an den beiden
Schulprojekten „Glocksee“ und „Laborschule Bielefeld“ entfaltet werden, die ohne ihre Initiatoren und intellektuellen Begleiter Oskar Negt und Hartmut von Hentig kaum denkbar sind
SCHULE LEBENSWERT MACHEN - EIN ZWISCHENRUF
No full textAutor podsjeća na obrazovni ideal reformske pedagogije u kojem
je naglasak na „glavu, srce i ruke“, a koji se gotovo u potpunosti suprotstavlja onome o čemu se raspravlja u projektu PISA. Stoga se postavlja pitanje kako školu učiniti vrijednu opstanka. Postavljajući to pitanje autor raspravlja o fizičkom izgledu škole i kompetencijama učitelja. Slijedi provokativno pitanje može li se oživjeti „škola s jednom prostorijom“. Rad završava listom kompetencija koje učitelj danas treba posjedovati kako bi mogao doprinijeti školi čiji je opstanak vrijedan.Der Autor erinnert an ein Bildungsideal, der mit dem,
was im Zuge der Bewertung von PISA-Ergebnissen diskutiert wird, kaum kompatibel ist: die reformpädagogische Betonung von “Kopf, Herz und Hand”. In der Folge geht es ihm um die Reflexion der Frage, wie die Schule lebenswert gemacht werden kann. Dabei werden zum einen die räumlichen Rahmungen, zum anderen die Kompetenzen der Lehrenden thematisiert. In einem weiteren Kapitel wird mit der Frage provoziert, ob die „Zwergschule“ wiederzubeleben sei, ehe am Ende in Stichworten zusammengetragen wird, welches Profil Lehrerinnen und Lehrer heute haben sollten, damit sie ihren Teil zu einer “lebenswerten Schule” leiste
RNase Y in Bacillus subtilis: a natively disordered protein that is the functional equivalent of RNase E from Escherichia coli
No full textThe control of mRNA stability is an important component of regulation in bacteria. Processing and degradation of mRNAs are initiated by an endonucleolytic attack, and the cleavage products are processively degraded by exoribonucleases. In many bacteria, these RNases, as well as RNA helicases and other proteins, are organized in a protein complex called the RNA degradosome. In Escherichia coli, the RNA degradosome is assembled around the essential endoribonuclease E. In Bacillus subtilis, the recently discovered essential endoribonuclease RNase Y is involved in the initiation of RNA degradation. Moreover, RNase Y interacts with other RNases, the RNA helicase CshA, and the glycolytic enzymes enolase and phosphofructokinase in a degradosome-like complex. In this work, we have studied the domain organization of RNase Y and the contribution of the domains to protein-protein interactions. We provide evidence for the physical interaction between RNase Y and the degradosome partners in vivo. We present experimental and bioinformatic data which indicate that the RNase Y contains significant regions of intrinsic disorder and discuss the possible functional implications of this finding. The localization of RNase Y in the membrane is essential both for the viability of B. subtilis and for all interactions that involve RNase Y. The results presented in this study provide novel evidence for the idea that RNase Y is the functional equivalent of RNase E, even though the two enzymes do not share any sequence similarity
Calibration and performance of the photon sensor response of FACT - the first G-APD Cherenkov telescope
No full textThe First G-APD Cherenkov Telescope (FACT) is the first in-operation test of the performance of silicon photo detectors in Cherenkov Astronomy. For more than two years it is operated on La Palma, Canary Islands (Spain), for the purpose of long-term monitoring of astrophysical sources. For this, the performance of the photo detectors is crucial and therefore has been studied in great detail. Special care has been taken for their temperature and voltage dependence implementing a correction method to keep their properties stable. Several measurements have been carried out to monitor the performance. The measurements and their results are shown, demonstrating the stability of the gain below the percent level. The resulting stability of the whole system is discussed, nicely demonstrating that silicon photo detectors are perfectly suited for the usage in Cherenkov telescopes, especially for long-term monitoring purpose.A. Biland, T. Bretz, J. Buß, V. Commichau, L. Djambazov, D. Dorner, S. Einecke, D. Eisenacher, J. Freiwald, O. Grimm, H. von Gunten, C. Haller, C. Hempfling, D. Hildebrand, G. Hughes, U. Horisberger, M.L. Knoetig, T. Krähenbühl, W. Lustermann, E. Lyard, K. Mannheim, K. Meier, S. Mueller, D. Neise, A.-K. Overkemping, A. Paravac, F. Pauss, W. Rhode, U. Röser, J.-P. Stucki, T. Steinbring, F. Temme, J. Thaele, P. Vogler, R. Walter and Q. Weitze
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