The COMET experiment at J-PARC aims to search for a lepton-flavour violating process of muon to electron conversion in a muonic atom, μ-e conversion, with a branching-ratio sensitivity of better than ...10−16, 4 orders of magnitude better than the present limit, in order to explore the parameter region predicted by most of well-motivated theoretical models beyond the Standard Model. The need for this sensitivity places several stringent requirements on the detector development. The experiment requires to detect the monochromatic electron of 105MeV, the momentum resolution is primarily limited by the multiple scattering effect for this momentum region. Thus we need the very light material detector in order to achieve an excellent momentum resolution, better than 2%, for 100MeV region. In order to fulfil such a requirement, the thin-wall straw-tube planar tracker has been developed by an extremely light material which is operational in vacuum. The COMET straw tracker consists of 9.8mm diameter straw tube, longer than 1m length, with 20-μm-thick Mylar foil and 70-nm-thick aluminium deposition. Currently even thinner and smaller, 12μm thick and 5mm diameter, straw is under development by the ultrasonic welding technique.
Objective:
Isolation of bacteria and fungi from porcine nasal microbiome and evaluation of antibioticproducing potential among them.
Methods:
Conventional isolation using Sabouraud and Mueller-Hinton ...nutrient media was carried out for collected samples. The isolated strains were subjected to antibiotic susceptibility testing and antimicrobial activity screening.
Results and Discussion:
Taxonomy positions of the 20 isolated strains (18 bacteria, 1 yeast, 1 fungus) were determined by phylogenetic analysis, morphological study and a substrate utilization assay. Pseudomonas aeruginosa SM-11 was found to produce 4 known antibacterial molecules (pyocyanine, pyochelin, pyoluteorin, monorhamnolipid). Production of pyocyanine was induced by cocultivation with test microorganisms.
Conclusions:
The mammal microbiota might serve as a valuable source of antimicrobialproducing strains, including those of rare taxa. Cocultivation techniques are a promising approach to exploring antimicrobials from silent biosynthetic gene clusters.
DNA Condensation in Bacteria Krupyanskii, Yu. F.; Generalova, A. A.; Kovalenko, V. V. ...
Russian journal of physical chemistry. B,
06/2023, Letnik:
17, Številka:
3
Journal Article
Recenzirano
Deoxyribonucleic acid (DNA) is organized hierarchically in the nucleoid of an actively growing cell, with three levels of DNA compaction. The lower level (small scale ≥1 kb base pairs (bps)) is ...provided by the interaction with DNA-bound proteins. Actively growing cells maintain a dynamic, far from equilibrium order through metabolism. When cells enter a dormant state (almost complete absence of metabolism), the usual biochemical methods of protecting DNA cease to work, and the cells, adapting to the new conditions, are forced to use the physical mechanisms of DNA protection. The structure of DNA in the nucleoid of dormant cells formed during starvation stress is studied using synchrotron radiation diffraction and transmission electron microscopy (TEM). The experimental results make it possible to visualize the structures of the lower hierarchical level of DNA compaction in the nucleoid of dormant cells. A series of diffraction experiments conducted for the first time indicate the presence of a periodic ordered organization of DNA in all the studied bacteria
.
The TEM method made it possible to extract fine visual information about the type of DNA condensation in the nucleoid of the bacterium
Escherichia coli
(
E. coli
). Intracellular nanocrystalline, as well as liquid-crystalline and folded nucleosome-like, structures of DNA are found. The folded nucleosome-like structure was observed for the first time and is the result of the multiple folding of long DNA molecules around the DNA-binding protein (Dps) of starved cells and its associates. The different types of condensed state of DNA found by us in the studied dormant
E. coli
cells (DNA condensation heterogeneity) provide additional arguments in favor of the concept that considers a microbial population as a multicellular organism. The study of changes in the DNA architecture under the effect of the chemical analog of the autoinducer of anabiosis 4-hexylresorcinol (4-HR) is studied. An increase in the 4-HR concentration induces the transition of a part of the cells of the population to anabiotic dormant state, and then to a mummified state. The studies of the structure of DNA in the anabiotic and mummified states show the spectroscopic identity of the DNA structure in the dormant anabiotic state and in the dormant state formed during starvation stress. Studies of the structure of DNA in the mummified state show a strong difference from the structure of DNA in the anabiotic state.
In this work, conditions were selected for obtaining a sample of eukaryotic chaperonin TRiC suitable for studying by cryo-electron microscopy. Using the method of differential scanning ...(time-resolved) fluorimetry, the temperature stability of protein samples at different concentrations of salt and glycerol was compared, and then the selected conditions were used to prepare the sample for microscopy. As a result, the structure of bovine TRiC in an open conformation was obtained at 4.42 Å resolution.
The architecture of DNA in the dormant cells was studied by synchrotron radiation diffraction and transmission electron microscopy. Diffraction experiments indicate the appearance of a periodic ...ordered organization of DNA. Transmission electron microscopy made it possible to visualize information about the type of DNA condensation. Intracellular nanocrystalline, liquid-crystalline and folded nucleosome-like structures of DNA have been found. Next, we studied changes in DNA architecture under stress of exposure to a chemical analogue of the anabiosis autoinducer (4-hexylresorcinol). Studies of the DNA architecture in the anabiotic and mummified states show the identity of the DNA structure in the anabiotic state and in the dormant state under starvation stress. The architecture of DNA in a mummified state is very different from that of DNA in an anabiotic state.
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