TY - JOUR A1 - Meyer, Susann A1 - Schröter, Maria-Astrid A1 - Hahn, Marc Benjamin A1 - Solumon, Tihomir A1 - Strum, Heinz A1 - Kunte, Hans-Jörg T1 - Ectoine can enhance structural changes in DNA in vitro N2 - Strand breaks and conformational changes of DNA have consequences for the physiological role of DNA. The natural protecting molecule ectoine is beneficial to entire bacterial cells and biomolecules such as proteins by mitigating detrimental effects of environmental stresses. It was postulated that ectoine-like molecules bind to negatively charged spheres that mimic DNA surfaces. We investigated the effect of ectoine on DNA and whether ectoine is able to protect DNA from damages caused by ultraviolet radiation (UV-A). In order to determine different isoforms of DNA, agarose gel electrophoresis and atomic force microscopy experiments were carried out with plasmid pUC19 DNA. Our quantitative results revealed that a prolonged incubation of DNA with ectoine leads to an increase in transitions from supercoiled (undamaged) to open circular (single-strand break) conformation at pH 6.6. The effect is pH dependent and no significant changes were observed at physiological pH of 7.5. After UV-A irradiation in ectoine solution, changes in DNA conformation were even more pronounced and this effect was pH dependent. We hypothesize that ectoine is attracted to the negatively charge surface of DNA at lower pH and therefore fails to act as a stabilizing agent for DNA in our in vitro experiments. KW - Ectoine KW - DNA KW - UV radiation PY - 2017 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-413139 DO - https://doi.org/10.1038/s41598-017-07441-z VL - 7 IS - 1 SP - Article 7170, 1 EP - 10 AN - OPUS4-41313 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Hahn, Marc Benjamin A1 - Solomun, Tihomir A1 - Meyer, Susann A1 - Kunte, Hans-Jörg A1 - Schröter, Maria-Astrid A1 - Sturm, Heinz T1 - Development of a standard procedure for the irradiation of biomolecules N2 - In dosimetry the determination of the effectiveness of the damaging processes is standardized and accounted for by the radiation and tissue weighting factor. For the underlying constituents of the tissue, that is the various biomolecules, such a systematic approach doesn't exist. This makes it difficult to compare results obtained under different experimental conditions. In the following work, we will describe a method to obtain comparable values for the radiation-biomolecule interaction, measured under different conditions. This approach can lead to standardization of dosedamage relationship at the molecular level. Such approach is necessary for a better understanding of the relations between the damage of the single constituents of biological tissue and the whole – finally gaining a more complete picture of irradiation damage. T2 - 14th International Congress of the International Raditation Protection Association (IRPA) CY - Cape Town, South Africa DA - 09.05.2016 KW - Dosimetry PY - 2017 VL - 14 SP - 1 EP - 5 AN - OPUS4-41164 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schröter, Maria-Astrid T1 - Structural changes in plasmid DNA caused by radiation and its protection by Ectoine: an AFM analysis N2 - Most ionizing radiation in water ends in an avalanche of low energy electrons which play a dominant role together with OH-radicals in damaging DNA. In the present study we irradiated plasmid DNA with electrons (primary energy 30keV) under physiological conditions, performed with as well as without Ectoine. Ectoine is a compatible solute, synthesized and accumulated in molar concentration within bacteria to withstand osmotic stress or different other stressors. Plasmid DNA (pUC19, 2686 bp) was studied due to its supercoiled isoform which is highly sensitive to radiation damage. In biochemistry gel electrophoresis is applied for structural analysis of DNA. Although it is a standard technique, a reliable discrimination of short fragments caused by radiation is often difficult. AFM is also commonly used for imaging susceptible biomolecules and, since it is based on a single molecule observation, for analysis of contour lengths of linear DNA as well. Therefore, in our study the structural changes in plasmid DNA after irradiation with different doses were quantitatively analyzed by means of intermittent contact AFM. The figure shows representative AFM images of electron irradiated pUC19 DNA (bar=200nm). For AFM imaging the DNA was chemically fixed on ultra-smooth mica. As can be clearly seen, with increasing radiation dose the number of undamaged DNA declines and fragmented DNA arises (A, B). In aqueous Ectoine solution (1M) the effect of radiation on DNA is dramatically depressed. Ectoine apparently confers protection even against high radiation: the plasmids remain predominantly in the supercoiled isoform (D). Therefore, we strongly believe that Ectoine is a potent protective substance of DNA against ionizing radiation. T2 - AFM BioMed CY - Krakau, Poland DA - 04.09.2017 KW - AFM KW - Plasmid DNA KW - Ectoine KW - Electron radiation PY - 2017 AN - OPUS4-42027 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schröter, Maria-Astrid T1 - Structural changes in plasmid DNA verified by gel electrophoresis and AFM: Sample AFM preparation and imaging (II) N2 - Tapping mode AFM (TM-AFM) is a standard technique to image biomolecules and cells avoiding damage to susceptible samples. For preparing AFM samples we fixed (untreated and radiated) plasmids chemically on ultra-smooth mica silanized with APTES. The recorded AFM images were examined concerning the contour length, the conformation and the writhing number of the plasmids. We found that the measured contour length is in accordance with the number of base pairs. Apart from that, we indicate different structures of plasmids from our AFM images, which were assigned to our plasmid data from agarose gel-electrophoresis. T2 - AFM BioMed Conference CY - Porto, Portugal DA - 11.04.2016 KW - Plasmid DNA KW - Sample AFM preparation PY - 2016 AN - OPUS4-35884 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schröter, Maria-Astrid T1 - Dynamic SEM image analysis of vibrating cantilevers (I) T2 - Deutsche Physikalische Gesellschaft (DPG) 2013 CY - Regensburg, Germany DA - 2013-03-10 PY - 2013 AN - OPUS4-27866 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schröter, Maria-Astrid T1 - Dynamic SEM image analysis of vibrating cantilevers (II) T2 - Deutsche Physikalische Gesellschaft (DPG) 2013 CY - Regensburg, Germany DA - 2013-03-10 PY - 2013 AN - OPUS4-27867 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schröter, Maria-Astrid T1 - Towards a simplified mechanical model of insect wings T2 - Microscopy Conference CY - Kiel, Germany DA - 2011-08-28 PY - 2011 AN - OPUS4-23581 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schröter, Maria-Astrid T1 - Analysis of vibrating microstructures using Dynamic Scanning Electron Microscopy (DySEM) T2 - Deutsche Physikalische Gesellschaft (DPG) 2015 CY - Berlin, Germany DA - 2015-03-15 PY - 2015 AN - OPUS4-32862 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schröter, Maria-Astrid T1 - Analysis of amplitude and phase patterns of vibrating cantilevers using Dynamic Scanning Electron Microscopy (DySEM) T2 - NanoMeasure 2013 CY - Warsaw, Poland DA - 2013-06-25 PY - 2013 AN - OPUS4-28747 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Sturm, Heinz A1 - Schröter, Maria-Astrid A1 - Weimann, Christiane T1 - Imaging method for vibrating scanning force microscopy cantilevers for the analysis of mode shapes and nonlinear harmonic motion N2 - A specially designed scanning force microscope (SFM, atomic force microscope – AFM) was incorporated into the chamber of a commercial scanning electron microscope (SEM) to investigate vibrating SFM cantilevers at their resonance. Inherently, the spatial resolution of electron microscopy is higher than that of optical methods. In this paper we present vibration modes (eigenmodes) of two different SFM cantilevers. Their nonlinear behavior is also explored in order to depict their 2nd harmonics (twice the fundamental frequency). Imaging of the local vibration is performed by measuring the frequency- and phase-selective responses of the SE signal at different X and Y positions of the scanned electron beam. KW - Electron microscopy KW - Scanning force microscopy KW - Motion detection KW - Cantilever KW - Eigenmode KW - Harmonic KW - Nonlinearity KW - Harmonix cantilever PY - 2012 DO - https://doi.org/10.1016/j.mee.2012.07.088 SN - 0167-9317 SN - 1873-5568 VL - 98 SP - 492 EP - 496 PB - Elsevier Science CY - Amsterdam, Netherlands AN - OPUS4-26431 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -