Scientists of the German Cancer Research Center (Deutsches Krebsforschungszentrum, DKFZ) and the Universities of Heidelberg and Bielefeld, Germany, have developed a highly sensitive test for detecting this genetic alteration at the level of a single molecule, thus providing information about the resistance status of an infected person.
Many resistances to antibiotics are based on specific mutations in the genetic material of the infectious agents. In the case of life-threatening infections it is vital to determine rapidly which medication will work for the patient. However, commonly used methods of resistance detection are too time-consuming, particularly with microorganisms such as tuberculosis bacteria, which grow very slowly in the culture dish.
Scientists headed by Dr. Jens-Peter Knemeyer of the Division of Functional Genome Analysis at the DKFZ have combined a hybridization method, where small DNA probes bind highly specifically and exclusively to the mutated gene sequence, with confocal microscopy technology. The DNA probes are coupled to a fluorescent dye that flashes under laser light. However, this light signal is emitted only if the probe attaches to the target sequence in the bacterial genetic material. ‘Unbound’ probe molecules do not emit a signal. Each of these tiny light flashes that occur when the probe and the target molecule bind to each other, detects a single mutated DNA molecule.
By measuring the duration and decay times of the light flashes, the researchers distinguish between real measurement results and the ubiquitous background fluorescence: Due to chemical properties of the molecules involved, spontaneous fluorescence decays much more quickly than the signal emitted by the dye-labeled probe.
Detection of resistance causing point mutations in the genetic material of the tuberculosis bacterium is just one of numerous possible applications of the new method called single-molecule fluorescence spectroscopy. The method has a big advantage: Instead of recording light flashes in a sample solution, as is done in antibiotic resistance detection, the investigation method can also be used in living cells. Dr. Jörg Hoheisel, head of the Division of Functional Genome Analysis at the DKFZ, explains: “Just as we can detect DNA mutations, we can also use suitable probes to detect all molecules in a cell that are characteristic of a specific disease. Since the test identifies single molecules, it is highly sensitive – but reliable at the same time, because we have an internal control using the decay times.”
Julia Rautenstrauch | alfa
New contents: Neuronal Parkinson inclusions are different than expected
26.06.2019 | Universität Basel
An ion channel with a doorkeeper: The pH of calcium ions controls ion channel opening
25.06.2019 | Johannes Gutenberg-Universität Mainz
From June 25th to 27th 2019, the Fraunhofer Institute for Digital Media Technology IDMT in Ilmenau (Germany) will be presenting a new solution for acoustic quality inspection allowing contact-free, non-destructive testing of manufactured parts and components. The method which has reached Technology Readiness Level 6 already, is currently being successfully tested in practical use together with a number of industrial partners.
Reducing machine downtime, manufacturing defects, and excessive scrap
The quality of additively manufactured components depends not only on the manufacturing process, but also on the inline process control. The process control ensures a reliable coating process because it detects deviations from the target geometry immediately. At LASER World of PHOTONICS 2019, the Fraunhofer Institute for Laser Technology ILT will be demonstrating how well bi-directional sensor technology can already be used for Laser Material Deposition (LMD) in combination with commercial optics at booth A2.431.
Fraunhofer ILT has been developing optical sensor technology specifically for production measurement technology for around 10 years. In particular, its »bd-1«...
The well-known representation of chemical elements is just one example of how objects can be arranged and classified
The periodic table of elements that most chemistry books depict is only one special case. This tabular overview of the chemical elements, which goes back to...
Light can be used not only to measure materials’ properties, but also to change them. Especially interesting are those cases in which the function of a material can be modified, such as its ability to conduct electricity or to store information in its magnetic state. A team led by Andrea Cavalleri from the Max Planck Institute for the Structure and Dynamics of Matter in Hamburg used terahertz frequency light pulses to transform a non-ferroelectric material into a ferroelectric one.
Ferroelectricity is a state in which the constituent lattice “looks” in one specific direction, forming a macroscopic electrical polarisation. The ability to...
Researchers at TU Graz calculate the most accurate gravity field determination of the Earth using 1.16 billion satellite measurements. This yields valuable knowledge for climate research.
The Earth’s gravity fluctuates from place to place. Geodesists use this phenomenon to observe geodynamic and climatological processes. Using...
24.06.2019 | Event News
29.04.2019 | Event News
17.04.2019 | Event News
26.06.2019 | Materials Sciences
26.06.2019 | Physics and Astronomy
26.06.2019 | Health and Medicine