0000000000390932
AUTHOR
Claudia Schmid
Further development of the β-lactamase MutaGen assay and evaluation by comparison with Ames fluctuation tests and theumu test
A rapid, high-throughput bacterial mutagenicity test system has been developed (MutaGen test) that detects reversions of inactivating base-pair substitutions and frameshifts in a TEM-1 class A β-lactamase (ampicillinase) gene. To quickly and sensitively detect mutagens, the system utilises a series of plasmids that contain the mutated ampicillinase gene and the mucAB operon. Inactivating mutations in the ampicillinase gene include frameshifts integrated into repetitive GC-sequences and G-runs known to be mutagenic hot-spots, and base-pair substitutions inserted in or around the β-lactamase active site. Frameshift mutations completely inactivated the enzyme only when located downstream of th…
Increase of sensitivity and validity of the SOS/umu-test after replacement of the beta-galactosidase reporter gene with luciferase.
The SOS/umu-test with Salmonella typhimurium TA1535/pSK1002 as tester strain is a rapid and valuable bacterial assay for screening of umuC-dependent mutagenic potential of chemical compounds and chemicals relevant to environmental pollution. The initial assay was modified by replacing the beta-galactosidase reporter gene with luciferase. Thereby, the sensitivity of the umu-test was increased significantly and the susceptibility to intensively coloured solutions was reduced. The alternative enzyme assay in the modified umu-test (umu-Luc) represents an independent method which allows to confirm the colorimetric results obtained with the original SOS/umu-test system (umu-Gal) by measuring the …
Der strategische Einsatz von Fake News zur Propaganda im Wahlkampf
Im Zeitalter digitaler Medien und Sozialer Netzwerke sind Fake News kein neues Phanomen, haben aber eine Radikalisierung erfahren. Kennzeichnend sind hierbei vier Aspekte: Skandalisierung und Emporung, die Instrumentalisierung von Verbreitungsalgorithmen, neue Rezeptionsdynamiken und fehlende Gatekeeper-Funktionen. Mit Blick auf den US-Wahlkampf 2016 und die Bundestagswahl 2017 werden diese Facetten naher beleuchtet, vorliegende Untersuchungsergebnisse dabei einbezogen und auf Aufklarungs- als Gegenmasnahmen eingegangen.
Mutagenicity test system based on a reporter gene assay for short-term detection of mutagens (MutaGen assay).
Abstract The construction of a bacterial mutation assay system detecting reversions of base substitutions and frameshifts in tetracycline (tet) and ampicillin resistance genes located on low copy plasmids is described. Frameshift mutations were introduced into repetitive GC-sequences and G-repeats known to be mutagenic hot-spots. Base pair substitutions were inserted in or around the active site of the ampicillinase gene thus generating reversibility of the ampicilline sensitivity. The plasmids carry genes to enable sensitive, fast and specific detection of mutagens in bacteria. MucAB was cloned into the test plasmid to enhance error-prone DNA-repair. The conventional reversion principle ha…