Although it is well known that microbial populations can respond adaptively to challenges from antibiotics, empirical difficulties in distinguishing the roles of de novo mutation and natural selection have left several issues unresolved. Here, we explore the mutational properties of Escherichia coli exposed to long-term sublethal levels of the antibiotic norfloxacin, using a mutation accumulati...

Dose-response curves for inactivation of synchronized cells from the human cell line NHK 3025 in the presence of hematoporphyrin and light are shown. Sensitivity toward photodynamic inactivation is increasing as the cells move in the cell cycle from G1 to mid-S. The increase is mostly due to a change in the extent of the shoulder of the dose-response curve at low doses. The quasithreshold dose ...

A putative transcriptional regulator of the AraC/XylS family was identified in a genomic genebank of Bacteroides fragilis Bf-1, which partially relieved the sensitivity of Escherichia coli DNA repair mutants to the DNA-damaging agents, metronidazole and mitomycin C. A homologue of this gene with the same phenotype was identified as BF638R3281 in B. fragilis 638R. Transcription of BF638R3281 was...

Unstimulated human T lymphocytes are exquisitely sensitive to UVB irradiation. This hypersensitivity appears to relate to low deoxyribonucleotide pool sizes. They have also been reported to be defective in global excision of cyclobutane pyrimidine dimers, but such experiments may have been carried out at supralethal doses, where unrepaired excision breaks persist indefinitely. We use a T4 endon...

The histopathological effects of Linear Alkylbenzene Sulfonate on the gill, liver and kidney tissues of the Caspian kutum, Rutilus frisii kutum were studied. The fish were exposed to three sublethal concentrations of anionic detergent, Linear Alkylbenzene Sulfonate (LAS) for short term intervals (192 h). Gill, liver and kidney samples were collected after 192 h of exposure to LAS and lesions we...

background: over the past few years, the rapid use of high frequency electromagnetic fields like mobile phones has raised global concerns about the negative health effects of its use. adaptive response is the ability of a cell or tissue to better resist stress damage by prior exposure to a lesser amount of stress. this study aimed to assess whether radiofrequency radiation can induce adaptive r...

Apurinic/apyrimidinic (AP) endonuclease (APE; EC 4.2.99.18) plays a central role in repair of DNA damage due to reactive oxygen species (ROS) because its DNA 3'-phosphoesterase activity removes 3' blocking groups in DNA that are generated by DNA glycosylase/AP-lyases during removal of oxidized bases and by direct ROS reaction with DNA. The major human APE (APE-1) gene is activated selectively b...

Metals are the major pollutants in aquatic environment. A lot of research literature is available globally about accumulation of heavy metals in aquatic ecosystems as well as in different body organs of aquatic animals, especially fish. Heavy metals mainly generate reactive oxygen species (ROS) in aquatic animals that lead to oxidative stress production. ROS cause oxidative damage to different ...