Accumulation of clinically relevant antibiotic-resistance genes, bacterial load, and metals in freshwater lake sediments in Central Europe.

Wastewater treatment plants (WWTP) receive the effluents from various sources (communities, industrial, and hospital effluents) and are recognized as reservoir for antibiotic-resistance genes (ARGs) that are associated with clinical pathogens. The aquatic environment is considered a hot-spot for horizontal gene transfer, and lake sediments offer the opportunity for reconstructing the pollution history and evaluating the impacts. In this context, variation with depth and time of the total bacterial load, the abundance of faecal indicator bacteria (FIB; E. coli and Enterococcus spp. (ENT)), Pseudomonas spp., and ARGs (blaTEM, blaSHV, blaCTX-M, blaNDM, and aadA) were quantified in sediment profiles of different parts of Lake Geneva using quantitative PCR. The abundance of bacterial marker genes was identified in sediments contaminated by WWTP following eutrophication of the lake. Additionally, ARGs, including the extended-spectrum ß-lactam- and aminoglycoside-resistance genes, were identified in the surface sediments. The ARG and FIB abundance strongly correlated (r ≥ 0.403, p < 0.05, n = 34) with organic matter and metal concentrations in the sediments, indicating a common and contemporary source of contamination. The contamination of sediments by untreated or partially treated effluent water can affect the quality of ecosystem. Therefore, the reduction of contaminants from the source is recommended for further improvement of water quality.

Human ING1 proteins differentially regulate histone acetylation.

ING1 proteins are nuclear, growth inhibitory, and regulate apoptosis in different experimental systems. Here we show that similar to their yeast homologs, human ING1 proteins interact with proteins associated with histone acetyltransferase (HAT) activity, such as TRRAP, PCAF, CBP, and p300. Human ING1 immunocomplexes contain HAT activity, and overexpression of p33(ING1b), but not of p47(ING1a), induces hyperacetylation of histones H3 and H4, in vitro and in vivo at the single cell level. p47(ING1a) inhibits histone acetylation in vitro and in vivo and binds the histone deacetylase HDAC1. Finally, we present evidence indicating that p33(ING1b) affects the degree of physical association between proliferating cell nuclear antigen (PCNA) and p300, an association that has been proposed to link DNA repair to chromatin remodeling. Together with the finding that human ING1 proteins bind PCNA in a DNA damage-dependent manner, these data suggest that ING1 proteins provide a direct linkage between DNA repair, apoptosis, and chromatin remodeling via multiple HAT.ING1.PCNA protein complexes.

Pnk1, a DNA kinase/phosphatase required for normal response to DNA damage by gamma-radiation or camptothecin in Schizosaccharomyces pombe.

We report the characterization of Pnk1, a 45-kDa homolog of the human polynucleotide kinase PNKP in Schizosaccharomyces pombe. Recombinant Pnk1 like human PNKP exhibits both 5'-DNA kinase and 3'-DNA phosphatase activities in vitro. Furthermore, we detected 3'-DNA phosphatase activity with a single-stranded substrate in extracts from wild-type yeast, but no activity was detected in pnk1delta strains. We have shown that GFP-tagged Pnk1 like mammalian PNKP localizes to the nucleus. Deletion of pnk1 does not affect cell growth under normal conditions but results in significant hypersensitivity to gamma-radiation or camptothecin, an inhibitor of topoisomerase I, suggesting that Pnk1 plays an important role in the repair of DNA strand breaks produced by these agents. The pnk1 deletion mutants were not hypersensitive to ethyl methanesulfonate, methyl methanesulfonate, or 4-nitroquinoline N-oxide. Expression of human PNKP in pnk1delta cells restores resistance to gamma-radiation or camptothecin, suggesting that the functions of yeast Pnk1 and human PNKP have been conserved.