DNA damage in mouse lymphocytes exposed to curcumin and copper

Dietary polyphenolics, such as curcumin, have shown antioxidant and anti-inflammatory effects. Some antioxidants cause DNA strand breaks in excess of transition metal ions, such as copper. The aim of this study was to evaluate thein vitro effect of curcumin in the presence of increasing concentrations of copper to induce DNA damage in murine leukocytes by the comet assay. Balb-C mouse lymphocytes were exposed to 50 μM curcumin and various concentrations of copper (10 μM, 100 μM and 200 μM). Cellular DNA damage was detected by means of the alkaline comet assay. Our results show that 50 μM curcumin in the presence of 100–200 μM copper induced DNA damage in murine lymphocytes. Curcumin did not inhibit the oxidative DNA damage caused by 50 μM H₂O₂ in mouse lymphocytes. Moreover, 50 μM curcumin alone was capable of inducing DNA strand breaks under the tested conditions. The increased DNA damage by 50 μM curcumin was observed in the presence of various concentrations of copper, as detected by the alkaline comet assay.     

Characterization of an osteoblast-specific enhancer element in the CBFA1 gene

Cbfa1 is a critical regulator of cell differentiation expressed only in the osteochondrogenic lineage. To define the molecular basis of this cell-specific expression we analyzed the murine Cbfa1 promoter. Here we show that the first 976 bp of this promoter are specifically active in osteoblastic cells. Within this region DNase I footprinting delineated a 40-bp area (CE1) protected differently by nuclear extracts from osteoblastic cells and from non-osteoblastic cells. When multimerized, CE1 conferred an osteoblast-specific activity to a heterologous promoter in DNA transfection experiments; this enhancing ability was conserved between mouse, rat, and human CE1 present in the respective Cbfa1 promoters. CE1 site-specific mutagenesis determined that it binds NF1- and AP1-like activities. Further analyses revealed that the NF1 site acts as a repressor in non-osteoblastic cells due to the binding of NF1-A, a NF1 isoform not expressed in osteoblastic cells. In contrast, the AP1 site mediates an osteoblast-specific activation caused by the preferential binding of FosB to CE1 in osteoblastic cells. In summary, this study identified an osteoblast-specific enhancer in the Cbfa1 promoter whose activity is achieved by the combination of an inhibitory and an activatory mechanism.     

RIF1 Is Essential for 53BP1-Dependent Nonhomologous End Joining and Suppression of DNA Double-Strand Break Resection

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Highlights? RIF1 is essential for 53BP1-dependent CSR and fusion of dysfunctional telomeres ? BRCA1 antagonizes RIF1 in S phase to prevent error-prone repair by toxic NHEJ ? N-terminal phospho-SQ/TQ domain of 53BP1 interacts with and recruits RIF1 to DSBs ? RIF1 and 53BP1 promote NHEJ in G1 by blocking 5′ end resection of DSBs     

Fluctuation of microbial activities after influent load variations in a full-scale SBR: recovery of the biomass after starvation

Due to variations in the production levels, a full-scale sequencing batch reactor (SBR) for post-treatment of tannery wastewater was exposed to low and high ammonia load periods. In order to study how these changes affected the N-removal capacity, the microbiology of the reactor was studied by a diverse set of techniques including molecular tools, activity tests, and microbial counts in samples taken along 3 years. The recover capacity of the biomass was also studied in a lab-scale reactor operated with intermittent aeration without feeding for 36 days. The results showed that changes in the feeding negatively affected the nitrifying community, but the nitrogen removal efficiencies could be restored after the concentration stress. Species substitution was observed within the nitrifying bacteria, Nitrosomonas europaea and Nitrobacter predominated initially, and after an ammonia overload period, Nitrosomonas nitrosa and Nitrospira became dominant. Some denitrifiers, with nirS related to Alicycliphilus, Azospirillum, and Marinobacter nirS, persisted during long-term reactor operation, but the community fluctuated both in composition and in abundance. This fluctuating community may better resist the continuous changes in the feeding regime. Our results showed that a nitrifying–denitrifying SBR could be operated with low loads or even without feeding during production shut down periods.     

Changes in flagellin glycosylation affect Campylobacter autoagglutination and virulence

Analysis of the complete flagellin glycosylation locus of Campylobacter jejuni strain 81-176 revealed a less complex genomic organization than the corresponding region in the genome strain, C. jejuni NCTC 11168. Twenty-four of the 45 genes found between Cj1293 and Cj1337 in NCTC 11168 are missing in 81-176. Mutation of six new genes, in addition to three previously reported, resulted in a non-motile phenotype, consistent with a role in synthesis of pseudaminic acid (PseAc) or transfer of PseAc to flagellin. Mutation of Cj1316c or pseA had been shown to result in loss of the acetamidino form of pseudaminic acid (PseAm). Mutation of a second gene also resulted in loss of PseAm, as well as a minor modification that appears to be PseAm extended with N-acetyl-glutamic acid. Previously described mutants in C. jejuni 81-176 and Campylobacter coli VC167 that produced flagella lacking PseAm or PseAc failed to autoagglutinate. This suggests that interactions between modifications on adjacent flagella filaments are required for autoagglutination. Mutants (81-176) defective in autoagglutination showed a modest reduction in adherence and invasion of INT407 cells. However, there was a qualitative difference in binding patterns to INT407 cells using GFP-labelled 81-176 and mutants lacking PseAm. A mutant lacking PseAm was attenuated in the ferret diarrhoeal disease model.     

Spatial Ecology of the Endangered Milne-Edwards’ Sifaka (Propithecus edwardsi): Do Logging and Season Affect Home Range and Daily Ranging Patterns?

Primates often live in human-altered habitats; Malagasy lemurs are no exception. It is important to understand if habitat alteration affects primates’ space use patterns across multiple spatial and temporal scales, as this drives population density. We quantified the daily, seasonal, and annual space-use of seven groups of Milne-Edwards’ sifaka (Propithecus edwardsi) living in unlogged and logged rain forest in Ranomafana National Park, Madagascar between December 2002 and November 2003. Concurrent data showed that sifakas consumed higher quality foods in the unlogged than in logged forests; thus we explored how space use patterns were related to energy use strategies. Sifaka groups in the logged rain forest traveled 7–13% less per day than groups in the unlogged rain forest, despite their larger home ranges (median: 46.12 and 23.52 ha, in the logged and unlogged forests, respectively). Sifakas may thus use an energy-minimizing strategy at the scale of the individual day but an energy-maximizing strategy at the annual home range scale. Sifakas exhibited fidelity to the home range across seasons, but their core area of use shifted considerably with season. We found no difference in population density between sites. However, given the interannual variability in sifaka foods, a multiyear study is needed to assess if energy strategies observed in this study are consistent across longer time periods. Our findings suggest that lemurs may persist in logged habitats by altering spatial use patterns; future work should attempt to quantify the threshold level of forest regeneration from logging that will allow lemurs to persist at similar densities as in unlogged forest.     

Molecular phylogenetic analyses indicate a wide and ancient radiation of African hepatitis delta virus, suggesting a deltavirus genus of at least seven major clades

Hepatitis D virus (HDV) is a satellite of hepatitis B virus (HBV) for transmission and propagation and infects nearly 20 million people worldwide. The HDV genome is a compact circular single-stranded RNA genome with extensive intramolecular complementarity. Despite its different epidemiological and pathological patterns, the variability and geographical distribution of HDV are limited to three genotypes and two subtypes that have been characterized to date. Phylogenetic reconstructions based on the delta antigen gene and full-length genome sequence data show an extensive and probably ancient radiation of African lineages, suggesting that the genetic variability of HDV is much more complex than was previously thought, with evidence of additional clades. These results relate the geographic distribution of HDV more closely to the genetic variability of its helper HBV.