Persistence of Environmental DNA in Freshwater Ecosystems

The precise knowledge of species distribution is a key step in conservation biology. However, species detection can be extremely difficult in many environments, specific life stages and in populations at very low density. The aim of this study was to improve the knowledge on DNA persistence in water in order to confirm the presence of the focus species in freshwater ecosystems. Aquatic vertebrates (fish: Siberian sturgeon and amphibian: Bullfrog tadpoles) were used as target species. In control conditions (tanks) and in the field (ponds), the DNA detectability decreases with time after the removal of the species source of DNA. DNA was detectable for less than one month in both conditions. The density of individuals also influences the dynamics of DNA detectability in water samples. The dynamics of detectability reflects the persistence of DNA fragments in freshwater ecosystems. The short time persistence of detectable amounts of DNA opens perspectives in conservation biology, by allowing access to the presence or absence of species e.g. rare, secretive, potentially invasive, or at low density. This knowledge of DNA persistence will greatly influence planning of biodiversity inventories and biosecurity surveys

Analysis of the effects of exposure to acute hypoxia on oxidative lesions and tumour progression in a transgenic mouse breast cancer model

<p>Abstract</p> <p>Background</p> <p>Tumour hypoxia is known to be a poor prognostic indicator, predictive of increased risk of metastatic disease and reduced survival. Genomic instability has been proposed as one of the potential mechanisms for hypoxic tumour progression. Both of these features are commonly found in many cancer types, but their relationship and association with tumour progression has not been examined in the same model.</p> <p>Methods</p> <p>To address this issue, we determined the effects of 6 week <it>in vivo </it>acute hypoxic exposure on the levels of mutagenic lipid peroxidation product, malondialdehyde, and 8-oxo-7,8-dihydro-2'-deoxyguanosine DNA (8-oxo-dG) lesions in the transgenic polyomavirus middle T (PyMT) breast cancer mouse model.</p> <p>Results</p> <p>We observed significantly increased plasma lipid peroxidation and 8-oxo-dG lesion levels in the hypoxia-exposed mice. Consumption of malondialdehyde also induced a significant increase in the PyMT tumour DNA lesion levels, however, these increases did not translate into enhanced tumour progression. We further showed that the <it>in vivo </it>exposure to acute hypoxia induced accumulation of F4/80 positive tumour-associated macrophages (TAMs), demonstrating a relationship between hypoxia and macrophages in an experimental model.</p> <p>Conclusion</p> <p>These data suggest that although exposure to acute hypoxia causes an increase in 8-oxo-dG lesions and TAMs in the PyMT tumours, these increases do not translate into significant changes in tumour progression at the primary or metastatic levels in this strong viral oncogene-driven breast cancer model.</p

Aerosolized Human Extracellular Superoxide Dismutase Prevents Hyperoxia-Induced Lung Injury

An important issue in critical care medicine is the identification of ways to protect the lungs from oxygen toxicity and reduce systemic oxidative stress in conditions requiring mechanical ventilation and high levels of oxygen. One way to prevent oxygen toxicity is to augment antioxidant enzyme activity in the respiratory system. The current study investigated the ability of aerosolized extracellular superoxide dismutase (EC-SOD) to protect the lungs from hyperoxic injury. Recombinant human EC-SOD (rhEC-SOD) was produced from a synthetic cassette constructed in the methylotrophic yeast Pichia pastoris. Female CD-1 mice were exposed in hyperoxia (FiO2>95%) to induce lung injury. The therapeutic effects of EC-SOD and copper-zinc SOD (CuZn-SOD) via an aerosol delivery system for lung injury and systemic oxidative stress at 24, 48, 72 and 96 h of hyperoxia were measured by bronchoalveolar lavage, wet/dry ratio, lung histology, and 8-oxo-2′-deoxyguanosine (8-oxo-dG) in lung and liver tissues. After exposure to hyperoxia, the wet/dry weight ratio remained stable before day 2 but increased significantly after day 3. The levels of oxidative biomarker 8-oxo-dG in the lung and liver were significantly decreased on day 2 (P<0.01) but the marker in the liver increased abruptly after day 3 of hyperoxia when the mortality increased. Treatment with aerosolized rhEC-SOD increased the survival rate at day 3 under hyperoxia to 95.8%, which was significantly higher than that of the control group (57.1%), albumin treated group (33.3%), and CuZn-SOD treated group (75%). The protective effects of EC-SOD against hyperoxia were further confirmed by reduced lung edema and systemic oxidative stress. Aerosolized EC-SOD protected mice against oxygen toxicity and reduced mortality in a hyperoxic model. The results encourage the use of an aerosol therapy with EC-SOD in intensive care units to reduce oxidative injury in patients with severe hypoxemic respiratory failure, including acute respiratory distress syndrome (ARDS)

Measurement of oxidized bases in DNA. Comparison between HPLC-EC and GC-MS assays

The detection of oxidized bases in cellular DNA is a challenging problem due to the sensitivity required that should be high enough in order to detect one modification per 106 DNA bases. In this respect, gas chromatography mass spectrometry (GC-MS) has been extensively used during the last ten years. However, comparison of the results obtained by this method and those inferred from high performance liquid chromatography analyses coupled with an electrochemical detection (HPLC-EC) indicated an overestimation in the level of the oxidized DNA bases in the GC-M

Excision of 7,8-dihydro-8-oxoguanine from DNA by the Fpg protein

A sensitive method involving the combined use of reversed-phase high- performance liquid chromatography and electrochemical detection was used in order to monitor the formation of 7,8-dihydro-8-oxoguanine (8-oxoG) within double stranded DNA photooxidized by methylene blue. The assay requires acidic hydrolysis of the macromolecule. Excision of 7,8-dihydro-8- oxoguanine was found to occur almost quantitatively when photooxidized DNA was incubated with the Fpg protein, a DNA repair enzyme

Urinary excretion of 5-(hydroxymethyl)uracil in healthy volunteers: effect of active and passive tobacco smoke.

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Photooxydation sensibilisée de la désoxy-2’ guanosine par des phtalocyanines et naphtalocyanines. Détermination de l’importance des mécanismes de type I et de type II

L’étude des propriétés photodynamiques de dérivés sulfonés de phtalocyanines et d’une naphtalocyanine a été effectuée en utilisant la désoxy-2’ guanosine comme composé modèle de l’ADN. Les produits majoritaires de photooxydation de ce nucléoside ont été identifiés et classés en deux catégories. La dégradation Impliquant le mécanisme radicalaire de type I génère la diamino-2,2[(désoxy-2-β-D-érythropentofurannosyl)amino]-4 oxazolone-5. La réaction de l’oxygène singulet et de la désoxy-2’ guanosine (type II) engendre la formation de deux photoproduits, les deux diastéréoisomères 4R* et 4S* de la (désoxy-2-p-D-érythropentofurannosyl)-9 dihydro-4,8 hydroxy-4 oxo-8 guanine. On note aussi la présence d’oxo-8 dihydro-7,8 guanosine qui résulterait d’un mécanisme de type II. La mesure qualitative et quantitative de ces produits de dégradation de la désoxy-2’ guanosine a permis de déterminer l’importance des deux mécanismes de photooxydation pour trois phtalocyanines disulfonées complexées au zinc, au gallium, à l’aluminium et d’une naphtalocyanine tétrasulfonée complexée à l’aluminium. Il apparaît que le mécanisme de type II est prépondérant