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Signaling of chromosomal DNA breaks is of primary importance for initiation of repair and, thus, for global genomic stability. Although the Mre11-Rad50-Nbs1 (MRN) complex is the first sensor of double-strand breaks, its role in double-strand break (DSB) signaling is not fully understood. We report the absence of γ-ray-induced, ATM/ATR-dependent histone H2AX phosphorylation in Arabidopsis thaliana rad50 and mre11 mutants, confirming that the MRN complex is required for H2AX phosphorylation by the ATM and ATR kinases in response to irradiation-induced DSB in ARABIDOPSIS: rad50 and mre11 mutants spontaneously activate a DNA damage response, as shown by the presence of γ-H2AX foci and activation of cell cycle arrest in nonirradiated plants. This response is ATR dependent as shown both by the absence of these spontaneous foci and by the wild-type mitotic indices of double rad50 atr and mre11 atr plants. EdU S-phase labeling and fluorescence in situ hybridization analysis using specific subtelomeric probes point to a replicative S-phase origin of this chromosome damage in the double mutants and not to telomere destabilization. Thus, the data presented here show the exclusive involvement of ATR in DNA damage signaling in MRN mutants and provide evidence for a role for ATR in the avoidance of S-phase DNA damage.

Springs are abundant and present worldwide and are among the most threatened ecosystems on Earth. The main aim of this study was to evaluate the biodiversity of seventy-nine (79) mineral saline springs situated in the French Massif Central, focusing on the species richness and the estimated richness and also on the diatom community composition. The influence of physical and chemical factors on both richness and communities was analyzed in order to have a better knowledge of the diatom ecological preferences and identify species typical of saline springs. Since December 2014, an on-going inventory of mineral springs has been in progress. For each spring, physical and chemical characteristics were measured, and benthic diatoms were sampled. The richness was the lowest in the springs presenting a man-made construction around the emergence. In the other springs, the highest richness was associated with the lowest lithium, sodium, total dissolved solid concentrations, and conductivity. Mineralization and some ions (bromine, calcium, chloride, fluoride, lithium, potassium, and sodium) were found to be the most critical drivers of diatom community composition. Some diatom species were typical of specific abiotic conditions, such as Navicula sanctamargaritae, which was associated with the highest potassium concentration. These species could appear as bio-indicators of these conditions.

This study investigated and compared the diatom flora from thermo-mineral springs in Auvergne (France) and Sardinia (Italy). Samples were collected from rock/cobbles and fine sediments in 16 springs between January 2015 and March 2017. A total of 207 taxa (59 genera) were found. Multivariate analyses revealed significant differences in species composition and abundance among diatom assemblages both within each geographic region and between Auvergne and Sardinia (global R  = 0.516; p  = 0.002), suggesting the importance of local and climatic factors in species distribution. Based on abundance and common occurrence in multiple sites, some taxa can be considered more representative of springs in each region: Crenotia thermalis for Auvergne and Lemnicola exigua , Nitzschia amphibia , N. inconspicua and Rhopalodia operculata for Sardinia. pH, conductivity and HCO 3 − were the most significant environmental variables for diatom assemblages. Our results highlight the high heterogeneity of these spring systems. Future taxonomic insights can be useful to define the identity of some abundant and dominant taxa not identified at the species level in this study. Their identification is a crucial step for a more precise ecological characterization and comparison of these peculiar spring systems.

A floristic survey was performed on a temporary pond, “Laqui du Seignavoux”, situated in the Mont-Dore massif of the French Massif Central, between 2017 and 2019. Except in 2017, each year, we performed four sampling campaigns from April/May to December. Water samples and diatoms were collected. The temporary pond evolved from a poorly mineralized ecosystem due to snow, inducing oligotrophic and oligosaprobic water, well oxygenated in spring, to a more mineralized, less oxygenated, eutrophic–hypereutrophic, and polysaprobic environment in summer. This change in abiotic conditions was found to be linked to the presence of cattle, beginning in May, that trample and excrete in the pond, leading to higher ammonium and nitrate concentrations. During this period, the dominant species were Pinnularia sp., Nitzschia palea, and Nitzschia palea var. tenuirostris. In spring and winter, different species of Eunotia dominated the community such as Eunotia pseudogroenlandica. Finally, light microscopy (LM) and scanning electron microscopy (SEM) observations on a new species of the genus Pinnularia from the temporary pond are presented and the ecological preferences are discussed.

The TIRAMISU collaboration gathers expertise from biologists, physicists, radiochemists and geologists within the Zone-Atelier Territoires Uranifères (ZATU) in France to analyze the radiation exposure of microorganisms living in naturally radioactive mineral springs. These springs are small waterbodies that are extremely stable over geological time scales and display different physicochemical and radiological parameters compared to their surroundings. Water and sediment samples collected in 27 mineral springs of the volcanic Auvergne region (Massif Central, France) have been studied for their microbial biodiversity and their radionuclide content. Among the microorganisms present, microalgae (diatoms), widely used as environmental indicators of water quality, have shown to display an exceptional abundance of teratogenic forms in the most radioactive springs studied (radon activity up to 3700 Bq/L). The current work presents a first assessment of the dose received by the diatoms inhabiting these ecosystems. According to ERICA tool, microorganisms living in most of the sampled mineral springs were exposed to dose rates above 10 μGy/h due to the large concentration of radium in the sediments (up to 50 Bq/g). Radiological analyses of water and sediments were used as inputs to Monte Carlo simulations at micro-(GATE) and nano- (Geant4-DNA) scale in order to assess the direct and indirect damages on the diatom DNA.

INTRODUCTION:Popliteal artery aneurysm (PAA) is the most common peripheral arterial aneurysm and the second most common aneurysm after abdominal aortic aneurysm (AAA). It presents a risk of occlusion, which may lead to acute ischemia and leg amputation. To prevent these risks, asymptomatic PAA >2cm and symptomatic PAA must be treated. Although open PPA repair (OPAR) is still the gold standard, endovascular PAA repair (EPAR) is increasingly used to manage PAA. The objective of this study is to compare the cost of these two medical procedures from the hospital perspective.METHODS:Data were retrieved from the administrative database of Lausanne University Hospital (CHUV - Switzerland). Based on diagnostic codes and medical procedure codes, we selected all patients who underwent OPAR or EPAR between 2011 and 2015. Patient's age, length of stay and cost were compared between both groups using Student t-test.RESULTS:We included seventy-three patient stays (OPAR forty and EPAR thirty-three). Gender balance was identical between groups (97 percent of male), but age was statistically significantly different (OPAR 67.5, EPAR 73, p = .04). EPAR induced shorter mean length of stay (5.1 days versus 11.7 days, p = .0000) and lower mean global cost (CHF 16,555 versus CHF23,514, p = .0085). Cost of procedure amounted to CHF 9,536 for OPAR versus CHF 3,848 for EPAR, medical supply and implants amounted to CHF 1,284 for OPAR versus CHF 7,041 for EPAR and other costs of hospital stay amounted to CHF 12,694 for OPAR versus CHF 5,666 for EPAR. (CHF 1.00 = USD1.00 = EURO 0.93)CONCLUSIONS:With higher patency rate, OPAR is still associated with better medical outcomes than EPAR. But EPAR is significantly less costly than OPAR. Implant cost of EPAR is more than offset by longer length of stay and operating time of OPAR.

Thermo-mineral springs are specific ecosystems with extreme environmental conditions that constitute interesting models for studying metacommunity processes. Since these springs can be considered as islands within a terrestrial context, we first aimed to test some predictions of the theory of island biogeography and the distance-decay hypothesis on benthic diatom communities. Then, we aimed to quantify the influence of physical, chemical, climatic and spatial factors on species assemblages. We evaluated the species-area relationship for all springs and for several group of springs classified according to their environmental and hydrochemical composition. The influence of environmental variables on α-diversity was tested. We also investigated whether β-diversity was related to spring isolation or changes in environmental conditions. Finally, we determined the importance of environmental and spatial variables in shaping diatom communities using ordination and variation partitioning. We did not find any species-area relationship whatever the group of springs investigated, and no geographical distance-decay pattern was observed. We found a significant effect of physical and chemical parameters on α-diversity and composition. Thus, diatoms communities of thermo-mineral springs did not seem to be influenced by dispersal processes at the scale of our study but appeared to be patterned by physical and chemical factors.

Although a strong link between viruses and prokaryotes is commonly known to exist in aquatic systems, few studies have investigated their relationship in spring waters. In the French Massif Central, certain springs are known to exhibit varying levels of naturally occurring radioactivity. Therefore, the aim of this study was to examine the standing stock of viruses together with prokaryotes and determine the potential environmental factors influencing them in springs characterized by contrasted radioactivity gradient. Among the investigated 15 spring habitats, flow cytometry analyses indicated that both viral (VA) and prokaryotic abundances (PA) varied by an order of magnitude accompanied by virus-to-prokaryote ratio ranging between 8 and 144.2. Significant differences in VA was evident among springs where low abundances (mean ± SD: 21.3 ± 7.0 × 107 VLP l−1) corresponded to high (mean ± SD: 1911 ± 814.0 nGy h−1) gamma (γ) dose radiation (222Rn) and vice versa. Adverse effect of water radioactivity (222Rn) on VA could perhaps corroborate our hypothesis of drastic effect of ionizing radiations on viruses, which might explain for lack of significant relationship between PA and VA. In such a scenario of prevailing low VA, the adopted phage life strategies could define their existence in these specialized ecosystems.

The ends of linear eukaryotic chromosomes are hidden in nucleoprotein structures called telomeres, and loss of the telomere structure causes inappropriate repair, leading to severe karyotypic and genomic instability. Although it has been shown that DNA damaging agents activate a DNA damage response (DDR), little is known about the signaling of dysfunctional plant telomeres. We show that absence of telomerase in Arabidopsis thaliana elicits an ATAXIA-TELANGIECTASIA MUTATED (ATM) and ATM AND RAD3-RELATED (ATR)-dependent DDR at telomeres, principally through ATM. By contrast, telomere dysfunction induces an ATR-dependent response in telomeric Conserved telomere maintenance component! (Ctc1)-Suppressor of cdc thirteen (Stn1)-Telomeric pathways in association with Stn1 (CST)-complex mutants. These results uncover a new role for the CST complex in repressing the ATR-dependent DDR pathway in plant cells and show that plant cells use two different DNA damage surveillance pathways to signal telomere dysfunction. The absence of either ATM or ATR in ctc1 and stn1 mutants significantly enhances developmental and genome instability while reducing stem cell death. These data thus give a clear illustration of the action of ATM/ATR-dependent programmed cell death in maintaining genomic integrity through elimination of genetically unstable cells.

This study investigated and compared the diatom flora from thermo-mineral springs in Auvergne (France) and Sardinia (Italy). Samples were collected from rock/cobbles and fine sediments in 16 springs between January 2015 and March 2017. A total of 207 taxa (59 genera) were found. Multivariate analyses revealed significant differences in species composition and abundance among diatom assemblages both within each geographic region and between Auvergne and Sardinia (global R=0.516; p=0.002), suggesting the importance of local and climatic factors in species distribution. Based on abundance and common occurrence in multiple sites, some taxa can be considered more representative of springs in each region: Crenotia thermalis for Auvergne and Lemnicola exigua, Nitzschia amphibia, N. inconspicua and Rhopalodia operculata for Sardinia. pH, conductivity and HCO.sub.3 .sup.- were the most significant environmental variables for diatom assemblages. Our results highlight the high heterogeneity of these spring systems. Future taxonomic insights can be useful to define the identity of some abundant and dominant taxa not identified at the species level in this study. Their identification is a crucial step for a more precise ecological characterization and comparison of these peculiar spring systems.