Multidisciplinary investigation on cold seeps with vigorous gas emissions in the Sea of Marmara (MarsiteCruise): Strategy for site detection and sampling and first scientific outcome

MarsiteCruise was undertaken in October/November 2014 in the Sea of Marmara to gain detailed insight into the fate of fluids migrating within the sedimentary column and partially released into the water column. The overall objective of the project was to achieve a more global understanding of cold-seep dynamics in the context of a major active strike-slip fault. Five remotely operated vehicle (ROV) dives were performed at selected areas along the North Anatolian Fault and inherited faults. To efficiently detect, select and sample the gas seeps, we applied an original procedure. It combines sequentially (1) the acquisition of ship-borne multibeam acoustic data from the water column prior to each dive to detect gas emission sites and to design the tracks of the ROV dives, (2) in situ and real-time Raman spectroscopy analysis of the gas stream, and (3) onboard determination of molecular and isotopic compositions of the collected gas bubbles. The in situ Raman spectroscopy was used as a decision-making tool to evaluate the need for continuing with the sampling of gases from the discovered seep, or to move to another one. Push cores were gathered to study buried carbonates and pore waters at the surficial sediment, while CTD-Rosette allowed collecting samples to measure dissolved-methane concentration within the water column followed by a comparison with measurements from samples collected with the submersible Nautile during the Marnaut cruise in 2007. Overall, the visited sites were characterized by a wide diversity of seeps. CO2- and oil-rich seeps were found at the westernmost part of the sea in the Tekirdag Basin, while amphipods, anemones and coral populated the sites visited at the easternmost part in the Cinarcik Basin. Methane-derived authigenic carbonates and bacterial mats were widespread on the seafloor at all sites with variable size and distributions. The measured methane concentrations in the water column were up to 377 μmol, and the dissolved pore-water profiles indicated the occurrence of sulfate depleting processes accompanied with carbonate precipitation. The pore-water profiles display evidence of biogeochemical transformations leading to the fast depletion of seawater sulfate within the first 25-cm depth of the sediment. These results show that the North Anatolian Fault and inherited faults are important migration paths for fluids for which a significant part is discharged into the water column, contributing to the increase of methane concentration at the bottom seawater and favoring the development of specific ecosystems

Exploring the link between MORF4L1 and risk of breast cancer.

INTRODUCTION: Proteins encoded by Fanconi anemia (FA) and/or breast cancer (BrCa) susceptibility genes cooperate in a common DNA damage repair signaling pathway. To gain deeper insight into this pathway and its influence on cancer risk, we searched for novel components through protein physical interaction screens. METHODS: Protein physical interactions were screened using the yeast two-hybrid system. Co-affinity purifications and endogenous co-immunoprecipitation assays were performed to corroborate interactions. Biochemical and functional assays in human, mouse and Caenorhabditis elegans models were carried out to characterize pathway components. Thirteen FANCD2-monoubiquitinylation-positive FA cell lines excluded for genetic defects in the downstream pathway components and 300 familial BrCa patients negative for BRCA1/2 mutations were analyzed for genetic mutations. Common genetic variants were genotyped in 9,573 BRCA1/2 mutation carriers for associations with BrCa risk. RESULTS: A previously identified co-purifying protein with PALB2 was identified, MRG15 (MORF4L1 gene). Results in human, mouse and C. elegans models delineate molecular and functional relationships with BRCA2, PALB2, RAD51 and RPA1 that suggest a role for MRG15 in the repair of DNA double-strand breaks. Mrg15-deficient murine embryonic fibroblasts showed moderate sensitivity to γ-irradiation relative to controls and reduced formation of Rad51 nuclear foci. Examination of mutants of MRG15 and BRCA2 C. elegans orthologs revealed phenocopy by accumulation of RPA-1 (human RPA1) nuclear foci and aberrant chromosomal compactions in meiotic cells. However, no alterations or mutations were identified for MRG15/MORF4L1 in unclassified FA patients and BrCa familial cases. Finally, no significant associations between common MORF4L1 variants and BrCa risk for BRCA1 or BRCA2 mutation carriers were identified: rs7164529, Ptrend = 0.45 and 0.05, P2df = 0.51 and 0.14, respectively; and rs10519219, Ptrend = 0.92 and 0.72, P2df = 0.76 and 0.07, respectively. CONCLUSIONS: While the present study expands on the role of MRG15 in the control of genomic stability, weak associations cannot be ruled out for potential low-penetrance variants at MORF4L1 and BrCa risk among BRCA2 mutation carriers.RIGHTS : This article is licensed under the BioMed Central licence at http://www.biomedcentral.com/about/license which is similar to the 'Creative Commons Attribution Licence'. In brief you may : copy, distribute, and display the work; make derivative works; or make commercial use of the work - under the following conditions: the original author must be given credit; for any reuse or distribution, it must be made clear to others what the license terms of this work are

Contribution to computational design methods for titanium and high entropy alloys : prediction of martensite occurrence upon quenching and deformation

On cherche à prédire l’occurrence de la transformation martensitique dans les alliages de titane en fonction de leur composition, dans la perspective de concevoir des alliages dits « TRIP » (TRansformation-Induced Plasticity). Des pistes sont évoquées pour adapter la méthode aux alliages à haute entropie. Un modèle s’appuyant sur la thermodynamique prédictive et sur l’évaluation de la contribution de l’énergie élastique permet de prévoir la température de début de transformation martensitique (Ms). On propose une explication à la rétention sous trempe de la phase de haute température beta, qui serait plus vraisemblablement due au caractère thermiquement activé de la germination de la martensite qu’à une Ms inférieure à la température ambiante. Par ailleurs, on s’appuie sur la théorie phénoménologique de la cristallographie de la martensite (PTMC) pour suggérer une explication à l’inhibition de la martensite dans des conditions qui lui sont thermo-élastiquement favorables. On constate en effet que la formation de martensite pourrait être rendue irréalisable par l’impossibilité d’accommoder la transformation via une déformation à plan invariant. On utilise finalement un algorithme génétique pour illustrer l’approche par des cas théoriques de conception visant à trouver des alliages escomptés présenter un effet TRIP tout en en maximisant le durcissement par solution solide et en minimisant l’impact environnemental ou le risque géo-stratégique associés à leur production. On montre aussi des cas de conception d’alliages à partir d’alliages recyclés, ou de conception de paires d’alliages pour une « structure bi-métal en couches » réalisable par fabrication additive.The object of this work is to develop tools for the design of titanium alloys displaying TRIP (TRansformation-Induced Plasticity) effect, through modelling the occurrence of martensitic transformation as a function of composition. The applicability of the approach to high entropy alloys is discussed. Using computational thermodynamics, and calculating the contribution of the elastic strain energy, we propose a method to predict the martensite start temperature (Ms). We suggest that the retention of the high temperature beta phase upon quenching may be due to the thermally activated character of martensite nucleation, rather than to an Ms below room temperature. Additionally, we exploit the phenomenological theory of martensite crystallography (PTMC) to suggest an explanation to the inhibition of martensite in conditions where it is thermo-elastically favourable. Martensite formation may in turn be prevented, for some compositions, by the impossibility to crystallographically accommodate the transformation via an invariant plane strain. Eventually, we use a multi-objective genetic algorithm to illustrate the approach through the theoretical design of alloys expected to display TRIP effect with maximized solid solution hardening and minimal environmental impact or geo-political risk. Other design examples show how alloys can be designed from recycled alloys, or how pairs of alloys can be simultaneously designed, in such a way as to obtain a bi-metal structure producible by additive manufacturing

Physical mechanisms leading to recrystallized grains free of precipitates after hot forging of a typical γ − γ′ nickel- based superalloy

International audienceNickel-based polycrystalline γ - γ' superalloys are used for manufacturing the hottest parts of new generation aircraft engines, such as turbine discs. These materials exhibit a trimodal distribution of γ' precipitates. The largest precipitates, referred to as γ' I (primary precipitates), contribute to grain size control via Smith-Zener pinning effect, while finer precipitate populations, referred to as γ' II and γ' III (resp. secondary and tertiary), induce significant strengthening. Within this family of alloys, recrystallization behavior, and thus microstructure evolution, is significantly influenced by the presence of γ' precipitates whose kinetics of evolution are comparable to those of recrystallization. However, the interaction mechanisms between precipitates and recrystallization remain little understood. While deformed grains exhibit a fine and dense distribution of γ' , no precipitates are observed inside recrystallized grains. This work focuses on the reason for the latter being free of fine precipitates. The hypothesis advanced to explain this interaction mechanism is the dissolution of the fine γ' precipitates present on the recrystallization front, caused by Ostwald ripening, and favored by grain boundary diffusion. A campaign of hot thermo-mechanical tests and SEM-EBSD analysis was defined to study the interaction mechanisms between fine γ' precipitates and the recrystallization front, supported by local chemical analysis via ATP and TEM observations

Modelling martensitic transformation in titanium alloys:The influence of temperature and deformation

New theory is presented to describe the occurrence of plasticity-induced transitions in titanium alloys. The approach is able to predict the composition dependence of transformation induced plasticity (TRIP), superelasticity, as well as martensite formation upon quenching. Martensite formation in the absence of stress is considered as the result of a competition between elastic strain energy and chemical driving force. Assuming that the formation of martensite is the result of a thermally activated nucleation process followed by athermal growth, a nucleation parameter is postulated to describe the conditions under which martensite is formed upon quenching; the parameter accounts for the ratio between the available thermal energy and an energy barrier for nucleation, suggesting that ω phase is not the main factor controlling martensite inhibition. This nucleation parameter is able to describe, for the first time, martensite occurrence in 130 alloys from the literature, quantifying the martensite start temperature (Ms) reported for 49 alloys with great precision. An empirical parameter ([Fe]eq) is proposed and, when combined with the Ms prediction, it allows to define regions within which TRIP and superelasticity occur. By defining threshold values for the Ms, the [Fe]eq and the nucleation parameter, candidate alloys likely to display TRIP, superelasticity or martensitic transformation upon quenching can be identified. As a result, this method can be adopted to design alloys with tailored plasticity behaviour. © 2019 Acta Materialia Inc

Exploring the link between MORF4L1 and risk of breast cancer

Introduction: Proteins encoded by Fanconi anemia (FA) and/or breast cancer (BrCa) susceptibility genes cooperate in a common DNA damage repair signaling pathway. To gain deeper insight into this pathway and its influence on cancer risk, we searched for novel components through protein physical interaction screens. Methods: Protein physical interactions were screened using the yeast two-hybrid system. Co-affinity purifications and endogenous co-immunoprecipitation assays were performed to corroborate interactions. Biochemical and functional assays in human, mouse and Caenorhabditis elegans models were carried out to characterize pathway components. Thirteen FANCD2-monoubiquitinylation-positive FA cell lines excluded for genetic defects in the downstream pathway components and 300 familial BrCa patients negative for BRCA1/2 mutations were analyzed for genetic mutations. Common genetic variants were genotyped in 9,573 BRCA1/2 mutation carriers for associations with BrCa risk. Results: A previously identified co-purifying protein with PALB2 was identified, MRG15 (MORF4L1 gene). Results in human, mouse and C. elegans models delineate molecular and functional relationships with BRCA2, PALB2, RAD51 and RPA1 that suggest a role for MRG15 in the repair of DNA double-strand breaks. Mrg15-deficient murine embryonic fibroblasts showed moderate sensitivity to γ-irradiation relative to controls and reduced formation of Rad51 nuclear foci. Examination of mutants of MRG15 and BRCA2 C. elegans orthologs revealed phenocopy by accumulation of RPA-1 (human RPA1) nuclear foci and aberrant chromosomal compactions in meiotic cells. However, no alterations or mutations were identified for MRG15/MORF4L1 in unclassified FA patients and BrCa familial cases. Finally, no significant associations between common MORF4L1 variants and BrCa risk for BRCA1 or BRCA2 mutation carriers were identified: rs7164529, Ptrend = 0.45 and 0.05, P2df = 0.51 and 0.14, respectively; and rs10519219, Ptrend = 0.92 and 0.72, P2df = 0.76 and 0.07, respectively. Conclusions: While the present study expands on the role of MRG15 in the control of genomic stability, weak associations cannot be ruled out for potential low-penetrance variants at MORF4L1 and BrCa risk among BRCA2 mutation carriers