Analysis of the postglaciaire deposits of the Rhône shelf (golfe du Lion). Implementation to the study of the late Quaternary depostional sequences

Les dépôts postglaciaires de la plate-forme continentale du Rhône ont été étudiés à partir de données de sismique haute résolution et de carottages Kullenberg. Du rebord de la plate-forme à la plaine deltaïque, ils sont organisés en un ensemble transgressif et rétrogradant constitué par plusieurs unités ou paraséquences. Au niveau de la plaine deltaïque, cet ensemble est recouvert par plusieurs paraséquences mises en place depuis la fin de la remontée Holocène. A l’échelle régionale, du fait du peu d’importance de la composante tectonique durant la période considérée, ce sont pour l’essentiel les variations glacio-eustatiques qui contrôlent l’agencement des dépôts. Durant la remontée postglaciaire, chaque paraséquence se construit par progradation durant une période de diminution du taux de remontée puis est ennoyée et partiellement remaniée à son toit durant la période suivante d’accélération de la remontée et de migration de la ligne de rivage vers le continent. A l’échelle locale, l’interaction de l’eustatisme avec des facteurs tels que l’apport sédimentaire, la morphologie antérieure et la dynamique océanique entraîne des variations de la géométrie et de l’arrangement stratigraphique des corps sédimentaires. Dans l’axe de migration de l’embouchure du Rhône, où le taux d’apports a été le plus important, un ensemble continu de dépôts s’est mis en place sur toute la plate-forme. Latéralement, le taux d’apports étant moindre, les dépôts transgressifs ne se développent que sur la plate-forme externe et interne. Ils sont pratiquement absents de la plate-forme médiane où la faible pente a permis une accélération de la vitesse de migration du rivage vers le continent et une diminution du temps de résidence des centres de dépôts. D’autre part, la direction est/sud-est des houles efficaces a engendré une dérive littorale à composante de transport vers l’ouest et en conséquence la plate-forme moyenne-externe du domaine oriental ne présente pas de dépôts caractéristiques de la remontée eustatique. Sur la plate-forme externe, les paraséquences postglaciaires présentent un fort potentiel sableux car il s’agit de dépôts de plage et avant-plage résultant du remaniement sous faible profondeur d’eau des dépôts de bas niveau sous-jacents. Sur la plate-forme interne, les paraséquences contiennent une plus forte proportion de dépôts fins (plage sous-marine et prodeltas) provenant de l’émissaire rhodanien dont la compétence et la charge solide ont évolué au fur et à mesure de la remontée du niveau de base et de la modification des conditions climatiques. Les séquences de dépôts pléistocènes sous-jacentes sont composées à la fois d’Unités Progradantes Régionales, qui sont des unités de bas-niveau présentes sur toutes les plates-formes de Méditerranée occidentale, et d’Unités Intercalées en grande partie assimilables à des dépôts transgressifs tels que ceux décrits dans cet article

Stratral architectures of late Quaternary regressive–transgressive cycles in the Roussillon Shelf (SW Gulf of Lions, France)

23 pages, 18 figures.A seismic and sequence stratigraphy scheme of the southwestern area of the Gulf of Lions Shelf (NW Mediterranean Basin) is presented, through the analysis of high-resolution seismic profiles obtained with a Minisparker system and calibrated with published seismic and core data of the adjacent Languedoc area. The observed stratigraphic architecture records the repetition of four regressive–transgressive cycles, which constitute high-frequency depositional sequences (DSs). Regressive intervals dominate the generation of shelf sedimentary architecture. Within regressive intervals, the identification of progressively shallower clinoforms, from proximal to distal in a downdip direction, constitutes a strong indicator of the occurrence of forced regressions. This stratigraphic pattern documents the preservation of potential sand-prone reservoirs encased within widespread regressive wedges and directly connected with organic matter rich muds, as distally there is no sharp basal contact between the two. The unusual preservation of pre-Last Glacial Maximum transgressive deposits is attributed to the combined influence of previous shelf topography and dominant wave regime. The most significant transgressions were recorded by shallow-water deposits in distal, middle and proximal locations. Distal and proximal deposits develop over relatively steep surfaces, which caused slower transgressions and favoured the generation of wave-dominated coastal deposits. In contrast, middle deposits show moderate development over a smooth shelf profile as a consequence of rapid shoreline translation. The analysis of spatial changes of regressive–transgressive cycles provided important information about the nature of shelf processes and about the relative significance of regressive versus transgressive intervals within each individual DS, whose development was led by recent, high-frequency sea-level cycles. Dominance of 120 ka cycles would imply that transgressive deposits represent a partial record of glacial–interglacial transgressions. Dominance of 20 ka cycles is not favoured by the fact that the preservation of Quaternary deposits is apparently limited on the shelf.Data have been acquired through the STRARHO project conducted by the University of Perpignan and thanks to the high-resolution seismic laboratory furnished by the GD ARGO scientific research group. Useful remarks and comments were provided by Dr Sanjeev Gupta (Imperial College, London) and by an anonymous referee. Support at sea and funds were obtained from French CNRS/INSU programs (DBT and DYTEC) and private societies (TOTAL and Institut Franc¸ais du Petrole). Officers and crew members of the INSU R/V C. Laurence, Prof. G. Petit and Tethys II are gratefully acknowledged.Peer reviewe

Age-Related DNA Methylation Changes: Potential Impact on Skeletal Muscle Aging in Humans

10.3389/fphys.2019.00996FRONTIERS IN PHYSIOLOGY10JU

Age-Related DNA Methylation Changes: Potential Impact on Skeletal Muscle Aging in Humans

Human aging is accompanied by a decline in muscle mass and muscle function, which is commonly referred to as sarcopenia. Sarcopenia is associated with detrimental clinical outcomes, such as a reduced quality of life, frailty, an increased risk of falls, fractures, hospitalization, and mortality. The exact underlying mechanisms of sarcopenia are poorly delineated and the molecular mechanisms driving the development and progression of this disorder remain to be uncovered. Previous studies have described age-related differences in gene expression, with one study identifying an age-specific expression signature of sarcopenia, but little is known about the influence of epigenetics, and specially of DNA methylation, in its pathogenesis. In this review, we will focus on the available knowledge in literature on the characterization of DNA methylation profiles during skeletal muscle aging and the possible impact of physical activity and nutrition. We will consider the possible use of the recently developed DNA methylation-based biomarkers of aging called epigenetic clocks in the assessment of physical performance in older individuals. Finally, we will discuss limitations and future directions of this field

Burkholderia novacaledonica sp. nov. and B. ultramafica sp. nov. isolated from roots of Costularia spp. pioneer plants of ultramaficsoils in New Caledonia [Plus corrigenda]

tThe taxonomic status of eleven rhizospheric bacterial strains belonging to the genus Burkholderia andisolated from roots of Costularia (Cyperaceae), tropical herbaceous pioneer plants growing on ultramaficsoils in New Caledonia, was investigated using a polyphasic taxonomic approach. The genetic analyses(16S rRNA genes, gyrB, recA, nreB and cnr) confirmed that all strains are Burkholderia and cluster into twoseparated groups. The DNA hybridization results showed low relatedness values to the closest relativesBurkholderia species. The phenotypic analyses confirmed that the two groups of strains could be differ-entiated from each other and from other known Burkholderia species. This polyphasic study revealedthat these two groups of strains represent each a novel species of Burkholderia, for which the namesBurkholderia novacaledonica sp. nov. (type strain STM10272T= LMG28615T= CIP110887T) and B. ultra-mafica sp. nov. (type strain STM10279T= LMG28614T= CIP110886T) are proposed, respectively. Thesestrains of Burkholderia presented specific ecological traits such as the tolerance to the extreme edaphicconstraints of ultramafic soils: they grew at pH between 4 and 8 and tolerate the strong unbalancedCa/Mg ratio (1/19) and the high concentrations of heavy metals i.e. Co, Cr, Mn and Ni. Noteworthy B.ultramafica tolerated nickel until 10 mM and B. novacaledonica up to 5 mM. The presence of the nickel(nreB) and cobalt/nickel (cnr) resistance determinants encoding for protein involved in metal tolerancewas found in all strains of both groups. Moreover, most of the strains were able to produce plant growthpromoting molecules (ACC, IAA, NH3and siderophores). Such ecological traits suggest that these newspecies of Burkholderia might be environmentally adaptable plant-associated bacteria and beneficialto plants

Responders and non-responders to influenza vaccination: A DNA methylation approach on blood cells

Several evidences indicate that aging negatively affects the effectiveness of influenza vaccination. Although it is well established that immunosenescence has an important role in vaccination response, the molecular pathways underlying this process are largely unknown. Given the importance of epigenetic remodeling in aging, here we analyzed the relationship between responsiveness to influenza vaccination and DNA methylation profiles in healthy subjects of different ages. Peripheral blood mononuclear cells were collected from 44 subjects (age range: 19-90\u202fyears old) immediately before influenza vaccination. Subjects were subsequently classified as responders or non-responders according to hemagglutination inhibition assay 4-6\u202fweeks after the vaccination. Baseline whole genome DNA methylation in peripheral blood mononuclear cells was analyzed using the Illumina\uae Infinium 450\u202fk microarray. Differential methylation analysis between the two groups (responders and non-responders) was performed through an analysis of variance, correcting for age, sex and batch. We identified 83 CpG sites having a nominal p-value <.001 and absolute difference in DNA methylation of at least 0.05 between the two groups. For some CpG sites, we observed age-dependent decrease or increase in methylation, which in some cases was specific for the responders and non-responders groups. Finally, we divided the cohort in two subgroups including younger (age\u202f<\u202f50) and older (age\u202f 65\u202f50) subjects and compared DNA methylation between responders and non-responders, correcting for sex and batch in each subgroup. We identified 142 differentially methylated CpG sites in the young subgroup and 305 in the old subgroup, suggesting a larger epigenetic remodeling at older ages. Interestingly, some of the differentially methylated probes mapped in genes involved in immunosenescence (CD40) and in innate immunity responses (CXCL16, ULK1, BCL11B, BTC). In conclusion, the analysis of epigenetic landscape can shed light on the biological basis of vaccine responsiveness during aging, possibly providing new appropriate biomarkers of this process