Assessment of sea surface temperature changes in the Gulf of Cadiz during the last 30 ka: Implications for glacial changes in the regional hydrography

New dinocyst analyses were conducted on core MD99-2339 retrieved from the central Gulf of Cadiz. Dinocyst and foraminiferal assemblages from this core are combined with existing data off SW Portugal and NW Morocco to investigate past hydrological and primary productivity regimes in the subtropical NE Atlantic Ocean over the last 30 ka. Our results have revealed highest upwelling intensity during Heinrich Stadial 1 (HS 1) and the Younger Dryas and weaker upwelling cells during the Last Glacial Maximum (LGM) and HS 2, off the SW Iberian and NW Moroccan margins. Similar assemblages between the Gulf of Cadiz and the NW Moroccan margin, and distinct species off Portugal, were observed during the cold climatic extremes that punctuated the last 30 ka. This pattern has been linked to the occurrence of a hydrological structure between SW Iberia and Cadiz during the last glacial period, perhaps similar to the modern Azores Front. This front was probably responsible locally for heterotrophic dinocysts found in the Gulf of Cadiz during the last glacial period, even if this sector is not conductive to upwelling phenomena by Ekman transport. Regional reconstructions of paleo-sea-surface temperatures (SSTs) using dinocyst and foraminiferal transfer functions, as well as alkenones, are also discussed and depict coherent scenarios over the last 30 ka. Seasonal reconstructions Correspondence to: A. Penaud ([email protected].) of LGM SSTs obtained with this multi-proxy panel are discussed jointly with model outputs in order to contribute to ongoing efforts in model-data comparisonC2007-FCT/319/2006info:eu-repo/semantics/publishedVersio

X chromosome inactivation does not necessarily determine the severity of the phenotype in Rett syndrome patients

Rett syndrome (RTT) is a severe neurological disorder usually caused by mutations in the MECP2 gene. Since the MECP2 gene is located on the X chromosome, X chromosome inactivation (XCI) could play a role in the wide range of phenotypic variation of RTT patients; however, classical methylation-based protocols to evaluate XCI could not determine whether the preferentially inactivated X chromosome carried the mutant or the wild-type allele. Therefore, we developed an allele-specific methylation-based assay to evaluate methylation at the loci of several recurrent MECP2 mutations. We analyzed the XCI patterns in the blood of 174 RTT patients, but we did not find a clear correlation between XCI and the clinical presentation. We also compared XCI in blood and brain cortex samples of two patients and found differences between XCI patterns in these tissues. However, RTT mainly being a neurological disease complicates the establishment of a correlation between the XCI in blood and the clinical presentation of the patients. Furthermore, we analyzed MECP2 transcript levels and found differences from the expected levels according to XCI. Many factors other than XCI could affect the RTT phenotype, which in combination could influence the clinical presentation of RTT patients to a greater extent than slight variations in the XCI pattern

Genetic insights into biological mechanisms governing human ovarian ageing

Reproductive longevity is essential for fertility and influences healthy ageing in women, but insights into its underlying biological mechanisms and treatments to preserve it are limited. Here we identify 290 genetic determinants of ovarian ageing, assessed using normal variation in age at natural menopause in approximately 200,000 women of European ancestry. These common alleles were associated with clinical extremes of age at natural menopause; women in the top 1% of genetic susceptibility have an equivalent risk of premature ovarian insufficiency to those carrying monogenic FMR1 premutations. The identified loci implicate a broad range of DNA damage response (DDR) processes and include loss-of-function variants in key DDR-associated genes. Integration with experimental models demonstrates that these DDR processes act across the lifecourse to shape the ovarian reserve and its rate of depletion. Furthermore, we demonstrate that experimental manipulation of DDR pathways highlighted by human genetics increases fertility and extends reproductive life in mice. Causal inference analyses using the identified genetic variants indicate that extending reproductive life in women improves bone health and reduces risk of type 2 diabetes, but increases the risk of hormone-sensitive cancers. These findings provide insight into the mechanisms that govern ovarian ageing, when they act, and how they might be targeted by therapeutic approaches to extend fertility and prevent disease

Deglacial warming of the northeastern Atlantic ocean: correlation with the paleoclimatic evolution of the european continent

International audienc

Enhanced aridity and atmospheric high-pressure stability over the western Mediterranean during the North Atlantic cold events of the past 50 k.y.

International audienc

Decadal variability of sea surface temperatures off North Iceland over the last 2000 years

International audienceOcean variability at decadal time-scales remains poorly described partly because of the scarcity of high temporal resolution marine records. Here, we present a reconstruction of Sea Surface Temperatures (SSTs) over the past twomillennia at unprecedented temporal resolution (2 to 5 years), from a marine core located off North Iceland. Alkenone paleothermometry was used to infer SST variability, and tephrochronology to build the age model. Spectral analyses of the SSTsignal indicate intermittent 20–25 year oscillations, with periods of strong and weak power, that are likely reflecting the ocean response to wind forcing, presumably the North Atlantic Oscillation (NAO). Warmer SSTs and paleo-magnetic proxy data, between 1000 and 1350 year A.D., overlapping theMedievalWarm Period (MWP), suggest enhanced heat transport across the Denmark Strait by the North Icelandic IrmingerCurrent (NIIC). This is in contrast with the subsequent period, which includes the Little IceAge (LIA), showing continuous cooling towards the 20th century.Reduced NIIC flow through theDenmark Strait likely resulting from higher freshwater and sea ice export from the Arctic would account for the observed colder conditions

Contrasting paleoceanographic conditions off Morocco during Heinrich events (1 and 2) and the Last Glacial Maximum

Past hydrological and primary productivity regimes, on the basis of dinocyst and foraminiferal fossil assemblages as well as on stable isotopes (O, C) and alkenones, were investigated over the last 30 ka at upwelling site MD04-2805 CQ off Morocco. The results show highest upwelling intensity during Heinrich event (HE) 1, time-coeval with a distinct plateau of heavy planktonic δ13C values, high concentrations of Pinus pollen and heterotrophic dinocysts, caused by an increased northern wind regime. In addition, we also present regional reconstructions of paleo-sea-surface temperatures (SSTs) using three different proxy tools: dinocyst and foraminiferal transfer functions as well as alkenones (Uk′37 – SST). The reconstructed SSTs depict coherent scenarios as modulated by the typical Northern Hemisphere climatic fluctuations. Furthermore, specific occurrences of the dinocyst Spiniferites lazus and of the foraminifer Turborotalita quinqueloba are noted for HE 2, HE 1, and the Younger Dryas, whereas in the Alboran Sea and in peri-Iberian waters these cold events were accompanied by the dinocyst Bitectatodinium tepikiense and the subpolar foraminifer Neogloboquadrina pachyderma s., both implying a marked southward shift in the planktonic population in response to the migration of polar water masses. This very pronounced demarcation between the planktonic communities better seems to attest the presence of a distinct hydrological structure in proximity of the strait of Gibraltar which separated at that time African (north of Morocco) from European (southern Iberia) water masses.IPEV, the captain and the crew of the Marion Dufresne and the scientific team of the PRIVILEGE cruise. We wish to thank Mr. Y. Balut for his assistance at sea and M. Castera, and O. Ther for invaluable technical assistance at the laboratory. We gratefully acknowledge the reviewers, whose comments permit to greatly improve this manuscript. Part of this study was supported by the French CNRS.Peer reviewe

A 1.2Ma record of glaciation and fluvial discharge from the West European Atlantic margin

International audienc