Geomagnetic Field Behavior at High Latitudes from a Paleomagnetic Record from Eltanin Core 27-21 in the Ross Sea Sector, Antarctica

We present a high-resolution paleomagnetic record from 682 discrete samples from Eltanin 27-21 (69.03°S 179.83°E), a 16-meter long piston core recovered in 1968 at a water depth of 3456 meters by the USNS Eltanin as part of Operation Deep Freeze. After removal of a low-coercivity overprint, most samples yield stable characteristic remanent magnetization directions. The downhole variation in the magnetic inclination provides a well-resolved magnetostratigraphy from the Brunhes Chron (0-0.78 Ma), through the Reunion Subchron (2.128-2.148 Ma), and into Chron C2r.2r. The sedimentation rates are sufficiently high that even short-term geomagnetic features, like the Cobb Mountain excursion, are resolved. The record from Eltanin 27-21 provides new insights into the behavior of the geomagnetic field at high latitudes, about which very little is currently known. Using the variability in the inclinations during stable polarity intervals, we estimate that the dispersion in the paleomagnetic pole position over the past ~2 Myr is 30.3°±4.3°, which is significantly greater than observed at low to mid latitude sites. The higher dispersion observed at Eltanin 27-21 is consistent with numerical modeling of the geodynamo. That modeling has shown that polar vortices can develop in the Earth’s core within the tangent cylinder, defined as the cylinder coaxial with the Earth’s rotation axis and tangent to the inner core/outer core boundary. The polar vortices produce vigorous fluid motion in the core, which creates greater geomagnetic field variability above the tangent cylinder at the surface of the Earth. The tangent cylinder intersects the Earth’s surface in the polar regions at 69.6° latitude, which is very close to the latitude of Eltanin 27-21

Epigenetics for Ecologists

There is now mounting evidence that heritable variation in ecologically relevant traits can be generated through a suite of epigenetic mechanisms, even in the absence of genetic variation. Moreover, recent studies indicate that epigenetic variation in natural populations can be independent from genetic variation, and that in some cases environmentally induced epigenetic changes may be inherited by future generations. These novel findings are potentially highly relevant to ecologists because they could significantly improve our understanding of the mechanisms underlying natural phenotypic variation and the responses of organisms to environmental change. To understand the full significance of epigenetic processes, however, it is imperative to study them in an ecological context. Ecologists should therefore start using a combination of experimental approaches borrowed from ecological genetics, novel techniques to analyse and manipulate epigenetic variation, and genomic tools, to investigate the extent and structure of epigenetic variation within and among natural populations, as well as the interrelations between epigenetic variation, phenotypic variation and ecological interactions

Targeting the epigenetic modifications of synovial cells

Rheumatoid arthritis (RA) is a systemic inflammatory disease that mainly affects the synovial tissues of joints. Like in other autoimmune-related disorders, both the etiology as well as the pathogenesis of RA has not yet been completely unravelled. It is generally accepted, though, that autoimmune disorders develop through a combination of the individual genetic susceptibility, environmental factors, and dysregulated immune responses. Genetic predisposition has been described in RA, in particular as “shared epitope”, a distinct sequence of amino acids within the antigen presenting peptide groove of the major histocompatibility complex (MHC). Imbalanced immunity is reflected by the production of autoantibodies and the accumulation of reactive helper T cells within the rheumatoid synovium. In addition, environmental factors have been postulated as disease modulating agents, including smoking, nutrition and infectious agents. So far, these factors have been studied almost exclusively as separate agents. However, the way genes are transcribed can be affected by environment, nutrition, and ageing – without changes in the nucleotide sequence of the underlying DNA. These patterns of alterations in the gene expression profiles are called epigenetics. The term epigenetics is used to refer to molecular processes that regulate gene expression patterns, however without changing the DNA nucleotide sequence. These epigenetic changes comprise the postsynthetical methylation of DNA and posttranscriptional modifications of histones, including methylation, phosphorylation, ubiquitination, sumoylation, biotinlyation and, most importantly, deacetylation and acetylation. With respect to the complex pathogenesis of rheumatic diseases, the epigenome is an emerging concept that integrates different etiologies and, thus, offers the opportunity for novel therapeutic strategies. Based on the fact that current therapies have not resulted in an ACR 70 above 60% and have never been targeting the activated synovial fibroblast, novel therapeutic strategies should target the epigenetic pathways of synovial activation in RA