High CD8 T-cell receptor clonality and altered CDR3 properties are associated with elevated isolevuglandins in adipose tissue during diet-induced obesity

Adipose tissue (AT) CD4+ and CD8+ T cells contribute to obesity-associated insulin resistance. Prior studies identified conserved T-cell receptor (TCR) chain families in obese AT, but the presence and clonal expansion of specific TCR sequences in obesity has not been assessed. We characterized AT and liver CD8+ and CD4+ TCR repertoires of mice fed a low-fat diet (LFD) and high-fat diet (HFD) using deep sequencing of the TCRβ chain to quantify clonal expansion, gene usage, and CDR3 sequence. In AT CD8+ T cells, HFD reduced TCR diversity, increased the prevalence of public TCR clonotypes, and selected for TCR CDR3 regions enriched in positively charged and less polarized amino acids. Although TCR repertoire alone could distinguish between LFD- and HFD-fed mice, these properties of the CDR3 region of AT CD8+ T cells from HFD-fed mice led us to examine the role of negatively charged and nonpolar isolevuglandin (isoLG) adduct-containing antigen-presenting cells within AT. IsoLG-adducted protein species were significantly higher in AT macrophages of HFD-fed mice; isoLGs were elevated in M2-polarized macrophages, promoting CD8+ T-cell activation. Our findings demonstrate that clonal TCR expansion that favors positively charged CDR3s accompanies HFD-induced obesity, which may be an antigen-driven response to isoLG accumulation in macrophages

South China continental margin signature for sandstones and granites from Palawan, Philippines

We report results of heavy mineral analysis and U-Pb dating of detrital zircons from metasediments and Cenozoic sandstones, and U-Pb dating of zircons from Cenozoic granites of the North Palawan Continental Terrane (NPCT) and the South Palawan Terrane (SPT). The NPCT metasediments are derived mainly from granitic and metamorphic rocks of continental character. They contain zircons that indicate a maximum depositional age of Late Cretaceous and other age populations indicating a South China origin. The sediments were deposited on the South China margin before rifting of the continental margin during opening of the South China Sea. Miocene SPT sandstones contain similar heavy mineral assemblages suggesting sources that included NPCT metasediments, metamorphic basement rocks at the contact between the SPT and the NPCT, South China Sea rift volcanic and/or minor intrusive rocks, and the Palawan ophiolite complex. The SPT sandstones are very similar to Lower Miocene Kudat Formation sandstones of northern Borneo suggesting a short-lived episode of sediment transport from Palawan to Borneo in the Early Miocene following arc-continent collision. U-Pb dating of zircons show the Central Palawan granite is Eocene (42 ± 0.5 Ma). The Capoas granite was intruded during a single pulse, or as two separate pulses, between 13.8 ± 0.2 Ma and 13.5 ± 0.2 Ma. Inherited zircon ages from the Capoas granite imply melting of continental crust derived from the South China margin with a contribution from Cenozoic rift-related and arc material

Genetic linkage between the Yellow River, the Mu Us desert and the Chinese Loess Plateau

Arid and semi arid northern China holds some of the world's most significant sand sea and loess deposits. In particular, arguably the most important late Cenozoic wind-blown dust archives on land are exposed on the Chinese Loess Plateau. The origin of this loess-forming dust and its relationship to adjacent sand seas is unclear and has been the subject of considerable debate. Polarization of opinion over the sources of loess also reflects uncertainty over its relationship to large river systems and to the sources of proximal desert sands. It is critical to resolve this in order to elucidate the origins of sand seas, to determine the activity of past dust emitting regions and to fully exploit loess climate archives. Here we combine zircon U–Pb, fission-track and double dating with heavy mineral analysis to test the role of proximal deserts and rivers in contributing dust to the Loess Plateau. We focus on the Mu Us desert to test hypotheses over its sediment sources and because previous studies have often presented contrasting interpretations over its importance as a loess source. Spatial complexity of zircon ages and heavy mineral assemblages in Mu Us sand rules out significant aeolian mixing and shows that grains originating in northern Tibet dominate in the western Mu Us, with local sources dominating in the east of the desert. The western Mu Us far-travelled grains are shown to be delivered by the Yellow River and associated systems. Crucially, the western Mu Us grains and Yellow River grains show U–Pb age distributions and heavy mineral assemblages virtually identical to those of the Quaternary loess. Thus, our results demonstrate that the Yellow River and associated systems transports large quantities of sediment from northern Tibet to the Mu Us desert and further suggest that the river contributes a significant volume of material to the Loess Plateau. This provides the first evidence of a genetic link between the Yellow River and formation of the Chinese Loess Plateau and suggests a greater role for fluvial activity in past dust and desert sand sea formation

GRB emission in Neutron Star transitions

In this contribution we briefly introduce a mechanism for short gamma ray burst emission different from the usually assumed compact objects binary merger progenitor model. It is based on the energy release in the central regions of neutron stars. This energy injection may be due to internal self-annihilation of dark matter gravitationally accreted from the galactic halo. We explain how this effect may trigger its full or partial conversion into a quark star and, in such a case, induce a gamma ray burst with isotropic equivalent energies in agreement with those measured experimentally. Additionally, we show how the ejection of the outer crust in such events may be accelerated enough to produce Lorentz factors over those required for gamma ray emission

Performance and results of the reflection grating spectrometers onboard XMM-Newton

XMM-Newton was launched in December 1999 and science operations started in March 2000. Following two Years of very successful operations, a report, on the instrument performance and a selection of exciting new results are presented. Behind two of the three telescopes of XMM-Newton Reflection Grating Spectrometers (RGS) are placed. Each spectrometer consists of an array of reflection gratings and a set of back illuminated CCDs. They cover the wavelength band between 6 and 38 Angstrom with a resolution varying between 100 and 600 (E/DeltaE) and a maximum effective area of 140 cm(2) for the two spectrometers combined. The selected wavelength band covers the K-shell transitions of C, N, O, Ne, Mg and Si as well as the L- and M-shell transitions of Fe. After a short introduction to the instrument design, the in-orbit performance is given. This includes the line spread function, the wavelength scale arid the effective area including their stability during the more than 2 Years of operations. Following this a number of key scientific results are briefly addressed, illustrating the power of the RGS instrument in combination with the other instruments on-board of XXM-Newton as well as the wealth of information which is obtained as the RGS instruments operate continuously