Large-scale protein/antibody patterning with limiting unspecific adsorption

International audienceA simple synthetic route based on nanosphere lithography has been developed in order to design largescale nanoarray for specific control of protein anchoring. This technique based on two-dimensional (2D) colloidal crystals composed of polystyrene spheres allows the easy and inexpensive fabrication of large arrays (up to several centimeters) by reducing the cost. A silicon wafer coated with a thin adhesion layer of chromium (15 nm) and a layer of Gold (50 nm) is used as a substrate. PS spheres aredeposited on the gold surface using the floating-transferring technique. The PS spheres were then functionalized with PEG-biotin and the defects by self-assembly monolayer (SAMs) PEG to prevent unspecific adsorption. Using epifluorescence microscopy, we show that after immersion of sample ontarget protein (avidin and anti-avidin) solution, the latter are specifically located on polystyrene spheres. Thus, these results are meaningful for exploration of devices based on large-scale nanoarray of PS spheres and can be used for detection of target proteins or simply to pattern a surface with specific proteins

A record of igneous evolution in Elysium, a major martian volcanic province

A major knowledge gap exists on how eruptive compositions of a single martian volcanic province change over time. Here we seek to fill that gap by assessing the compositional evolution of Elysium, a major martian volcanic province. A unique geochemical signature overlaps with the southeastern flows of this volcano, which provides the context for this study of variability of martian magmatism. The southeastern lava fields of Elysium Planitia show distinct chemistry in the shallow subsurface (down to several decimeters) relative to the rest of the martian mid-to-low latitudes (average crust) and flows in northwest Elysium. By impact crater counting chronology we estimated the age of the southeastern province to be 0.85 ± 0.08 Ga younger than the northwestern fields. This study of the geochemical and temporal differences between the NW and SE Elysium lava fields is the first to demonstrate compositional variation within a single volcanic province on Mars. We interpret the geochemical and temporal differences between the SE and NW lava fields to be consistent with primary magmatic processes, such as mantle heterogeneity or change in depth of melt formation within the martian mantle due to crustal loading

Age and pattern of the southern high-latitude continental end-Permian extinction constrained by multiproxy analysis

Past studies of the end-Permian extinction (EPE), the largest biotic crisis of the Phanerozoic, have not resolved the timing of events in southern high-latitudes. Here we use palynology coupled with high-precision CA-ID-TIMS dating of euhedral zircons from continental sequences of the Sydney Basin, Australia, to show that the collapse of the austral Permian Glossopteris flora occurred prior to 252.3 Ma (~370 kyrs before the main marine extinction). Weathering proxies indicate that floristic changes occurred during a brief climate perturbation in a regional alluvial landscape that otherwise experienced insubstantial change in fluvial style, insignificant reorganization of the depositional surface, and no abrupt aridification. Palaeoclimate modelling suggests a moderate shift to warmer summer temperatures and amplified seasonality in temperature across the EPE, and warmer and wetter conditions for all seasons into the Early Triassic. The terrestrial EPE and a succeeding peak in Ni concentration in the Sydney Basin correlate, respectively, to the onset of the primary extrusive and intrusive phases of the Siberian Traps Large Igneous Province.This research was additionally funded by collaborative research grants from the National Science Foundation (EAR-1636625 to C.R.F. and T.D.F. and EAR-1636629 to A.W. and C.W.).</p

Thyroid-hormone therapy and thyroid cancer: a reassessment

Experimental studies and clinical data have demonstrated that thyroid-cell proliferation is dependent on thyroid-stimulating hormone (TSH), thereby providing the rationale for TSH suppression as a treatment for differentiated thyroid cancer. Several reports have shown that hormone-suppressive treatment with the L-enantiomer of tetraiodothyronine (L-T-4) benefits high-risk thyroid cancer patients by decreasing progression and recurrence rates, and cancer-related mortality. Evidence suggests, however, that complex regulatory mechanisms (including both TSH-dependent and TSH-independent pathways) are involved in thyroid-cell regulation. Indeed, no significant improvement has been obtained by suppressing TSH in patients with low-risk thyroid cancer. Moreover, TSH suppression implies a state of subclinical thyrotoxicosis. In low-risk patients, the goal of L-T-4 treatment is therefore to obtain a TSH level in the normal range (0.5-2.5 mU/1). Only selected patients with high-risk papillary and follicular thyroid cancer require long-term TSH-suppressive doses of L-T-4. In these patients, careful monitoring is necessary to avoid undesirable effects on bone and heart