Radiation damage allows identification of truly inherited zircon

Many studies have reported U-Pb dates of zircon that are older than the igneous rocks that contain them, and they are therefore thought to be inherited from older rock complexes. Their presence has profound geodynamic implications and has been used to hypothesize about concealed micro-continents, continental crust beneath ocean islands, and recycling of continental material in the mantle beneath mid-ocean ridges. Here, we combine single zircon U-Pb dates and structural radiation damage determined by Raman spectroscopy from a Pliocene mid-ocean ridge gabbro and from Cenozoic igneous rocks to test whether radiation damage allows distinction between contamination and truly inherited zircon. We find that Precambrian zircon found in the Pliocene sample has accumulated substantially more radiation damage than could be explained if they had truly been inherited. In the Cenozoic samples, however, we find that the radiation damage of old grains corresponds with that of young magmatic zircon, suggesting they are genuinely inherited.publishedVersio

Volcanic evolution of an ultraslow-spreading ridge

Nearly 30% of ocean crust forms at mid-ocean ridges where the spreading rate is less than 20 mm per year. According to the seafloor spreading paradigm, oceanic crust forms along a narrow axial zone and is transported away from the rift valley. However, because quantitative age data of volcanic eruptions are lacking, constructing geological models for the evolution of ultraslow-spreading crust remains a challenge. In this contribution, we use sediment thicknesses acquired from ~4000 km of sub-bottom profiler data combined with 14C ages from sediment cores to determine the age of the ocean floor of the oblique ultraslow-spreading Mohns Ridge to reveal a systematic pattern of young volcanism outside axial volcanic ridges. Here, we present an age map of the upper lava flows within the rift valley of a mid-ocean ridge and find that nearly half of the rift valley floor has been rejuvenated by volcanic activity during the last 25 Kyr.publishedVersio

A Highly Depleted and Subduction-Modified Mantle Beneath the Slow-Spreading Mohns Ridge

The Mohns Ridge is a very slow-spreading ridge that, together with the Knipovich Ridge, marks the boundary between the North American and Eurasian plates in the Norwegian-Greenland Sea. In this study, we report the major and trace element composition of spatially associated basalts and peridotites from a gabbro-peridotite complex ∼20 km west of the Mohns Ridge rift flank. Formation of the ∼4–5 Myr crustal section involved accretion of normal mid-ocean ridge basalts with Na-content suggesting derivation from a depleted mantle source. This is consistent with the degree of partial melting estimated for clinopyroxene poor harzburgites using the Cr-number of spinel (14%–18%) and rare earth element modeling of orthopyroxene (16%–24%) and reconstructed whole-rock composition (14%–20%). If all the melting took place beneath the paleo-Mohns Ridge, a crustal thickness of ∼7–8 km is expected, which is nearly double the observed thickness. Orthopyroxene trace elements are not consistent with typical fractional melting expected for mid-ocean ridges but rather resemble that seen in supra-subduction zone peridotites. The geochemistry of both the basalts and the peridotites suggests that a water-rich slab flux in the past has influenced the mantle source. In turn, this caused hydrous melting which increased the depletion of the pyroxene components, leading to a highly depleted mantle that is now underlying much of the Arctic Mid-Ocean Ridges and represents the source for the spreading related magmatism.publishedVersio

Easily denaturing nucleic acids derived from intercalating nucleic acids: thermal stability studies, dual duplex invasion and inhibition of transcription start

The bulged insertions of (R)-1-O-(pyren-1-ylmethyl)glycerol (monomer P) in two complementary 8mer DNA strands (intercalating nucleic acids) opposite to each other resulted in the formation of an easily denaturing duplex, which had lower thermal stability (21.0°C) than the wild-type double-stranded DNA (dsDNA, 26.0°C), but both modified oligodeoxynucleotides had increased binding affinity toward complementary single-stranded DNA (ssDNA) (41.5 and 39.0°C). Zipping of pyrene moieties in an easily denaturing duplex gave formation of a strong excimer band at 480 nm upon excitation at 343 nm in the steady-state fluorescence spectra. The excimer band disappeared upon addition of a similar short dsDNA, but remained when adding a 128mer dsDNA containing the same sequence. When P was inserted into 2′-OMe-RNA strands, the duplex with zipping P was found to be more stable (42.0°C) than duplexes with the complementary ssDNAs (31.5 and 19.5°C). The excimer band observed in the ds2′-OMe-RNA with zipping P had marginal changes upon addition of both 8 and 128mer dsDNA. Synthesized oligonucleotides were tested in a transcriptional inhibition assay for targeting of the open complex formed by Escherichia coli RNA polymerase with the lac UV-5 promoter using the above mentioned 128mer dsDNA. Inhibition of transcription was observed for 8mer DNAs possessing pyrene intercalators and designed to target both template and non-template DNA strands within the open complex. The observed inhibition was partly a result of unspecific binding of the modified DNAs to the RNA polymerase. Furthermore, the addition of 8mer DNA with three bulged insertions of P designed to be complementary to the template strand at the +36 to +43 position downstream of the transcription start resulted in a specific halt of transcription producing a truncated RNA transcript. This is to our knowledge the first report of an RNA elongation stop mediated by a small DNA sequence possessing intercalators. The insertions of P opposite to each other in ds2′-OMe-RNA showed inhibition efficiency of 96% compared with 25% for unmodified ds2′-OMe-RNA

Estrogen Receptors are Present in Neocortical Transplants

Fetal neocortical tissue was grafted into neocortical lesion cavities made in newborn rats. After two weeks survival, in vitro binding of [3H]- estradiol to cytosolic preparations provided evidence of estrogen receptors within the transplants. The observed high levels correspond to previous work demonstrating elevated estrogen receptor levels during the first postnatal week in the rat cerebral cortex

Superparamagnetic iron oxide polyacrylic acid coated {\gamma}-Fe2O3 nanoparticles does not affect kidney function but causes acute effect on the cardiovascular function in healthy mice

This study describes the distribution of intravenously injected polyacrylic acid (PAA) coated {\gamma}-Fe2O3 NPs (10 mg kg-1) at the organ, cellular and subcellular levels in healthy BALB/cJ mice and in parallel addresses the effects of NP injection on kidney function, blood pressure and vascular contractility. Magnetic resonance imaging (MRI) and transmission electron microscopy (TEM) showed accumulation of NPs in the liver within 1h after intravenous infusion, accommodated by intracellular uptake in endothelial and Kupffer cells with subsequent intracellular uptake in renal cells, particularly the cytoplasm of the proximal tubule, in podocytes and mesangial cells. The renofunctional effects of NPs were evaluated by arterial acid-base status and measurements of glomerular filtration rate (GFR) after instrumentation with chronically indwelling catheters. Arterial pH was 7.46 and 7.41 in mice 0.5 h after injections of saline or NP, and did not change over the next 12h. In addition, the injections of NP did not affect arterial PCO2 or [HCO3-] either. Twenty-four and 96h after NP injections, the GFR averaged 11.0 and 13.0 ml min-1 g-1, respectively, values which were statistically comparable with controls (14.0 and 14.0 ml min-1 g-1). Mean arterial blood pressure (MAP) decreased 12-24h after NP injections (111 vs 123 min-1) associated with a decreased contractility of small mesenteric arteries revealed by myography to characterise endothelial function. In conclusion, our study demonstrates that accumulation of superparamagnetic iron oxide nanoparticles does not affect kidney function in healthy mice but temporarily decreases blood pressure.Comment: 21 pages, 12 figures, published in Toxicology and Applied Pharmacology 201

Outcome in design-specific comparisons between highly crosslinked and conventional polyethylene in total hip arthroplasty

<p>Background and purpose — Most registry studies regarding highly crosslinked polyethylene (XLPE) have focused on the overall revision risk. We compared the risk of cup and/or liner revision for specific cup and liner designs made of either XLPE or conventional polyethylene (CPE), regarding revision for any reason and revision due to aseptic loosening and/or osteolysis.</p> <p>Patients and methods — Using the Nordic Arthroplasty Register Association (NARA) database, we identified cup and liner designs where either XLPE or CPE had been used in more than 500 THAs performed for primary hip osteoarthritis. We assessed risk of revision for any reason and for aseptic loosening using Cox regression adjusted for age, sex, femoral head material and size, surgical approach, stem fixation, and presence of hydroxyapatite coating (uncemented cups).</p> <p>Results — The CPE version of the ZCA cup had a risk of revision for any reason similar to that of the XLPE version (p = 0.09), but showed a 6-fold higher risk of revision for aseptic loosening (p < 0.001). The CPE version of the Reflection All Poly cup had an 8-fold elevated risk of revision for any reason (p < 0.001) and a 5-fold increased risk of revision for aseptic loosening (p < 0.001). The Charnley Elite Ogee/Marathon cup and the Trilogy cup did not show such differences.</p> <p>Interpretation — Whether XLPE has any advantage over CPE regarding revision risk may depend on the properties of the polyethylene materials being compared, as well as the respective cup designs, fixation type, and follow-up times. Further research is needed to elucidate how cup design factors interact with polyethylene type to affect the risk of revision.</p

Midler til bekæmpelse af skurv i økologiske æbler

Brochuren præsenterer FØJO II projektet StopScab: Bekæmpelse af æbleskurv. I projektet afprøves potentielle alternative bekæmpelsesmidler (planteekstrakter, olier og biologiske bekæmpelsesorganismer)for deres bekæmpelseseffekt overfor æbleskurv (Venturia inaequalis) i laboratorie, vækstkammer og plantage. Udvalgte midler undersøges nærmere for deres virkemekanismer