The Marinoan cap carbonate of Svalbard: Syngenetic marine dolomite with ¹⁷O-anomalous carbonate‐associated sulphate

Two cap carbonates overlying Cryogenian panglacial deposits are found in North- East Svalbard of which the younger (635 Ma) forms the base of the Ediacaran Period. It is represented by a transgressive succession in which laminated do-lostone, typically around 20 m thick (Member D1), is succeeded transitionally by a similar thickness of impure carbonates (Member D2). In Spitsbergen, there is evidence of microbially influenced sediment stabilisation and carbonate precipitation in the lower part of D1, whilst the upper part of D1 and D2 show centimetre- decimetre- scale graded units with undulatory lamination interpreted as evidence of storm activity. Carbonate originated as possible freshwater whitings, as well as microbial precipitates. Exhumed and eroded hardgrounds display replacive 10– 30 μm dolomite crystals with cathodoluminescence characteris-tics consistent with early diagenetic manganese and iron reduction. Regionally, carbon isotope values consistently decrease by around 2‰ from around −3‰ over 30 m of section which is both a temporal and a bathymetric signal, but not a global one. An exponential decline in carbonate production predicted by box models is fitted by a semi- quantitative sedimentation model. A mass- anomalous 17O depletion in carbonate- associated sulphate in dolomite, inherited from pre-cursor calcite, decreases from −0.6 to −0.3‰ in the basal 15 m of section and then approaches background values. The post- glacial anomalous 17O depletion in carbonate- associated sulphate and barite elsewhere has been interpreted in terms of ultra- high pCO2 at the onset of deglaciation. Such anomalies, with larger amplitude, have been reported in Svalbard from underlying lacustrine and tufa-ceous limestones representing a hyperarid glacial environment. The anomalous sulphate could be produced contemporarily, or the internally drained landscape may have continued to release 17O-anomalous sulphate as it was transgressed during cap carbonate deposition. The late Cryogenian to earliest Ediacaran record in Svalbard provides the most complete record of the basal 17O - depletion event in the world

Isotopic evidence for pallasite formation by impact mixing of olivine and metal during the first 10 million years of the Solar System

Pallasites are mixtures of core and mantle material that may have originated from the core-mantle boundary of a differentiated body. However, recent studies have introduced the possibility that they record an impact mix, in which case an isotopic difference between metal and silicates in pallasites may be expected. We report a statistically significant oxygen isotope disequilibrium between olivine and chromite in main group pallasites that implies the silicate and metal portions of these meteorites stem from distinct isotopic reservoirs. This indicates that these meteorites were formed by impact mixing, during which a planetary core was injected into the mantle of another body. The impactor likely differentiated within ∼1–2 Myr of the start of the Solar System based on Hf-W chronology of pallasite metal, and we infer the age of the impact based on Mn-Cr systematics and cooling rates at between ∼1.5 and 9.5 Myr after CAIs. When combined with published slow sub-solidus cooling rates for these meteorites and considering that several pallasite groups exist, our results indicate that such impacts may be an important stage in the evolution of planetary bodies

Volcanic ash as a resource for future research on Earth and the Moon

When a volcano erupts, it is often associated with destruction, particularly damage to infrastructure and loss of life. But these natural events also offer unexpected research opportunities, leading to serendipitous discoveries. This was the case for the volcanic events that made the headlines during 19 September to 25 December 2021, on the Canarian Island of La Palma. Rather than viewing the voluminous ash that erupted as a waste material needing to be removed as soon as possible, we saw the many possibilities that this remarkable material could offer science and engineering. Sustainability is a word that is commonly used in connection with geology these days. Here we present some possibilities of how the La Palma ash can be re‐purposed for use on this planet but also help us to develop new ideas for the future living on the Moon

An Isotopic Investigation Of Early Planetesimal Differentiation Processes

The differentiation and early evolution of planetesimals is relatively poorly understood. The Main Group pallasites (PMGs) and IIIAB irons are differentiated meteorite groups from deep planetesimal interiors. They provide a window into the early evolution of rocky planets because of the abundance of samples from these groups and because a common planetary provenance has been proposed. Oxygen isotope analyses are crucial in understanding these relationships. The mineralogy of the PMGs and IIIABs, which seemingly record the magmatic evolution of their parent body, offers a unique opportunity to study early planetary differentiation processes. High-precision oxygen isotope analyses are used in conjunction with petrological characteristics and Cr and W isotope analyses to subdivide these groups and investigate formation processes. Two subgroups are identified in PMGs: PMG-low and PMG-high. The former exhibits an oxygen isotopic disequilibrium between olivine and chromite that is unexplainable through known mass-dependent processes. These minerals therefore either sample multiple isotopic reservoirs mixed during an impact or, less likely, are affected by complex anharmonic or nuclear field shift effects. Further investigation on these effects must be executed to completely discount these latter possibilities. The PMG-high chromite isotope ratios probably record equilibration between these two reservoirs. Chromium and W isotope analyses on PMG samples show no disequilibrium but provide an excellent chronology. High-precision oxygen isotope analyses of IIIABs has identified three previously unknown subgroups with serious implications for the interpretation of the IIIAB suite of samples. These likely originate from different planetesimals and not from complex core evolution. Finally, chromite in PMGs and IIIABs is shown to be resolvable in Δ17O which precludes a common parent planetesimal. The findings of this study suggest that there may have been many more differentiated planetesimals in the early Solar System than previously thought and necessitate care in future studies linking meteorite groups by parent body

Developing and investigating a nanovibration intervention for the prevention/reversal of bone loss following spinal cord injury

Osteoporosis disrupts the fine-tuned balance between bone formation and resorption, leading to reductions in bone quantity and quality and ultimately increasing fracture risk. Prevention and treatment of osteoporotic fractures is essential for reductions in mortality, morbidity and the economic burden, particularly considering the ageing global population. Extreme bone loss that mimics time-accelerated osteoporosis develops in the paralysed limbs following complete spinal cord injury (SCI). In vitro nanoscale vibration (1 kHz, 30- or 90 nm amplitude) has been shown to drive differentiation of mesenchymal stem cells towards osteoblast-like phenotypes, enhancing osteogenesis and inhibiting osteoclastogenesis simultaneously. Here, we develop and characterise a wearable device designed to deliver and monitor continuous nano-amplitude vibration to the hindlimb long bones of rats with complete SCI. We investigate whether a clinically feasible dose of nanovibration (two 2-hours/day, 5-days/week for 6 weeks) is effective at reversing the established SCI-induced osteoporosis. Laser interferometry and finite element analysis confirmed transmission of nanovibration into the bone, and micro-computed tomography and serum bone formation and resorption markers assessed effectiveness. The intervention did not reverse SCI-induced osteoporosis. However, serum analysis indicated an elevated concentration of the bone formation marker procollagen type 1 N-terminal propeptide (P1NP) in rats receiving 40 nm amplitude nanovibration, suggesting increased synthesis of type 1 collagen, the major organic component of bone. Therefore, enhanced doses of nanovibrational stimulus may yet prove beneficial in attenuating/reversing osteoporosis, particularly in less severe forms of osteoporosis

Localization and expression of selenoprotein S in the testis of Psammomys obesus

Selenium is an essential trace element and selenoprotein S is a member of the selenoprotein family that has the non-standard amino acid selenocysteine incorporated into the polypeptide. Dietary selenium has been shown to play an important protective role in a number of diseases including cancer, immune function and the male reproductive system. In this study, we have observed high levels of selenoprotein S gene expression in the testis from Psammomys obesus. Real-time PCR and immunofluorescence demonstrate that selenoprotein S expression is low in testes from 4-week-old animals but increases significantly by 8 weeks of age and remains high until 17 weeks of age. Selenoprotein S protein is detected in primary spermatocytes, Leydig and Sertoli cells of 8, 12 and 17-week-old animals. These results suggest that selenoprotein S may play a role in spermatogenesis.<br /

A gene expression signature for insulin resistance

Insulin resistance is a heterogeneous disorder caused by a range of genetic and environmental factors, and we hypothesize that its aetiology varies considerably between individuals. This heterogeneity provides significant challenges to the development of effective therapeutic regimes for long-term management of type 2 diabetes. We describe a novel strategy, using large-scale gene expression profiling, to develop a Gene Expression Signature (GES) that reflects the overall state of insulin resistance in cells and patients. The GES was developed from 3T3-L1 adipocytes that were made &lsquo;insulin resistant&rsquo; by treatment with tumour necrosis factor-alpha (TNF&alpha;) and then reversed with aspirin and troglitazone (&lsquo;re-sensitized&rsquo;). The GES consisted of five genes whose expression levels best discriminated between the insulin resistant and insulin re-sensitized states. We then used this GES to screen a compound library for agents that affected the GES genes in 3T3- L1 adipocytes in a way that most closely resembled the changes seen when insulin resistance was successfully reversed using aspirin and troglitazone. This screen identified both known and new insulin sensitizing compounds including non-steroidal anti inflammatory agents, &beta;-adrenergic antagonists, beta-lactams and sodium channel blockers. We tested the biological relevance of this GES in participants in the San Antonio Family Heart Study (n = 1,240) and showed that patients with the lowest GES scores were more insulin resistant (according to HOMA_IR and fasting plasma insulin levels, P &lt; 0.001). These findings show that GES technology can be used for both the discovery of insulin sensitizing compounds and the characterization of patients into subtypes of insulin resistance according to GES scores, opening the possibility of developing a personalized medicine approach to type 2 diabetes.<br /