Functional analyses of transcription factor binding sites that differ between present-day and archaic humans

We analyze 25 previously identified transcription factor binding sites that carry DNA sequence changes that are present in all or nearly all present-day humans, yet occur in the ancestral state in Neandertals and Denisovans, the closest evolutionary relatives of humans. When the ancestral and derived forms of the transcription factor binding sites are tested using reporter constructs in 3 neuronal cell lines, the activity of 12 of the derived versions of transcription factor binding sites differ from the respective ancestral variants. This suggests that the majority of this class of evolutionary differences between modern humans and Neandertals may affect gene expression in at least some tissue or cell type

U mobilization and associated U isotope fractionation by sulfur-oxidizing bacteria

Uranium (U) contamination of the environment causes high risk to health, demanding for effective and sustainable remediation. Bioremediation via microbial reduction of soluble U(VI) is generating high fractions (>50%) of insoluble non-crystalline U(IV) which, however, might be remobilized by sulfur-oxidizing bacteria. In this study, the efficacy of Acidithiobacillus (At.) ferrooxidans and Thiobacillus (T.) denitrificans to mobilize non-crystalline U(IV) and associated U isotope fractionation were investigated. At. ferrooxidans mobilized between 74 and 91% U after 1 week, and U mobilization was observed for both, living and inactive cells. Contrary to previous observations, no mobilization by T. denitrificans could be observed. Uranium mobilization by At. ferrooxidans did not cause U isotope fractionation suggesting that U isotope ratio determination is unsuitable as a direct proxy for bacterial U remobilization. The similar mobilization capability of active and inactive At. ferrooxidans cells suggests that the mobilization is based on the reaction with the cell biomass. This study raises doubts about the long-term sustainability of in-situ bioremediation measures at U-contaminated sites, especially with regard to non-crystalline U(IV) being the main component of U bioremediation

Vacancy complexes with oversized impurities in Si and Ge

In this paper we examine the electronic and geometrical structure of impurity-vacancy complexes in Si and Ge. Already Watkins suggested that in Si the pairing of Sn with the vacancy produces a complex with the Sn-atom at the bond center and the vacancy split into two half vacancies on the neighboring sites. Within the framework of density-functional theory we use two complementary ab initio methods, the pseudopotential plane wave (PPW) method and the all-electron Kohn-Korringa-Rostoker (KKR) method, to investigate the structure of vacancy complexes with 11 different sp-impurities. For the case of Sn in Si, we confirm the split configuration and obtain good agreement with EPR data of Watkins. In general we find that all impurities of the 5sp and 6sp series in Si and Ge prefer the split-vacancy configuration, with an energy gain of 0.5 to 1 eV compared to the substitutional complex. On the other hand, impurities of the 3sp and 4sp series form a (slightly distorted) substitutional complex. Al impurities show an exception from this rule, forming a split complex in Si and a strongly distorted substitutional complex in Ge. We find a strong correlation of these data with the size of the isolated impurities, being defined via the lattice relaxations of the nearest neighbors.Comment: 8 pages, 4 bw figure

Experiments reveal enrichment of 11B in granitic melt resulting from tourmaline crystallisation

Tourmaline is the most common boron-rich mineral in magmatic systems. In this study, we determined experimentally the fractionation of boron isotopes between granitic melt and tourmaline for the first time. Our crystallisation experiments were performed using a boron-rich granitic glass (B2O3 ≈ 8 wt. %) at 660−800 °C, 300 MPa, and aH2O = 1, in which tourmaline occurs as the only boron-hosting mineral. Our experimental results at four different temperatures show a small and temperature-dependent boron isotope fractionation between granitic melt and tourmaline (Δ11Bmelt–Tur = þ0.90 ± 0.05 ‰ at 660 °C and þ0.23 ± 0.12 ‰ at 800 °C), and the temperature dependence can be defined as Δ11Bmelt–Tur = 4.51 × (1000/T [K]) − 3.94 (R2 = 0.96). Using these boron isotope fractionation factors, tourmaline can serve as a tracer to quantitatively interpret boron isotopic ratios in evolved magmatic systems. Our observation that 11B is enriched in granitic melt relative to tourmaline suggests that the δ11B of late-magmatic tourmaline should be higher than tourmaline that crystallised at an early stage, if B isotope fractionation is not affected by other processes, such as fluid loss. © 2022 The Authors

Background Independence and Asymptotic Safety in Conformally Reduced Gravity

We analyze the conceptual role of background independence in the application of the effective average action to quantum gravity. Insisting on a background independent renormalization group (RG) flow the coarse graining operation must be defined in terms of an unspecified variable metric since no rigid metric of a fixed background spacetime is available. This leads to an extra field dependence in the functional RG equation and a significantly different RG flow in comparison to the standard flow equation with a rigid metric in the mode cutoff. The background independent RG flow can possess a non-Gaussian fixed point, for instance, even though the corresponding standard one does not. We demonstrate the importance of this universal, essentially kinematical effect by computing the RG flow of Quantum Einstein Gravity in the ``conformally reduced'' Einstein--Hilbert approximation which discards all degrees of freedom contained in the metric except the conformal one. Without the extra field dependence the resulting RG flow is that of a simple $\phi^4$-theory. Including it one obtains a flow with exactly the same qualitative properties as in the full Einstein--Hilbert truncation. In particular it possesses the non-Gaussian fixed point which is necessary for asymptotic safety.Comment: 4 figures

On the Possibility of Quantum Gravity Effects at Astrophysical Scales

The nonperturbative renormalization group flow of Quantum Einstein Gravity (QEG) is reviewed. It is argued that at large distances there could be strong renormalization effects, including a scale dependence of Newton's constant, which mimic the presence of dark matter at galactic and cosmological scales.Comment: LaTeX, 18 pages, 4 figures. Invited contribution to the Int. J. Mod. Phys. D special issue on dark matter and dark energ

African horse sickness

African horse sickness (AHS) is a devastating disease of equids caused by an arthropod-borne virus belonging to the Reoviridae family, genus Orbivirus. It is considered a major health threat for horses in endemic areas in sub-Saharan Africa. African horse sickness virus (AHSV) repeatedly caused large epizootics in the Mediterranean region (North Africa and southern Europe in particular) as a result of trade in infected equids. The unexpected emergence of a closely related virus, the bluetongue virus, in northern Europe in 2006 has raised fears about AHSV introduction into Europe, and more specifically into AHSV-free regions that have reported the presence of AHSV vectors, e.g. Culicoides midges. North African and European countries should be prepared to face AHSV incursions in the future, especially since two AHSV serotypes (serotypes 2 and 7) have recently spread northwards to western (e.g. Senegal, Nigeria, Gambia) and eastern Africa (Ethiopia), where historically only serotype 9 had been isolated. The authors review key elements of AHS epidemiology, surveillance and prophylaxis.La peste équine est une maladie extrêmement grave des équidés causée par un Orbivirus appartenant à la famille des Reoviridae. Le virus est transmis par des arthropodes. La maladie constitue une menace sanitaire majeure pour les équidés des régions endémiques de l’Afrique subsaharienne. Le virus de la peste équine est à l’origine de vastes épizooties récurrentes dans la région méditerranéenne (particulièrement au nord de l’Afrique et au sud de l’Europe), associées aux échanges internationaux d’équidés infectés. L’émergence inattendue du virus de la fièvre catarrhale ovine dans le nord de l’Europe en 2006, virus étroitement apparenté à celui de la peste équine, a suscité de grandes inquiétudes quant au risque d’introduction du virus de la peste équine en Europe et plus particulièrement dans les régions indemnes de cette maladie mais ayant rapporté la présence des vecteurs compétents pour le virus, notamment les moucherons du genre Culicoides. Les pays d’Afrique du Nord et d’Europe devraient se préparer à faire face à des incursions du virus de la peste équine à l’avenir, en particulier depuis la récente propagation de deux sérotypes du virus (les sérotypes 2 et 7) en direction du nord, aussi bien en Afrique occidentale (Sénégal, Nigeria, Gambie...) qu’en Afrique orientale (Éthiopie), régions où par le passé seul le sérotype 9 avait été isolé. Les auteurs font le point sur les principaux éléments de l’épidémiologie, la surveillance et la prophylaxie de la peste équine.La peste equina es una devastadora enfermedad de los équidos cuyo agente etiológico es un virus transmitido por artrópodos del género Orbivirus, familia Reoviridae. Esá considerada una importante amenaza sanitaria para los caballos de las zonas del África subsahariana en las que es endémica. En repetidas ocasiones, las operaciones comerciales con équidos infectados por el virus han causado grandes epizootias en la región del Mediterráneo (norte de África y sur de Europa en particular). Desde 2006, cuando en el norte de Europa apareció inesperadamente el virus de la lengua azul, estrechamente emparentado con el de la peste equina, existe el temor de que este último penetre en Europa, y más concretamente en regiones hasta ahora exentas de él donde está descrita la presencia de vectores como los jejenes Culicoides. Los países norteafricanos y europeos deben estar preparados para responder en el futuro a incursiones del virus de la peste equina, máxime cuando dos de sus serotipos (el 2 y el 7) se han propagado en fechas recientes hacia el norte hasta alcanzar el África Occidental (Senegal, Nigeria, Gambia...) y Oriental (Etiopía), zonas donde hasta entonces solo se había aislado el serotipo 9. Los autores pasan revista a los principales aspectos de la epidemiología, vigilancia y profilaxis de la enfermedad.http://www.oie.int/en/publications-and-documentation/scientific-and-technical-review-free-accessam201

Persistence of the Isotopic Signature of Pentavalent Uranium in Magnetite

Uranium isotopic signatures can be harnessed to monitor the reductive remediation of subsurface contamination or to reconstruct paleo-redox environments. However, the mechanistic underpinnings of the isotope fractionation associated with U reduction remain poorly understood. Here, we present a coprecipitation study, in which hexavalent U (U(VI)) was reduced during the synthesis of magnetite and pentavalent U (U(V)) was the dominant species. The measured δ$^{238}$U values for unreduced U(VI) (∼−1.0‰), incorporated U (96 ± 2% U(V), ∼−0.1‰), and extracted surface U (mostly U(IV), ∼0.3‰) suggested the preferential accumulation of the heavy isotope in reduced species. Upon exposure of the U-magnetite coprecipitate to air, U(V) was partially reoxidized to U(VI) with no significant change in the δ$^{238}$U value. In contrast, anoxic amendment of a heavy isotope-doped U(VI) solution resulted in an increase in the δ$^{238}$U of the incorporated U species over time, suggesting an exchange between incorporated and surface/aqueous U. Overall, the results support the presence of persistent U(V) with a light isotope signature and suggest that the mineral dynamics of iron oxides may allow overprinting of the isotopic signature of incorporated U species. This work furthers the understanding of the isotope fractionation of U associated with iron oxides in both modern and paleo-environments