Replication termination and chromosome dimer resolution in the archaeon Sulfolobus solfataricus

Eubacteria and archaea possess single-circular chromosomes, yet some archaea resemble eukaryotes in using multiple origins and replication forks. Replication termination in Sulfolobus is found to occur by stochastic collision of these forks, and—unlike the situation in eubacteria—it is not linked to chromosome segregation

Design and feasibility testing of a novel group intervention for young women who binge drink in groups

BackgroundYoung women frequently drink alcohol in groups and binge drinking within these natural drinking groups is common. This study describes the design of a theoretically and empirically based group intervention to reduce binge drinking among young women. It also evaluates their engagement with the intervention and the acceptability of the study methods.MethodsFriendship groups of women aged 18–35 years, who had two or more episodes of binge drinking (>6 UK units on one occasion; 48g of alcohol) in the previous 30 days, were recruited from the community. A face-to-face group intervention, based on the Health Action Process Approach, was delivered over three sessions. Components of the intervention were woven around fun activities, such as making alcohol free cocktails. Women were followed up four months after the intervention was delivered. Results The target of 24 groups (comprising 97 women) was recruited. The common pattern of drinking was infrequent, heavy drinking (mean consumption on the heaviest drinking day was UK 18.1 units). Process evaluation revealed that the intervention was delivered with high fidelity and acceptability of the study methods was high. The women engaged positively with intervention components and made group decisions about cutting down. Twenty two groups set goals to reduce their drinking, and these were translated into action plans. Retention of individuals at follow up was 87%.ConclusionsThis study successfully recruited groups of young women whose patterns of drinking place them at high risk of acute harm. This novel approach to delivering an alcohol intervention has potential to reduce binge drinking among young women. The high levels of engagement with key steps in the behavior change process suggests that the group intervention should be tested in a full randomised controlled trial

Case Reports1. A Late Presentation of Loeys-Dietz Syndrome: Beware of TGFβ Receptor Mutations in Benign Joint Hypermobility

Background: Thoracic aortic aneurysms (TAA) and dissections are not uncommon causes of sudden death in young adults. Loeys-Dietz syndrome (LDS) is a rare, recently described, autosomal dominant, connective tissue disease characterized by aggressive arterial aneurysms, resulting from mutations in the transforming growth factor beta (TGFβ) receptor genes TGFBR1 and TGFBR2. Mean age at death is 26.1 years, most often due to aortic dissection. We report an unusually late presentation of LDS, diagnosed following elective surgery in a female with a long history of joint hypermobility. Methods: A 51-year-old Caucasian lady complained of chest pain and headache following a dural leak from spinal anaesthesia for an elective ankle arthroscopy. CT scan and echocardiography demonstrated a dilated aortic root and significant aortic regurgitation. MRA demonstrated aortic tortuosity, an infrarenal aortic aneurysm and aneurysms in the left renal and right internal mammary arteries. She underwent aortic root repair and aortic valve replacement. She had a background of long-standing joint pains secondary to hypermobility, easy bruising, unusual fracture susceptibility and mild bronchiectasis. She had one healthy child age 32, after which she suffered a uterine prolapse. Examination revealed mild Marfanoid features. Uvula, skin and ophthalmological examination was normal. Results: Fibrillin-1 testing for Marfan syndrome (MFS) was negative. Detection of a c.1270G > C (p.Gly424Arg) TGFBR2 mutation confirmed the diagnosis of LDS. Losartan was started for vascular protection. Conclusions: LDS is a severe inherited vasculopathy that usually presents in childhood. It is characterized by aortic root dilatation and ascending aneurysms. There is a higher risk of aortic dissection compared with MFS. Clinical features overlap with MFS and Ehlers Danlos syndrome Type IV, but differentiating dysmorphogenic features include ocular hypertelorism, bifid uvula and cleft palate. Echocardiography and MRA or CT scanning from head to pelvis is recommended to establish the extent of vascular involvement. Management involves early surgical intervention, including early valve-sparing aortic root replacement, genetic counselling and close monitoring in pregnancy. Despite being caused by loss of function mutations in either TGFβ receptor, paradoxical activation of TGFβ signalling is seen, suggesting that TGFβ antagonism may confer disease modifying effects similar to those observed in MFS. TGFβ antagonism can be achieved with angiotensin antagonists, such as Losartan, which is able to delay aortic aneurysm development in preclinical models and in patients with MFS. Our case emphasizes the importance of timely recognition of vasculopathy syndromes in patients with hypermobility and the need for early surgical intervention. It also highlights their heterogeneity and the potential for late presentation. Disclosures: The authors have declared no conflicts of interes

Scandium

International audienceAtomic symbol: Sc Atomic number: 21 Atomic weight: 44.95591 Isotopes and abundances: 45 Sc 100 % 1 Atm melting point: 1541 C 1 Atm boiling point: 2836 C Common valences: 3+ Ionic radii: 6-fold, 74.5 pm, 8-fold, 87 pm Pauling electronegativity: 1.36 First ionization energy: 633.1 kJ/mol Chondritic (CI) abundance: 5.81 ppm Silicate Earth abundance: 16.4 ppm Crustal abundance: 21.9 Seawater abundance: 2–20 pmol/L Core abundance: $0 Properties Scandium is the lightest group 3 (IIIB) element and is the lightest of the transition metals. Its atomic number (proton number) is 21, has only one long-lived isotope, and has an atomic mass of 44.95591 u. Scandium's electronic configuration is [Ar]4s 2 3d 1 and only occurs in the trivalent state (Sc 3+) in nature. Thus, unlike most other period 4 transition metals, the geochemical behavior of scandium is not affected by redox conditions and shows lithophile behavior. The effective ionic radii in six-and eightfold coordination are 74.5 and 87 pm, respectively (Shannon, 1976), and its Pauling electronegativ-ity is 1.36. Pure scandium metal has a melting point of 1541 C at 1 atm. The International Union of Pure and Applied Chemistry considers Sc to be a rare earth element (REE) (Damhus et al., 2005); however, the ionic radius and electronic configuration of Sc are sufficiently different from yttrium and the lanthanides that it is generally excluded from discussions of the REE. History and Use Scandium was " discovered " by Lars Fredrik Nilson in 1879 by separation from rare earth mixtures from euxenite and gadolinite and is named for Scandinavia. Global production of Sc is small ($10 tonnes per year) as a by-product from mining of ores of titanium, rare earths, apatite, and uranium. Bauxites are another potential source of Sc, as it gets concentrated, along with other elements, in the " red mud " residue that results from Al processing (Deady et al., 2016). The principal uses of Sc are in Sc-Al alloys and in solid oxide fuel cells. Minor amounts of Sc are also used in a variety of other applications including electronics, lasers, and lighting. Natural Abundances The abundance of Sc in the solar system, as estimated from chondritic meteorites, is ca. 5.81 ppm (McDonough and Sun, 1995). The refractory behavior of this element in the solar nebula as well as its lithophile behavior led to the relative concentration of this element in the silicate Earth, with an estimated abundance of about 16 ppm, which is also th

Solubility of Ore Minerals and Complexation of Ore Metals in Hydrothermal Solutions

Knowledge of the solubility of ore minerals and the speciation of ore metals in hydrothermal solutions is required for a complete understanding of the genesis of hydrothermal ores. In this chapter, we explore the factors that control solubility and speciation, demonstrate how to carry out quantitative calculations, and review the current state of knowledge for a number of economically important metals. The term solubility refers to the sum of the concentrations of all dissolved forms of a given metal in a hydrothermal solution in equilibrium with a mineral (or minerals) containing that metal. We use the term speciation to denote the relative concentrations of the various forms of a metal in solution

Applications of the combined portable XRF-benchtop SEM methodology to PGE exploration

Portable XRF (pXRF) and benchtop scanning electron microscopes equipped with energy dispersive systems (bSEM-EDS) are two real-time analytical techniques that can be combined to collect on-site lithogeochemical and mineral chemical results at dramatically reduced cost and time compared to traditional analytical methods. The Coldwell Complex, northwestern Ontario, is used as a case study on how the combination of these techniques can be applied to mineral exploration. Our results show that whole-rock Ba, V/Ti, Cu/S determined by pXRF, and plagioclase, olivine, and clinopyroxene compositions measured by bSEM-EDS can be applied to exploration for PGE deposits. Cu/S ratios for disseminated sulfides are a proxy for metal tenor, which can be applied as a vector towards higher grade mineralization. Potential magma recharge zones are identified by inspecting down-hole variations in plagioclase, olivine, and clinopyroxene compositions. Fluctuating down-hole variations in these parameters are interpreted to reflect episodic magma recharge. Whether rocks contain PGE mineralization can initially be assessed by documenting the variability of mineral chemistry, i.e., the greater variability of mineral chemistry could be used to vector higher grade PGE mineralization, particularly if the mineralization is conduit-related. Lastly, geochemical mapping of the igneous stratigraphy enables identification of favorable hosts for mineralization. Down-hole whole-rock variations in Ba and V/Ti from pXRF, and mineral chemical profiles from bSEM-EDS are used to discriminate the mineralized Marathon Series from the barren Layered Series throughout the Coldwell Complex. Whole-rock Ba and V/Ti from pXRF and mineral chemical results from bSEM-EDS could prove useful in other settings of the Midcontinent Rift (e.g., the Duluth Complex, Eagle and Eagle East intrusions, Tamarack Intrusive Complex, and the Sonju Lake intrusion) and elsewhere (e.g., the Stillwater Complex) to identify mineralized host rock types. An additional important application is a rapid interpretation of petrogenesis. Down-hole variations in olivine-clinopyroxene Mg-Fe exchange coefficients determined by bSEM-EDS analyses show that olivine-clinopyroxene pairs in the Marathon Series units, particularly for those within PGE mineralized zones, have compositions that are closer to chemical equilibrium (constant) compared to units of the barren Layered Series (highly variable), and thus could be a tool for interpreting petrogenetic processes active in the magma chamber or during the mineralization forming event

Igneous architecture and implications for diverse Cu-PGE mineralization styles in a conduit system: an example from the Area 41 Cu-PGE occurrence, Coldwell Complex, Canada

The Area 41 copper-platinum-group element (PGE) occurrence was discovered in 2006 at the northwestern margin of the Coldwell Complex. The discovery was significant because of the sizable mineralized intersections, including 1.4ppm Pd+Pt and 0.32% Cu over 43m. Since then, exploration along the northern margin has resulted in the discovery of several other Cu-PGE zones with similar grades and host rocks. Field relationships, drill-core logging, petrography, and lithogeochemistry indicate that the rocks formed from several extrusive and intrusive events related to at least three magmatic series that are from oldest to youngest: Metabasalt, the Layered Series, and the Marathon Series. Three types of Cu-PGE mineralization are hosted within separate intrusions of the Marathon Series. Type 1 is hosted by coarse-grained subophitic gabbro and exhibits high Cu/Pd (>100,000) and low PGE grades, formed at R-factors of 10(5)) and low S/Se ratios (800-2000) that suggest S loss. Three-dimensional modeling of the occurrence shows a north-south, keel-shaped trough at the western end of mineralization and a systematic spatial variation in the proportions of various Marathon Series units, including pegmatitic subophitic gabbro, breccia units, apatitic clinopyroxenite, and oxide melatroctolite, that correlate with decreasing thickness of mineralization, eastward and away from the trough. These observations suggest that multiple intrusions were emplaced along a feeder channel, some of which flowed laterally outwards to form sills. Taken together, these characteristics are consistent with a conduit model for deposit formation and are thus important vectors for exploration

Au-Bi-Te(-Cu) Mineralization in the Wawa Gold Corridor (Ontario, Canada): Implications for the Role of Bi-Rich Polymetallic Melts in Orogenic Au Systems

The Wawa Gold Corridor, a series of Archean orogenic Au deposits in the Michipicoten greenstone belt, Canada, comprises two styles of Au mineralization: (1) syn-deformation gold associated with pyrite and arsenopyrite; and (2) late- to post-deformation gold associated with chalcopyrite and Bi-Te(-S) phases. Through petrographic and mineral–chemical analysis, it was determined that gold in the latter assemblages precipitated from Bi-rich polymetallic melts during hydrothermal overprinting of the earlier Au-As-S mineralization; this event was likely driven by the emplacement of Archean lamprophyres. The formation and evolution of these melts was governed by fluid–pyrite reaction interfaces, where the bulk composition of the melts was broadly controlled by the trace-element chemistry of the sulphide minerals in the local host rocks. This suggests that the melt-formation event involved mobilization of existing metal endowments related to early Au events, rather than addition of new Au, Bi, and Te. Thus, the deposition of high-grade Au by Bi-rich melts was dependent on pre-existing sulphide mineralization, both as a source of metals and as micro-environments that stabilized the melts. The paragenesis documented in the Wawa Gold Corridor (i.e., early hydrothermal Au-As-S mineralization and late melt-related Au-Bi-Te mineralization) has been previously recognized in numerous other orogenic and non-orogenic Au deposits. Herein, it is suggested that this apparent consistency in the timing of melt events across multiple systems probably reflects the physicochemical conditions (i.e., fO2-aH2S) of orogenic fluids being incompatible with molten Bi. Bi-rich polymetallic melts are hence unlikely to form primary Au mineralization in orogenic systems but can, however, have a significant impact on the ultimate deposit-scale distribution of Au via secondary mobilization and enrichment

The role of magma injection and crystal sorting in the formation of early gabbros at the Coldwell Complex, Ontario, Canada

The Layered Series of the Midcontinent Rift related Coldwell Complex comprises thick sections of gabbro, without any known associated ultramafic rocks. It represents a major early intrusive unit of the Coldwell Complex and consists of thick accumulations of olivine gabbro and oxide augite melatroctolite. This study combines petrography, mineral chemistry, and lithogeochemistry to constrain the magma composition and petrogenesis of the layered Series. The presence of cumulus orthoclase together with the observation that the Layered Series rocks plot in the alkaline field on a total alkali-silica diagram indicate that the Layered Series magma has an alkaline parentage. The stratigraphy of the Layered Series cannot be fully correlated between different areas using lithogeochemistry and mineral chemistry. This together with observed normal and reverse trends for mineral chemical compositions in different areas suggest that the processes related to magma emplacement and crystallization were different in different locations. The whole-rock concentrations of incompatible elements and the compositions of major minerals of the olivine gabbro and oxide augite melatroctolite units are chemically similar. However, major element lithogeochemistry is variable, dominantly due to differences in the abundances of olivine, clinopyroxene, plagioclase, and magnetite. An additional observation is that olivine and clinopyroxene are not in chemical equilibrium. Together, these observations are interpreted to reflect a combination of multiple injections of magma and crystal sorting in an open system