776 research outputs found
Biophysical Features of Bacillithiol, the Glutathione Surrogate of Bacillus subtilis and other Firmicutes
Bacillithiol (BSH) is the major low-molecular-weight (LMW) thiol in many low-G+C Gram-positive bacteria (Firmicutes). Evidence now emerging suggests that BSH functions as an important LMW thiol in redox regulation and xenobiotic detoxification, analogous to what is already known for glutathione and mycothiol in other microorganisms. The biophysical properties and cellular concentrations of such LMW thiols are important determinants of their biochemical efficiency both as biochemical nucleophiles and as redox buffers. Here, BSH has been characterised and compared with other LMW thiols in terms of its thiol pKa, redox potential and thiolâdisulfide exchange reactivity. Both the thiol pKa and the standard thiol redox potential of BSH are shown to be significantly lower than those of glutathione whereas the reactivities of the two compounds in thiolâdisulfide reactions are comparable. The cellular concentration of BSH in Bacillus subtilis varied over different growth phases and reached up to 5 mM, which is significantly greater than previously observed from single measurements taken during mid-exponential growth. These results demonstrate that the biophysical characteristics of BSH are distinctively different from those of GSH and that its cellular concentrations can reach levels much higher than previously reported
Experimental verification of minima in excited long-range Rydberg states of Rb_2
Recent theoretical studies with alkali atoms A excited to high
Rydberg states predicted the existence of ultra long-range molecular bound
states. Such excited dimers have large electric dipole moments which, in
combination with their long radiative lifetimes, make them excellent candidates
for manipulation in applications. This letter reports on experimental
investigations of the self-broadening of Rb principal series lines, which
revealed multiple satellites in the line wings. The positions of the satellites
agree quantitatively with theoretically-predicted minima in the excited
long-range Rydberg states of Rb.Comment: 3 figures, 5 pages in two-column forma
Lower Coverdale and Gaytons: Middle Devonian and possibly older anorthosite-ferronorite, gabbro, and quartz monzonite intrusions in southeastern New Brunswick
The Lower Coverdale intrusion near Moncton, New Brunswick, has been intersected in drill holes at depths of 100â200 m below unconformably overlying Carboniferous sandstone, onglomerate and, locally, limestone of the Windsor, Mabou, and Cumberland groups. A large positive aeromagnetic anomaly suggests that the intrusion has a subsurface area of at least 30â40 km2. As revealed by drill core and cuttings, the intrusion consists of interlayered coarse-grained anorthosite and ferronorite, both intruded by gabbro, quartz monzonite, and minor felsic dykes. The ferronorite is high in Ti and P, and contains interstitial patite and ilmenite/magnetite and layers of apatite-ilmenite rock (nelsonite) up to several metres thick. Much of the core shows pervasive effects of metamorphism and alteration but microprobe analyses of the freshest samples revealed that the plagioclase in both anorthosite and ferronorite has andesine composition. The anorthosite and ferronorite are chemically distinct, but their close spatial association suggests a genetic link. In contrast, the younger gabbroic rocks differ in mineralogy and chemistry from, and appear unrelated to, the anorthosite and ferronorite. They are altered but not metamorphosed, and preserve intergranular textures. They contain more calcic plagioclase and augite, and have low Ti and P. The deepest drill hole in the Lower Coverdale intrusion encountered highly altered coarse-grained quartz monzonite at a depth of 1095â1206 m. The quartz monzonite is mineralogically and chemically similar to quartz monzonite in quarries near Gaytons, 20 km to the east. Virtually identical Middle Devonian U-Pb zircon ages of 90.6 ± 1.0 Ma and 390.0 ± 0.5 Ma were obtained for samples from the Lower Coverdale and Gaytons quartz monzonite, espectively. However, the anorthosite-ferronoritegabbro is likely considerably older: perhaps ca. 540 Ma like gabbroic rocks elsewhere in the Brookville terrane; or possibly esoproterozoic, like intrusions with similar characteristics in Grenvillian parts of the Precambrian shield.
RĂSUMĂ
On a croisĂ© lâintrusion de Lower Coverdale prĂšs de Moncton (Nouveau-Brunswick) dans des puits forĂ©s Ă des profondeurs de 100 Ă 200 m au-dessous de grĂšs du CarbonifĂšre sus-jacent non concordant, de conglomĂ©rat et, par endroits, de calcaire des groupes de Windsor, de Mabou et de Cumberland. Une anomalie aĂ©romagnĂ©tique positive Ă©tendue permet de supposer que lâintrusion a une superficie souterraine dâau moins 30 Ă 40 kilomĂštres carrĂ©s. Les carottes de forage et les dĂ©blais rĂ©vĂšlent que lâintrusion est constituĂ©e de ferronorite et dâanorthosite Ă grains grossiers interstratifiĂ©es, toutes deux pĂ©nĂ©trĂ©es par du gabbro, de lâadamellite et des dykes felsiques secondaires. La ferronorite est riche en Ti et en P et renferme de âilmĂ©nite/magnĂ©tite et de lâapatite interstitielles ainsi que des couches dâilmĂ©nite-apatite (nelsonite) pouvant avoir plusieurs mĂštres dâĂ©paisseur. Une vaste part des carottes tĂ©moignent des effets intenses dâun mĂ©tamorphisme et dâune altĂ©ration, mais des analyses Ă la microsonde des Ă©chantillons les plus frais ont rĂ©vĂ©lĂ© que le plagioclase Ă lâintĂ©rieur de lâanorthosite et de la ferronorite est composĂ© dâandĂ©sine. Lâanorthosite et la ferronorite sont chimiquement distinctes, mais leur association spatiale Ă©troite laisse supposer un lien gĂ©nĂ©tique. Par contre, les roches gabbroĂŻques plus rĂ©centes ont une composition minĂ©ralogique et chimique diffĂ©rant de celles de lâanorthosite et de la ferronorite et elles ne semblent pas y ĂȘtre apparentĂ©es. Elles sont altĂ©rĂ©es mais ne sont pas mĂ©tamorphisĂ©es et elles conservent des textures intergranulaires. Elles renferment plus de plagioclase calcique et dâaugite et ont une faible teneur en Ti et en P. Le puits de forage le plus profond dans lâintrusion de Lower Coverdale a recoupĂ© de lâadamellite Ă grains grossiers fortement altĂ©rĂ©e Ă une profondeur de 1 095 Ă 1 206 m. Lâadamellite est minĂ©ralogiquement et chimiquement similaire Ă lâadamellite des carriĂšres situĂ©es prĂšs de Gaytons, Ă 20 kilomĂštres Ă lâest. On a obtenu des datations U-Pb sur zircon pratiquement identiques du DĂ©vonien moyen de 390,6 ± 1,0 Ma et de 390,0 ± 0,5 Ma dâĂ©chantillons dâadamellite de Lower Coverdale et de Gaytons, respectivement. Le gabbro lâanorthosite-ferronorite, toutefois, est probablement beaucoup plus ĂągĂ© : il a peut-ĂȘtre 540 Ma, comme les roches gabbroĂŻques dâailleurs Ă lâintĂ©rieur du terrane de Brookville, ou il pourrait remonter au MĂ©soprotĂ©rozoĂŻque, comme les intrusions prĂ©sentant des caractĂ©ristiques analogues dans les parties grenvilliennes du bouclier prĂ©cambrien
Granitoid plutons of the Brookville terrane, southern New Brunswick: petrology, age, and tectonic setting
Latest Neoproterozoic and Cambrian plutons in the Brookville terrane of southern New Brunswick are termed the Golden Grove Plutonic Suite. Four groups are recognized on the basis of composition: gabbro (2 plutons), diorite - granodiorite (17 plutons), granodiorite - monzogranite (8 plutons), and syenogranite - monzogranite (7 plutons). The dioritic to granodioritic and most of the granodioritic to monzogranitic plutons form linear trends on chemical variation diagrams, suggesting that magma evolution was dominated by plagioclase and amphibole fractionation. These plutons appear to constitute a typical I-type, calc-alkaline suite characteristic of continental margin subduction zones. This interpretation is supported by U-Pb zircon ages, which show that these plutons have ages between 540 Ma and 526 Ma. A new U-Pb age of 539.6 ± 1.2 Ma from one of the gabbroic plutons shows that the gabbroic plutons are co-genetic with the dioritic to granitic plutons, although they show varied ultramafic to anorthositic and dioritic compositions as a result of crystal accumulation. The syenogranitic to monzogranitic plutons and two of the granodioritic and monzogranitic plutons, as well as felsic volcanic rocks of the Dipper Harbour volcanic unit, show chemical trends that differ from the other plutons in having A-type characteristics. A U-Pb age of 548 ± 2 Ma for the Fairville Granite, as well as similar ages for a syenogranitic pluton and the Dipper Harbour volcanic unit, suggests that these units represent early stages of magmatism in the Golden Grove Plutonic Suite.
RESUMĂ
Les plutons du Cambrien et des pĂ©riodes les plus anciennes du NĂ©oprotĂ©rozoĂŻque Ă l'intĂ©rieur du terrane de Brookville dans le Sud du Nouveau-Brunswick sont dĂ©signĂ©s sous le nom de « cortĂšge plutonique de Golden Grove ». On y distingue quatre groupes en fonction de leur composition : ceux Ă base de gabbro (deux plutons), de diorite - granodiorite (17 plutons), de granodiorite - monzogranite (huit plutons) et de syĂ©nogranite - monzogranite (sept plutons). Les plutons dioritiques Ă granodioritiques et la majoritĂ© des plutons granodioritiques Ă monzogranitiques forment des tracĂ©s linĂ©aires sur les schĂ©mas de diversitĂ© de la composition chimique, ce qui laisse supposer que l'Ă©volution magmatique a Ă©tĂ© dominĂ©e par une cristallisation fractionnĂ©e des plagioclases et des amphiboles. Ces plutons semblent constituer un cortĂšge calco-alcalin intrusif typique, caractĂ©ristique des zones de subduction de la marge continentale. Cette interprĂ©tation est corroborĂ©e par la datation au U-Pb, obtenue Ă partir de zircon, qui rĂ©vĂšle que ces plutons ont des Ăąges entre 540 Ma et 526 Ma. Une nouvelle datation au U-Pb obtenue Ă partir de zircon situant Ă 539,6 ± 1,2 Ma l'Ăąge de l'un des plutons gabbroĂŻques, signale que les plutons gabbroĂŻques sont cogĂ©nĂ©tiques avec les plutons dioritiques Ă granitiques, mĂȘme s'ils prĂ©sentent des compositions ultramafi ques Ă anorthositiques et dioritiques diversifi Ă©es par suite d'une accumulation de cristaux. Les plutons syĂ©nogranitiques Ă monzogranitiques et deux des plutons granodioritiques et monzogranitiques, de mĂȘme que les roches volcanofelsiques de l'unitĂ© volcanique de Dipper Harbour, livrent des tracĂ©s chimiques diffĂ©rents des autres plutons du fait qu'ils possĂšdent les caractĂ©ristiques des plutons de type anorogĂ©nique. L'Ăąge au U-Pb de 548 ± 2 Ma du granite de Fairville ainsi que les Ăąges similaires d'un pluton syĂ©nogranitique et de l'unitĂ© volcanique de Dipper Harbour permettent de supposer que ces unitĂ©s reprĂ©sentent les stades prĂ©coces du magmatisme Ă l'intĂ©rieur du cortĂšge plutonique de Golden Grove
Beyond the plane-parallel and Newtonian approach: Wide-angle redshift distortions and convergence in general relativity
We extend previous analyses of wide-angle correlations in the galaxy power
spectrum in redshift space to include all general relativistic effects. These
general relativistic corrections to the standard approach become important on
large scales and at high redshifts, and they lead to new terms in the
wide-angle correlations. We show that in principle the new terms can produce
corrections of nearly 10 % on Gpc scales over the usual Newtonian
approximation. General relativistic corrections will be important for future
large-volume surveys such as SKA and Euclid, although the problem of cosmic
variance will present a challenge in observing this.Comment: 14 pages, 5 figures; Typo in equation 5 corrected; results unaffecte
The Evolution of Anti-Bat Sensory Illusions in Moths
Prey transmit sensory illusions to redirect predatory strikes, creating a discrepancy between what a predator perceives and reality. We use the acoustic arms race between bats and moths to investigate the evolution and function of a sensory illusion. The spinning hindwing tails of silk moths (Saturniidae) divert bat attack by reflecting sonar to create a misleading echoic target. We characterized geometric morphometrics of moth hindwings across silk moths, mapped these traits onto a new, robust phylogeny, and found that elaborated hindwing structures have converged on four adaptive shape peaks. To test the mechanism underlying these anti-bat traits, we pit bats against three species of silk moths with experimentally altered hindwings that created a representative gradient of ancestral and extant hindwing shapes. High-speed videography of battles reveals that moths with longer hindwings and tails more successfully divert bat attack. We postulate that sensory illusions are widespread and are underappreciated drivers of diversity across systems
Action on the ground: A review of community environmental groupsâ restoration objectives, activities and partnerships in New Zealand
More than 600 community environmental groups across New Zealand are engaged in restoring degraded sites and improving and protecting habitat for native species. In the face of ongoing biodiversity declines, resource management agencies are increasing their reliance on these groups to enhance conservation outcomes nationally. However, little is known about community groups and their activities beyond local or regional studies. Our aim was to develop a profile of community groups and their projects through examining group and project characteristics, objectives, activities and the support provided by project partners. A total of 296 community groups from all mainland regions of New Zealand responded to an online questionnaire. Nearly 80% of these groups were established for â„6 years and 72% operated with â€20 participants (e.g. staff, members, and unpaid volunteers). For over half (54%) of groups, participants were mostly aged 51â65 years. Small groupsizes, combined with ageing participants, may threaten groupsâ longevity. More than 20% of groupsâ projects covered areas > 501 ha. Ecosystems represented within groupsâ project areas included forests (64.0%), streams (42.0%) and freshwater wetlands (33.2%). Over one-third (37.2%) of freshwater wetland restoration projects occurred on private or Maori-owned land. Nearly 70% of groups carried out weed/pest control, native tree planting and advocacy/educational activities, underscoring the combination of social and ecological dimensions shaping most groupsâ projects. Over 90% of groups were supported by project partners (e.g. resource management agencies for site visits, funding and technical support), highlighting the interdependence between groups and their partners. Developing a more complete profile of New Zealand community groups and their projects will assist with improving the delivery of support to groups by project partners and developing an inclusive and cohesive sector based on meaningful partnerships. These two factors combined will ultimately enhance groupsâ environmental outcomes at the local level, while contributing to national biodiversity conservation goals
Differential localization and anabolic responsiveness of mTOR complexes in human skeletal muscle in response to feeding and exercise
Mechanistic target of rapamycin (mTOR) resides as two complexes within skeletal muscle. mTOR complex 1 (mTORC1-Raptor positive) regulates skeletal muscle growth, whereas mTORC2 (Rictor positive) regulates insulin sensitivity. To examine the regulation of these complexes in human skeletal muscle, we utilised immunohistochemical analysis to study the localisation of mTOR complexes prior to and following protein-carbohydrate feeding (FED) and resistance exercise plus protein-carbohydrate feeding (EXFED) in unilateral exercise model. In basal samples, mTOR and the lysosomal marker LAMP2 were highly co-localized and remained so throughout. In the FED and EXFED states, mTOR/LAMP2 complexes were redistributed to the cell periphery (WGA positive staining) (time effect; p=.025), with 39\% (FED) and 26\% (EXFED) increases in mTOR/WGA association observed 1h post-feeding/exercise. mTOR/WGA colocalisation continued to increase in EXFED at 3h (48\% above baseline) whereas colocalisation decreased in FED (21\% above baseline). A significant effect of condition (p=.05) was noted suggesting mTOR/WGA co-localization was greater during EXFED. This pattern was replicated in Raptor/WGA association, where a significant difference between EXFED and FED was noted at 3h post-exercise/feeding (p=.014). Rictor/WGA colocalization remained unaltered throughout the trial. Alterations in mTORC1 cellular location coincided with elevated S6K1 kinase activity, which rose to a greater extent in EXFED compared to FED at 1h post-exercise/feeding (p<.001), and only remained elevated in EXFED at the 3h time point (p=.037). Collectively these data suggest that mTORC1 redistribution within the cell is a fundamental response to resistance exercise and feeding, whereas mTORC2 is predominantly situated at the sarcolemma and does not alter localisation
The transcriptome of Euglena gracilis reveals unexpected metabolic capabilities for carbohydrate and natural product biochemistry
Euglena gracilis is a highly complex alga belonging to the green plant line that shows characteristics of both plants and animals, while in evolutionary terms it is most closely related to the protozoan parasites Trypanosoma and Leishmania. This well-studied organism has long been known as a rich source of vitamins A, C and E, as well as amino acids that are essential for the human diet. Here we present de novo transcriptome sequencing and preliminary analysis, providing a basis for the molecular and functional genomics studies that will be required to direct metabolic engineering efforts aimed at enhancing the quality and quantity of high value products from E. gracilis. The transcriptome contains over 30?000 protein-encoding genes, supporting metabolic pathways for lipids, amino acids, carbohydrates and vitamins, along with capabilities for polyketide and non-ribosomal peptide biosynthesis. The metabolic and environmental robustness of Euglena is supported by a substantial capacity for responding to biotic and abiotic stress: it has the capacity to deploy three separate pathways for vitamin C (ascorbate) production, as well as producing vitamin E (?-tocopherol) and, in addition to glutathione, the redox-active thiols nor-trypanothione and ovothiol
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