Spectroscopic Studies on \u3cem\u3eArabidopsis\u3c/em\u3e ETHE1, a Glyoxalase II-like Protein

ETHE1 (ethylmalonic encephalopathy protein 1) is a β-lactamase fold-containing protein that is essential for the survival of a range of organisms. In spite of the apparent importance of this enzyme, very little is known about its function or biochemical properties. In this study Arabidopsis ETHE1 was over-expressed and purified and shown to bind tightly to 1.2 ± 0.2 equivalents of iron. 1H NMR and EPR studies demonstrate that the predominant oxidation state of Fe in ETHE1 is Fe(II), and NMR studies confirm that two histidines are bound to Fe(II). EPR studies show that there is no antiferromagnetically coupled Fe(III)Fe(II) center in ETHE1. Gel filtration studies reveal that ETHE1 is a dimer in solution, which is consistent with previous crystallographic studies. Although very similar in terms of amino acid sequence to glyoxalase II, ETHE1 exhibits no thioester hydrolase activity, and activity screening assays reveal that ETHE1 exhibits low level esterase activity. Taken together, ETHE1 is a novel, mononuclear Fe(II)-containing member of the β-lactamase fold superfamily

Body Weight Penalties in the Physical Fitness Tests of the Army, Air Force, and Navy

Recent research has empirically documented a consistent penalty against heavier service members for events identical or similar to those in the physical fitness tests of the Army, Air Force, and Navy. These penalties, not related to body fatness, are based on biological scaling models and have a physiologic basis. Using hypothetical cases, we quantified the penalties for males, 60 vs. 90 kg body weight, and females, 45 vs. 75 kg, to be 15-20% for the fitness tests of these three services. Such penalties alone can adversely impact awards and promotions for heavier service members. To deal equitably with these penalties in a practical manner, we offer two recommendations: Implementation of revised fitness tests with balanced events: penalties of one event against heavier service members are balanced by an equal and opposite bias against lighter service members. Development of correction factors which can be multiplied by raw scores to yield adjusted scores free of body weight bias

Structural Studies on a Mitochondrial Glyoxalase II

Glyoxalase 2 is a β-lactamase fold-containing enzyme that appears to be involved with cellular chemical detoxification. Although the cytoplasmic isozyme has been characterized from several organisms, essentially nothing is known about the mitochondrial proteins. As a first step in understanding the structure and function of mitochondrial glyoxalase 2 enzymes, a mitochondrial isozyme (GLX2-5) from Arabidopsis thaliana was cloned, overexpressed, purified, and characterized using metal analyses, EPR and 1H NMR spectroscopies, and x-ray crystallography. The recombinant enzyme was shown to bind 1.04 ± 0.15 eq of iron and 1.31 ± 0.05 eq of Zn(II) and to exhibit kcat and Km values of 129 ± 10 s-1 and 391 ± 48 μm, respectively, when using S-d-lactoylglutathione as the substrate. EPR spectra revealed that recombinant GLX2-5 contains multiple metal centers, including a predominant Fe(III)Z-n(II) center and an anti-ferromagnetically coupled Fe(III)Fe(II) center. Unlike cytosolic glyoxalase 2 from A. thaliana, GLX2-5 does not appear to specifically bind manganese. 1H NMR spectra revealed the presence of at least eight paramagnetically shifted resonances that arise from protons in close proximity to a Fe(III)Fe(II) center. Five of these resonances arose from solvent-exchangeable protons, and four of these have been assigned to NH protons on metal-bound histidines. A 1.74-Å resolution crystal structure of the enzyme revealed that although GLX2-5 shares a number of structural features with human GLX2, several important differences exist. These data demonstrate that mitochondrial glyoxalase 2 can accommodate a number of different metal centers and that the predominant metal center is Fe(III)Zn(II)

Observed Limits on Charge Exchange Contributions to the Diffuse X-ray Background

We present a high resolution spectrum of the diffuse X-ray background from 0.1 to 1 keV for a ~1 region of the sky centered at l=90, b=+60 using a 36-pixel array of microcalorimeters flown on a sounding rocket. With an energy resolution of 11 eV FWHM below 1 keV, the spectrum's observed line ratios help separate charge exchange contributions originating within the heliosphere from thermal emission of hot gas in the interstellar medium. The X-ray sensitivity below 1 keV was reduced by about a factor of four from contamination that occurred early in the flight, limiting the significance of the results. The observed centroid of helium-like O VII is 568+2-3 eV at 90% confidence. Since the centroid expected for thermal emission is 568.4 eV while for charge exchange is 564.2 eV, thermal emission appears to dominate for this line complex, consistent with much of the high-latitude O VII emission originating in 2-3 x 10^6 K gas in the Galactic halo. On the other hand, the observed ratio of C VI Ly gamma to Ly alpha is 0.3+-0.2. The expected ratios are 0.04 for thermal emission and 0.24 for charge exchange, indicating that charge exchange must contribute strongly to this line and therefore potentially to the rest of the ROSAT R12 band usually associated with 10^6 K emission from the Local Hot Bubble. The limited statistics of this experiment and systematic uncertainties due to the contamination require only >32% thermal emission for O VII and >20% from charge exchange for C VI at the 90% confidence level. An experimental gold coating on the silicon substrate of the array greatly reduced extraneous signals induced on nearby pixels from cosmic rays passing through the substrate, reducing the triggered event rate by a factor of 15 from a previous flight of the instrument.Comment: 14 pages, 7 figures, to be published in Ap

Structure and Metal Binding Properties of ZnuA, a Periplasmic Zinc Transporter from \u3cem\u3eEscherichia coli\u3c/em\u3e

ZnuA is the periplasmic Zn2+-binding protein associated with the high-affinity ATP-binding cassette ZnuABC transporter from Escherichia coli. Although several structures of ZnuA and its homologs have been determined, details regarding metal ion stoichiometry, affinity, and specificity as well as the mechanism of metal uptake and transfer remain unclear. The crystal structures of E. coli ZnuA (Eco-ZnuA) in the apo, Zn2+-bound, and Co2+-bound forms have been determined. ZnZnuA binds at least two metal ions. The first, observed previously in other structures, is coordinated tetrahedrally by Glu59, His60, His143, and His207. Replacement of Zn2+ with Co2+ results in almost identical coordination geometry at this site. The second metal binding site involves His224 and several yet to be identified residues from the His-rich loop that is unique to Zn2+ periplasmic metal binding receptors. Electron paramagnetic resonance and X-ray absorption spectroscopic data on CoZnuA provide additional insight into possible residues involved in this second site. The second site is also detected by metal analysis and circular dichroism (CD) titrations. Eco-ZnuA binds Zn2+ (estimated K d \u3c 20 nM), Co2+, Ni2+, Cu2+, Cu+, and Cd2+, but not Mn2+. Finally, conformational changes upon metal binding observed in the crystal structures together with fluorescence and CD data indicate that only Zn2+ substantially stabilizes ZnuA and might facilitate recognition of ZnuB and subsequent metal transfer

The Southern Zagros Collisional Orogen: New Insights From Transdimensional Trees Inversion of Seismic Noise

Imaging and resolving the lateral continuity of 3-D crustal structures enhances our ability to interpret seismicity, and to understand how orogens are created. We apply a Bayesian, hierarchical inversion approach based on a transdimensional trees-structured wavelet parameterisation to recover phase-velocity maps at 2-40 second periods. We then invert phase-velocity dispersion to constrain a 3-D shear-velocity model of the crust beneath south-central Iran. Together with accurate earthquake centroid depths and focal mechanisms, the pattern of 3-D velocity variations supports recent suggestions that most large earthquakes in the Zagros occur within the lower sedimentary cover, or close to the sediment-basement interface. Furthermore, we fi nd evidence for Arabian basement underthrusting beneath central Iran, although only in one location does it appear to generate earthquakes. Our new 3-D tomographic model clarifi es and throws new light on the crustal structure of the SE Zagros and its relation to seismicity and active faulting.NERC Horizon 2020 Petroleum Institute Research Centr

LISA Data Analysis using MCMC methods

The Laser Interferometer Space Antenna (LISA) is expected to simultaneously detect many thousands of low frequency gravitational wave signals. This presents a data analysis challenge that is very different to the one encountered in ground based gravitational wave astronomy. LISA data analysis requires the identification of individual signals from a data stream containing an unknown number of overlapping signals. Because of the signal overlaps, a global fit to all the signals has to be performed in order to avoid biasing the solution. However, performing such a global fit requires the exploration of an enormous parameter space with a dimension upwards of 50,000. Markov Chain Monte Carlo (MCMC) methods offer a very promising solution to the LISA data analysis problem. MCMC algorithms are able to efficiently explore large parameter spaces, simultaneously providing parameter estimates, error analyses and even model selection. Here we present the first application of MCMC methods to simulated LISA data and demonstrate the great potential of the MCMC approach. Our implementation uses a generalized F-statistic to evaluate the likelihoods, and simulated annealing to speed convergence of the Markov chains. As a final step we super-cool the chains to extract maximum likelihood estimates, and estimates of the Bayes factors for competing models. We find that the MCMC approach is able to correctly identify the number of signals present, extract the source parameters, and return error estimates consistent with Fisher information matrix predictions.Comment: 14 pages, 7 figure

Sensitivity and parameter-estimation precision for alternate LISA configurations

We describe a simple framework to assess the LISA scientific performance (more specifically, its sensitivity and expected parameter-estimation precision for prescribed gravitational-wave signals) under the assumption of failure of one or two inter-spacecraft laser measurements (links) and of one to four intra-spacecraft laser measurements. We apply the framework to the simple case of measuring the LISA sensitivity to monochromatic circular binaries, and the LISA parameter-estimation precision for the gravitational-wave polarization angle of these systems. Compared to the six-link baseline configuration, the five-link case is characterized by a small loss in signal-to-noise ratio (SNR) in the high-frequency section of the LISA band; the four-link case shows a reduction by a factor of sqrt(2) at low frequencies, and by up to ~2 at high frequencies. The uncertainty in the estimate of polarization, as computed in the Fisher-matrix formalism, also worsens when moving from six to five, and then to four links: this can be explained by the reduced SNR available in those configurations (except for observations shorter than three months, where five and six links do better than four even with the same SNR). In addition, we prove (for generic signals) that the SNR and Fisher matrix are invariant with respect to the choice of a basis of TDI observables; rather, they depend only on which inter-spacecraft and intra-spacecraft measurements are available.Comment: 17 pages, 4 EPS figures, IOP style, corrected CQG versio

Project 400: The Plymouth Colony Archaeological Survey, Report on the 2014 Field Season, Burial Hill Plymouth, Massachusetts

In May and June of 2014, a field school from the University of Massachusetts Boston, in partnership with Plimoth Plantation, undertook a second season of work in Plymouth, Massachusetts, as part of Project 400: The Plymouth Colony Archaeological Survey, a site survey and excavation program leading up to the 400th anniversary of New England’s first permanent English settlement in 1620, the founding of Plymouth Colony. This work was conducted under permit #3384 from the State Archaeologist’s office at the Massachusetts Historical Commission. The 2014 work focused on the eastern edge of Burial Hill along School Street in downtown Plymouth and consisted of ground penetrating radar survey and excavation (3 STPs and 9 EUs). Burial Hill, formerly Fort Hill, is understood as the location of the original fort built by the English colonists, and the walls that enclosed the fort and town stretched down the hill towards the harbor. The precise locations of any of these features have never been archaeologically identified. In the 18th and 19th centuries, the land on the eastern edge of the hill along School Street was sold to individuals who built houses and stables, all demolished by the early 20th century. Our test excavations were designed to see if any 17th-century features or deposits existed either under the floors of these buildings or in the strip of land between the backs of the buildings and the burials, which begin roughly 20 meters from the street. During the 2014 season, we did not locate any 17th-century features or deposits. The 2014 excavation units tested the footprints of 4 different 19th-century building lots (an 1827 school and three barn or stable buildings), all of which were demolished between 1882 and 1901. With the exception of the school, the buildings completely filled the 30 foot deep lots that existed along School Street. The excavations revealed that the buildings had been cut into the hill, destroying any earlier deposits that might have existed in those areas. Because of their particular construction and the area topography, there was almost no trash deposition behind the buildings, up the slope of Burial Hill. As each building was taken down, its footprint was filled, first to create a level surface, then to create a regular slope for this edge of Burial Hill. Each building appears to have been filled individually, since the deposits within each building footprint were quite different from each other. Material to fill these substantial building footprints must have been brought in from elsewhere; the slag in EU3 is the clearest evidence of this. Although we found flaked tools (a quartz flake drill, a rhyolite unifacial scraper, and quartz Small Stemmed points) in the topsoil and fill layers of EUs 8 and 9 and chipping debris (quartz and rhyolite) in all excavation units, we found no in-situ Native artifacts or features. With the exception of the large metal pieces in EU2 and some related deposits in EU9 which seem to be primary trash deposits, most other deposits contained either predominantly architectural materials (brick, nails, window glass), or a mixture of architectural materials and redeposited sheet refuse (ceramics and glass in small fragments). One of the only in situ, non-fill deposits that we encountered was the test pit that we dug below the building floor layer of EU2 which uncovered an associated late 18th or early 19th century pipe bowl and a dog skeleton, either a burial or an animal that died below the floor. From other units, there were a number of interesting small finds such as buttons, pins, an 1874 Indian Head penny, and buckles, including an early 20th-century Red Cross pin. Other notable artifacts include fragments of six possible gravestones in both slate and marble. One of these is decorated and appears to be a fragment of a slate Medusa style design from the Soule family of carvers, probably from the 1750s or 1760s. An analysis of all of the bone and tooth fragments recovered during the field season confirmed that the whole collection consisted of the remains of common animals (cat, dog, rat, duck, chicken, sheep/goat, pig, and cow) and included no human remains. EU7, located in the lot that held the 1827 school, yielded a significant collection of small finds related to the school including pen nibs, slate pencils, and a possible compass fragment. The report illustrates these materials and presents comparative research on the archaeology of school sites and artifacts