3,366 research outputs found
\u3cem\u3eArabidopsis thaliana\u3c/em\u3e GLX2-1 Contains a Dinuclear Metal Binding Site, but Is Not a Glyoxalase 2
In an effort to probe the structure and function of a predicted mitochondrial glyoxalase 2, GLX2-1, from Arabidopsis thaliana, GLX2-1 was cloned, overexpressed, purified and characterized using metal analyses, kinetics, and UV–visible, EPR, and 1H-NMR spectroscopies. The purified enzyme was purple and contained substoichiometric amounts of iron and zinc; however, metal-binding studies reveal that GLX2-1 can bind nearly two equivalents of either iron or zinc and that the most stable analogue of GLX2-1 is the iron-containing form. UV–visible spectra of the purified enzyme suggest the presence of Fe(II) in the protein, but the Fe(II) can be oxidized over time or by the addition of metal ions to the protein. EPR spectra revealed the presence of an anti-ferromagnetically-coupled Fe(III)Fe(II) centre and the presence of a protein-bound high-spin Fe(III) centre, perhaps as part of a FeZn centre. No paramagnetically shifted peaks were observed in 1H-NMR spectra of the GLX2-1 analogues, suggesting low amounts of the paramagnetic, anti-ferromagnetically coupled centre. Steady-state kinetic studies with several thiolester substrates indicate that GLX2-1 is not a GLX2. In contrast with all of the other GLX2 proteins characterized, GLX2-1 contains an arginine in place of one of the metal-binding histidine residues at position 246. In order to evaluate further whether Arg246 binds metal, the R246L mutant was prepared. The metal binding results are very similar to those of native GLX2-1, suggesting that a different amino acid is recruited as a metal-binding ligand. These results demonstrate that Arabidopsis GLX2-1 is a novel member of the metallo-β-lactamase superfamily
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
Automated angular scans to determine flaw orientation for use in model-based flaw reconstruction
In manufacturing, the ability to detect and characterize failure-initiating flaws is important in the assurance of the structural integrity of materials and components. One major technique in the detection and characterization of such flaws is ultrasonics. In recent years, significant advances have been made in inverse ultrasonic scattering in the region where the ultrasonic wavelength is of the same order as the radius of the flaw. Such work is based on physical models that describe the interaction between an elastic wave and the flaw for both long and intermediate wavelength inverse scattering.
To exploit these theoretical advances in elastic wave inverse scattering, an automated multiviewing ultrasonic transducer system and associated software has been designed and built in order to perform characterization and analysis of volumetric flaws. The flaw is characterized by its size, shape, and orientation within a material. Utilizing inverse ultrasonic scattering theories, signal processing algorithms perform three-dimensional reconstruction by finding an ellipsoid that best fits the inverse scattering data taken from many independent perspectives within a specified aperture
Registration of retinal images from Public Health by minimising an error between vessels using an affine model with radial distortions
In order to estimate a registration model of eye fundus images made of an
affinity and two radial distortions, we introduce an estimation criterion based
on an error between the vessels. In [1], we estimated this model by minimising
the error between characteristics points. In this paper, the detected vessels
are selected using the circle and ellipse equations of the overlap area
boundaries deduced from our model. Our method successfully registers 96 % of
the 271 pairs in a Public Health dataset acquired mostly with different
cameras. This is better than our previous method [1] and better than three
other state-of-the-art methods. On a publicly available dataset, ours still
better register the images than the reference method
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
Assessing Population Responses to Multiple Anthropogenic Effects: A Case Study with Brook Trout
Population declines are often caused by multiple factors, including anthropogenic
ones that can be mitigated or reversed to enhance population recovery. We used
a size-classified matrix population model to examine multiple anthropogenic effects on a
population and determine which factors are most (or least) important to population dynamics.
We modeled brook trout (Salvelinus fontinalis) in southern Appalachian mountain
streams responding to multiple anthropogenic effects including the introduction of an exotic
salmonid species (rainbow trout, Oncorhynchus mykiss), a decrease in pH (through acidic
deposition), an increase in siltation (from roadbuilding and logging), and an increase in
fishing pressure.
Potential brook trout responses to rainbow trout include a decrease in survival rate of
small fish, a change in density dependence in survival of small fish, and a decrease in growth
rates of all sizes. When we included these responses in the population model, we found that
population size tended to decrease with an increase in small-fish growth rate (producing a
population with fewer, but larger, fish). In addition, changes in patterns of density-dependent
survival also had a strong impact on both population size and size structure. Brook trout
respond to decreases in pH with decreased growth rate in all size classes, decreased survival
rates of small fish, and decreased egg-to-larva survival rates. This combination of effects, at
magnitudes documented in laboratory experiments, had severe negative impacts on the modeled
population. If siltation effects were severe, the extreme increase in egg-to-larva mortality
could have strong negative effects on the population. However, even very strong increases
in large fish mortality associated with sport harvesting were not likely to cause a local
extinction. In all of these cases, the interaction of drastic changes in population size structure
with randomly occurring floods or droughts may lead to even stronger negative impacts than
those predicted from the deterministic model.
Because these fish can reproduce at a small size, negative impacts on survival of the
largest fish were not detrimental to the persistence of the population. Because survival of
small juveniles is density dependent, even moderate decreases in survival in this stage had
little effect on the ultimate population size. In general, a brook trout population will respond
most negatively to factors that decrease survival of large juveniles and small adults, and
growth rates of small juveniles.This work was supported by the Lucas Fellowship in Biomathematics at North Carolina State University (to E. A.
Marschall), the J. F. Allen Award from the American Fisheries Society (to E. A. Marschall), an Electric Power Research
Institute Fellowship in Population Dynamics (to E. A. Marschall), a U.S. Forest Service Cost-Share Agreement (to L.B. Crowder and E. A. Marschall), the Department of Zoology
at North Carolina State University (to L. B. Crowder), and the Department of Zoology at The Ohio State University (to E. A. Marschall)
Disrupting the Drivers of Inequity in Biloxi: Assessing Federal Opportunity Zones
As wages have stagnated for the majority of workers in the U.S. and inequality has skyrocketed, racial inequity has grown. Since the late 1970s, the racial wealth gap has reached critical levels. In Biloxi, Mississippi, the inequities are deep, leaving many Black and Latinx households facing racial and geographic barriers to economic opportunity. Yet, communities of color have been driving the city's population growth and spurring change and will continue to do so for the foreseeable future. This diversity can be a tremendous economic asset for the city if people of color are fully included as workers, entrepreneurs, and innovators. Knowing where the city stands in terms of equity—just and fair inclusion into a society in which all can participate, prosper, and reach their full potential—is the first This research brief draws from data in the National Equity Atlas—an online resource for data to track, measure, and make the case for inclusive growth in America's cities, regions, states, and nationwide.The USC Program for Environmental and Regional Equity (PERE) provides forward-looking, actionable research to support community-based organizations, funders, and other stakeholders working towards social, racial, economic and environmental justice. www.dornsife.usc.edu/pere James Crowder Jr. and Justin Scoggins March 2020 2 step in planning for a brighter future for all Biloxians. To that end, the East Biloxi Community Collaborative (EBCC) partnered with the National Equity Atlas, a partnership between PolicyLink and the University of Southern California Program for Environmental and Regional Equity (PERE), to better understand the landscape for inclusive growth in the city, particularly given the new Opportunity Zone program which has the potential to bring a significant amount of private investment into the city. This brief describes Opportunity Zones and how they can be leveraged to promote equitable development in East Biloxi
Notes on Succession in Old Fields in Southeastern Ontario: the Herbs
Vegetation in abandoned hayfields was monitored during 1976-1998. An earlier successional stage followed ploughing. Changes in tree, shrub and vine populations have been reported earlier and showed expected increases in species richness and cover. Highest species richness of herbs occurred three years after ploughing. Non-woody species richness trended irregularly downward, while non-woody cover was variable, peaking in 1987. Within the herbaceous community, year-to-year changes in cover and frequency of species in the following selected groups are reported here: 18 grasses including sown and adventive species; 13 legumes including two sown species; 14 macroforbs of the Compositae, including a goldenrod, Solidago canadensis, which dominated parts of the fields; a rosette weed, Taraxacum officinalis; sedges, horsetails and some other minor components. Grasses and goldenrods were grazed, sometimes intensively and repeatedly, by insects; grasses were impacted by skipper larvae (Thymelicus lineola), and goldenrods by beetle larvae (Trirhabda spp.). Effects of repeated outbreaks on host plant cover are shown for two plots (100 m2) matching the scale of outbreaks
Coming Back Better: Leveraging Crisis-Response Task Forces to Advance Racial Equity and Worker Justice
As the United States enters its third year of navigating the global Covid-19 pandemic, the coronavirus continues to disrupt the lives of millions of workers and their families. About a quarter of the US workforce—nearly 41 million workers -- experienced at least one spell of unemployment due to the coronavirus. As of February 2022, some 3 million fewer people are employed than before the pandemic. While nearly all workers have been affected, yet these impacts are highly unequal: low-wage workers, Black workers, and other workers of color, particularly women of color, have experienced the greatest health and economic harms. This lop-sided labor market recovery has done little to buoy low-wage workers of color who continue to face heavy burdens in terms of rent debt and childcare access
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