Coordinated surface activities in Variovorax paradoxus EPS

<p>Abstract</p> <p>Background</p> <p><it>Variovorax paradoxus </it>is an aerobic soil bacterium frequently associated with important biodegradative processes in nature. Our group has cultivated a mucoid strain of <it>Variovorax paradoxus </it>for study as a model of bacterial development and response to environmental conditions. Colonies of this organism vary widely in appearance depending on agar plate type.</p> <p>Results</p> <p>Surface motility was observed on minimal defined agar plates with 0.5% agarose, similar in nature to swarming motility identified in <it>Pseudomonas aeruginosa </it>PAO1. We examined this motility under several culture conditions, including inhibition of flagellar motility using Congo Red. We demonstrated that the presence of a wetting agent, mineral, and nutrient content of the media altered the swarming phenotype. We also demonstrated that the wetting agent reduces the surface tension of the agar. We were able to directly observe the presence of the wetting agent in the presence and absence of Congo Red, and found that incubation in a humidified chamber inhibited the production of wetting agent, and also slowed the progression of the swarming colony. We observed that swarming was related to both carbon and nitrogen sources, as well as mineral salts base. The phosphate concentration of the mineral base was critical for growth and swarming on glucose, but not succinate. Swarming on other carbon sources was generally only observed using M9 salts mineral base. Rapid swarming was observed on malic acid, d-sorbitol, casamino acids, and succinate. Swarming at a lower but still detectable rate was observed on glucose and sucrose, with weak swarming on maltose. Nitrogen source tests using succinate as carbon source demonstrated two distinct forms of swarming, with very different macroscopic swarm characteristics. Rapid swarming was observed when ammonium ion was provided as nitrogen source, as well as when histidine, tryptophan, or glycine was provided. Slower swarming was observed with methionine, arginine, or tyrosine. Large effects of mineral content on swarming were seen with tyrosine and methionine as nitrogen sources. Biofilms form readily under various culture circumstances, and show wide variance in structure under different conditions. The amount of biofilm as measured by crystal violet retention was dependent on carbon source, but not nitrogen source. Filamentous growth in the biofilm depends on shear stress, and is enhanced by continuous input of nutrients in chemostat culture.</p> <p>Conclusion</p> <p>Our studies have established that the beta-proteobacterium <it>Variovorax paradoxus </it>displays a number of distinct physiologies when grown on surfaces, indicative of a complex response to several growth parameters. We have identified a number of factors that drive sessile and motile surface phenotypes. This work forms a basis for future studies using this genetically tractable soil bacterium to study the regulation of microbial development on surfaces.</p

Examination of Different Accelerometer Cut-Points for Assessing Sedentary Behaviors in Children

Background: Public health research on sedentary behavior (SB) in youth has heavily relied on accelerometers. However, ithas been limited by the lack of consensus on the most accurate accelerometer cut-points as well as by unknown effectscaused by accelerometer position (wrist vs. hip) and output (single axis vs. multiple axes). The present study systematicallyevaluates classification accuracy of different Actigraph cut-points for classifying SB using hip and wrist-worn monitors andestablishes new cut-points to enable use of the 3-dimensional vector magnitude data (for both hip and wrist placement).Methods: A total of 125 children ages 7–13 yrs performed 12 randomly selected activities (from a set of 24 differentactivities) for 5 min each while wearing tri-axial Actigraph accelerometers on both the hip and wrist. The accelerometer datawere categorized as either sedentary or non-sedentary minutes using six previously studied cut-points: 100counts-per-minute (CPM), 200CPM, 300CPM, 500CPM, 800CPM and 1100CPM. Classification accuracy was evaluated with Cohen’s Kappa(k) and new cut-points were identified from Receiver Operating Characteristic (ROC).Results: Of the six cut-points, the 100CPM value yielded the highest classification accuracy (k = 0.81) for hip placement. Forwrist placement, all of the cut-points produced low classification accuracy (ranges of k from 0.44 to 0.67). Optimal sedentarycut-points derived from ROC were 554.3CPM (ROC-AUC of 0.99) for vector magnitude for hip, 1756CPM (ROC-AUC of 0.94)for vertical axis for wrist, and 3958.3CPM (ROC-AUC of 0.93) for vector magnitude for wrist placement.Conclusions: The 100CPM was supported for use with vertical axis for hip placement, but not for wrist placement. The ROC-derived cut-points can be used to classify youth SB with the wrist and with vector magnitude data

Accuracy of Neck Circumference in Classifying Overweight and Obese US Children

Objective. To evaluate classification accuracy of NC and compare it with body mass index (BMI) in identifying overweight/obese US children. Methods. Data were collected from 92 children (boys: 61) aged 7 to 13 over a 2-year period. NC, BMI, and percent of body fat (BF%) were measured in each child and their corresponding cut-off values were applied to classify the children as being overweight/obese. Classification accuracy of NC and BMI was systematically investigated for boys and girls in relation to true overweight/obesity categorization as assessed with a criterion measure of BF% (i.e., Bod Pod). Results. For boys, Cohen's κ (0.25), sensitivity (38.1%), and specificity (85.0%) of NC were smaller in comparison with Cohen's κ (0.57), sensitivity (57.1%), and specificity (95.0%) of BMI in relation to BF% categorization. For girls, Cohen's κ (0.45), sensitivity (50.0%), and specificity (91.3%) of NC were smaller in comparison with Cohen's κ (0.52), sensitivity (50.0%), and specificity (95.7%) of BMI. Conclusion. NC measurement was not better than BMI in classifying childhood overweight/obesity and, for boys, NC was inferior to BMI. Pediatricians and/or pediatric researchers should be cautious or wary about incorporating NC measurements in their pediatric care and/or research

Accuracy of Neck Circumference in Classifying Overweight and Obese US Children

Objective. To evaluate classification accuracy of NC and compare it with body mass index (BMI) in identifying overweight/obese US children. Methods. Data were collected from 92 children (boys: 61) aged 7 to 13 over a 2-year period. NC, BMI, and percent of body fat (BF%) were measured in each child and their corresponding cut-off values were applied to classify the children as being overweight/obese. Classification accuracy of NC and BMI was systematically investigated for boys and girls in relation to true overweight/obesity categorization as assessed with a criterion measure of BF% (i.e., Bod Pod). Results. For boys, Cohen’s k (0.25), sensitivity (38.1%), and specificity (85.0%) of NC were smaller in comparison with Cohen’s k (0.57), sensitivity (57.1%), and specificity (95.0%) of BMI in relation to BF% categorization. For girls, Cohen’s k (0.45), sensitivity (50.0%), and specificity (91.3%) of NC were smaller in comparison with Cohen’s k (0.52), sensitivity (50.0%), and specificity (95.7%) of BMI. Conclusion. NC measurement was not better than BMI in classifying childhood overweight/obesity and, for boys, NC was inferior to BMI. Pediatricians and/or pediatric researchers should be cautious or wary about incorporating NC measurements in their pediatric care and/or research

Phosphorus and Nitrogen Transport in the Binational Great Lakes Basin Estimated Using SPARROW Watershed Models

AbstractEutrophication problems in the Great Lakes are caused by excessive nutrient inputs (primarily phosphorus, P, and nitrogen, N) from various sources throughout its basin. In developing protection and restoration plans, it is important to know where and from what sources the nutrients originate. As part of a binational effort, Midcontinent SPARROW (SPAtially Referenced Regression On Watershed attributes) models were developed and used to estimate P and N loading from throughout the entire basin based on nutrient inputs similar to 2002; previous SPARROW models only estimated U.S. contributions. The new models have a higher resolution (~2‐km2 catchments) enabling improved descriptions of where nutrients originate and the sources at various spatial scales. The models were developed using harmonized geospatial datasets describing the stream network, nutrient sources, and environmental characteristics affecting P and N delivery. The models were calibrated using loads from sites estimated with ratio estimator and regression techniques and additional statistical approaches to reduce spatial correlation in the residuals and have all monitoring sites equally influence model development. SPARROW results, along with interlake transfers and direct atmospheric inputs, were used to quantify the entire P and N input to each lake and describe the importance of each nutrient source. Model results can be used to compare loading and yields from various tributaries and jurisdictions

Field Guide to Big Bone Lick, Kentucky: Birthplace of American Vertebrate Paleontology

Big Bone Lick is the birthplace of vertebrate paleontology in the Western Hemisphere and has a long and celebrated history in the exploration of the American colonial frontier and of the early United States. Notable European scientists of the 18th century such as Buffon, Cuvier, and Hunter discussed the fossils found there. Prominent Americans of the time, such as Boone, Washington, Franklin, and Jefferson are also part of the site’s history. It is the type locality for several extinct late Pleistocene megafaunal mammals, most notably the iconic American Mastodon, who were attracted to the area by salt licks dictated by the local geology. The valley of Big Bone Creek was unglaciated during the Wisconsinan advance and numerous saline springs well up through fractured bedrock of the Cincinnati Arch, providing essential minerals for the physiology of mammalian herbivores. The fossil remains at Big Bone Lick are an attritional assemblage, apparently including those that are the result of Native American predation. Archaeological remains from all local Native American cultural periods have also been found at the lick. The site is perhaps most notable in the history of science for its role in the development of comparative morphology and the establishment of the concept of extinction. This special publication reflects research and scholarship produced in conjunction with the April 2022 joint North-Central and Southeastern section meeting of the Geological Society of America. As the authors are not Kentucky Geological Survey staff, the work described herein is not a product of KGS scholarship or explicitly reflective of KGS views. Additionally, cited historical documents included in this publication may include biased language or views that misrepresent indigenous cultures.https://uknowledge.uky.edu/kgs_sp/1000/thumbnail.jp

Long-range vibrational dynamics are directed by Watson-Crick base-pairing in duplex DNA

Ultrafast two-dimensional infrared (2D-IR) spectroscopy of a 15-mer A-T DNA duplex in solution has revealed structure-dependent vibrational coupling and energy transfer processes linking bases with the sugar-phosphate backbone. Duplex melting induces significant changes in the positions of off-diagonal peaks linking carbonyl and ring-stretching vibrational modes of the adenine and thymine bases with vibrations of the phosphate group and phosphodiester linkage. These indicate that Watson-Crick hydrogen bonding and helix formation leads to a unique vibrational coupling arrangement of base vibrational modes with those of the phosphate unit. Based on observations from time-resolved 2D-IR data, we conclude that rapid energy transfer processes occur between base and backbone, mediated by additional modes located on the deoxyribose moiety within the same nucleotide. These relaxation dynamics are insensitive to duplex melting, showing that efficient intramo-lecular energy relaxation to the solvent via the phosphate groups is the key to excess energy dissipation in both single and double-stranded DNA

Preventing soil erosion with polymer additives

The agricultural use of polyacrylamide, PAM, as an additive in irrigation water has grown rapidly since commercial introduction in 1995, with over l million acres treated in 1998. PAM provides both economic and environmental benefits by improving water infiltration and reducing up to 98% of erosion-induced soil losses — a yearly saving of tons of topsoil per acre. With as little as 5 ppm of PAM in the first irrigation water to run across the field, soil cohesion increases enough to prevent particle detachment and erosion. Stable soil/polymer flocs result from PAM's high molecular weight (typically > 12 million) and its affinity to soil via coulombic and Van der Waals attraction. Although water soluble linear PAM is the only class of commercial polymer presently used to reduce erosion during irrigation, other polymer additives have shown some potential. Biopolymers such as chitosan, starch xanthate, cellulose xanthate, and acid-hydrolyzed cellulose microfibrils reduce shear-induced erosion; however concentrations at least 6-10 times higher than PAM are required to obtain the > 90% runoff sediment reduction shown by commercial PAM. The application of PAM in agricultural irrigation water and potential biopolymer alternatives to PAM are discusse

NIHAO XVI: The properties and evolution of kinematically selected discs, bulges and stellar haloes

We use 25 simulated galaxies from the NIHAO project to define and characterize a variety of kinematic stellar structures: thin and thick discs, large scale single discs, classical and pseudo bulges, spheroids, inner discs, and stellar haloes. These structures have masses, spins, shapes and rotational support in good agreement with theoretical expectations and observational data. Above a dark matter halo mass of $2.5\times10^{\rm~11}M_{\rm\odot}$, all galaxies have a classical bulge and 70\% have a thin and thick disc. The kinematic (thin) discs follow a power-law relation between angular momentum and stellar mass $J_{\rm *}=3.4M_{\rm *}^{\rm1.26\pm0.06}$, in very good agreement with the prediction based on the empirical stellar-to-halo mass relation in the same mass range, and show a strong correlation between maximum `observed' rotation velocity and dark matter halo circular velocity $v_{\rm c}=6.4v_{\rm max}^{0.64\pm0.04}$. Tracing back in time these structures' progenitors, we find all to lose a fraction $1-f_j$ of their maximum angular momentum. Thin discs are significantly better at retaining their high-redshift spins ($f_j\sim0.70$) than thick ones ($f_j\sim0.40$). Stellar haloes have their progenitor baryons assembled the latest ($z_{\rm~1/2}\sim1.1$) and over the longest timescales ($\tau\sim6.2$~Gyr), and have the smallest fraction of stars born in-situ ($f_{\rm in-situ}=0.35\pm0.14$). All other structures have $1.5\lesssim z_{\rm1/2}\lesssim3$, $\tau=4\pm2$~Gyr and $f_{\rm in-situ}\gtrsim0.9$.Comment: Accepted by MNRAS. First application of the methods described in arXiv:1804.0557