Pseudomonas aeruginosa can be detected in a polymicrobial competition model using impedance spectroscopy with a novel biosensor

Electrochemical Impedance Spectroscopy (EIS) is a powerful technique that can be used to elicit information about an electrode interface. In this article, we highlight six principal processes by which the presence of microorganisms can affect impedance and show how one of these - the production of electroactive metabolites - changes the impedance signature of culture media containing Pseudomonas aeruginosa. EIS, was used in conjunction with a low cost screen printed carbon sensor to detect the presence of P. aeruginosa when grown in isolation or as part of a polymicrobial infection with Staphylococcus aureus. By comparing the electrode to a starting measurement, we were able to identify an impedance signature characteristic of P. aeruginosa. Furthermore, we are able to show that one of the changes in the impedance signature is due to pyocyanin and associated phenazine compounds. The findings of this study indicate that it might be possible to develop a low cost sensor for the detection of P. aeruginosa in important point of care diagnostic applications. In particular, we suggest that a development of the device described here could be used in a polymicrobial clinical sample such as sputum from a CF patient to detect P. aeruginosa

On the Diversity of Erosion Control Products: Implications for Snake Entanglement

After a road construction project, Texas Department of Transportation (TxDOT) mandates that erosion control products (ECPs) are installed to prevent soil loss and promote plant growth. However, their presence on the landscape pose negative consequences to wildlife via entanglement. TxDOT provides an Approved Products List (APL) of ECPs meeting soil erosion prevention and plant growth standards. In Texas, multiple types of ECPs are produced with a range of materials and attributes to decrease the erosion potential on multiple soil types and slopes. Certain attributes are more likely to lead to snake entanglement (Ebert et al. 2019 Wildl. Soc. Bull.; Fig. 1A & B). The purpose of this study was to quantify the diversity of traits of the erosion control products to determine which products pose the least risk of snake entanglement to limit this additional source of mortality

NITROGEN AND WATER EFFECTS ON CANOPY SENSOR MEASUREMENTS FOR SITE-SPECIFIC MANAGEMENT OF CROPS

Water and nitrogen (N) are undoubtedly the two largest agricultural inputs globally. Coupled with advances in site-specific management technology their integration into production agriculture will allow for the most efficient use these crop input resources. Active canopy sensors offer the ability to measure biophysical plant traits rapidly and make assessments about plant status. Specifically, optical sensor measurements of light reflectance assess plant N status allowing for in-season and on-the-go N recommendations and applications; while infrared thermometers (IRT) measurement of canopy temperature can be used a tool for irrigation management. To evaluate how these technologies work among different plant stress environments a series of experiments were formulated. The first experiment compared reference strategies for normalizing reflectance data across multiple vegetation indices (VI). We found the virtual reference concept helped reduce variation of the calculated reference and placed sufficiency index values in a range that corresponded to plant N status. Additionally, VI varied in their ability to show significant responses to applied N fertilizer. In the second experiment, we sought to understand the influence of VI on how an in-season N application algorithm performs as well as the confounding effects of irrigation might have. We found N application rates would change based on algorithm and VI. Also, N rate can be affected by apparent water stress. In this case, reduced reflectance in the NIR spectrum reduced leaf area from leaf rolling. The final objective was to quantify the effect of N fertility on plant canopy temperature and determine if functions of canopy temperature could be useful for detecting apparent N stress. We concluded that plant canopy temperature can be affected by N stresses and that canopy temperature and canopy/air temperature difference provided equal sensitivity to plant stress. Therefore, these technologies will be vital to help conserve resources and maximize efficiency in production agriculture. Advisor: Richard Ferguso

Reduced dynamics of Ward solitons

The moduli space of static finite energy solutions to Ward's integrable chiral model is the space $M_N$ of based rational maps from \CP^1 to itself with degree $N$. The Lagrangian of Ward's model gives rise to a K\"ahler metric and a magnetic vector potential on this space. However, the magnetic field strength vanishes, and the approximate non--relativistic solutions to Ward's model correspond to a geodesic motion on $M_N$. These solutions can be compared with exact solutions which describe non--scattering or scattering solitons.Comment: Final version, to appear in Nonlinearit

Development of a diagnostic device to detect different pseudomonas aeruginosa phenotypes in medically relevant contexts

Pseudomonas aeruginosa, widely present in the environment, is well known for its ability to cause infection in immune compromised individuals. For example, P. aeruginosa is the leading cause of morbidity and mortality in patients with cystic fibrosis (CF). Here, we describe how Electrochemical Impedance Spectroscopy (EIS) can be used to detect the presence of four different strains of P. aeruginosa. Using a low cost, screen printed carbon electrode significant changes can be seen in impedance data in the presence of P. aeruginosa after 24 hours. Furthermore, through the use of a normalization technique whereby the phase angle of the impedance (a commonly used parameter) is divided by a starting measurement, it is possible to identify differences between a non-mucoid and mucoid strain of P. aeruginosa. Sensors based upon the techniques described here could be used in a number of healthcare scenarios, where there is a need for low cost, real time detection of P. aeruginosa, such as CF

Does Installation Method Affect Snake Entanglement in Erosion Control Blankets?

Erosion control blankets (ECBs) are installed at construction sites to mitigate against soil loss and promote plant growth. Wildlife, particularly snakes, are prone to becoming entangled in ECBs that contain fixed‐intersection, small‐diameter polypropylene mesh with multiple layers (Ebert et al. 2019 Wildl. Soc. Bull.; Fig. 1). The majority of ECBs on the Texas Department of Transportation’s Approved Product List contain fixed-intersection mesh, which pose a risk to snakes. Snake entanglements often occur at the edge of an ECB where the snake often passes between the multiple mesh layers (Ebert et al. 2019 Wildl. Soc. Bull.) Burying the edge of an ECB may decrease the risk of snake entanglement by allowing them to pass over the ECB edge reducing their encounters with the multiple layers of mesh netting. We hypothesized burying the ECB edge would reduce snakes attempting to pass through the mesh and reducing their risk of entanglement and that there will be a positive correlation between circumference and entanglement

RpfC (Rv1884) atomic structure shows high structural conservation within the resuscitation promoting factor catalytic domain

We report the first structure of the catalytic domain of RpfC (Rv1884), one of theresuscitation-promoting factors (RPFs) from Mycobacterium tuberculosis. The structure was solved using molecular replacement, once the space group had been correctly identified as twinned P21 rather than the apparent C2221 by searching for anomalous scattering sites in P1. The structure displays a very high degree of structural conservation with the structures of the catalytic domains of RpfB (Rv1009) and RpfE (Rv2450) already published. This structural conservation highlights the importance of the versatile domain composition of the RPF family

Metabolic Profiling Reveals Biochemical Pathways Responsible for Eelgrass Response to Elevated CO\u3csub\u3e2\u3c/sub\u3e and Temperature

As CO2 levels in Earth’s atmosphere and oceans steadily rise, varying organismal responses may produce ecological losers and winners. Increased ocean CO2 can enhance seagrass productivity and thermal tolerance, providing some compensation for climate warming. However, the metabolic shifts driving the positive response to elevated CO2 by these important ecosystem engineers remain unknown. We analyzed whole-plant performance and metabolic profiles of two geographically distinct eelgrass (Zostera marina L.) populations in response to CO2 enrichment. In addition to enhancing overall plant size, growth and survival, CO2 enrichment increased the abundance of Calvin Cycle and nitrogen assimilation metabolites while suppressing the abundance of stress-related metabolites. Overall metabolome differences between populations suggest that some eelgrass phenotypes may be better suited than others to cope with an increasingly hot and sour sea. Our results suggest that seagrass populations will respond variably, but overall positively, to increasing CO2 concentrations, generating negative feedbacks to climate change

Research Opportunities in Interdisciplinary Ground-Water Science

The U.S. Geological Survey (USGS) has a long-standing reputation for providing unbiased scientific leadership and excellence in the field of ground-water hydrology and geological research. This report provides a framework for continuing this scientific leadership by describing six interdisciplinary topics for research opportunities in ground-water science in the USGS. These topics build on recommendations of the National Research Council (2000) contained in the report, “Investigating Groundwater Systems on Regional and National Scales,” and emphasize research topics that would benefit from the integrated capabilities of all parts of the USGS. Understanding the relations between ground water and the geological characteristics of aquifers within which ground water resides, and the relation of ground water to surface-water resources and terrestrial and aquatic biota is increasingly important and presents a considerable opportunity to draw on expertise throughout the USGS, including the science disciplines of biology, geography, geology, and hydrology. The National Research Council (2000) also emphasizes that USGS regional and national assessments of ground-water resources should focus on aspects that foster the sustainability of the resource. The need for a comprehensive program addressing the sustainability of ground-water resources can be stated very concisely—we need enough ground water of good quality to sustain our lives, our economy, and our aquatic ecosystems. Although societal needs for high-quality, objective ground-water science are increasing, current funding for USGS regional ground-water programs is about 40 percent of the funding available 20–25 years ago. Given the current challenges of budgetary constraints, however, this report provides a flexible set of interrelated research topics that enhance the ability of the USGS to focus limited fiscal resources on developing ground-water science tools and methods that provide high-quality, objective scientific information