Soil organic carbon determination for Louisiana soils via portable x-ray fluorescence spectroscopy

As scientists work to investigate the mechanisms underlying the depletion of carbon from terrestrial ecosystems, there has been an urgent call for the development of test methods that offer reduced analysis times for soil organic carbon (SOC) determinations. Traditional laboratory techniques can be time-consuming and costly, making high-volume sample analyses problematic. Portable x-ray fluorescence spectroscopy (PXRF) provides quantitative, multi-elemental data for soil samples in as little as 60 seconds; and, unlike other spectroscopic methods, differences in elemental concentrations between field-moist and oven-dry samples are considered to be negligible when soil moisture contents are less than 20%, by weight. This study aims to evaluate the performance of various SOC prediction models, constructed from PXRF elemental data from 300 soil samples collected from alluvium and loess parent materials found in Louisiana, USA. Elemental data, in addition to pH and depth measurements, were used in the construction of prediction models using multiple linear regression (MLR) analysis and principal components analysis (PCA) statistical techniques. Previous research indicates that the use of a stability index may enhance SOC prediction modeling capabilities. Therefore, models utilized relative elemental abundances on the basis on Zr and Ti concentrations, and performances were compared to those resulting from models developed from ‘Raw’ PXRF data. Results show that models constructed using field-moist PXRF elemental data provide excellent SOC prediction capabilities (R \u3e 0.90) for both alluvium and loess datasets. Optimal performances resulted from the use of Ti as a stability index for field-moist datasets, producing accurate SOC predictions for both wet and dry validation sub-datasets. Findings indicate that PXRF elemental analysis, conducted under field conditions, provide for accurate SOC content determinations via MLR modeling of Louisiana alluvium and loess soil types examined in this study

Finding Submerged Sites : An Exploration of Shoreline and Environmental Change in Oregon’s Yaquina River Basin using GIS Predictive Modeling

Investigations of the Pleistocene peopling of the New World require archaeologists to establish an understanding of the paleoenvironmental conditions that would have affected early foraging peoples. Other studies have focused on the timing and route of migration and the peopling of the Americas. This project contributes to the body of work that explores these questions, by examining the Yaquina River basin of Oregon’s coast through time to better understand how local populations may have utilized and moved throughout this landscape. This is done through detailed examination of GIS based shoreline mapping and predictive modeling for the Yaquina River basin from around 20,000 years ago to the present. Results show that the earliest time periods between 20,000 and 11,000 years ago and the latest time periods after 8,000 years ago had very slow rates of shoreline change and sea level rise. These slow rates of change may not have significantly influenced foraging behavior. Between 10,000 and 8,000 years ago, drastic changes in shoreline shape and sea level rise present a unique and dramatically different environment for coastal foragers not found on Oregon’s coast today. By increasing our understanding of this landscape through time, this study will aid in our ability to protect submerged archaeological materials that may be contained in these currently offshore areas

Moderate hypoxia induces metabolic divergence in circulating monocytes and tissue resident macrophages from Berkeley sickle cell anemia mice

IntroductionHuman and murine sickle cell disease (SCD) associated pulmonary hypertension (PH) is defined by hemolysis, nitric oxide depletion, inflammation, and thrombosis. Further, hemoglobin (Hb), heme, and iron accumulation are consistently observed in pulmonary adventitial macrophages at autopsy and in hypoxia driven rodent models of SCD, which show distribution of ferric and ferrous Hb as well as HO-1 and ferritin heavy chain. The anatomic localization of these macrophages is consistent with areas of significant vascular remodeling. However, their contributions toward progressive disease may include unique, but also common mechanisms, that overlap with idiopathic and other forms of pulmonary hypertension. These processes likely extend to the vasculature of other organs that are consistently impaired in advanced SCD.MethodsTo date, limited information is available on the metabolism of macrophages or monocytes isolated from lung, spleen, and peripheral blood in humans or murine models of SCD.ResultsHere we hypothesize that metabolism of macrophages and monocytes isolated from this triad of tissue differs between Berkley SCD mice exposed for ten weeks to moderate hypobaric hypoxia (simulated 8,000 ft, 15.4% O2) or normoxia (Denver altitude, 5000 ft) with normoxia exposed wild type mice evaluated as controls.DiscussionThis study represents an initial set of data that describes the metabolism in monocytes and macrophages isolated from moderately hypoxic SCD mice peripheral lung, spleen, and blood mononuclear cells

From insect to man: Photorhabdus sheds light on the emergence of human pathogenicity

Photorhabdus are highly effective insect pathogenic bacteria that exist in a mutualistic relationship with Heterorhabditid nematodes. Unlike other members of the genus, Photorhabdus asymbiotica can also infect humans. Most Photorhabdus cannot replicate above 34°C, limiting their host-range to poikilothermic invertebrates. In contrast, P. asymbiotica must necessarily be able to replicate at 37°C or above. Many well-studied mammalian pathogens use the elevated temperature of their host as a signal to regulate the necessary changes in gene expression required for infection. Here we use RNA-seq, proteomics and phenotype microarrays to examine temperature dependent differences in transcription, translation and phenotype of P. asymbiotica at 28°C versus 37°C, relevant to the insect or human hosts respectively. Our findings reveal relatively few temperature dependant differences in gene expression. There is however a striking difference in metabolism at 37°C, with a significant reduction in the range of carbon and nitrogen sources that otherwise support respiration at 28°C. We propose that the key adaptation that enables P. asymbiotica to infect humans is to aggressively acquire amino acids, peptides and other nutrients from the human host, employing a so called “nutritional virulence” strategy. This would simultaneously cripple the host immune response while providing nutrients sufficient for reproduction. This might explain the severity of ulcerated lesions observed in clinical cases of Photorhabdosis. Furthermore, while P. asymbiotica can invade mammalian cells they must also resist immediate killing by humoral immunity components in serum. We observed an increase in the production of the insect Phenol-oxidase inhibitor Rhabduscin normally deployed to inhibit the melanisation immune cascade. Crucially we demonstrated this molecule also facilitates protection against killing by the alternative human complement pathway