Effect of thermal additions on the density and distribution of thermophilic amoebae and pathogenic Naegleria fowleri in a newly created cooling lake

Pathogenic Naegleria fowleri is the causative agent of fatal human amoebic meningoencephalitis. The protozoan is ubiquitous in nature, and its presence is enhanced by thermal additions. In this investigation, water and sediments from a newly created cooling lake were quantitatively analyzed for the presence of thermophilic amoebae, thermophilic Naegleria spp., and the pathogen Naegleria fowleri. During periods of thermal additions, the concentrations of thermophilic amoebae and thermophilic Naegleria spp. increased as much as 5 orders of magnitude, and the concentration of the pathogen N. fowleri increased as much as 2 orders of magnitude. Concentrations of amoebae returned to prior thermal perturbation levels within 30 to 60 days after cessation of thermal additions. Increases in the thermophilic amoeba concentrations were noted in Savannah River oxbows downriver from the Savannah River plant discharge streams as compared with oxbows upriver from the discharges. Concentrations of thermophilic amoebae and thermophilic Naegleria spp. correlated significantly with temperature and conductivity. Air samples taken proximal to the lake during periods of thermal addition showed no evidence of thermophilic Naegleria spp. Isoenzyme patterns of the N. fowleri isolated from the cooling lake were identical to patterns of N. fowleri isolated from other sites in the United States and Belgium.</jats:p

Enhanced Proton Translocating Pyrophosphatase Activity Improves Nitrogen Use Efficiency in Romaine Lettuce

Abstract Plant nitrate (NO3  −) acquisition depends on the combined activities of root high- and low-affinity NO3  − transporters and the proton gradient generated by the plasma membrane H+-ATPase. These processes are coordinated with photosynthesis and the carbon status of the plant. Here, we present the characterization of romaine lettuce (Lactuca sativa ‘Conquistador’) plants engineered to overexpress an intragenic gain-of-function allele of the type I proton translocating pyrophosphatase (H+-PPase) of Arabidopsis (Arabidopsis thaliana). The proton-pumping and inorganic pyrophosphate hydrolytic activities of these plants are augmented compared with control plants. Immunohistochemical data show a conspicuous increase in H+-PPase protein abundance at the vasculature of the transgenic plants. Transgenic plants displayed an enhanced rhizosphere acidification capacity consistent with the augmented plasma membrane H+-ATPase proton transport values, and ATP hydrolytic capacities evaluated in vitro. These transgenic lines outperform control plants when challenged with NO3  − limitations in laboratory, greenhouse, and field scenarios. Furthermore, we report the characterization of a lettuce LsNRT2.1 gene that is constitutive up-regulated in the transgenic plants. Of note, the expression of the LsNRT2.1 gene in control plants is regulated by NO3  − and sugars. Enhanced accumulation of 15N-labeled fertilizer by transgenic lettuce compared with control plants was observed in greenhouse experiments. A negative correlation between the level of root soluble sugars and biomass is consistent with the strong root growth that characterizes these transgenic plants.</jats:p

Table_1_Coastal landforms and fetch influence shoreline restoration effectiveness.docx

Coastal shorelines are a key interface between terrestrial and aquatic ecosystems and are vital for human livelihood. As a result, shorelines have experienced substantial human modifications worldwide. Shoreline “hardening” – the construction of armor including seawalls, bulkheads, or rip-rap – is a common modification that has substantial negative ecological effects. Currently, restoration involving the removal of armor and replacement with “living” shorelines is becoming an established practice. Still, the ecological response to armor removal is oftentimes unpredictable and site-specific. We hypothesized that the confluence of larger-scale geophysical features might strongly influence ecological restoration outcomes at particular locations. To measure the effectiveness of armor removal in the context of broad-scale geophysical features across the Salish Sea, WA, USA, we studied 26 paired restored and natural reference beaches of the same shoretype (feeder bluff, accretion shoreform, or pocket beach), as well as corresponding fetch, sub-basin, and percent of shoreline sediment drift cell armored. Sites were restored for an average of six years. We gauged restoration effectiveness based on levels of five ecological response variables: beach wrack (percent, depth), logs (count, width), sediments (percent sand), vegetation (percent overhanging, count of fallen trees), and insects (density, taxa richness). We found that armor removal often restored these variables to natural levels, but that restoration response was dependent on geophysical features such as shoretype and fetch. Natural beaches did have higher measurements of overhanging vegetation, fallen trees, and insect taxa richness, as these features likely take time to mature at restored beaches. Feeder bluffs had a higher proportion of surface sand and number of fallen trees than other shoretypes, coinciding with the erosion of bluff material, whereas natural pocket beaches within bordering rocky headlands had higher insect densities. Sites with a large fetch had higher input of deposited wrack and logs, whereas sites with a small fetch had higher input from localized terrestrial sources – fallen trees and eroding sand. By incorporating the effectiveness of restoration with landscape features such as shoretype and fetch, we can more effectively plan for future restoration actions and better predict their outcomes.</p