DIRECT DETECTION OF ESCHERICHIA COLI 0157:H7 IN UNPASTEURIZED APPLE JUICE WITH AN EVANESCENT WAVE BIOSENSOR

An evanescent wave biosensor was used to detect Escherichia coli O157:H7 in unpasteurized apple juice. Light is launched from a 635 nm laser diode into silica or polystyrene optical waveguides, generating an evanescent field which extends from the waveguide surface. Fluorescent molecules within the evanescent field are excited resulting in an emission signal that the biosensor then detects and quantifies. A sandwich immunoassay was performed on the waveguides using cyanine 5 dye-labeled anti-E. coli O157:H7 antibodies for generation of the specific fluorescent signal. The lower limit of detection was between 6.0 × 10² and 6.0 × 10⁴ CFU/mL with silica waveguides and between 3.2 × 10⁴ and 3.2 × 10⁴ CFU/mL using polystyrene waveguides. One-hundred percent correct identification of true positive samples occurred at 6.0 × 10⁴ and 3.2 × 10⁴ CFU/mL for silica and polystyrene waveguides, respectively. Signals from a variety of non-E. coli O157 bacteria, including closely related enterotoxigenic strains of E. coli at concentrations of ˜ 10⁶ CFU/mL, were below the limits of detection. Assays were conducted in near real-time with results obtained within 15 min of sample processing.     

A role for oxalic acid generation in ozone‐induced signallization in Arabidopis cells

Ozone (O₃) is an air pollutant with an impact increasingly important in our industrialized world. It affects human health and productivity in various crops. We provide the evidences that treatment of Arabidopsis thaliana with O₃ results in ascorbate‐derived oxalic acid production. Using cultured cells of A. thaliana as a model, here we further showed that oxalic acid induces activation of anion channels that trigger depolarization of the cell, increase in cytosolic Ca²⁺ concentration, generation of reactive oxygen species and cell death. We confirmed that O₃ reacts with ascorbate in the culture, thus resulting in production of oxalic acid and this could be part of the O₃‐induced signalling pathways that trigger programmed cell death.     

Effects of environmental stress cascade up through four trophic levels in a salt marsh study system

1. Although in recent years there have been a number of studies demonstrating trophic cascades in terrestrial systems, it is still unclear what environmental conditions enable or enhance such cascades, especially among four trophic levels. 2. In this study, the influence of environmental stress (increased soil pore water salinity) on a four trophic level study system in a Florida salt marsh was examined by experimentally increasing soil pore water salinity. Effects of increased salinity on the quality of the host plant, Batis maritima, were assessed, as were resulting effects on the lepidopteran herbivore Ascia monuste, and the primary parasitoids and hyperparasitoids of its caterpillars. 3. Increased salinity altered host‐plant quality, which subsequently affected the consumer species. These effects of altered plant quality cascaded up through the herbivore and primary parasitoid to the hyperparasitoid Hypopteromalus inimicus, influencing its density, sex ratio, body size, and initial egg load. 4. These results demonstrate how heterogeneity in environmental stress can result in effects that cascade up through four trophic levels. We suggest that such strong effects at higher trophic levels may be more likely in systems in which relationships are more specific and intimate such as those among hosts, parasitoids, and hyperparasitoids.     

Carbon sequestration in tropical forests and water: a critical look at the basis for commonly used generalizations

Tree planting in the tropics is conducted for a number of reasons including carbon sequestration, but often competes with increasingly scarce water resources. The basics of forest and water relations are frequently said to be well understood but there is a pressing need to better understand and predict the hydrological effects of land‐use and climate change in the complex and dynamic landscapes of the tropics. This will remain elusive without the empirical data required to feed hydrological process models. It is argued that the current state of knowledge is confused by too broad a use of the terms ‘forest’ and ‘(af)forestation’, as well as by a bias towards using data generated mostly outside the tropics and for nondegraded soil conditions. Definitions of forest, afforestation and reforestation as used in the climate change community and their application by land and water managers need to be reconciled.     

Guilt by Association: The Culture of Accusation and the American Anthropological Association's Investigation of Darkness in El Dorado

The American Anthropological Association's investigation of the charges in Darkness in El Dorado (Tierney 2000) found that the late James Neel and Napoleon Chagnon harmed the Yanomami in the course of their research in Venezuela and Brazil, and that Chagnon had violated the ethics code of the association. The association's inquiry contravened its own policy prohibiting ethics adjudications and was structured not by the standards of an objective investigation but by aspects of contemporary anthropology. Moralized approaches to information and postmodern rejection of objectivity mark the language and methods of the inquiry. The investigating task force did not observe reasonable standards of evidence, the targets of the investigation were not represented, and task force members were compromised by conflicts of interest. The investigation and its collateral activities reflect a culture of accusation and an anthropology uncertain of its ethical or scientific stature.     

Breeding status, contaminant burden and helminth parasites of Northern Fulmars Fulmarus glacialis from the Canadian high Arctic

We studied the relationship between contaminant concentrations in livers, endohelminth prevalence and physiological indices of chronic stress (spleen size, heterophil/lymphocyte ratios) in Northern Fulmars Fulmarus glacialis collected during the breeding season in Nunavut, Canada. No blood parasites were found, similar to reports for other petrel species elsewhere. However, 54% of Fulmars had gastrointestinal helminths, principally cestodes (52% prevalence, mean intensity of 11 worms), nematodes (34% prevalence, 3.6 worms) and acanthocephalans (3%, eight worms). Both prevalence and intensity of helminth infections were lower for Arctic Fulmars than for Fulmars and other petrels found in southern parts of the species' range. Spleen size was not significantly related to either contaminant concentration or presence of parasites, suggesting that Fulmar health was generally unaffected by contaminant and parasite levels at the colony. However, we cannot rule out the possibility that Fulmars with higher parasitaemias or contaminant loads were in poorer condition and did not attend the breeding colony.     

The taxonomy, biogeography and host plant relationships of jumping plant-lice (Hemiptera: Psyllidae) associated with creosote bushes (Larrea spp., Zygophyllaceae)

Abstract.  The Neotropical genus Panisopelma (Psyllidae: Aphalaroidinae) is revised and its internal phylogeny analysed. The constituent species, including five new ones, are described and illustrated. Keys are provided for the adults and the last instar larvae. Eight species are associated with creosote bushes ( Larrea , Zygophyllaceae): five with L. nitida and three with L. divaricata . There is evidence that another three species, the larvae of which are unknown, also develop on L. divaricata . Seven species are restricted to Argentina, one to Bolivia and three to Chile. The cladistic analysis based on male, female and larval morphological characters yielded a single most-parsimonious tree. The species associated with L. nitida form a monophyletic clade, those on L. divaricata , by contrast, are paraphyletic. One clade with three species is restricted to Argentina, but three clades each contain a species from Argentina and Chile. Although a close association exists between Panisopelma and Larrea , there is no evidence for cospeciation, but rather an initial shift from an unknown host to L. divaricata and a second shift from L. divaricata to L. nitida . In three species pairs of Panisopelma , the distribution patterns suggest geographical vicariance between Argentina and Chile.