Twenty year contrast of non-native parrotfeather distribution and abundance in an unregulated river

Hydrobiologia - Efficient management of invasive species benefits from understanding patterns of persistence and change over time. In this study, we compare distribution and abundance of the...     

Neutron radiography as a tool for revealing root development in soil: capabilities and limitations

Chronic atmospheric nitrogen deposition affects the cycling of carbon (C) and nitrogen (N) in forest ecosystems, and thereby alters the stable C isotopic abundance of plant and soil. Three successional stages, disturbed, rehabilitated and mature forests were studied for their responses to different nitrogen input levels. N-addition manipulative experiments were conducted at low, medium and high N levels. To study the responses of C cycling to N addition, the C concentration and ¹³C natural abundances for leaf, litter and soil were measured. Labile organic carbon fractions in mineral soils were measured to quantify the dynamics of soil organic C (SOC). Results showed that three-year continuous N addition did not significantly increase foliar C and N concentration, but decreased C/N ratio and enriched ¹³C in N-rich forests. In addition, N addition significantly decreased microbial biomass C, and increased water soluble organic C in surface soils of N-rich forests. This study suggests that N addition enhances the water consumption per unit C assimilation of dominant plant species, restricts SOC turnover in N-poor forests at early and medium successional stages (thus favored SOC sequestration), and vice versa for N-rich mature forests.     

Mortality,Morbidity and Health-Seeking Behaviour during the Ebola Epidemic 2014–2015 in Monrovia Results from a Mobile Phone Survey

Between March 2014 and July 2015 at least 10,500 Ebola cases including more than 4,800 deaths occurred in Liberia, the majority in Monrovia. However, official numbers may have underestimated the size of the outbreak. Closure of health facilities and mistrust in existing structures may have additionally impacted on all-cause morbidity and mortality. To quantify mortality and morbidity and describe health-seeking behaviour in Monrovia, Médecins sans Frontières (MSF) conducted a mobile phone survey from December 2014 to March 2015. We drew a random sample of households in Monrovia and conducted structured mobile phone interviews, covering morbidity, mortality and health-seeking behaviour from 14 May 2014 until the day of the survey. We defined an Ebola-related death as any death meeting the Liberian Ebola case definition. We calculated all-cause and Ebola-specific mortality rates. The sample consisted of 6,813 household members in 905 households. We estimated a crude mortality rate (CMR) of 0.33/10,000 persons/day (95%CI:0.25–0.43) and an Ebola-specific mortality rate of 0.06/10,000 persons/day (95%-CI:0.03–0.11). During the recall period, 17 Ebola cases were reported including those who died. In the 30 days prior to the survey 277 household members were reported sick; malaria accounted for 54% (150/277). Of the sick household members, 43% (122/276) did not visit any health care facility. The mobile phone-based survey was found to be a feasible and acceptable alternative method when data collection in the community is impossible. CMR was estimated well below the emergency threshold of 1/10,000 persons/day. Non-Ebola-related mortality in Monrovia was not higher than previous national estimates of mortality for Liberia. However, excess mortality directly resulting from Ebola did occur in the population. Importantly, the small proportion of sick household members presenting to official health facilities when sick might pose a challenge for future outbreak detection and mitigation. Substantial reported health-seeking behaviour outside of health facilities may also suggest the need for adapted health messaging and improved access to health care.     

Global Metabolic Responses to Salt Stress in Fifteen Species

Cells constantly adapt to unpredictably changing extracellular solute concentrations. A cornerstone of the cellular osmotic stress response is the metabolic supply of energy and building blocks to mount appropriate defenses. Yet, the extent to which osmotic stress impinges on the metabolic network remains largely unknown. Moreover, it is mostly unclear which, if any, of the metabolic responses to osmotic stress are conserved among diverse organisms or confined to particular groups of species. Here we investigate the global metabolic responses of twelve bacteria, two yeasts and two human cell lines exposed to sustained hyperosmotic salt stress by measuring semiquantitative levels of hundreds of cellular metabolites using nontargeted metabolomics. Beyond the accumulation of osmoprotectants, we observed significant changes of numerous metabolites in all species. Global metabolic responses were predominantly species-specific, yet individual metabolites were characteristically affected depending on species’ taxonomy, natural habitat, envelope structure or salt tolerance. Exploiting the breadth of our dataset, the correlation of individual metabolite response magnitudes across all species implicated lower glycolysis, tricarboxylic acid cycle, branched-chain amino acid metabolism and heme biosynthesis to be generally important for salt tolerance. Thus, our findings place the global metabolic salt stress response into a phylogenetic context and provide insights into the cellular phenotype associated with salt tolerance.     

Synthesis and characterization of membrane-active GALA-OKT9 conjugates

Cellular processing of immunotoxins is inefficient, limiting the overall effectiveness of current immunotoxin therapies. Specifically, translocation of ribosome-inactivating toxins across intracellular membranes is agonizingly slow. In one strategy to improve immunotoxin efficacy, membrane-active peptides are attached to immunotoxins to facilitate transfer of the toxic moiety across a cellular membrane to the cytosol. pH-sensitive peptides are of particular interest, as the membrane activity can be localized to the endosomal/lysosomal pathway, reducing nonspecific interactions at the cell surface. In this study, GALA, a pH-sensitive peptide that forms multimeric pores in membranes, was chemically attached to OKT9, an anti-transferrin receptor mAb. Conjugates were tested by measuring release of encapsulated dyes from liposomes to determine the extent to which the membrane-lytic properties of GALA were retained. The most significant feature affecting the lytic properties of GALA-OKT9 conjugates was the number of attached GALA per OKT9. Conjugates with a single GALA per OKT9 caused almost no leakage while conjugates with two or three GALA per OKT9 caused significant leakage in a concentration-dependent manner. Invariably, GALA-OKT9 conjugates were significantly less active than unconjugated GALA, attributable to a decrease both in partitioning and in surface aggregation. No improvement in membrane-lytic activity was achieved by using a longer, more flexible poly(ethylene glycol) cross-linker. Attachment of GALA via C- versus N-terminal linkage had no effect on membrane-lytic properties. Size-selective release of high molecular weight dextrans was almost identical for conjugated and unconjugated GALA, suggesting that GALA forms the same pore structure regardless of conjugation state.     

Sympatric natural Saccharomyces cerevisiae and S. paradoxus populations have different thermal growth profiles

Saccharomyces cerevisiae and its close congener S. paradoxus are typically indistinguishable by the phenotypic criteria of classical yeast taxonomy, but they are evolutionarily distinct as indicated by hybrid spore inviability and genomic sequence divergence. Previous work has shown that these two species coexist in oak-associated microhabitats at natural woodland sites in North America. Here, we show that sympatric populations of S. cerevisiae and S. paradoxus from a single natural site are phenotypically differentiated in their growth rate responses to temperature. Our main finding is that the S. cerevisiae population exhibits a markedly higher growth rate at 37 degrees C than the S. paradoxus population; we also find possible differences in growth rate between these populations at two lower temperatures. We discuss the implications of our results for the coexistence of these yeasts in natural environments, and we suggest that thermal growth response may be an evolutionarily labile feature of these organisms that could be analyzed using genomic approaches.     

Protective neutralizing antibodies from human survivors of Crimean-Congo hemorrhagic fever

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Histology of the trachea and lung of Siphonops annulatus (Amphibia, Gymnophiona)

The structure of the trachea and lung of Siphonops annulatus was studied in ten specimens of routinely fed animals. The trachea is constituted mainly by incomplete cartilage rings lined by a respiratory epithelium (ciliated and mucous cells) with variable morphology according to the region observed. A rich vascularization of this organ suggests its participation in blood-air gas exchange. The right lung in this species is developed and the left one is atrophied. This organ is constituted mainly by longitudinal septa formed by connective tissue, smooth muscle cells and blood capillaries. These structures are covered by pneumocytes of one type only, which present cytoplasmic particles that have been related with surfactant activity described in the lung of Gymnophiona.