A family of three mouse potassium channel genes with intronless coding regions

To understand the molecular mechanisms responsible for generating physiologically diverse potassium channels in mammalian cells, mouse genomic clones have been isolated with a potassium channel complementary DNA, MBK1, that is homologous to the Drosophila potassium channel gene, Shaker. A family of three closely related potassium channel genes (MK1, MK2, and MK3) that are encoded at distinct genomic loci has been isolated. Sequence analysis reveals that the coding region of each of these three genes exists as a single uninterrupted exon in the mouse genome. This organization precludes the generation of multiple forms of the protein by alternative RNA splicing, a mechanism known to characterize the Drosophila potassium channel genes Shaker and Shab. Thus, mammals may use a different strategy for generating diverse K+ channels by encoding related genes at multiple distinct genomic loci, each of which produces only a single protein.     

Discovery of gaseous S2 in Io's Pele plume

Spectroscopy of Io's Pele plume against Jupiter by the Hubble Space Telescope in October 1999 revealed absorption due to S2 gas, with a column density of 1.0 +/- 0.2 x 10(16) per square centimeter, and probably also SO(2) gas with a column density of 7 +/- 3 x 10(16) per square centimeter. This SO2/S2 ratio (3 to 12) is expected from equilibration with silicate magmas near the quartz-fayalite-magnetite or wüstite-magnetite buffers. Condensed S3 and S4, probable coloring agents in Pele's red plume deposits, may form by polymerization of the S2, which is unstable to ultraviolet photolysis. Diffuse red deposits near other Io volcanoes suggest that venting and polymerization of S2 gas is a widespread feature of Io volcanism.     

Late Pleistocene Desiccation of Lake Victoria and Rapid Evolution of Cichlid Fishes

Lake Victoria is the largest lake in Africa and harbors more than 300 endemic species of haplochromine cichlid fish. Seismic reflection profiles and piston cores show that the lake not only was at a low stand but dried up completely during the Late Pleistocene, before 12,400 carbon-14 years before the present. These results imply that the rate of speciation of cichlid fish in this tropical lake has been extremely rapid.     

Volatile monoterpenes inhibit potato tuber sprouting

Several volatile monoterpenes, which are among the major constituents of several easily obtainable essential oils, were phytotoxic in the gaseous phase to emerged potato tuber sprouts. Analyses of the more phytotoxic monoterpenes were conducted using a continuous-flow system in which the compounds were released as volatiles into the headspace surrounding the tubers. Several of these compounds, which have low mammalian toxicities and are currently used in large amounts as flavorings, over-the-counter medications and perfumes, effectively inhibited sprouting and fungal growth at relatively low molar concentrations.     

Demographic consequences of adaptive growth and the ramifications for conservation of long-lived organisms

Understanding how organisms respond to human impacts is increasingly challenging biologists. Short-lived organisms can adapt rapidly to changes in environmental hazards, but only recently have long-lived organisms been shown to adapt to human impacts. Changes in any life-history trait, such as individual growth rates, may affect demographic model predictions and reliability of elasticity analyses that are often used to help manage and conserve long-lived organisms. The aim of this study was to test model predictions of the effect of increased recruitment and density-dependent processes to manage populations of long-lived turtles in two continents. We explored how human-induced changes in juvenile density affect population growth estimates and the strength of selection on stage-based life-history traits. Model projections undervalued the potential effect of an increase in nest survival. Sensitivity calculations indicated greatest selection intensities for juvenile growth or maturation, whereas elasticity analyses indicated that changes in adult survival have the largest proportional effect on population fitness. Long-term use of the locality of our North American population as a recreational site may have increased adult mortality of turtles and reduced the number of nest predators, inducing rapid individual growth and early maturation. The traditional static view of turtle life history and demography thus is inappropriate even over relatively short periods of time. Anthropogenically-induced changes in demographic processes can potentially induce adaptive changes to life-history processes, which can seriously impact the reliability of long-term projections from common demographic models. Management practices must account for this dynamism accordingly.     

Inferring source attribution from a multiyear multisource data set of Salmonella in Minnesota

Salmonella enterica is a global health concern because of its widespread association with foodborne illness. Bayesian models have been developed to attribute the burden of human salmonellosis to specific sources with the ultimate objective of prioritizing intervention strategies. Important considerations of source attribution models include the evaluation of the quality of input data, assessment of whether attribution results logically reflect the data trends and identification of patterns within the data that might explain the detailed contribution of different sources to the disease burden. Here, more than 12,000 non‐typhoidal Salmonella isolates from human, bovine, porcine, chicken and turkey sources that originated in Minnesota were analysed. A modified Bayesian source attribution model (available in a dedicated R package), accounting for non‐sampled sources of infection, attributed 4,672 human cases to sources assessed here. Most (60%) cases were attributed to chicken, although there was a spike in cases attributed to a non‐sampled source in the second half of the study period. Molecular epidemiological analysis methods were used to supplement risk modelling, and a visual attribution application was developed to facilitate data exploration and comprehension of the large multiyear data set assessed here. A large amount of within‐source diversity and low similarity between sources was observed, and visual exploration of data provided clues into variations driving the attribution modelling results. Results from this pillared approach provided first attribution estimates for Salmonella in Minnesota and offer an understanding of current data gaps as well as key pathogen population features, such as serotype frequency, similarity and diversity across the sources. Results here will be used to inform policy and management strategies ultimately intended to prevent and control Salmonella infection in the state.     

Long-Term Effect of Nitrogen and Tillage Management on Soil Carbon Pools in the Semiarid Northern Great Plains

No-tillage and manure application effect on soil organic carbon (SOC) and total nitrogen (N) concentrations were studied under a 27-year-old 4-year rotation consisting corn (Zea mays L.)-soybean (Glycine max L.)-wheat (Triticum aestivum L.)-field pea (Pisum sativum L.). Under each crop, four applied N treatments were control, annual urea-N applications at the rate of 45 and 89 kg N ha^?1, and composted beef cattle feedlot manure-N at the rate 179 kg N ha^?1 applied once every four year. For each fertilizer treatment, no-till (NT) and conventional till (CT) were compared for basic soil properties, SOC, and total N within 0–15 cm soil. Manure application significantly reduced soil bulk density and increased SOC and total N over urea-N. Particulate organic matter, mineralizable N, and permanganate-oxidizable C fractions significantly related with SOC. Long-term manure additions and no-tillage had potential to improve soil compaction and maintain SOC over chemical fertilizer N and CT.