Influence of host resistance on the genetic structure of the white pine blister rust fungus in the western United States

Cronartium ribicola, the causal agent of white pine blister rust, has been devastating to five-needled white pines in North America since its introduction nearly a century ago. However, dynamic and complex interactions occur among C. ribicola, five-needled white pines, and the environment. To examine potential evolutionary influences on genetic structure and diversity of C. ribicola in western United States, population genetic analyses of C. ribicola were conducted using amplified fragment length polymorphism (AFLP) molecular markers. The fungus was sampled at six sites. Collections for two of the six sites were from separate plantings of resistant-selected western white pine and sugar pine. Heterozygosity based on polymorphic loci among populations ranged from 0.28 to 0.40, with resistant-selected plantations at the extremes. Genetic differentiation was also highest between these two populations. Principal coordinates analysis and Bayesian assignment placed most isolates that are putative carriers of virulence to major-gene resistance into a discernable cluster, while other isolates showed no clustering by site or host species. These results indicate that C. ribicola in western North America is not genetically uniform, despite its presumed single site of introduction and relatively brief residence. Moreover, major-gene resistance appears to have imposed strong selection on the rust, resulting in reduced genetic diversity. In contrast, no evidence of selection was observed in C. ribicola from hosts that exhibit only multigenic resistance.     

Summary of findings from a participant country pollen beetle questionnaire

A questionnaire was sent to all participating countries to gain some background information on rape growing and on pollen beetle ( Meligethes aeneus ). Information was sought on the use of thresholds, the availability of active substances and on the year in which resistance, if present, had been observed. A summary of the main findings of the questionnaire are presented. In total 20 countries responded and resistance in pollen beetle was reported in 12 of those countries. Information presented shows the range of active substances and doses recommended, frequency of use of insecticides on rape, and year when resistance was reported.     

Effective Removal of Toxic Heavy Metal Ions from Aqueous Solution by CaCO<Subscript>3</Subscript> Microparticles

Heavy metals are a common contaminant in water supplies and pose a variety of serious health risks to nearby human populations. A promising approach to heavy metal decontamination is the sequestration of heavy metal ions in porous materials; however, current technologies involve materials which can be difficult to synthesize, are high-cost, or are themselves potentially toxic. Herein, we demonstrate that rapidly synthesized calcium carbonate (CaCO₃) microparticles can effectively remove high quantities of Pb²⁺, Cd²⁺, and Cu²⁺ ions (1869, 1320, and 1293 mg per gram of CaCO₃ microparticles, respectively) from aqueous media. The CaCO₃ microparticles were characterized with powder X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), and Brunauer–Emmett–Teller (BET) N₂ sorption–desorption. It was found that the Ca²⁺ ions of the microparticles were replaced by the heavy metal ions, leading to partially recrystallized nanoparticles of new compositional phases such as cerussite (PbCO₃). The adsorption, surface dissolution/re-precipitation, and nucleation/crystal growth mechanisms were determined by investigating the Ca²⁺ released, along with the changes to particle morphology and crystal structure. Importantly, this study demonstrates that the porous CaCO₃ microparticles performed well in a system with multiple heavy metal ion species: 100% of Cu²⁺, 97.5% of Pb²⁺, and 37.0% Cd²⁺ were removed from an aqueous solution of all cations with initial individual metal concentrations of 50 mg/L and 1.5 g/L of CaCO₃ microparticles. At this concentration, the CaCO₃ microparticles significantly outperformed activated carbon. These results help to establish CaCO₃ microparticles as a promising low-cost and scalable technology for removing heavy metal ions from contaminated water.

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Challenges and Solutions for Applying the Travel Cost Demand Model to Geographically Remote Visitor Destinations: A Case Study of Bear Viewing at Katmai National Park and Preserve

Remote and unique destinations present difficulties when attempting to construct traditional travel cost models to value recreation demand. The biggest limitation comes from the lack of variation in the dependent variable, defined as the number of trips taken over a set time frame. There are various approaches that can be used for overcoming limitations of the traditional travel cost model in the context of remote destinations. This study applies an adaptation of the standard model to estimate recreation benefits of bear viewing at Katmai National Park and Preserve in Alaska, which represents a once-in-a-lifetime experience for many visitors. Results demonstrate that visitors to this park’s Brooks Camp area are willing to pay an average of US$287 per day of bear viewing. Implications of these findings for valuing recreation at other remote destinations are discussed.     

Efficacy of three tourniquet types for intravenous antimicrobial regional limb perfusion in standing horses

Objective: To determine (1) if clinically useful concentrations of amikacin sulfate can be obtained in synovial fluid during regional limb perfusion (RLP) performed above the carpus in standing sedated horses and (2) to determine the efficacy of 3 tourniquet types (narrow rubber [NR], wide rubber [WR], pneumatic [PN]). Animals: Horses (n=9). Methods: Bilateral forelimb RLP with amikacin sulfate (2.5 g) were administered through the cephalic vein in standing sedated horses. Limbs were randomly assigned to the 3 tourniquet types (NR, WR, PN) applied above the carpus. Metacarpophalangeal synovial fluid was obtained 0.5 hour after perfusion. Amikacin concentration in the synovial fluid was detected using fluorescence polarization immunoassay. Results: Mean synovial concentrations of amikacin in the PN (mean 236 μg/mL; range 23–913 μg/mL) and WR (mean 64.2 μg/mL; range 7–315 μg/mL) were significantly higher (P=.000 and .032, respectively) than the NR tourniquet (mean 2.1 μg/mL; range 0.9–3.3 μg/mL). Conclusions: The PN tourniquet resulted in the highest synovial fluid amikacin concentrations in all horses, although administration with PN and WR tourniquets achieved adequate amikacin concentrations. NR tourniquet is ineffective and should not be used for RLP above the carpus in the standing horse.     

Serous cystadenoma in a normally cyclic mare with high plasma testosterone values

Serous cystadenoma was diagnosed by histologic examination of a large ovary removed from a 16-year-old Thoroughbred mare with normal estrous cycles. Palpation and ultrasound examination per rectum had revealed an excessive number of follicles in the right ovary. The ovulation fossa was palpable on the right ovary, and the left ovary appeared to have normal activity. Plasma testosterone values were high at the time of examination (0.15 ng/ml), but decreased to normal values (0.09 ng/ml) after removal of the cystadenoma.