Measuring and modeling the variation in species-specific transpiration in temperate deciduous hardwoods

We investigated which parameters required by the MAESTRA model were most important in predicting leaf-area-based transpiration in 5-year-old trees of five deciduous hardwood species-yoshino cherry (Prunus x yedoensis Matsum.), red maple (Acer rubrum L. 'Autumn Flame'), trident maple (Acer buergeranum Miq.), Japanese flowering cherry (Prunus serrulata Lindl. 'Kwanzan') and London plane-tree (Platanus x acerifolia (Ait.) Willd.). Transpiration estimated from sap flow measured by the heat balance method in branches and trunks was compared with estimates predicted by the three-dimensional transpiration, photosynthesis and absorbed radiation model, MAESTRA. MAESTRA predicted species-specific transpiration from the interactions of leaf-level physiology and spatially explicit micro-scale weather patterns in a mixed deciduous hardwood plantation on a 15-min time step. The monthly differences between modeled mean daily transpiration estimates and measured mean daily sap flow ranged from a 35% underestimation for Acer buergeranum in June to a 25% overestimation for A. rubrum in July. The sensitivity of the modeled transpiration estimates was examined across a 30% error range for seven physiological input parameters. The minimum value of stomatal conductance as incident solar radiation tends to zero was determined to be eight times more influential than all other physiological model input parameters. This work quantified the major factors that influence modeled species-specific transpiration and confirmed the ability to scale leaf-level physiological attributes to whole-crown transpiration on a species-specific basis.     

Combating plant diseases—the Darwin connection

Although Darwin knew of plant diseases, he did not study them as part of his analysis of natural selection. Effective plant disease control has only been developed after his death. This article explores the relevance of Darwin's ideas to three problem areas with respect to diseases caused by fungi: emergence of new diseases, loss of disease resistance bred into plants and development of fungicide resistance. Darwin's concept of change through natural or artificial selection relied on selection of many small changes, but subsequent genetic research has shown that change can also occur through large steps. Appearance of new diseases can involve gene duplication, transfer or recombination, but all evidence points to both host plant resistance and fungicide susceptibility being overcome through point mutations. Because the population size of diseases such as rusts and powdery and downy mildews is so large, all possible point mutations are likely to occur daily, even during moderate epidemics. Overcoming control measures therefore reflects the overall fitness of these mutants, and much resource effort is being directed towards assessment of their fitness, both in the presence and in the absence of selection. While recent developments in comparative genomics have caused some revision of Darwin's ideas, experience in managing plant disease control measures clearly demonstrates the relevance of concepts he introduced 150 years ago. It also reveals the remarkable speed and the practical impact of adaptation in wild microorganism populations to changes in their environment, and the difficulty of stopping or delaying such adaptation. Copyright © 2009 Society of Chemical Industry     

Experimental demonstration of an antigenic relationship between Leptospira and equine cornea

Horses inoculated with either equine cornea or killed Leptospira interrogans serovars pomona, tarassovi, icterohaemorrhagiae, wolffi and hardjo, developed corneal opacity and produced antibodies which made it possible to demonstrate partial antigenic identity between equine cornea and four of those serovars employed. These antibodies were isolated by means of immunoadsorptions, purified by ion-exchange chromatography (DEAE-Sephadex A-50) and run by immuno-electrophoresis in agar gel. Both antibodies, anti-equine cornea and anti-leptospira, showed that they corresponded to the IgGb subclass. They bound themselves to equine cornea in vivo and in vitro as was proved by immunofluorescence. This antigenic relationship may be in part responsible for pathogenesis of corneal opacity in leptospirosis of horses.     

Unilateral ventral strabismus in an aquarium Silver Arowana (Osteoglossum bicirrhosum)

An adult silver arowana (Osteoglossum bicirrhosum) presented with a 2‐month history of acute onset ventral strabismus of the right eye associated with a cystic structure overlying the dorsal aspect of the globe. Aspiration of the cyst, removal of redundant conjunctival tissue, and apposition of the surgical edges of the conjunctiva did not correct the strabismus. Magnetic resonance imaging of the head and histopathology of the eye did not reveal significant differences between affected and unaffected eyes except for a more posterior dorsal rectus muscle insertion site in the affected eye. This case report documents and describes a syndrome well known among arowana hobbyists as ‘drop eye’.     

Transport and loss of nitrous oxide in soil water after forest clear-cutting

Whole-tree harvesting increased the concentration of nitrous oxide dissolved in soil water by two orders of magnitude over the concentration expected in equilibrium with the atmosphere. In contrast, the nitrous oxide content of soil water in an intact, second-growth forest was close to the expected theoretical value. Nitrous oxide, produced at active sites in the soil, dissolves in soil water and is transported to seeps and streams where it rapidly degasses from the solution and is released into the atmosphere. This loss of nitrous oxide after clear-cutting is not important to the nitrogen economy of the site; however, it may be important to the global atmospheric budget of nitrous oxide. Sources of nitrous oxide may have been overlooked because nitrous oxide emissions can be separated in time and space from the sites of the most intense production of nitrous oxide.     

Magnetic resonance imaging of the femoral head of normal dogs and dogs with avascular necrosis.

The purpose of this study was to describe the appearance of the femoral head of normal, young, small breed dogs, and dogs with avascular necrosis using low-field (0.3 T) magnetic resonance (MR) imaging. Images of the femoral heads were obtained in the dorsal plane, and included T1-weighted spin-echo, T2-weighted fast spin-echo, fast spin echo-inversion recovery, and fluid attenuated inversion recovery pulse sequences. MR imaging features of the asymptomatic femoral heads and necks included uniform high signal intensity compared with muscle on T1- and T2-weighted images. There was either uniform enhancement or no enhancement on postcontrast T1-weighted images. The MR imaging findings of dogs affected with avascular necrosis differed from those of asymptomatic dogs. Typically, the affected dogs had inhomogeneous intermediate to low-signal intensity within the femoral head and neck compared with muscle on T1-weighted images, inhomogeneous enhancement of the femoral head and/or neck on postcontrast T1-weighted images, and inhomogeneous low- to high- signal intensity within the femoral head and neck on T2-weighted images.     

Modeling Large Carnivore and Ranch Attribute Effects on Livestock Predation and Nonlethal Losses

Predator-livestock interactions are a major concern for both agriculture and conservation globally. Using retrospective survey data from 274 ranches in Wyoming, United States, we used information theory to model how ranch attributes and large carnivores influenced the timing, duration, and severity of livestock predation. We then used constrained ordination to understand how 1) landscape, weather, and animal features influence predation and 2) how livestock behavior and nonlethal loss relate to ranch attributes and large carnivores. Timing, duration, and severity of livestock predation were generally not explained by ranch size or number of counties but were explained by livestock type, livestock parturition (either timing or duration), and documented large carnivore loss. Addition of the large carnivore loss variable to global models always improved Akaike information criterion scores. Rangelands characterized as rough, forested, shrubby, or a public grazing allotment reportedly increased predation risk, in part, due to large carnivore exposure. Approximately two-thirds of participants noticed livestock nervousness if a predator was nearby, half of participants noted changes in livestock distribution patterns, and a quarter of participants noted a reduction in livestock grazing time. Nonlethal losses such as lower weight gains, lower conception rates, lower birth rates, and delayed birth season were reported by 27%, 19%, 12%, and 11% of participants, respectively. Ordination revealed separation between behavioral changes and nonlethal losses, attributed to large carnivore exposure. Parturition relative to livestock type was also strongly correlated to timing and duration of predation for cattle-only operations but not for operations with sheep. The predictive cattle predation-parturition model suggests that for each additional month of calving, producers should anticipate 21 additional d of predation. Understanding predator-livestock interactions relative to ranch and rangeland features, parturition, large carnivore exposure, and losses that extend beyond mortalities can assist in developing novel strategies to mitigate lethal and nonlethal losses.     

A generalized framework for AMOVA with multiple hierarchies and ploidies

The analysis of molecular variance (AMOVA) is a widely used statistical method in population genetics and molecular ecology. The classic framework of AMOVA only supports haploid and diploid data, in which the number of hierarchies ranges from two to four. In practice, natural populations can be classified into more hierarchies, and polyploidy is frequently observed in extant species. The ploidy level may even vary within the same species, and/or within the same individual. We generalized the framework of AMOVA such that it can be used for any number of hierarchies and any level of ploidy. Based on this framework, we present four methods to account for data that are multilocus genotypic and allelic phenotypic (with unknown allele dosage). We use simulated datasets and an empirical dataset to evaluate the performance of our framework. We make freely available our methods in a new software package, polygene , which is freely available at https://github.com/huangkang1987/polygene .