A Quantitative Assay Using Mycelial Fragments to Assess Virulence of Mycosphaerella fijiensis

ABSTRACT We describe a method to evaluate the virulence of Mycosphaerella fijiensis, the causal agent of black leaf streak disease (BLSD) of banana and plantain. The method is based on the delivery of weighed slurries of fragmented mycelia by camel's hair brush to 5-by-5-cm areas on the abaxial surface of banana leaf blades. Reliable BLSD development was attained in an environmental growth chamber with stringent lighting and humidity controls. By localizing inoculum onto small areas of large leaves, we achieved a dramatic increase in the number of strains that can be tested on each leaf and plant, which is critical for comparing the virulence of numerous strains concurrently. Image analysis software was used to measure the percentage of each inoculated leaf section showing BLSD symptoms over time. We demonstrated that the level of disease of four isolates was correlated with the weight of the mycelium applied and relatively insensitive to the degree of fragmentation of hyphae. This is the first report demonstrating that weighed mycelial inoculum, combined with image analysis software to measure disease severity, can be used to quantitatively assess the virulence of M. fijiensis under rigorously controlled environmental conditions.     

Influence of wetland networks on bat activity in mixed-use landscapes

Parks and other protected lands can provide important source habitat and act as valuable dispersal corridors in urbanizing environments. However, most wetlands within protected areas are managed in isolation without consideration of the broader landscape connections. We studied the importance of wetland habitat connectivity and landscape context to bat activity in five National Parks along a gradient of increasing urbanization within the Mid-Atlantic United States. Ninety-six Anabat stations were set up throughout the parks, from which we derived the characteristic spatial scales at which bat activity was associated with wetlands. This information was used in a graph theoretic framework to construct network models of potential landscape connectivity for those species that had positive associations with wetland land cover. We found that the importance of wetlands as a predictor of bat activity varied on a species-by-species basis and increased when network measures were used that accounted for connected area in a broad spatial context. The results demonstrate that both area and connectivity of wetland foraging habitat may act as orthogonal variables to availability of roosting habitat in explaining the distribution of highly mobile species. We use the results to illustrate the value of network analysis to guide the coordinated management of two of the parks’ most valued natural resources - wetlands and bats.     

Liquid chromatographic and spectroscopic characterization of pentamidine isethionate and impurities in bulk drug and injectables

A liquid chromatographic (LC) method is described for evaluating purity of pentamidine isethionate (PI), a life-saving drug used in the treatment of Pneumocystis carinii pneumonia, which is a leading cause of death in persons with acquired immunodeficiency syndrome (AIDS). Six potential impurity compounds were synthesized to test the selectivity of the chromatographic system and to permit quantitation of impurities in various lots of PI products. The drug and impurities were separated with gradient elution on a cyano-bonded LC column. The analytic system provided information on the identities and levels of impurities in early experimental lots of PI. These results assisted the manufacturer in altering reaction conditions and purification procedures to ensure that succeeding lots were within the specification limits, i.e., no more than 0.4% of any single impurity or 0.7% of total impurities found in the final product.     

Teaching nutrition to the left and right brain: an overview of learning styles

Functioning effectively as a veterinarian requires proficiency in multiple learning styles. Whether the goal is to design a nutrition course, plan a veterinary curriculum, or help students develop interpersonal, communication, and leadership skills, students benefit when content, design, and delivery are balanced to meet their learning-style preferences. An overview of four different learning style models is presented: the Myers-Briggs Type Indicator (MBTI), Kolb's Learning Style Model, the Felder-Silverman Learning Style Model, and the Herrmann Brain Dominance Instrument (HBDI). A whole-brain approach (HBDI) was used in the development and implementation of the small-animal clinical nutrition course at the University of Minnesota College of Veterinary Medicine. One educational objective of this course is to help students develop mental dexterity, increasing their proficiency in both their preferred and their less preferred modes of learning. The instructional goals are to deliver the content of the small-animal clinical nutrition course through exercises that meet the needs of learners in each thinking quadrant (left and right, cerebral and limbic) at least part of the time. Examples of exercises are presented to portray a balanced or whole-brain approach to teaching clinical nutrition.     

AGE AND DIET EFFECTS ON RELATIVE RENAL ECHOGENICITY IN GERIATRIC BITCHES

Under controlled, but varied dietary conditions 35 geriatric, uninephrectomized, spayed Beagle bitches (dogs) observed for 4 years, renal cortical and renal medullary echogenicity was measured relative to hepatic and splenic echogenicity. Regardless of the diet fed, 60-75% of these aged dogs had renal cortical echogenicity less than that of either the liver or spleen across time; 25-35% of these dogs had renal cortical echogenicity equal to that of the liver, but less than that of the spleen across time. Less than 3% of these dogs had renal cortical echogenicity greater than that of the liver, but less than that of the spleen. Only 1 (one) of these dogs had renal cortical echogenicity equal to that of the spleen and that occurred at only one of the 14 chronologic assessments. Therefore, in either mature or aged dogs imaged with 4.0 to 5.0 MHz equipment, the renal cortical echogenicity should be considered normal if it is less than or equal to that of the liver and less than that of the spleen. In 29 dogs imaged with the 4.0/5.0 MHz equipment and 6 dogs imaged with 7.5 MHz equipment, there was no significant diet or individual dog effect. The 7.5 MHz (6 dog) group had significantly higher average cortical echogenicity scores than the 4.0/5.0 MHz (29 dog) group. However, the occurrence of renal cortical echogenicity greater than liver echogenicity was seen in only 5 of 83 samples (approximately 6.0%) made on 6 dogs imaged with 7.5 MHz equipment and only 1 of 375 samples (approximately 0.27%) made on 29 dogs with 4.0/5.0 MHz equipment. With the exception of one occurrence, all dogs had renal medullary echogenicity less than that of the liver or spleen regardless of imaging equipment frequency. The renal medulla was always hypoechoic compared to the cortex.     

Establishment of native <Emphasis Type="Italic">Eucalyptus pauciflora</Emphasis> and exotic <Emphasis Type="Italic">Eucalyptus nitens</Emphasis> on former grazing land

The success of tree plantings in agricultural landscapes within dry and variable rainfall regions is often below expectations. The aims of this study were to investigate techniques for establishing a local native species (Eucalyptus pauciflora) and an exotic species (E. nitens) in the Midlands of Tasmania, a tree-denuded region that has been grazed for over 100 years in Australia. We established trials at the Sorrel Springs and Woodland Park properties. We compared six establishment techniques: control; understorey nurse planting; spot burn; mulch; tree-guard and; self-watering tree-guard. Three months, 1 and 6 years after planting we measured tree height, health index and mortality. At Sorrell Springs tree-guarded treatments had greater height than other treatments at year one, but there were no effects of treatment at year six on height, health or mortality. At Woodland Park mulch, burn and tree-guarded treatments had greater height 1 and 6 years after planting. At year six tree-guarded treatments had lower mortality than other treatments. At Sorrell Springs height of E. nitens was greater than E. pauciflora at year one but not at year six. At Woodland Park height of E. nitens was generally greater at year six but having almost double the incidence of mortality relative to E. pauciflora. We conclude that expensive tree-guarding is only warranted where high browse pressure is expected and that on such sites species with tough leaves that are resistant to browsing should be considered. Further that in environments marginal for growing trees, best practice establishment technique is generally as effective as additional treatments of understorey nurse planting, spot burning or mulching.