Serologic correlation of suspected Leptospira interrogans serovar pomona-induced uveitis in a group of horses

After the observation of 2 horses with uveitis on a horse farm in the Minnesota River valley, 100 horses from this geographic area were given ophthalmologic examinations and were evaluated serologically for leptospirosis. A statistically significant (P less than 0.001) association was observed between the finding of antibodies against Leptospira interrogans serovar pomona and uveitis.     

Spectrophotometric determination of polyacrylamide in waters containing dissolved organic matter

Using polyacrylamide (PAM) to reduce soil erosion in irrigated land has increased rapidly in recent years. A simple and reliable method to measure the PAM concentration in waters containing dissolved organic matter (DOM) is of great importance in assessing the fate and efficiency of PAM application. In this research, an analytical method to determine the PAM concentration of waters with correction for DOM interference was developed and tested. The method is based on a combination of determining the total concentration of amide groups by the N-bromination method (NBM) and determining the DOM content spectrophotometrically. The total concentration of amide groups of both PAM and DOM was determined by NBM at 570 nm. The DOM moiety, which is proportional to DOM concentration, was determined by spectrophotometry using a UV 254-nm wavelength. The actual PAM concentration of a water sample (soil extract containing PAM in this study) was obtained from NBM readings subtracted by the interferential DOM contribution using a correction curve. Analysis of PAM in two soil-water samples showed that the recoveries ranged from 94 to 100.3% for the 2 mg/L PAM sample and from 98.4 to 101.4% for the 10 mg/L PAM sample with various DOM concentrations. The coefficients of variation were <6% in all cases.     

Use of Internet-based resources to support an introductory animal and poultry science course.

This article describes the development and implementation of a World Wide Web page to support a team-taught introductory animal and poultry science course. The objectives were to examine the capabilities of this type of instructional resource, determine students' willingness to use this type of resource, create opportunities for interactive learning, and improve students' enthusiasm for the subject area. A variety of course materials were made available through the Internet, including the class syllabus, lecture notes, and practice questions to support and augment class lectures. Additional on-line resources included a bulletin board for instructor announcements, a list-serve for student discussions concerning administrative and educational issues arising during the semester, a class E-mail list, and a page with links to other sites of agricultural interest. Materials were accessible from a variety of computer resources, including campus computing laboratories, dial-up access, and access via other Internet service providers. Use of the materials was evaluated by analysis of log files from the server. Effectiveness of the resources was determined from surveys of students conducted before and after implementation of the on-line resource. Students indicated that the most useful components of the Web page were the class notes and practice/review questions. Effectiveness of the site was related to the amount of material available through the site, the level of interaction, whether the task was required, and the ease of access to computers and the Web site. Student evaluations indicated that this form of instructional supplement is a viable method for enhancing the learning experience in the introductory animal sciences.     

Hormonal stimulation of lactose synthetase in mammary carcinoma

A transplantable rat mammary carcinoma (R3230AC) synthesizes significant quantities of the mammary gland enzyme lactose synthetase in the immature virgin female rat. In this hormonal environment, mammary glands do not synthesize the enzyme. Prolactin further stimulates the enzyme activity in the tumors to levels found only in mammary glands of rats in late pregnancy or during lactation.     

Biological activity in the profiles of chernozems as dependent on the character of their agricultural use and microtopography

The biological activity of soil samples taken from genetic horizons of plowed and virgin chernozems in the Kamennaya Steppe Reserve was determined as the amount evolved from the soil upon its incubation in laboratory conditions. In the top humus horizons, the biological activity of virgin chernozem was two to three times higher as compared with that in the plowed chernozem. The intensity of biological processes and the microbial biomass in the soil profile was mainly controlled by the quantity and quality of soil organic matter. Long-term agricultural use exerted a weaker effect on the biological properties of chernozems developed on microelevations (blocks) of the paleocryogenic microtopography in comparison with chernozems developed in the microdepressions between the blocks. The factor analysis showed that soil characteristics related to the biological processes comprise more than 50% of the total variance of factor loads and are distinctly differentiated in the soil profile.     

Survival of myxobacter strain 8 in natural soil in the presence and absence of host cells

Myxobacter strain 8 is one component of a sequence of three predatory bacteria that develop in soil when Micrococcus luteus host cells are added to the soil. The survival of strain 8 in the presence and absence of added host cells in natural soil not allowed to dry out was examined. Strain 8 vegetative cells died relatively rapidly in unamended soil. Death was faster and occurred to a greater extent in acidic than in neutral pH soil. However, in both cases death was accompanied by formation of sonication-resistant myxospores so that they comprised the ultimate population. These myxospores survived for prolonged periods in both acidic and neutral pH soils.Vegetative cells added in high numbers to soil did not multiply under any of the conditions tested. They did multiply, however, when they were added in low numbers to soil (including acidic soil) receiving sequential (additive) amendments of heart infusion broth or living M. luteus cells. This multiplication produced strain 8 cell numbers approximating those in the above experiments receiving high strain 8 cell number inoculations. Possibly, this represents a maximum vegetative cell number for soil.Germination of the myxospores in soil, followed by growth, seemed to require an approximately neutral pH and the presence of a proper host organism. Germination occurred with M. luteus as host, but not with Escherichia coli. A delayed germination occurred when sequential amendments of heart infusion broth, instead of M. luteus host cells, were made, but this could reflect a growth response by some indigenous components of the soil microflora that then served as host cells for germination.     

Rhizomania disease of sugar beet in England

Rhizomania disease was first detected in the UK in 1987, in a single crop in Suffolk. Affected plants had pale leaves, often upright, narrow and rolled; roots were small, often with constrictions, warty outgrowths, proliferation of fibrous roots, and vascular staining. Disease occurred in strips at right angles to one another, parallel with directions of cultivation, suggesting that the previous beet crop had also been infected. Beet necrotic yellow vein virus was detected by ELISA, by electron microscopy, and by transmission to indicator species. It was sometimes associated with beet soil-borne virus. The affected crop was destroyed with herbicide. No other outbreaks were detected in subsequent surveys of crops in 1987.