Evoked response and behavior in cats

Electroencephalographic averaged evoked responses to flashing lights of four different intensities were recorded in ten cats and correlated with behavior. Animals showing a high degree of exploratory behavior, aggressiveness, and activity and little withdrawal showed relatively large increases in amplitude of the averaged evoked response with increases of stimulus intensity. Those showing opposite behavioral traits had small increases or decreases of average evoked response amplitude with increases of stimulus intensity. These findings are compatible with those reported for human subjects. Inference is made about a neurophysiological mechanism for stimulus intensity modulation.     

Enzyme-linked immunosorbent assay for detecting antibodies in swine infected with Mycobacterium avium

Enzyme-linked immunosorbent assay (ELISA) was used for detecting the antibodies in sera from swine experimentally infected with Mycobacterium avium. Positive ELISA reactions were observed in the sera of each of six swine at postinoculation weeks 2, 4, 6, 8, and 10; no reaction was observed in noninoculated controls. The ELISA reactions were observed in each of two swine at 4, 6, 8, 10 weeks following exposure to M avium-infected swine. Mycobacterium avium-purified protein derivative and killed cells of M avium serotype 4/8 and serotype 8 provided suitable ELISA reactions in M avium-infected swine.     

Biology and integrated control of Pestalotiopsis on container-grown ericaceous crops

Pestalotiopsis isolates obtained from the foliage, stem-base and roots of diseased container-grown ericaceous crops (Calluna, Erica, Pieris and Rhododendron) collected from UK nurseries were identified as Pestalotiopsis sydowiana (Bresad) B Sutton on the basis of conidia morphology. Inoculum sources of the pathogen included diseased stock plants, crop debris, nursery soils, used growing media, pots and floor covering, and dust collected from greenhouse walkways. Isolates were not host-specific and infected other species of ericaceous plants, with typical symptoms including browning of foliage, stems and roots, and the presence of black or greenish black acervuli on diseased tissue. The optimum temperature for growth of three selected isolates of the pathogen was 20-25 degrees C, with little or no growth occurring below 5 or above 30 degrees C. Growth occurred over pH 2.6-8.6, with optimum at 5.5. Decreases in matric potential from -0.3 to -4.0 MPa reduced growth, which was totally inhibited at -6.5 MPa. Greenhouse trials were conducted to evaluate the effects of disease management methods (irrigation, flooring/pot disinfection and fungicide application) on control of the pathogen on potted plants of C vulgaris. Disease incidence and foliar browning caused by P sydowiana were less on fungicide-treated (five-spray programme of alternating prochloraz and carbendazim) potted plants watered by sub-irrigation compared with watering from overhead. Single and combined treatments of flooring/pot disinfection (hydrogen peroxide/peracetic acid) and the five-spray fungicide programme significantly reduced disease incidence and severity compared with dipping pots in water. The combined disinfection and fungicide programme significantly reduced disease incidence and severity, compared to disinfection or fungicide application alone. The importance of these findings for the integrated control of P sydowiana on ericaceous plant nurseries is discussed.     

Efficient and sensitive method for quantitative analysis of alkaloids in hardinggrass (Phalaris aquatica L.)

An efficient high-performance thin-layer chromatography (HPTLC) method for the analysis of alkaloids in hardinggrass (Phalaris aquatica L.) was developed. The method employed HPTLC glass plates precoated with silica gel 60F-254 as the stationary phase. The solvent system consisted of ethyl acetate/chloroform/7 N NH4OH in methanol (8:2:1, v/v/v). Using unidimensional double-development, bands were well separated for 10 alkaloid standards as well as alkaloids observed in hardinggrass plant extracts. Identities of compounds observed using HPTLC were validated by high-performance liquid chromatography-mass spectrometry (HPLC-MS). Software was used to quantify individual alkaloids in plant samples based on HPTLC retention factors and intensities relative to standards of known concentration. Correlation coefficients of 0.99 were obtained between estimated and actual concentrations for four standards (methyltyramine, hordenine, gramine, and 5-methoxydimethyltryptamine), with linearity in the range of 120-3840 ng/spot. The HPTLC method is repeatable and specific for beta-carboline, tryptamine, gramine, and tyramine type alkaloids in mixed standard and plant extracts. Initial results indicate substantial variation in alkaloid composition among and within hardinggrass populations.     

Role of lymph-borne cells in the early stages of scrapie agent dissemination from the skin

Scrapie is a natural transmissible spongiform encephalopathy (TSE) of sheep, infecting the animal via the gastrointestinal tract or the skin. This project tested the hypotheses that lymph-borne cells (especially dendritic cells) are crucial for the systemic dissemination of the infectious agent from the site of infection in the skin, that PrP genotype affects PrPSC association with dendritic cells and that PrPSC carriage by cells affects their expression of cytokines. Skin, of scrapie-susceptible VRQ/ARR and scrapie-resistant ARR/ARR PrP genotypes, was scarified with FITC-labelled PrPSC. Pseudoafferent lymphatic cannulation was then used to monitor the presence of FITC-PrPSC over time in different lymph cell populations and plasma in the draining afferent lymphatics. The major observation was that PrPSC did not associate significantly with any lymphocyte or dendritic cell population in the 5 days following PrPSC scarification. The only cells seen to associate with PrPSC were neutrophils. Furthermore, despite the quantity of PrPSC used for scarification being equivalent to a standard infectious dose (the VRQ/ARR sheep dying at approximately 260 days) the only PrP found in afferent lymph during the 0-5-day period was proteinase K sensitive (i.e. soluble PrPC). No differences were observed between the PrP genotypes. Analysis of the effects of PrPSC scarification of cellular cytokine mRNA expression (by a nuclease protection assay) showed raised levels of IL-1beta and IL-8 in the susceptible VRQ/ARR group and raised levels of IFNgamma in the resistant ARR/ARR animals.     

Comparison of Postfire Soil Water Repellency Amelioration Strategies on Bluebunch Wheatgrass and Cheatgrass Survival

Soil water repellency can limit postfire reseeding efforts and thus increase the susceptibility of a site to weed invasion. We evaluated the effectiveness of wetting agents and simulated anchor chaining for improving seedling growth and survival in water-repellent soil, for the native perennial bluebunch wheatgrass (Pseudoroegneria spicata) and invasive annual cheatgrass (Bromus tectorum). Research was performed in a glasshouse, on 20-cm-diameter soil cores that were excavated from underneath burned Utah juniper (Juniperus osteosperma) trees. The experiment was arranged as a randomized split-plot design, with the two grass species sown separately under four soil treatments: 1) no treatment (control), 2) simulated anchor chaining (hereafter referred to as “till”), 3) wetting agent, and 4) till plus wetting agent. Soil water content was highest in the wetting agent treatment, lower for till, and lowest in the control. Overall, the response of bluebunch wheatgrass and cheatgrass was similar among treatments. At the conclusion of the study, wetting agent cores had twice as many seedlings as the control, while the till and control were similar. Despite a lower number of seedlings, tilling in general resulted in the same level of biomass as the wetting agent treatment. Overall, biomass in the till and wetting agent treatments was at least twofold higher than the control. No benefit was found in applying both till and wetting agent treatments together in comparison to just applying wetting agent. Because of a lack of correlation between glasshouse and field settings the results of this study need to be interpreted with caution. Our data may indicate that if cheatgrass is not already present on the site, anchor chaining or treating the soil with wetting agent can increase establishment of seeded species.