Immunogenicity of recombinant Omp31 from Brucella melitensis in rams and serum bactericidal activity against B. ovis

Detergent-extracted recombinant Omp31 (rOmp31 extract) from Brucella melitensis produced in Escherichia coli was previously identified as a protective immunogen against B. ovis in mice. In this study, we evaluated the immunogenicity of rOmp31extract in rams. This immunogen was emulsified in an oil adjuvant and administered three times with 4 and 8 weeks intervals. Antibody response was measured in serum by whole B. ovis ELISA. Specific antibodies to purified rOmp31 (pET-Omp31) were detected by Western blotting and indirect ELISA. In addition, isotype specific antibodies were measured in tears. Serum bactericidal activity against B. ovis in the presence of complement was measured in vitro. Cellular immune response was explored by intradermal testing with purified rOmp31. Immunization with rOmp31 extract induced IgG specific antibodies in serum able to bind to whole B. ovis cells. Furthermore, strong inhibition in a competitive ELISA (with an Omp31-specific monoclonal antibody) suggested that a proportion of Omp31-specific antibodies were directed against a loop containing a protective epitope. Serum antibodies killed efficiently B. ovis in vitro in the presence of either guinea pig or ovine serum. Tears had both IgG and IgA antibodies to equivalent titers. Finally, immunized rams showed skin reactivity to Omp31. These data demonstrate that B. melitensis Omp31, a protective antigen identified in the mouse model, induces antibody and cellular immune mechanisms in sheep.     

Genetic Mapping of Pathogenicity and Aggressiveness of Gibberella zeae (Fusarium graminearum) Toward Wheat

ABSTRACT Gibberella zeae is the major fungal pathogen of Fusarium head blight of wheat and produces several mycotoxins that are harmful to humans and domesticated animals. We identified loci associated with pathogenicity and aggressiveness on an amplified fragment length polymorphism based genetic map of G. zeae in a cross between a lineage 6 nivalenol producer from Japan and a lineage 7 deoxynivalenol producer from Kansas. Ninety-nine progeny and the parents were tested in the greenhouse for 2 years. Progeny segregated qualitatively (61:38) for pathogenicity:nonpathogenicity, respectively. The trait maps to linkage group IV, which is adjacent to loci that affect colony pigmentation, perithecium production, and trichothecene toxin amount. Among the 61 pathogenic progeny, the amount of disease induced (aggressiveness) varied quantitatively. Two reproducible quantitative trait loci (QTL) for aggressiveness were detected on linkage group I using simple interval analysis. A QTL linked to the TRI5 locus (trichodiene synthase in the trichothecene pathway gene cluster) explained 51% of the variation observed, and a second QTL that was 50 centimorgans away explained 29% of the phenotypic variation. TRI5 is tightly linked to the locus controlling trichothecene toxin type. The two QTLs, however, were likely part of the same QTL using composite interval analysis. Progeny that produced deoxynivalenol were, on average, approximately twice as aggressive as those that produced nivalenol. No transgressive segregation for aggressiveness was detected. The rather simple inheritance of both traits in this interlineage cross suggests that relatively few loci for pathogenicity or aggressiveness differ between lineage 6 and 7.     

Meta-analysis in plant pathology: synthesizing research results

ABSTRACT Meta-analysis is a set of statistical procedures for synthesizing research results from a number of different studies. An estimate of a statistical effect, such as the difference in disease severity for plants with or without a management treatment, is collected from each study along with a measure of the variance of the estimate of the effect. Combining results from different studies will generally result in increased statistical power so that it is easier to detect small effects. Combining results from different studies may also make it possible to compare the size of the effect as a function of other predictor variables such as geographic region or pathogen species. We present a review of the basic methodology for meta-analysis. We also present an example of meta-analysis of the relationship between disease severity and yield loss for foliar wheat diseases, based on data collected from a decade of fungicide and nematicide test results.     

Husbandry Factors and the Resumption of Luteal Activity in Open and Zero‐Grazed Dairy Cows in Urban and Peri‐Urban Kampala,Uganda

The study investigated the influence of selected husbandry factors on interval to resumption of post‐partum cyclicity among dairy cows in urban and peri‐urban Kampala. A prospective study of 85 day post‐partum period of 59 dairy cows in open (n = 38) and zero grazing (n = 21) systems was conducted on 24 farms. Cows of parity 1–6 were recruited starting 15–30 days post‐partum. Progesterone (P4) content in milk taken at 10–12 day intervals was analysed using ELISA. The cow P4 profiles were classified into ‘normal’ (< 56 days), ‘delayed’ (> 56 days), ‘ceased’ or ‘prolonged’ (if started < 56 days but with abnormal P4 displays) resumption of luteal activity and tested for association with husbandry and cow factors. Of the 59 cows, luteal activity in 81.4% resumed normally and in 18.6%, delayed. Only 23.7% maintained regular luteal activity, while the others had ceased (10.2%), prolonged (37.3%) or unclear luteal activity (20.3%). There were no differences between open and zero‐grazed cows. Milk production was higher (p < 0.05) in zero than open grazing, in urban than peri‐urban and in cows fed on brew waste (p < 0.001) compared with mill products and banana peels. Results suggest that luteal activity resumes normally in a majority of cows, although only a minority experienced continued normal cyclicity once ovulation had occurred, in the two farming systems irrespective of feed supplements or water, and that supplementing with brew waste is beneficial for milk production.     

Adatom pairing structures for Ge on si(100): the initial stage of island formation

With the use of scanning tunneling microscopy, it is shown that germanium atoms adsorbed on the (100) surface of silicon near room temperature form chainlike structures that are tilted from the substrate dimer bond direction and that consist of two-atom units arranged in adjoining substrate troughs. These units are distinctly different from surface dimers. They may provide the link missing in our understanding of the elementary processes in epitaxial film growth: the step between monomer adsorption and the initial formation of two-dimensional growth islands.     

Atomistic Processes in the Early Stages of Thin-Film Growth

Growth of thin films from atoms deposited from the gas phase is intrinsically a nonequilibrium phenomenon governed by a competition between kinetics and thermodynamics. Precise control of the growth and thus of the properties of deposited films becomes possible only after an understanding of this competition is achieved. Here, the atomic nature of the most important kinetic mechanisms of film growth is explored. These mechanisms include adatom diffusion on terraces, along steps, and around island corners; nucleation and dynamics of the stable nucleus; atom attachment to and detachment from terraces and islands; and interlayer mass transport. Ways to manipulate the growth kinetics in order to select a desired growth mode are briefly addressed.