Population structure and frequency differences of CYP51 mutations in <Emphasis Type="Italic">Zymoseptoria tritici</Emphasis> populations in the Nordic and Baltic regions

Septoria tritici blotch caused by the fungus Zymoseptoria tritici (formerly Mycosphaerella graminicola) is one of the most yield-reducing diseases worldwide. Effective disease management involves the use of resistant cultivars and application of fungicides. In this study, the population structure and genetic diversity of 183 Z. tritici isolates from Denmark, Sweden, Finland and the Baltic countries were analysed by molecular markers. In population structure analysis, isolates from Denmark and Sweden were grouped together, whereas isolates from the Baltics and Finland were grouped together. Analysis of genetic diversity and ?-values confirmed the division of Nordic and Baltic regions. Danish isolates sampled from different regions and different varieties were not genetically different. However, significant genetic differences were detected between isolates sampled from different years in Denmark and for isolates sampled from specific cultivars in different years. Additionally, the frequency of several known point mutations in the gene cyp51, conferring decreased sensitivity to DMI fungicides, was investigated. Several of the examined mutations were detected at a lower frequency in Baltic isolates compared to Danish and Swedish isolates. Analysis of the Danish population revealed a significant increase in specific mutations over the years. Lastly, some mutations were significantly more frequent in isolates derived from certain varieties. By using different resistance sources in breeding programmes and application of a wide range of fungicides, a sustainable and efficient disease management can be obtained.     

PROSPECTIVE COMPARISON OF TUMOR STAGING USING COMPUTED TOMOGRAPHY VERSUS MAGNETIC RESONANCE IMAGING FINDINGS IN DOGS WITH NASAL NEOPLASIA: A PILOT STUDY

Identification of nasal neoplasia extension and tumor staging in dogs is most commonly performed using computed tomography (CT), however magnetic resonance imaging (MRI) is routinely used in human medicine. A prospective pilot study enrolling six dogs with nasal neoplasia was performed with CT and MRI studies acquired under the same anesthetic episode. Interobserver comparison and comparison between the two imaging modalities with regard to bidimensional measurements of the nasal tumors, tumor staging using historical schemes, and assignment of an ordinal scale of tumor margin clarity at the tumor‐soft tissue interface were performed. The hypotheses included that MRI would have greater tumor measurements, result in higher tumor staging, and more clearly define the tumor soft tissue interface when compared to CT. Evaluation of bone involvement of the nasal cavity and head showed a high level of agreement between CT and MRI. Estimation of tumor volume using bidimensional measurements was higher on MRI imaging in 5/6 dogs, and resulted in a median tumor volume which was 18.4% higher than CT imaging. Disagreement between CT and MRI was noted with meningeal enhancement, in which two dogs were positive for meningeal enhancement on MRI and negative on CT. One of six dogs had a higher tumor stage on MRI compared to CT, while the remaining five agreed. Magnetic resonance imaging resulted in larger bidimensional measurements and tumor volume estimates, along with a higher likelihood of identifying meningeal enhancement when compared to CT imaging. Magnetic resonance imaging may provide integral information for tumor staging, prognosis, and treatment planning.     

Resistance of wheat pathogen Zymoseptoria tritici to DMI and QoI fungicides in the Nordic-Baltic region - a status

Septoria tritici blotch (STB) caused by the ascomycete Zymoseptoria tritici (Z. tritici) is currently the most prevalent foliar disease in wheat in the Nordic-Baltic region. Fungicide availability in this region differs greatly and is generally more limited than in other European regions. Monitoring of fungicide sensitivity is an essential tool to survey changes in fungal populations in order to react and be able to adapt recommendations for fungicide use. In this study the authors give an overview of the current situation of 14α-demethylation inhibitor (DMI) and quinone outside inhibitor (QoI) sensitivity of Z. tritici from Scandinavia and the Baltic countries. A total of 985 isolates from the Nordic-Baltic region were investigated for EC₅₀ of DMI epoxiconazole and prothioconazole. Fungicide sensitivity remains at a high level with values ranging from 0.07 to 0.48 mg L^?1 for epoxiconazole and 1.17 to 9.47 mg L^?1 for prothioconazole. Point mutation I381V in the DMI target gene CYP51 was dominant throughout the region, but mutations D134G, V136A/C and S524T were also detected in the population in 2014. Screening for inserts in the CYP51 promoter region revealed that a ~ 1000 bp insert is predominant in the entire region. Only a single isolate was found in Denmark, harbouring the 120 bp insert, known to reduce fungicide sensitivity. Two Danish isolates which had elevated resistance levels were associated with an enhanced efflux. Significant differences were found across the area for the presence of G143A, conferring QoI resistance. As there is only limited access to results from this area, these findings can serve as reference for future fungicide sensitivity investigations and for evaluation of changes in the Northern European Z. tritici population.     

Genetic diversity and population structure of South African smallholder farmer sheep breeds determined using the OvineSNP50 beadchip

Tropical Animal Health and Production - A population structure study was performed in South African ovine populations using the OvineSNP50 beadchip. Blood samples were obtained from 295 sheep of...     

Quantification of the aggressiveness of a foliar pathogen, Colletotrichum gloeosporioides, responsible for water yam (Dioscorea alata) anthracnose

In the absence of a gene-for-gene relationship between a pathogen and its host, knowledge about aggressiveness is crucial to characterize novel pathogen populations that potentially emerge in agricultural pathosystems. Information about pathogen aggressiveness is also critical when establishing representative panels of pathogen isolates to test host resistance and in mapping quantitative trait loci involved in the host resistance. In this study, we focused on the fungus C. gloeosporioides that causes necrosis on the aerial part of one of its host plants, Dioscorea alata, and identified the in vitro conditions required to assess fungal aggressiveness on this host. Our main purpose was to convert the necrosis area development into a unique index for quantifying pathogen aggressiveness. The ??Ag?? index described here has two advantages. First, it integrates the variance of symptom evolution curves to estimate the lesion development rates (initial and secondary) and the maximal necrosis area. Secondly, the new index takes two different symptoms commonly observed when inoculating D. alata leaves with C. gloeosporioides into account, one correlated with high leaf colonisation efficiency and the other with low colonisation efficiency. The weights accorded to each symptom in the index were proportional to leaf colonisation efficiency. We propose a framework for the acquisition of this index that has been designed to be conveniently combined with the routine bioassays required to establish representative panels of pathogen isolates. The general framework for the construction of this index can be broadly applied to diseases with necrotic symptoms.     

Multiattribute evaluation of two simple tests for the detection of Cryptosporidium parvum in calf faeces

There is a need for simple and inexpensive diagnostic and screening tests for the detection of Cryptosporidium parvum infection in calves. A sucrose wet mount test and a lateral immunochromatography test were evaluated for epidemiological sensitivity and specificity, cost per test, simplicity, test time and ease of batching. Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) of the Cryptosporidium oocyst wall protein (COWP) gene locus, with gel electrophoresis, was used as a gold standard. Cohen's kappa statistic of agreement (kappa) between the Ontario Veterinary College (OVC) sucrose wet mount test and COWP PCR-RFLP was 0.82, and the sensitivity and specificity of the OVC sucrose wet mount test were 88.6% and 93.8%, respectively. The sensitivity and specificity of the lateral immunochromatography test were 78.3% and 93.3%, respectively, and agreement between this test and PCR-RFLP was good (kappa=0.73). There was substantial agreement between the OVC sucrose wet mount test and the lateral immunochromatography test (kappa=0.84). Both tests were inexpensive and easy to use; however, the lateral immunochromatography test was faster and simpler to perform than the sucrose wet mount test, and was generally more user-friendly. These tests provide practitioners and researchers with cheap, quick and accurate methods of detecting C. parvum infection in young calves.     

Concepts for the clinical use of stem cells in equine medicine

Stem cells from various tissues hold great promise for their therapeutic use in horses, but so far efficacy or proof-of-principle has not been established. The basic characteristics and properties of various equine stem cells remain largely unknown, despite their increasingly widespread experimental and empirical commercial use. A better understanding of equine stem cell biology and concepts is needed in order to develop and evaluate rational clinical applications in the horse. Controlled, well-designed studies of the basic biologic characteristics and properties of these cells are needed to move this new equine research field forward. Stem cell research in the horse has exciting equine specific and comparative perspectives that will most likely benefit the health of horses and, potentially, humans.     

Association between management practices and within-herd prevalence of Cryptosporidium parvum shedding on dairy farms in southern Ontario

To identify management practices associated with an increased within-herd prevalence of Cryptosporidium parvum shedding on dairy farms in southern Ontario, fecal samples were taken from 1089 calves aged 7-28 days, from 119 herds. Information on management practices was obtained by administering a questionnaire compiled using a modified Delphi technique. Data were analyzed using univariable and multivariable negative binomial regression. Overall, 30% of the calves in the study were shedding C. parvum oocysts, with at least one positive calf detected in 77% of herds. Within-herd prevalence ranged from 0 to 80%. Predictors significantly associated with an increased prevalence of shedding in multivariable modelling were the use of calf scour prophylaxis in cows (risk ratio [RR] 1.70, P<0.01) and calves (RR 1.38, P=0.02) and the feeding of milk replacer in the first week of life (RR 1.40, P=0.02). In contrast, the presence of concrete flooring in calf housing areas (RR 0.59, P<0.01) and the use of soap or detergent when washing calf feeding utensils (RR 0.61, P<0.01) appeared to be protective.     

Binding of mouse mannan-binding lectins to different bacterial pathogens of mice

Humans have one mannan-binding lectin (MBL) in circulation but rodents, pigs, rabbits and rhesus monkeys have two, MBL-A and MBL-C. Plasma forms of these proteins have similar mannan-binding activity in vitro, but might differ in their ability to bind other microbial targets. In these studies, we compared carbohydrate-dependent binding of mouse plasma MBL-A and MBL-C to mannan-sepharose beads and to intact bacteria isolated as pathogens from mice. After incubation of mouse plasma with intact bacteria, MBL-A and MBL-C were eluted with N-acetylglucosamine (GlcNAc) and identified in nonreducing SDS-PAGE using Western blot analysis and MBL-A or MBL-C specific monoclonal antibodies. GlcNAc eluates of plasma incubated with mannan-sepharose beads, Klebsiella oxytoca and Staphylococcus aureus contained similar bands (mainly approximately 50kDa) that were immunoreactive with MBL-C antibody. Furthermore, a smaller form of MBL-C (approximately 45kDa) was detected bound to Pseudomonas aeruginosa. By comparison, immunoreactive MBL-A (a ladder of approximately 175kDa and larger bands) was identified in these GlcNAc eluates from mannan-sepharose beads, S. aureus and K. oxytoca but not P. aeruginosa. These studies demonstrate that mouse MBL-A and MBL-C in plasma are not equivalent in their ability to recognize bacteria that are pathogens for mice.