Project description:Disease resistance is mediated by specific recognition of pathogen avriulence effectors (AVR) by nucleotide-binding leucine-rich repeat (NLR) receptors. The barley (Hordeum vulgare) mildew locus A (mla) resistance gene homolog 1 (RGH1) encoded NLRs (MLAs) confer isolate-specific resistance to the widespread mildew fungus Blumeria graminis forma specialis hordei (Bgh). In barley, MLA has been subject to extensive functional diversification, resulting in allelic resistance specificities, each recognizing a cognate Bgh AVRa. The by genetic association isolated AVRa1 and AVRa13 effectors belong to the candidate secreted effector protein (CSEP) gene family (Lu et al., 2016). To unravel the complex mechanisms underlying MLA functional diversification in barley and wheat, isolation of numerous Bgh AVRa genes and recognition of their gene products by MLA is necessary. Our here deployed higher resolution genetic association approach identified the Bgh avirulence gene candidate loci AVRa7, AVRa9, AVRa22 and AVRa10 by associating of transcript polymorphisms and AVRa phenotypes from a collection of 27 Bgh isolates. We collected 10 Bgh isolates from a local Bgh population in Cologne in addition to our previous collection of 17 Bgh isolates (Lu et al., 2016).
Project description:A testing association of parasite genotypes with clinical resistance phenotype. Submission of genotypes from all microarray genotyped samples Comparison of DNA from clinical isolates and generated by next-generation sequencing with prolonged clearance half-life
Project description:Here we fully characterize the genomes of 14 Plasmodium falciparum patient isolates taken recently from the Iquitos regions using genome-scanning, a microarray-based technique which delineates the majority of single-base changes, indels and copy number variants distinguishing the coding regions of two clones. We show that the parasite population in the Peruvian Amazon is highly structured with a limited number of genotypes and low recombination frequencies. Despite the essentially clonal nature of some isolates, we see high frequencies of mutations in subtelomeric highly variable genes and internal var genes indicating mutations arising during self-mating or mitotic replication. The data also reveal that 1 or 2 meioses separate different isolates showing that P. falciparum clones isolated from different individuals in defined geographical regions could be useful in linkage analyses or quantitative trait locus studies. Through pair-wise comparisons of different isolates we discovered point mutations in the apicoplast genome that are close to known mutations that confer clindamycin resistance in other species but which were hitherto unknown in malaria parasites. Subsequent drug sensitivity testing revealed over 100-fold increase clindamycin EC50 in strains harboring one of these mutations. This evidence of clindamycin resistant parasites in the Amazon suggests a shift should be made in health policy away from quinine+clindamycin therapy for malaria in pregnant women and infants and that the development of new lincosamide antibiotics for malaria should be reconsidered.
Project description:A collection of 61 Salmonella enterica serovar Typhimurium (S. Typhimurium) of animal and human origin, matched as closely as possible by phage type, antimicrobial resistance pattern and place / time of isolation, and sourced from farms or hospitals in Scotland, were analysed by antimicrobial susceptibility testing, phage typing, pulsed field gel electrophoresis (PFGE), plasmid profiling and DNA microarrays. PFGE of all 61 isolates revealed ten PFGE profiles, which clustered by phage type and antibiotic resistance pattern, with human and animal isolates distributed between PFGE profiles. Analysis of 23 representative S. Typhimurium strains hybridised to a composite Salmonella DNA microarray identified a small number of specific regions of genome variation between different phage types and PFGE profiles. These variable regions of DNA were typically located within prophage-like elements. Simple PCR assays were subsequently designed to discriminate between different isolates from the same geographical region.