Project description:Methicillin-resistant Staphylococcus aureus clonal complex (CC) 398 has emerged from pigs to cause human infections in Europe and North America. We used a new 62-strain S. aureus microarray (SAM-62) to compare genomes of isolates from three geographical areas (Belgium, Denmark, and Netherlands) to understand how CC398 colonizes different mammalian hosts. The core genomes of 44 pig isolates and 32 isolates from humans did not vary. However, mobile genetic element (MGE) distribution was variable including SCCmec. Phi3 bacteriophage and human specificity genes (chp, sak, scn) were found in invasive human but not pig isolates. SaPI5 and putative ruminant specificity gene variants (vwb and scn) were common but not pig specific. Virulence and resistance gene carriage was host associated but country specific. We conclude MGE exchange is frequent in CC398 and greatest among populations in close contact. This feature may help determine epidemiological associations among isolates of the same lineage. [Data is also available from http://bugs.sgul.ac.uk/E-BUGS-120]
Project description:The fraction of dissolved dimethylsulfoniopropionate (DMSPd) converted by marine bacterioplankton into the climate-active gas dimethylsulfide (DMS) varies widely in the ocean, with the factors that determine this value still largely unknown. One current hypothesis is that the ratio of DMS formation:DMSP demethylation is determined by DMSP availability, with 'availability' in both an absolute sense (i.e., concentration in seawater) and in a relative sense (i.e., proportionally to other labile organic S compounds) being proposed as the critical factor. We investigated these models during an experimentally-induced phytoplankton bloom using an environmental microarray targeting DMSP-related gene expression in the Roseobacter group, a taxon of marine bacteria known to play an important role in the surface ocean sulfur cycle. The array consisted of 1,578 probes to 431 genes, including those previously linked to DMSP degradation as well as core genes common in sequenced Roseobacter genomes. The prevailing pattern of Roseobacter gene expression showed depletion of DMSP-related transcripts during the peak of the bloom, despite the fact that absolute concentrations and flux of DMSP-related compounds were increasing. A likely interpretation is that DMSPd was assimilated by Roseobacter populations in proportion to its relative abundance in the organic matter pool (the “relative sense” hypothesis), and that it is not taken up in preference to other sources of labile organic sulfur or carbon produced during the bloom. The relative investment of the Roseobacter community in DMSP demethylation did not predict the fractional conversion of DMSP to DMS, however, suggesting a complex regulatory process that may involve multiple fates of DMSPd. DMSP-related gene expression in the Roseobacter group was investigated using an environmental microarray. Coastal seawater from the Gulf of Mexico was collected and dispensed into 20-L microcosms. Two replicate cubitainers were amended with nutrients (N and P) to stimulate phytoplankton bloom, while two untreated cubitainers served as controls. The microcosms were incubated at 27ºC in a temperature-controlled incubator on a 12 h light/dark cycle for total of 7 days. Ten RNA samples (Day 0: 2 conditions with 1 biological replicate each; Days 2 and 4: 2 conditions with 2 biological replicates each) were prepared for microarray hybridization. After total RNA extraction, rRNAs were removed and mRNA transcripts were amplified and labeled with Alexa Fluor 647. Two technical replicates were hybridized from each RNA sample. The microarray was designed based on selected Ruegeria pomeroyi DSS-3 genes and their orthologs in 12 other sequenced Roseobacter genomes. Probes were designed from the orthologs using the Hierarchical Probe Design (HPD) algorithm.
Project description:The fraction of dissolved dimethylsulfoniopropionate (DMSPd) converted by marine bacterioplankton into the climate-active gas dimethylsulfide (DMS) varies widely in the ocean, with the factors that determine this value still largely unknown. One current hypothesis is that the ratio of DMS formation:DMSP demethylation is determined by DMSP availability, with 'availability' in both an absolute sense (i.e., concentration in seawater) and in a relative sense (i.e., proportionally to other labile organic S compounds) being proposed as the critical factor. We investigated these models during an experimentally-induced phytoplankton bloom using an environmental microarray targeting DMSP-related gene expression in the Roseobacter group, a taxon of marine bacteria known to play an important role in the surface ocean sulfur cycle. The array consisted of 1,578 probes to 431 genes, including those previously linked to DMSP degradation as well as core genes common in sequenced Roseobacter genomes. The prevailing pattern of Roseobacter gene expression showed depletion of DMSP-related transcripts during the peak of the bloom, despite the fact that absolute concentrations and flux of DMSP-related compounds were increasing. A likely interpretation is that DMSPd was assimilated by Roseobacter populations in proportion to its relative abundance in the organic matter pool (the “relative sense” hypothesis), and that it is not taken up in preference to other sources of labile organic sulfur or carbon produced during the bloom. The relative investment of the Roseobacter community in DMSP demethylation did not predict the fractional conversion of DMSP to DMS, however, suggesting a complex regulatory process that may involve multiple fates of DMSPd.
2010-08-05 | GSE21325 | GEO
Project description:Genomes of carotenoid-containing novel Methylomonas isolates
Project description:Rhizoctonia solani Kühn is a soilborne basidiomycetous fungus that causes significant damage to many economically important crops. R. solani isolates are classified into 13 Anastomosis Groups (AGs) with interspecific subgroups having distinctive morphology, pathogenicity and wide host range. However, the genetic factors that drive the unique fungal pathology are still not well characterized due to the limited number of available annotated genomes. Therefore, we performed genome sequencing, assembly, annotation and functional analysis of 13 R. solani isolates covering 7 AGs and selected subgroups (AG1-IA, AG1-IB, AG1-IC, AG2-2IIIB, AG3-PT, AG3-TB, AG4-HG-I, AG5, AG6, and AG8). Here, we report a pangenome comparative analysis of 13 R. solani isolates covering important groups to elucidate unique and common attributes associated with each isolate, including molecular factors potentially involved in determining AG-specific host preference. Finally, we present the largest repertoire of annotated R. solani genomes, compiled as a comprehensive and user-friendly database, viz. RsolaniDB. Since 7 genomes are reported for the first time, the database stands as a valuable platform for formulating new hypotheses by hosting annotated genomes, with tools for functional enrichment, orthologs and sequence analysis, currently not available with other accessible state-of-the-art platforms hosting Rhizoctonia genome sequences.
Project description:Neisseria meningitidis is the leading cause of bacterial meningitis and septicemia worldwide. The novel ST-4821 clonal complex caused several serogroup C meningococcal outbreaks unexpectedly during 2003–2005 in China. We fabricated a whole-genome microarray of Chinese N. meningitidis serogroup C representative isolate 053442 and characterized 27 ST-4821 complex isolates which were isolated from different serogroups using comparative genomic hybridization (CGH) analysis. This paper provides important clues which are helpful to understand the genome composition and genetic background of different serogroups isolates, and possess significant meaning to the study of the newly emerged hyperinvasive lineage. Keywords: comparative genomic hybridization
Project description:Expression diversity of P. ramorum isolates belonging to the NA1 clonal lineage growing on solid CV8 was examined. It was found that although all the analyzed isolates belonged to a single clonal lineage, expression patterns were distinctive between isolates originating from coast live oak and California bay laurel.
Project description:Although the major food-borne pathogen Campylobacter jejuni has been isolated from diverse animal, human and environmental sources, our knowledge of genomic diversity in C. jejuni is based exclusively on human or human food-chain-associated isolates. Studies employing multilocus sequence typing have indicated that some clonal complexes are more commonly associated with particular sources. Using comparative genomic hybridization on a collection of 80 isolates representing diverse sources and clonal complexes, we identified a separate clade comprising a group of water/wildlife isolates of C. jejuni with multilocus sequence types uncharacteristic of human food-chain-associated isolates. By genome sequencing one representative of this diverse group (C. jejuni 1336), and a representative of the bank-vole niche specialist ST-3704 (C. jejuni 414), we identified deletions of genomic regions normally carried by human food-chain-associated C. jejuni. Several of the deleted regions included genes implicated in chicken colonization or in virulence. Novel genomic insertions contributing to the accessory genomes of strains 1336 and 414 were identified. Comparative analysis using PCR assays indicated that novel regions were common but not ubiquitous among the water/wildlife group of isolates, indicating further genomic diversity among this group, whereas all ST-3704 isolates carried the same novel accessory regions. While strain 1336 was able to colonize chicks, strain 414 was not, suggesting that regions specifically absent from the genome of strain 414 may play an important role in this common route of Campylobacter infection of humans. We suggest that the genomic divergence observed constitutes evidence of adaptation leading to niche specialization. Data is also available from <ahref=http://bugs.sgul.ac.uk/E-BUGS-95 target=_blank>BuG@Sbase</a>
Project description:The basidiomycete Moniliophthora roreri causes frosty pod rot of cacao (Theobroma cacao) in the Western hemisphere. M. roreri is considered asexual and haploid throughout its hemibiotrophic lifecycle. To understand the processes driving genome modification, using long-read sequencing technology we sequenced and assembled five high quality M. roreri genomes out of a collection of ninety-nine isolates collected throughout the pathogen's range. We obtained chromosome-scale assemblies composed of eleven scaffolds. We used short-read technology to sequence the genomes of twenty-two similarly chosen isolates. Alignments among the five reference assemblies revealed inversions and segmental translocations and duplications between and within scaffolds. Isolates at the front of the pathogens’ expanding range tend to share lineage-specific structural variants, as confirmed by short-read sequencing. We identified, for the first time, three new mating type A locus alleles (five in total) and one new potential mating type B locus allele (three in total). Currently only two mating type combinations, A1B1 and A2B2, are known to exist outside of Colombia. A systematic survey of the M. roreri transcriptome across twenty-two isolates identified an expanded candidate effector pool and provided evidence that effector candidate genes unique to the Moniliophthoras have been selected for preferential expression during the biotrophic phase of disease. Notably, M. roreri isolates in Costa Rica carry a chromosome segment duplication that has doubled the associated gene complement and includes secreted proteins and candidate effectors. Clonal propagation of the haploid M. roreri genome has allowed lineages with unique genome structures and compositions to dominate as it expands its range, displaying a significant founder effect.