Dataset Information

Whole-genome analyses of speciation events in pathogenic Brucellae.

ABSTRACT: Despite their high DNA identity and a proposal to group classical Brucella species as biovars of Brucella melitensis, the commonly recognized Brucella species can be distinguished by distinct biochemical and fatty acid characters, as well as by a marked host range (e.g., Brucella suis for swine, B. melitensis for sheep and goats, and Brucella abortus for cattle). Here we present the genome of B. abortus 2308, the virulent prototype biovar 1 strain, and its comparison to the two other human pathogenic Brucella species and to B. abortus field isolate 9-941. The global distribution of pseudogenes, deletions, and insertions supports previous indications that B. abortus and B. melitensis share a common ancestor that diverged from B. suis. With the exception of a dozen genes, the genetic complements of both B. abortus strains are identical, whereas the three species differ in gene content and pseudogenes. The pattern of species-specific gene inactivations affecting transcriptional regulators and outer membrane proteins suggests that these inactivations may play an important role in the establishment of host specificity and may have been a primary driver of speciation in the genus Brucella. Despite being nonmotile, the brucellae contain flagellum gene clusters and display species-specific flagellar gene inactivations, which lead to the putative generation of different versions of flagellum-derived structures and may contribute to differences in host specificity and virulence. Metabolic changes such as the lack of complete metabolic pathways for the synthesis of numerous compounds (e.g., glycogen, biotin, NAD, and choline) are consistent with adaptation of brucellae to an intracellular life-style.

SUBMITTER: Chain PS

PROVIDER: S-EPMC1307078 | biostudies-literature | 2005 Dec

REPOSITORIES: biostudies-literature

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Whole-genome analyses of speciation events in pathogenic Brucellae.

Chain Patrick S G PS Comerci Diego J DJ Tolmasky Marcelo E ME Larimer Frank W FW Malfatti Stephanie A SA Vergez Lisa M LM Aguero Fernan F Land Miriam L ML Ugalde Rodolfo A RA Garcia Emilio E

Infection and immunity 20051201 12

Despite their high DNA identity and a proposal to group classical Brucella species as biovars of Brucella melitensis, the commonly recognized Brucella species can be distinguished by distinct biochemical and fatty acid characters, as well as by a marked host range (e.g., Brucella suis for swine, B. melitensis for sheep and goats, and Brucella abortus for cattle). Here we present the genome of B. abortus 2308, the virulent prototype biovar 1 strain, and its comparison to the two other human patho ...[more]

PMID: 16299333

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Project description:Background and aimsThe Araceae are one of the most diverse monocot families with numerous morphological and ecological novelties. Plastid and mitochondrial genes have been used to investigate the phylogeny and to interpret shifts in the pollination biology and biogeography of the Araceae. In contrast, the role of whole-genome duplication (WGD) in the evolution of eight subfamilies remains unclear.MethodsNew transcriptomes or low-depth whole-genome sequences of 65 species were generated through Illumina sequencing. We reconstructed the phylogenetic relationships of Araceae using concatenated and species tree methods, and then estimated the age of major clades using TreePL. We inferred the WGD events by Ks and gene tree methods. We investigated the diversification patterns applying time-dependent and trait-dependent models. The expansions of gene families and functional enrichments were analysed using CAFE and InterProScan.Key resultsGymnostachydoideae was the earliest diverging lineage followed successively by Orontioideae, Lemnoideae and Lasioideae. In turn, they were followed by the clade of 'bisexual climbers' comprised of Pothoideae and Monsteroideae, which was resolved as the sister to the unisexual flowers clade of Zamioculcadoideae and Aroideae. A special WGD event ψ (psi) shared by the True-Araceae clade occurred in the Early Cretaceous. Net diversification rates first declined and then increased through time in the Araceae. The best diversification rate shift along the stem lineage of the True-Araceae clade was detected, and net diversification rates were enhanced following the ψ-WGD. Functional enrichment analyses revealed that some genes, such as those encoding heat shock proteins, glycosyl hydrolase and cytochrome P450, expanded within the True-Araceae clade.ConclusionsOur results improve our understanding of aroid phylogeny using the large number of single-/low-copy nuclear genes. In contrast to the Proto-Araceae group and the lemnoid clade adaption to aquatic environments, our analyses of WGD, diversification and functional enrichment indicated that WGD may play a more important role in the evolution of adaptations to tropical, terrestrial environments in the True-Araceae clade. These insights provide us with new resources to interpret the evolution of the Araceae.

Dataset Information

Whole-genome analyses of speciation events in pathogenic Brucellae.

Publications

Whole-genome analyses of speciation events in pathogenic Brucellae.

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