Dating the cyanobacterial ancestor of the chloroplast.

Cyanobacteria have had a pivotal role in the history of life on Earth being the first organisms to perform oxygenic photosynthesis, which changed the atmospheric chemistry and allowed the evolution of aerobic Eukarya. Chloroplasts are the cellular organelles of photoautotrophic eukaryotes in which most portions of photosynthesis occur. Although the initial suggestion that cyanobacteria are the ancestors of chloroplasts was greeted with skepticism, the idea is now widely accepted.

Angiosperm diversification through time.

The extraordinary diversity of angiosperms is the ultimate outcome of the interplay of speciation and extinction, which determine the net diversification of different lineages. We document the temporal trends of angiosperm diversification rates during their early history. Absolute diversification rates were estimated for order-level clades using ages derived from relaxed molecular clock analyses that included or excluded a maximal constraint to angiosperm age.

Molecular diversity of rabies viruses associated with bats in Mexico and other countries of the Americas.

Bat rabies and its transmission to humans and other species in Mexico were investigated. Eighty-nine samples obtained from rabid livestock, cats, dogs, and humans in Mexico were studied by antigenic typing and partial sequence analysis. Samples were further compared with enzootic rabies associated with different species of bats in the Americas.

Molecular epizootiology of rabies associated with terrestrial carnivores in Mexico.

Epizootiological patterns of rabies are described, using antigenic and genetic analysis of samples obtained from infected domestic and wild mammals in 20 Mexican states during 1976-2002. Two independent origins are suggested for rabies in Mexican carnivores. One group shares ancestry with canine rabies, while the other group appears to share a common origin with bat rabies in North America.

A genomic population genetics analysis of the pathogenic enterocyte effacement island in Escherichia coli: the search for the unit of selection.

Comparative genomic analysis is a powerful tool for understanding the history and organization of complete genomes. The mathematical tools of population genetics combined with genomic analysis provide a powerful approach to dissect heterogeneities in genome evolution. This study presents a hierarchical analysis of the enterocyte and effacement island (35 kb), which is found in the enteropathogenic and enterohemorrhagic strains in Escherichia coli and in Citrobacter rodentium.