The School of Molecular and Cellular Biology at the University of Illinois at Urbana-Champaign

I am a molecular biologist turned evolutionist. My evolutionary concerns center on the bacteria and the archaea, whose evolutions cover most of the planet's 4.5-billion-year history. Using ribosomal RNA sequence as an evolutionary measure, my laboratory has reconstructed the phylogeny of both groups, and thereby provided a phylogenetically valid system of classification for prokaryotes. The discovery of the archaea was in fact a product of these studies.

The archaea are unique organisms. While prokaryotes in the cytological sense, they are actually more closely related to eukaryotes than to the bacteria. They are of particular interest for this reason alone-they are simple organisms whose study should provide insights into the nature and evolution of the eukaryotic cell. Their study is also central to an understanding of the nature of the ancestor common to all life. The archaea are, of course, interesting in their own right. The group contains both the methanogens and numerous organisms that grow at extremely high temperatures (in some cases above 100°C). As such, they provide potential insights into mechanisms of thermophilia and methanogenesis.

My work over the last 5 years has centered on genomic analysis, with an emphasis on understanding the evolutionary significance of the phenomenon of horizontal gene transfer (HGT). This has involved in particular an in detail analysis of the phylogenies of the aminoacyl-tRNA synthetases and the effect HGT has had upon the distribution of these key enzymes. The ultimate goal is to construct a model (theory) of how the primary cell types (the archaeal, eubacterial, and eukaryotic) have evolved, from some ancestral state in the RNA-world