Jeffrey Lawrence


Genome evolution

Jeffrey Lawrence
Office: (412) 624-4204
Lab: (412) 624-4205
103B Clapp Hall
4249 Fifth Avenue
Pittsburgh, PA 15260

Dr. Lawrence received his Ph.D. in 1991 with Daniel L. Hartl at Washington University, St. Louis, performed his postdoctoral studies with John Roth at the University of Utah, and joined the Department in 1996.

Our research is directed toward elucidating the evolution of bacterial genomes, including their size, composition, variability and organization. In other words, why do genomes have the genes that they do? An understanding of the evolutionary process that leads to differences in genomes will shed light on how species themselves differentiate. We take computations, theoretical and experimental approaches to understanding how genomes evolve.

Speciation. Bacterial speciation - the process by which lineages become genetically and ecologically distinct from one another - is quite different from its eukaryotic counterpart. The differences arise from both the manner by which bacteria adapt (by gene acquisition, rather than gene modification) and the constraints on their gene exchange. Our work has supported a "fragmented" model of speciation, whereby lineages become genetically isolated on a gene-by-gene basis over a period of tens of millions of years.

Ecological adaptation. Which are the first genes to become genetically isolated in nascent species? Among the earliest diverging genes in the Salmonella chromosome are those that encode the O-antigen biosynthetic machinery. We have been investigating the role of protozoan predation in driving this diversification. Here, different antigens allow the newly-diverging Salmonella to escape protozoan predators in different environments.

Recent Publications
  • Lawrence, J.G., K. Butela, A. Atzinger (2013) A likelihood approach to classifying fluorescent events collected by multicolor flow cytometry. J. Microbiol. Methods In Press.

  • Butela, K., and J.G. Lawrence (2012) Genetic manipulation of pathogenicity loci in non-Typhimurium Salmonella. J. Microbiol. Methods 91(3):477-482

  • Retchless, A.C. and J.G. Lawrence (2012) Ecological adaptation in bacteria: Speciation driven by codon selection. Mol Biol Evol 29:3669-3683

  • Retchless, A.C. and J.G. Lawrence (2011) Quantification of codon selection for comparative bacterial genomics. BMC Genomics 12:374

  • Ricotta, E.E., N. Wang, R. Cutler, J.G. Lawrence, and T.L. Humpries (2011) Rapid divergence of two classes of Haemophilus ducreyi. J Bacteriol 193:2941-2947

  • Azad, R.K., and J.G. Lawrence (2011) Towards more robust methods of alien gene detection. Nucleic Acids Res 39(9):e56

  • Retchless, A.C., and J.G. Lawrence (2010) Phylogenetic incongruence arising from fragmented speciation in enteric bacteria. Proc. Natl. Acad. Sci., USA 107:11453-11458

  • Lawrence, J.G., and A.C. Retchless (2010) The myth of bacterial species and speciation. Biol. Philos. 25:569-588

  • Arvey, A.J., R.K. Azad, A. Raval, and J.G. Lawrence (2009) Detection of genomic islands via segmental genome heterogeneity. Nucleic Acids Res. 37:5255-5266

  • Lawrence, J.G., and A.C. Retchless (2009) The interplay of homologous recombination and horizontal gene transfer in bacterial speciation. Methods Mol. Biol. 532:29-53

  • Lawrence, J.G., and H. Hendrickson (2008) Genomes in motion: gene transfer as a catalyst for genomic change. Pp 3-22 in Horizontal Gene Transfer in the Evolution of Pathogenesis, Schmidt, H., and M. Hensel, Ed. Unknown Publisher

  • Retchless, A.C., and J.G. Lawrence (2007) Temporal fragmentation of speciation in bacteria. Science 317:1093-1096

  • Azad, R.K., and J.G. Lawrence (2007) Detecting laterally-transferred genes: Use of entropic clustering methods and genome position. Nucleic Acids Res. 35:4629-4639

  • Wildschutte, H., and J.G. Lawrence (2007) Differential Salmonella survival against communities of intestinal amoebae. Microbiology 1789:1781

  • Hendrickson, H., and J.G. Lawrence (2007) Mutational bias suggests that replication termination occurs near the dif site, not at Ter sites. Mol. Microbiol. 64:42-56

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