Dennis W. Grogan

	Dennis W. Grogan Professor Ph.D., University of Illinois, Urbana-Champaign Microbiology

Mailing Address: Dennis Grogan Department of Biological Sciences, ML006 University of Cincinnati Cincinnati, Ohio 45221-0006	Telephone: (513) 556-9748 FAX: (513) 556-5299 Email: GroganDW@email.uc.edu Office & Lab: 732 Rieveschl

Much of the biochemical diversity of life on earth is embodied in single-celled organisms. The smallest and most widely distributed of these are prokaryotic, consisting of extremely small cells that lack nuclei or other membranous organelles. The best-known prokaryotes, bacteria, include a few species that cause disease, and many others that mediate geochemical cycling, degrade toxic pollutants, or produce antibiotics or other useful products. About 30 years ago, Carl Woese at the University of Illinois discovered a second, evolutionarily distinct, group of prokaryotes through analysis of ribosomal RNA sequences. Much less is known about this second lineage, called " Archaea". Many of the archaea that have been successfully grown in pure culture come from hostile or otherwise unusual environments, yet they show certain similarities to eukaryotic cells at the molecular level.

The Grogan lab focuses on thermoacidophilic archaea of the genus Sulfolobus. These species normally live in acidic hot springs, and their optimal growth conditions (80º C and pH 3) quickly inactivate the DNA, RNA, enzymes, and membranes of "ordinary" cells. We want to understand in molecular terms how the Sulfolobus cell functions under these harsh conditions.

Like other hyperthermophiles, Sulfolobus spp. have thermostable enzymes that exhibit maximal activity at extremely high temperatures. Like other archaea, their cells have an unusual cell envelope composed of ether-linked isoprenoid lipids and a flexible layer of glycoprotein subunits. These features, though unusual, seem to be very effective for preserving cellular integrity at high temperature and low external pH. Intracellular processes, such as DNA metabolism, are also expected to have molecular adaptations for life under these conditions, but are more difficult to observe and manipulate experimentally.

To address this challenge, research in the Grogan lab emphasizes development of basic genetic techniques that allow specific molecular processes to be analyzed in vivo under extreme conditions. We have isolated various mutant strains of S. acidocaldarius and used them to investigate archaeal cell division, responses to DNA damage, transfer and recombination of chromosomal DNA, and fidelity of genome replication. We have also analyzed homologous recombination, deletion formation, and the properties of insertion sequences in Sulfolobus. With collaborators, we have analyzed the genetic diversity of natural Sulfolobus populations around the world, using PCR, sequence analysis, and microarray hybridization.

Progress on these and related questions has been helped greatly by the availability of genomic sequences and various other genetic resources for Sulfolobus species.

Prospective graduate students are encouraged to contact Dr. Grogan for information on current research themes. For general information on applying to the graduate program in Biological Sciences, follow the Graduate Student link on the Department’s Web page.

Biological Sciences majors interested in fulfilling the Capstone or Departmental Honors requirements through an undergraduate research project should check out the option on molecular genetics of hyperthermophiles.