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- Topics in Biology: The Unseen World
My research concerns the physiology and ecology of microorganisms. I am especially interested in bacteria that thrive in extreme habitats, and I have recently been studying catabolite repression in the highly thermophilic bacterium Thermotoga neapolitana. Thermotoga thrives at deep-sea vents where temperatures exceed 100 C. Besides living in a fascinating habitat, Thermotoga is interesting from an evolutionary point of view because its phylogenetic lineage includes the first known bacterial heterotrophs. My research has focused on the metabolic characteristics of Thermotoga, especially how it prioritizes growth substrates and regulates the synthesis of degradative enzymes. This research combines microbiological culture techniques, biochemical analysis, and immunoassays. These methods have shown that catabolite repression in Thermotoga differs from that in commonly studied enteric bacteria such as E. coli with respect to the role of cyclic AMP in genetic regulation. Studies of Thermotoga and related thermophiles can provide insight into the physiological processes of the most ancient heterotrophs.
Yu, J.S., Vargas, M., Mityaf, C., and Noll, K.M. (2001). Liposome-mediated DNA uptake and transient expression in Thermotoga. Extremophiles 5:53-60.
Lovley, D.R., Kashefi, K., Vargas, M. Tor J.M. and Blunt-Harris, E.L. (2000). Reduction of humic substances and Fe(III) by hyperthermophilic microorganisms. Chem. Geol. 169-289-298..
Vargas, M., Kashefi, K., Blunt-Harris, E. L., and Lovley, D. R. (1998). Microbiological evidence for Fe(III) reduction on early earth. Nature 395:65-67.
Noll, K. M. and Vargas, M. (1997). Recent advances in genetic analyses of hyperthermophilic archaea and bacteria. Arch. Microbiol. 168:73-80.
Vargas, M. and Noll, K. M. (1996). Catabolite repression in the hyperthermophilic bacterium Thermotoga neapolitana is independent of cAMP. Microbiol. 142: 139-144.
Vargas, M. and Noll, K. M. (1994). Isolation of auxotrophic and antimetabolite-resistant mutants of the hyperthermophilic bacterium Thermotoga neapolitana. Arch. Microbiol. 162: 357-361.
Childers, S.E., M. Vargas, and K.M. Noll. 1992. Improved methods for the cultivation of the extremely thermophilic bacterium Thermotoga neapolitana. Appl. Environ. Microbiol. 58:3949-3953.
Vargas, M., A. Lee, J.G. Fox, and D.R. Cave. 1991. Inhibition of acid secretion from parietal cells by non-human infecting Helicobacter species: a factor in colonization of gastric mucosa? Infect. and Immun. 59:3694-3699.
Cave, D.R., and M. Vargas. 1989. Effect of Campylobacter pylori protein on acid secretion by parietal cells. Lancet 2:187-189.