Researchers studying the newly sequenced genome of the marine bacterium V. fischeri, described this week in the Proceedings of the National Academy of Sciences (PNAS), have so far observed both differences and similarities in gene arrangement between it and pathogenic Vibrio species. V. fischeri has a lower GC content than other sequenced Vibrio species, but it is still more closely related to them than other organisms. (Among the four nucleotides that make up DNA ?adenine, guanine, thymine, and cytosine (ATGC) ?'A' pairs with 'T' and 'G' pairs with 'C'. The more GC content, the more tightly DNA strands bind.)
Despite the fact that it is a symbiont, V. fischer's genome contains genes that may have toxin activity. "Analysis of this sequence has revealed surprising parallels with Vibrio cholerae and other pathogens," said Ann Stevens, associate professor of biology at Virginia Tech.
This sequence research is described in the PNAS online early edition the week of February 7, 2005, (www.pnas.org), in the article, "Complete genome sequence of Vibrio fischeri: A symbiotic bacterium with pathogenic congeners," by E. G. Ruby, professor of medical microbiology and immunology at the University of Wisconsin, Madison, previously at the University of Hawaii; C. Lupp; J. McCann; D. Millikan; A. Schaefer; and C. Whistler of the University of Hawaii at Honolulu; M. Urbanowski and E. P. Greenberg of the University of Iowa at Iowa City; J. Campbell at Integrated Genomics; A. Dunn and E. Stabb at the University of Georgia at Athens; Marie Faini and Ann Stevens of Virginia Tech; R. Gunsalus of the University of California at Los Angeles; and K. Visick of Loyola Un