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 he aim of the Xenorhabdus genome sequencing project is to obtain the genome sequence of two species of Xenorhabdus bacteria: X. nematophila ATCC19061 and X. bovienii. Xenorhabdus bacteria are associated in a mutually beneficial relationship with soil-dwelling Steinernematid nematodes. Together, Xenorhabdus and their nematode host infect and kill insects that are used during their reproductive cycles. X. nematophila is the best understood of the five identified species of Xenorhabdus. As a mutalist, X. nematophila colonizes the intestine of a non-feeding stage of Steinernema carpocapsae nematodes. The nematode is the vector that shelters the bacteria from the competitive soil environment, and shuttles X. nematophila into insect hosts. The bacterium functions as a potent pathogen that infects and kills diverse insect species, which serve as the nutrient source for the development and reproduction of the nematode. X. nematophila has evolved functions necessary to be both a symbiont, benefiting one animal (the nematode) and a pathogen, causing death of another (the insect). Furthermore, the symbiotic interaction between X. nematophila and S.carpocapsae is species specific; other species of Xenorhabdus cannot colonize S. carpocapsae, although they can colonize their own Steinernematid hosts. Therefore the X. nematophila - S. carpocapsae model system can be further exploited as a model to understand host-range specificity. This phenomenon is not well understood and has implications in important agricultural and medical issues such as the effective use of probiotic treatments and prevention of pathogen transmission from animals to humans. These features make Xenorhabdus an excellent model to understand host colonization, pathogenicity and niche competition. The complete sequence of X. nematophila and X. bovienii will provide the essential tools to undertake a comparative genomics analysis of the Xenorhabdus, which will increase our understanding of its symbiotic/pathogenic nature.
The Xenorhabdus sequencing project is performed in collaboration between three academic institutions and the Monsanto Company, which is an industry leader in agricultural research, development and agricultural solutions. The sequencing goals of this project include the generation of eight genome equivalents of shotgun genomic sequence from both X. nematophila and X. bovienii followed by gap closure to ultimately produce two complete genomes. All high-throughput genomic sequence will be deposited in the GenBank through-out the course of the sequencing. A BLAST server is also available for community access to the Xenorhabdus genome sequence while the data is being acquired. The contiguous assembled sequences of X. nematophila and X. bovienii will be released upon completion.
Project Participants and Collaborators:
PI: Barry Goldman, Ph.D. - The Monsanto Company
Co-PIs: Brad Barbazuk Ph.D. - The Donald Danforth Plant Science Center
Heidi Goodrich-Blair, Ph.D. - University of Wisconsin, Madison
Creg Darby, Ph.D - University of Alabama, Birmingham
Steve Slater, Ph.D. - The Monsanto Company
Steve Forst, Ph.D. - University of Wisconsin, Milwaukee
Brad Goodner, Ph.D. - Hiram College
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Xenorhabdus and nematode
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Life cycle of Xenorhabdus /Steinernema symbiosis- pathogenesis
(from the laboratory of R.Gaugler)
The strain of Xenorhabdus bovienii was obtained from a new species of the nematode Steinernema. Information on its isolation can be obtained from the following publications.
A new entomopathogenic nematode from the American Midwest. Russian
Journal of Nematology, 2004, Vol. 12, N 1, P. 85-95.
Spiridonov S.E., Krasomil-Osterfeld K., Moens. M. Steinernema jollieti
sp. n. (Rhabditida: Steinernematidae)
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