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V. parahaemolyticus

V. parahaemolyticus. Sodium transport genes & Osmoregulatory pumps Andrea, Saikumar, Stacey, & Cesar. (Kozo, et. al, 2002). Intro to V . parahaemolyticus. Gram negative bacterium, curved rod shaped with single flagellum Part of bacterial Vibrionaceae family

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V. parahaemolyticus

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  1. V. parahaemolyticus Sodium transport genes & Osmoregulatory pumps Andrea, Saikumar, Stacey, & Cesar (Kozo, et. al, 2002)

  2. Intro to V. parahaemolyticus • Gram negative bacterium, curved rod shaped with single flagellum • Part of bacterial Vibrionaceae family • Thrives in salt water (halophilic) obligate heterotrophs • Found predominately in marine and estuary communities (Research in Microbiology, 2004; http://en.wikipedia.org/wiki/Vibrio_parahemolyticus)

  3. Pathogenesis of V. parahaemolyticus • Mutualistic state with oysters/shellfish • Concentrated in gills of oysters due to filtering • Pathogenic state with humans/mammals. • Causes gastrointestinal problems • Major cause of food poisoning from consuming raw/undercooked seafood (Research in Microbiology, 2004)

  4. Genome of V. Parahaemolyticus • Genome similar to V. cholerae • Two chromosomes (conserved vs. non-conserved genes) • Where would we expect to find Na+/H+ genes and how do we determine the chromosomal location of theses genes? • (FEMS Microbiology Review, 2001)

  5. Osmoregulatory Pumps • Specific genes that allows plasticity in marine hosts (non infectious) to human hosts (infectious) • Location of these genes within the genome • Antiporter regulation effects on virulence • The problem of the chicken and the egg • Evolutionary patterns

  6. Na+/H+ Antiporter • Na+/H+ Antiporter is a transport protein used to maintain gradients across the cell membrane http://upload.wikimedia.org/wikipedia/en/7/71/Antiporter.jpg

  7. Location of the Genes of Interest Na+/H+ are essential for survival Expect to be found on conserved regions of the chromosome FISH fluorescent in situ hybridization (http://www.genome.gov/glossary.cfm?key=fluorescence%20in%20situ%20hybridization%20%28FISH%29)

  8. Genome Map • Genes encoding sodium pumps are highly conserved closely together mostly on chromosome one • Gene VP2449 • Gene VP1092 (Kozo, et. al, 2002)

  9. Genes, Con’t… If Na+/H+ antiporter genes were found on non conserved regions this would indicate that the genes were not necessary for survival Genes evolved with a specific purpose and can be easily manipulated without killing the bacteria

  10. Na+/H+ Antiporter Expression in changing Environment • Experiment • Growing the bacteria under: • Optimum conditions (pH, salinity, temperature, food) • Decreased temperature • Decreased food • Varying pH • Cultures obtained and stain with the appropriate dye • Antiporters will be visualized and counted

  11. Expected Results • Under stressful conditions • pH extremes and varying salinity – up regulation or down regulation of antiporter proteins • Varying Temperature and Food supply • Expression of antiporters would not be affected but cell proliferation would be greatly affected

  12. Rabbit Model for Pathogenicity • V. parahaemolyticus collected from bivalves • Grown in cell broths • Inoculate rabbits with a fixed dosage of broth • Rabbits were sacrificed 24 hours post infection • Post mortem cell cultures Na+/H+ antiporter proteins stained • Cells visualized and compared with cell cultures from bivalves. (Lexomboon 2000)

  13. Expected Results • Original hypothesis: Due to a change in environmental conditions, there should be an up regulation of Na+/H+ antiporter proteins • The number of Na+/H+ antiporter proteins will remain relatively constant. • Side note: • This antiporter uses H+ concentrations to maintain Na+ gradients. • The digestive systems of animals have a high concentration of H+, thus enabling the antiporter to create a greater Na+ gradient causing osmotic diarrhea.

  14. Evolutionary Patterns • Environmental conditions • Oxygen, temperature, and salinity have significant affects on virulence • Higher salinity increases virulence towards shrimp • Composition and metabolism of V. parahaemolyticus • Altered for adaptation • Results in increased pathogenicity

  15. Evolutionary Patterns Con’t… • Outer membrane proteins (OMP) • Play key role in adaptation to changes in external environment • Osmolarity location is outermost part of cell. • Synthesis of OMPs • Regulation when V. parahaemolyticus is transferred to different salinity environments

  16. Did Pathogenesis Evolve from a Mutualist or Vice-Versa? • Specific virulence factors exhibited in colonization by V. parahaemolyticus • May be required for colonization • Defense mechanisms of host must be conquered in either case

  17. The problem of the Chicken and the egg • One view: • Pathogenicity evolve prior to mutualistic associations • Common ancestral origin of many characteristics of host-tissue colonization? • Most sensible for pathogen to lead to symbiont: allows host and attacker to survive. • V. parahaemolyticus pathogenicity islands (PAI) on chromosomeII: 80kb of DNA. (http://jb.asm.org/cgi/reprint/190/5/1835.pdf)

  18. A Different View • Human host gives V. parahaemolyticus perfect environment • Optimal temperature and nutrition allow for increase in proliferation and environment exploitation. • Virulence results from a “perfect” host

  19. References • C. Xu, H. Ren, S. Wang, and X. Peng. “Proteomic analysis of salt-sensitive outer membrane proteins of Vibrio parahaemolyticus.” Research in Microbiology 155 (2004) 835-842. • “Vibrio parahaemolyticus” Obtained from <http://en.wikipedia.org/wiki/Vibrio_parahemolyticus.> • Kozo Makimo, et. al. “Genomic Map of V. parahaemolyticus.” “V. Parahaemolyticus Image” July 2004. <http://images.google.com/imgres?imgurl=http://genome.naist.jp/bacteria/vpara/images/vpem.jpg&imgrefurl=http://genome.naist.jp/bacteria/vpara/index.html&h=540&w=600&sz=51&hl=en&start=1&um=1&usg=__EzFOOX4e2KQnHXnW7NqCC8ifylM=&tbnid=B1q8ILaobUJhkM:&tbnh=122&tbnw=135&prev=/images%3Fq%3Dv.%2Bparahaemolyticus%26um%3D1%26hl%3Den%26sa%3DN.> • R. Sleator, and Colin Hill. “Bacterial osmoadaptation: the role of osmolytes in bacterial stress and virulence.” FEMS Microbiology Reviews 26 (2001). 49-71. • Lexomboon, Udom. “The Infant Rabbit as a Model of Pathogenicity for Vibrio parahaemolyticus”, 2000, http://www.afrims.org/weblib/eapr/1971/APR71p178-181.pdf. • T.Sugiyama, T.Iida, K.Izutsu, K.Park and T.Honda. “ Precise region and character of the pathogenecity island in clinical Vibrio parahaemolyticus strains.” Journal of Bacteriology 190(2007)1835-1837.

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