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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

V. parahaemolyticus

Sodium transport genes & Osmoregulatory pumps

Andrea, Saikumar, Stacey, & Cesar

(Kozo, et. al, 2002)

Intro to v parahaemolyticus
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)

Pathogenesis of v parahaemolyticus
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)

Genome of v parahaemolyticus
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)

Osmoregulatory pumps
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

Na h antiporter
Na+/H+ Antiporter

  • Na+/H+ Antiporter is a transport protein used to maintain gradients across the cell membrane


Location of the genes of interest
Location of the Genes of Interest

Na+/H+ are essential for survival

Expect to be found on conserved regions of the chromosome


fluorescent in situ hybridization


Genome map
Genome Map

  • Genes encoding sodium pumps are highly conserved closely together mostly on chromosome one

    • Gene VP2449

    • Gene VP1092

(Kozo, et. al, 2002)

Genes con t
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

Na h antiporter expression in changing environment
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

  • Expected results
    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

    Rabbit model for pathogenicity
    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)

    Expected results1
    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.

    Evolutionary patterns
    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

    Evolutionary patterns con t
    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

    Did pathogenesis evolve from a mutualist or vice versa
    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

    The problem of the chicken and the egg
    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.


    A different view
    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


    • 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.


    • 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.