A research lab is using DNA microarrays to examine gene expression in Salmonella

Question

A research lab is using DNA microarrays to examine gene expression in Salmonella enterica during stress. It was noted that when exposed to nutrient limitations, 20 new genes were expressed (as compared to normal laboratory growth conditions); when exposed to oxidative stress, 24 new genes were expressed; and when exposed to low pH, 15 new genes were expressed. The lab then subjected the bacteria to growth in macrophage phagolysosomes, which mimicked the previous three conditions, and noted 59 new genes being expressed. What is your interpretation of this result?

Explanation / Answer

This reveals unexpected dominance of disease-specific genes. The bacterium is highly resistant to disease-specific markers, antibodies and stressors. Whenever a new stressor arrives, the bacterium immediately devises a new gene (and protocol) to combat the stress.

These bacteria is highly resistant. It possesses genes for all possible MHC haplotypes.

Note that Salmonella has rpoS regulon. This provides it great stress tolerance.

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