Light microscopy resolution barrier-broken!!!

A scanning electron micrograph depicting a mas...

Electron microscopic view of Y. pestis; Image via Wikipedia

I was checking out the news items at Science Daily today, and came across this news brief: at the recent annual meeting of the American Biophysical Society, held in Baltimore last week, a report was presented examining the surface of Yersinia pestis, the etiologic agent of Bubonic Plague. Researchers at Sandia National Laboratory in New Mexico, used the technique of Stochastic Optical Reconstruction Microscopy (STORM) to examine molecules on the surface of human neutrophils encountering either E. coli cells or Y. pestis cells. As we have learned in the chapter on Innate Immunity, this interaction is mediated by “patterns” found on the surface of the pathogen, and pattern recognition proteins on the surface of the immune cells. Specifically in these partners, Toll-like receptors found on the immune cells and lipopolysaccharide (LPS) on the bacterial cells interact with one another leading to the establishment of the immune response.

The scientists at Sandia National Laboratory have used the STORM technique, which utilizes a light-based microscope in combination with very precise wavelengths of light, beam splitters, color filters, and computer reconstruction to make an image with a resolution limit approximately ten times better than standard light microscopy. By using this technique, they have been able to see that when the immune cells and E. coli cells interact via the TLR4-LPS connection, the TLR proteins on the surface of the immune cell clump together, leading to the turning on of the immune response by the neutrophil. This clumping does not seem to occur with Y. pestis, meaning that the immune response doesn’t get initiated to the same degree with this organism. This may be one reason that Y. pestis is a much more virulent pathogen than E. coli; it is not as effectively cleared by the immune system when it initiates infection.

I don’t expect that we’ll be replacing all of our microscopes at YCP with STORM scopes anytime soon, as I imagine that the cost would mean a doubling of the yearly tuition costs.

BONUS: this report describes an immune interaction that is exploited by a specific microorganism to escape immune surveillance. In the comment thread, list other patterns that are recognized by the immune system to identify “foreign” objects.

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About ycpmicro

My name is David Singleton, and I am an Associate Professor of Microbiology at York College of Pennsylvania. My main course is BIO230, a course taken by allied-health students at YCP. Views on this site are my own.

Posted on March 19, 2011, in Bonus!, Microbes in the News. Bookmark the permalink. 7 Comments.

  1. One possibility is virulence factors. Virulence factors are molecules expressed and secreted by pathogens that enable them to preform a bunch of different functions, like obtaining entry and exit from host and also nutrition from the host. Even though they cause disease in the host by inhibiting different functions they still can prevent certain things from getting past the Gram negative walls of cells and are able to sort by endotoxins and exotoxins.

    • I’m not sure what you are getting at here. Things like exotoxins and endotoxins might be recognized, but what would be a specific example of a pattern that would be recognized?

      • Today like what we talked about the different ribosomes, but also specifically the lipid A and the peptidoglycan outer layer of the gram negative cells that they would have to get through.

  2. As talked about briefly in class today (even though we’ll cover in later chapters), the idea of memory helps the immune system to identify foreign objects coming into the body. If the body is infected once, if it gets infected again, it uses it’s memory from the first time it was infected in order to help fight off the infection the second time. Memory acts as a pattern to help the immune system to identify when foreigh objects come into the body.

  3. patterns would include: the presence of lipid A or peptidoglycan, or the size of the ribosome

  4. Brittany MacFadden

    B Cells are the major cells involved in the creation of antibodies that circulate in blood plasma and lymph, known as humoral immunity. Antibodies (or immunoglobulin, Ig), are large Y-shaped proteins used by the immune system to identify and neutralize foreign objects.

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