Tuesday, September 25, 2007

Deadly space bugs

It is known that microgravity (MG) affects the way cells react. For example, astronauts coming back to Earth after a long time spent under very low gravity show signs of bone resorption and muscle mass loss. Bacteria react to low gravity too. In a paper published in 2002, Dr. Cheryl Nickerson and her team (see reference and link to pdf file below) discovered that the expression of many genes is in fact affected by MG (Figure on right). As can be seen, some genes are expressedm or not under normal gravity (1xg) but this expression pattern can be almost completely reversed under MG (or LSMMG - Low Shear Modeled Micro Gravity).

Because gene expression seems to be influenced by microgravity, the obvious experiment was now to determine if the virulence of bacteria is increased un der MG...in other words are microbes susceptible to become "superbugs" in space? The answer, sadly, seems to be YES!

In another study, to be published in PNAS, Dickerson and fisrt author James Wilson show that some virulence genes are in fact turned on by microgravity. In a mere 12 days in september, during spaceflight STS-115, Salmonella tiphymurium became more virulent. According to the authors, the shape of bacteria did not change but they seem to form a biofilm which is more difficult to eliminate by the immune system. In fact, when these "spacebugs" were fed to mice, they show a 3-times increase in virulence.

Space is definitively a weird place to be...even for bacteria! Astronauts beware...bring your Purell!

For audio of this story follow this link


James W. Wilson, Rajee Ramamurthy, Steffen Porwollik, Michael McClelland, Timothy Hammond, Pat Allen, C. Mark Ott, Duane L. Pierson, and Cheryl A. Nickerson. Microarray analysis identifies Salmonella genes belonging to the low-shear modeled microgravity regulon
PNAS 2002 99: 13807-13812

Wilson et al. Space flight alters bacterial gene expression and virulence and reveals a role for global regulator Hfq.
PNAS doi/10/1073/pnas.0707155104.

NOTE: This blog post is also published on my other blog


cherryblogger71_is said...

It would be great if bone and muscle loss could somehow combat or make up for the new viral strength found by bacteria in space.

Dominic B. said...

Cherryblogger71....hilarious name...where did you think of a name like that? ;-)

A said...
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cherryblogger71_is said...

You actually spouted it in class as a random example. I thought to myself, 'That's great! I'll never think of anything better.' So the first thing I did when I got home was secure that name for myself