Bacteria More Virulent in Microgravity

Tortured Potato writes "Did you know that salmonella become more virulent in simulated microgravity? No one's sure why, either. Professor Cheryl Nickerson of Tulane University is hoping to find out why when an experiment with brewer's yeast gets sent up on a Russian Progress rocket to the Space Station next year."

Re:Relating to the layperson

[roshi]

I can't help myself....
From m-w.com:

Main Entry: virulent
Pronunciation: -l&nt
Function: adjective
Etymology: Middle English, from Latin virulentus, from viruspoison
Date: 14th century
1 a : marked by a rapid, severe, and malignant course b : able to overcome bodily defensive mechanisms
2 : extremely poisonous or venomous
3 : full of malice : MALIGNANT
4 : objectionably harsh or strong
- virulently adverb

Virulent, as applied to bacteria, refers to its propensity to a) multiply quickly b) infect a host efficiently and c) cause deleterious effects. It has nothing to do with that other "virulentas"-derived word, "virus" beyond sounding the same and sharing an etymological root.

There is no ambiguity or incorrectness in referring to a bacteria (or bacterial disease) as "virulent." It is, in fact, a very specific and technically correct term. (eg, one can and must talk about virulent vs benign strains of E. coli).

All that being said, you are dead right that the mean lay understanding of basic bio is woeful, though I would suggest that perhaps we need a Feynman, not an Asimov, but beggars can't be choosers, right?

Re:Simulated Microgravity?

[Oddly_Drac]

"But if you're going to assay the virulence of microorganisms, it stands to reason that you have to have them in micro-gravity for at least one round of cell division"

You're not wrong, but one method is through electronic suspension of liquids...another is using shearing forces on rotating cylinders.

I'd look for references, but I'm on my way home. ;)

Re:Simulated Microgravity?

[roshi]

I see. Did a bit of digging on my own. So the key point here is preventing the cells from accumulating on the bottom of a vessel and thereby forming unnatural multi-cell structures. You can't erase the acceleration on each individual cell (which is probably negligable anyway) but you can mitigate the collective effects, so the cells are "more micro-gravity like" in their conglomorate behavior.

Still not convinced that cells in a rotating bio-reactor are a good model for cells in an in vivo micro-gravitational environment, but at least "modeled micro-graviity" makes sense now!

Re:Relating to the layperson

[Scrameustache]

The world of biology needs an Asimov in my opinion.

It had one, his name was Isaac Asimov: Phd in microbiology.

Now you know : )

Re:Control in a centrifuge?

[Carnildo]

3 to 3.5 Gs, unless the Russian rockets are a lot harder on their occupants than US rockets are.

Re:Simulated Microgravity? From the article

[G4from128k]

How do you simulate u-G?

You use a rotating test chamber as shown in a figure from the fulltext [asm.org]. By rotating the chamber, gavity never acts in the same direction for very long and nothing settles out of solution. A second rotating chamber is oriented to let gravity work, while duplicating the effects of spin.

Personally, I am skeptical that bacteria really experience gravity. Bacteria are too small -- at that scale most "fluids" are effectively the consistency of molasses in January. I wonder if something as simple as light impacted their experiment. We shall see.....