Germs Taken Into Space May Come Back Deadlier

westlake writes "Sounds like the plot for a B-movie, doesn't it? Germs go into space and come back stronger and deadlier than ever. Except, it really happened. In a medical experiment, salmonella carried about the space shuttle in the fall of 2006 proved far more lethal to lab mice than their earth-bound source. 90% dead vs. 60% dead in twenty-six days, with half the mice dying at 1/3 the oral dose. Apparently 167 genes in the space-evolved strain had changed. The likely cause: In microgravity the force of fluids passing over the cells is low, similar to conditions in the gastrointestinal tract, and the cells adapted quickly to the new environment."

Comments

conditions outside the body

[mrvan]

TFS states that the deadliness is bacause the germs were adapter better to the conditions inside the body, so kill lab mice faster. Outside the lab, these germs will have to pass from host to host, and presumable in between the hosts conditions will be less like microgravity. SO, they might be deadlier, but with less rate of infection. A deadlier disease with lower infection rate might actually be less of a risk: hosts die more quickly and not enough new hosts get infected.

Also: if the new germs are really more well-adapted (ic better at multiplying and spreading), wouldn't they have evolved like that on earth? Especially since the evolutionary step is apparently small enough to be attained by a limited colony in a very limited time?

Re:conditions outside the body

[s_p_oneil]

"Also: if the new germs are really more well-adapted (ic better at multiplying and spreading), wouldn't they have evolved like that on earth? Especially since the evolutionary step is apparently small enough to be attained by a limited colony in a very limited time?"

Not necessarily. Evolution is like a simple hill-climbing algorithm in computer programming. It blindly heads in any upward direction without any way of knowing if it will get stuck at the top of a small hill when there is a much bigger hill right next to it. It is unnatural for it to go back downhill (to weaken itself) on purpose to look for bigger hills to climb. But changes to the environment distort the landscape, in some cases turning hills into valleys and forcing life to climb back up or die out.

So most likely the germs had their little hill turned upside down in micro-gravity and were forced to climb up to the top of a new one. Their landscape got turned upside down again when they came back down to Earth, and they ended up finding a bigger hill than the one they started on.