Roland98

That's what I was talking about above, and they mention that in the BBC article. If we found them existing on earth, obviously that would lend more weight to the idea of that kind of life on Mars. But I don't think anything's been conclusively demonstrated yet.

Roland98

I'd guess that they would have measured the OD after filtration, let it sit, and then measure it again after a day, or a week or whatever. So the blank should be medium that's been filtered in the same manner, but lacking any of the original sample.

Doubting Didymus

Does anyone know what the'yre actually made of? Surely there's a way of measuring the amount of, say, carbon?

Roland98

Don't know. There was an article on nanobacteria a few months ago in (I think) ASM news. Of course, I can't remember my damn password right now to log in and the "remind me" prompt isn't working. I'll try to find it tomorrow.

Jet Black

the BBC article mentions false positives, do you know much about the DNA stain and what else could give a DNA like result? I suppose testing for something we know to be a false positive would eliminate certain possibilities. If not, I will have a look at my cellular biology book later, it's probably in there somewhere.

Wounded King

This all seems highly speculative at the moment. If there are nucleic acids of any sort in the 'nanobacteria' then they should really be isolatable. The fact that they can aulture these 'nanobacteria' but not derive any nucleic acid extracts suggests that there isn't any RNA or DNA there. A 2000 paper in PNAS, here gives a rather more skeptical analysis and shows that the mineralising ability reported in 'nanobacteria' can be shown by non-living macromolecules..

TTFN,

WK

Roland98

I'm not sure about the stain, but certainly all tests can give false positives. So even if it stained positive for something we know didn't contain DNA, it wouldn't really tell us anything.

Roland98

Suggests it certainly, but can't 100% rule it out. For whatever reason, the protocol they're using to lyse the cells may not be working. I work with Streptococci, and we know quite a bit about the composition of their cell wall, and even with that knowledge the little buggers sometimes just don't want to lyse.

Yep. Which is one reason the Mars microbes have been treated with so much skepticism. But if it could be shown that these really are a new type of life form and can produce those as well, it would recharge the debate.

Peez

Very interesting, but the reports do seem a little overzealous.On what basis are they being described as "cell-like?"Which suggests that, if alive, they could be structurally more similar to viruses than cells. Note that the phospholipid bilayer of cells is typically about 5 nm thick, so a 30 nm spherical cell would loose 70% of its volume to the phospholipid bilayer, leaving a 20 nm sphere for contents. What could we fit into such a sphere? Here are a few approximate sizes from a quick scan:

water molecule: 0.3 nm
glucose molecule: 1.5 nm
diameter of DNA helix: 2 nm
length of DNA coding for a single very simple protein (50 amino acids): at least 52 nm
protein molecule (insulin): 5 nm
smallest known bacteria: 200 nm
smallest known virus (nothing more than a protein box containing minimal genes): 20 nm

Peez

wonkothesane

What the heck are nanobacteria? Lifeforms or just odd looking mineral formations? What's the latest opinion?

Just wondering...