Re: im not grasping this paper

[Guest guest]

On Thu, Jun 08, 2006 at 09:29:16PM -0000, wrote:

>This thing says that after 7 days of starvation, viable cell counts of

>Vibrio did not decline, but 99.8% of the lipids were gone. How can any

>intact membranes be left? I dont get how anyone could consider this to

>be possible?

>

>http://www.pubmedcentral.gov/picrender.fcgi?artid=239115 & blobtype=pdf

Hmm. Fat humans have been known to lose most of their lipids on a

starvation diet. Maybe the same thing happens to microbes?

They give absolute numbers, so one can do the math. Those poor starved

cholera microbes had 2.05 nanomoles of phospholipids per 10^4 cells,

after thirty days without food. That's 2.05 x 10^-13 moles per cell,

which multiplied by Avogadro's number is 12 x 10^10 molecules per cell.

The cell size is about 0.25 microns, and it's about spherical, so the

cell surface area is about 0.2 square microns, or 2 x 10^5 nm^2.

Google finds me a number for the area per lipid molecule: 0.6 nm^2,

which would mean that the cell needs (2 x 10^5 / 0.6 = 3.3 x 10^5)

molecules to put a single layer around itself. Maybe double that for

a bilayer, and it still has almost all of its 12 x 10^10 molecules

left, for use in internal membranes, or energy storage, or whatever.

--

Norman Yarvin http://yarchive.net

[Guest guest]

Geez...that's just not fair. Especially because I've been thinking drastic measures like going on a starvation diet, ingesting nothing but antimicrobials and salty fluids and see if I can get so near skelton-like that the bugs will no longer consider me a suitable host. But it sounds like they can get way skinnier than I can and still be fine. :-( I know it sounds ridiculous, but I've tried everything else. :-) pennyNorman Yarvin <norman.yarvin@...> wrote: On Thu, Jun 08, 2006 at 09:29:16PM

-0000, wrote:>This thing says that after 7 days of starvation, viable cell counts of >Vibrio did not decline, but 99.8% of the lipids were gone. How can any >intact membranes be left? I dont get how anyone could consider this to >be possible? >>http://www.pubmedcentral.gov/picrender.fcgi?artid=239115 & blobtype=pdfHmm. Fat humans have been known to lose most of their lipids on astarvation diet. Maybe the same thing happens to microbes?They give absolute numbers, so one can do the math. Those poor starvedcholera microbes had 2.05 nanomoles of phospholipids per 10^4 cells,after thirty days without food. That's 2.05 x 10^-13 moles per cell,which multiplied by Avogadro's number is 12 x 10^10 molecules per cell.The cell size is about 0.25 microns, and it's about

spherical, so thecell surface area is about 0.2 square microns, or 2 x 10^5 nm^2.Google finds me a number for the area per lipid molecule: 0.6 nm^2,which would mean that the cell needs (2 x 10^5 / 0.6 = 3.3 x 10^5)molecules to put a single layer around itself. Maybe double that fora bilayer, and it still has almost all of its 12 x 10^10 moleculesleft, for use in internal membranes, or energy storage, or whatever.-- Norman Yarvin http://yarchive.net

[Guest guest]

22,000,000 lipid molecules in E coli, says the outdated ed 1 of " E

coli and S typhimurium " (1987 if I recall).

Since both Escherichia and Vibrio have 2 bilayer membranes (4

monlayers), this tallies pretty well with Normans calculation from

the membrane area of a phospholipid. But not with what the paper says.

I think that paper is nuts.

> >This thing says that after 7 days of starvation, viable cell

counts of

> >Vibrio did not decline, but 99.8% of the lipids were gone. How can

any

> >intact membranes be left? I dont get how anyone could consider

this to

> >be possible?

> >

> >http://www.pubmedcentral.gov/picrender.fcgi?

artid=239115 & blobtype=pdf

>

> Hmm. Fat humans have been known to lose most of their lipids on a

> starvation diet. Maybe the same thing happens to microbes?

>

> They give absolute numbers, so one can do the math. Those poor

starved

> cholera microbes had 2.05 nanomoles of phospholipids per 10^4 cells,

> after thirty days without food. That's 2.05 x 10^-13 moles per

cell,

> which multiplied by Avogadro's number is 12 x 10^10 molecules per

cell.

>

> The cell size is about 0.25 microns, and it's about spherical, so

the

> cell surface area is about 0.2 square microns, or 2 x 10^5 nm^2.

>

> Google finds me a number for the area per lipid molecule: 0.6 nm^2,

> which would mean that the cell needs (2 x 10^5 / 0.6 = 3.3 x 10^5)

> molecules to put a single layer around itself. Maybe double that

for

> a bilayer, and it still has almost all of its 12 x 10^10 molecules

> left, for use in internal membranes, or energy storage, or whatever.

>

>

>

> --

> Norman Yarvin

http://yarchive.net

>