Why Are Cells the Size They Are? Gravity May Be a Factor

carmendrahl writes "Eukaryotic cells, which are defined by having a nucleus, rarely grow larger than 10 micrometers in diameter. Scientists know a few reasons why this is so. A new study suggests another reason — gravity. Studying egg cells from the frog Xenopus laevis, which reach as big as 1 mm across and are common research tools, Princeton researchers Marina Feric and Clifford Brangwynne noticed that the insides of the eggs' nuclei settled to the bottom when they disabled a mesh made from the cytoskeleton protein actin. They think the frog eggs evolved the mesh to counteract gravity, which according to their calculations becomes significant if cells get bigger than 10 micrometers in diameter."

Comments

Re:Think of the children!

[TheLink]

at a certain size the station would pull itself apart unless it was made of some sort of super strong exotic metal.

Attach space station to counterweight with a bunch of long tethers.
Spin to taste.
We've got cables holding up rather heavy stuff down on Earth.
No need to spin at high speeds, no need for big space stations.

Surface area

[king neckbeard]

I was under the impression that surface area played a significant role in this as well, which probably couldn't be easily discounted. The surface area of a sphere is 4 pi times the radius squared while the volume is 4/3 pi times the radius cubed. So, the greater the radius, the greater the ratio of volume to surface area. This usually doesn't scale well, as it means there is more mass to support and less means of getting the input and output needed to support it. I'm not saying that gravity doesn't contribute as well, but that's a fairly difficult barrier as well.