Biological complexity: the source of intracellular motion (Introduction)

by David Turell , Friday, February 02, 2024, 22:20 (84 days ago) @ David Turell

What is delivered on the microtubules:

https://www.newscientist.com/article/2415409-some-animal-cells-contain-tiny-tornadoes-t...

"The cells that make up all living things contain a fluid called the cytoplasm, which moves around in a process called cytoplasmic streaming. Although this internal movement was first observed more than a century ago, the full pattern and purpose of such fluid flows remain only partially understood.

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"The team used simulations to calculate the effect these microtubules and motor proteins might have on the cell’s fluid and vice versa, finding that they could closely reproduce the patterns they found when observing the cells using microscopes.

“'The motor is working on the microtubule: it’s carrying cargo and, as a consequence, it’s stirring the fluid,” says Shvartsman. “Now the fluid can influence the buckling of the microtubules, and all of these together can lead to self-organisation of a flow that spans the cell. This is absolutely remarkable.”

"To properly grow and divide, oocytes need to have a stage where they distribute and mix different cellular ingredients together before fixing certain elements in place. These twisters seem to be an essential part of this early mixing stage, says Shvartsman, and they could occur in other animal egg cells that are sufficiently large.

"Human egg cells are about a fifth as large as fruit fly egg cells and are probably too small for this effect to take place, but many insects, fish and amphibians have larger egg cells where these flows may be important, he says.

“'It’s super interesting from the perspective of how life works,” says Robert Cross at the University of Warwick, UK. “The interesting thing is how little, nanoscale autonomous walking machines which are doing this [cargo] transport generate these very large-scale, organised structures inside the cell. That’s the mind-boggling thing.” However, it’s important to note that the rotations are happening much more slowly than a real tornado, he says."

Comment: the cute talk about tornados is beside the point. All animals are mostly water. That means each person is 90% water.