Biological complexity: before splitting cells dump garbage (Introduction)

by David Turell , Thursday, May 12, 2022, 16:20 (926 days ago) @ David Turell

Just cleaning house:

https://www.sciencedaily.com/releases/2022/05/220510122446.htm

"'Our hypothesis is that cells might be throwing out things that are building up, toxic components or just things that don't function properly that you don't want to have there. It could allow the newborn cells to be born with more functional contents," says Teemu Miettinen, an MIT research scientist and the lead author of the new study.

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"In cells undergoing mitosis, the researchers used their new technique to study what happens to cell mass and composition during that process. In a 2019 paper, Miettinen and Manalis found that buoyant mass increases slightly as mitosis begins. However, other studies that used quantitative phase microscopy suggested that cells might retain or lose dry mass early in cell division.

"In the new study, the MIT team measured three types of cancer cells, which are easier to study because they divide more frequently than healthy cells. To their surprise, the researchers found that the dry mass of cells actually decreases when they enter the cell division cycle. This mass is regained later on, before division is complete.

"Further experiments revealed that as cells enter mitosis, they ramp up activity of a process called lysosomal exocytosis. Lysosomes are cell organelles that break down or recycle cellular waste products, and exocytosis is the process they use to jettison any molecules that aren't needed any more.

"The researchers also found that the density of the dry mass increases as the cells lose dry mass, leading them to believe that the cells are losing low-density molecules such as lipids or lipoproteins. They hypothesize that cells use this process to clear out toxic molecules before dividing. "What we are seeing is that cells might be trying to throw out damaged components before dividing," Miettinen says.

"The researchers speculate that their findings may help explain why neurons, which do not divide, are more likely to accumulate toxic proteins such as Tau or amyloid beta, which are linked to the development of Alzheimer's disease."

Comment: the result shows obvious purpose. Newly formed daughter cells have a fresh start. The comment about neurons not dividing suggests to me an unknown mechanism may clean neurons. The designing mind would not leave that as an unsolved problem