Genome complexity: stem cell controls (Introduction)

by David Turell , Saturday, October 31, 2015, 12:47 (3093 days ago) @ David Turell

Stem cells are the source of all cells. They can differentiate into any type of cell or simply reproduce themselves. They are the cells that make the embryo, but also are crucial for repair and maintenance during life. Gene control is shown here:- http://phys.org/news/2015-10-prkci-gene-stem-cells.html-"In a paper published in Stem Cell Reports, USC researcher In Kyoung Mah from the lab of Francesca Mariani and colleagues at the University of California, San Diego, (UCSD) describe a key gene in maintaining this critical balance between producing too many and too few stem cells. Called Prkci, the gene influences whether stem cells self-renew to produce more stem cells, or differentiate into more specialized cell types, such as blood or nerves.-"In their experiments, the team grew mouse embryonic stem cells, which lacked Prkci, into embryo-like structures in the laboratory. Without Prkci, the stem cells favored self-renewal, generating large numbers of stem cells and, subsequently, an abundance of secondary structures.-"Upon closer inspection, the stem cells lacking Prkci had many activated genes typical of stem cells, and some activated genes typical of neural, cardiac and blood-forming cells. Therefore, the loss of Prkci can also encourage stem cells to differentiate into the progenitor cells that form neurons, heart muscle and blood.-"Prkci achieves these effects by activating or deactivating a well-known group of interacting genes that are part of the "Notch signaling pathway." In the absence of Prkci, the Notch pathway produces a protein that signals to stem cells to make more stem cells. In the presence of Prkci, the Notch pathway remains silent, and stem cells differentiate into specific cell types."-Comment: Another example of the layers of control that must be present to manage the mechanisms of life. How can this be developed in new species, such as those in the Cambrian, without planning? The key to analysis is the fact that prior animals were very simplistic and lacked the organs of the Cambrian denizens. How do you get from stem cells in the pre-Cambrian producing two-three cell types to stem cells that produce 200 cell types? Oh, I forgot, committees of intelligent cells in the pre-Cambrian.