[edsheppa]

What is the level of understanding for the divergence between change in genome vs. expression? I dimly recall reading that phosphorylation has something to do with it. Is this thought to be a primary effect? What's the mechanism (if you can briefly describe it is medium-sized words)? How do identical DNA sequences end up differently affected? Or do they?

[Nebullis]

Phosphorylation is a post-translational modification at the protein level. It's actually a primary and ubiquitous method of cellular signalling. A way of a message to get from the cell surface to the nucleus, for example.

There's still an enormous gap in understanding of expression from gene sequence, especially in multicelled organisms. At each major level, starting with transcription through RNA processing, through translation and post-translational processing, there is an amplification of possibilities, cascading of effects, networked feedback loops, and so forth. You can see how this becomes complicated very quickly and how it's difficult to tease out one aspect of it.

Identical sequences end up affected differently in different cell types. The brain expresses different proteins than the liver. We already know about the differences between different cell types. This study shows that there is a species expression difference between same cell type.

All this can't be separated from development. The signals at the unicellular stage start the program of expression patters with morphogenic gradient fields.