Creation Moment 5/31/2020 - Clothesline and Pigeon Analogy

I will praise thee; for I am fearfully and wonderfully made:

Psalm 139:14

Clothesline and Pigeon Analogy

"Under-researched mechanism in fast-moving field of epigenetics focus of new study (University of New South Wales, Australia).

The old picture of DNA as the master, directing the synthesis of proteins, is being replaced by a new picturesque analogy:

“Think of DNA as a clothesline, epigenetic chemical marks as pegs, and regulatory proteins – that bind to specific DNA sequences and control which genes turn on or off – as pigeons that want to sit on the clothesline,” Prof Crossley says.
“If the line is covered with pegs, pigeons won’t be able to land. We used mice to look at a key gene in blood and changed it so it either had or did not have a peg, and found this determined whether a gene regulatory protein could bind and turn off the gene. The gene stayed on until the peg was removed.

Q: What are these pegs?
A: They are chemical tags made of methyl groups, acetyl groups and others that attach to DNA.

In addition, the pegs attach to histone proteins within chromatin, the balls of material around which DNA wraps to create its higher-order structure (i.e., above the double helix). Enzymes place these pegs on the ‘clothesline’ to determine what genes become accessible to the transcription machinery or not.

“In a nutshell, our study demonstrates that methylation – the biological process that adds methyl groups like epigenetic chemical marks to DNA – can affect the binding and activity of that protein in gene expression. It had long been suspected this would be the case but having a solid foundation, with one mark and one DNA-binding protein gives you the components with which to build.”

*We begin to see that DNA is covered with portable switches that a process places on genes to regulate them.
This sheds light on how different types of cells in the body express different genes.
--It also illuminates how environmental signals can alter the expression of genes.
--Scientists are finding that some of those altered epigenetic markers are heritable, and can affect future generations.

Q: But what controls the arrangement of these epigenetic switches? --This article doesn’t say.
A: It must be some kind of upstream code that is responsive to outside signals.
Scientists have been considering a “histone code” for years, but

little has been written about what process decides what coded messages (e.g., methyl groups) are to be placed onto the histones or nucleotides.
For those interested in the details, the paper behind the press release is open-access. published in Nature Communications, 22 May 2020, by Lu Yang et al., “Methylation of a CGATA element inhibits binding and regulation by GATA-1.” The authors make it clear that “the mechanisms by which the DNA methylation influences gene expression and differentiation are still not fully understood.”
CEH