A new gene control system:
Infertility from excessive population size develops faster than can be accounted for by the ordinarily understood mutations of DNA. This used to vex me. I was raised in the era when DNA was king. We were taught 1 base pair mutation alters one gene changing one protein causing one disease. This happens, but it is rare.
While DNA was the prince of chemicals, RNA was just a sort of errand boy. RNA transferred information from the DNA in the nucleus to the ribosome, itself made of RNA, where the protein was to be made. Other RNA brought the amino acids to the ribosome to be hooked up into a chain that became a protein. We didn’t worry much about how that protein got folded up into its proper shape. And we didn’t worry much about what turned genes on and off. We didn’t know and since we assumed we knew everything important there was to know – then as now – it couldn’t have been important.
Then some rogue started noticing that there were things that controlled genes. Best studied is methylation, which just means hooking a carbon atom and its attendant hydrogens onto the outside of a DNA double helix. This tends to turn the DNA off. Or, instead of a methyl group, you can put on an ethyl group, which means two carbon atoms and their hydrogens. Then changes in the chromosomes themselves can influence gene expression. The whole field is called epigenetics.
When the first papers about epigenetics came out I ignored them. I had been brainwashed with the DNA story and this only seemed to be a distraction. But eventually I as I learned more about epigenetics I realized that this was something inheritable and fast changing, exactly what I needed to account for the rapid change in fertility that is so obvious everywhere once you begin to look for it.
So I got smug again. Well now it turns out that there is an entirely new way of tweaking genes. (Hiding in Plane Sight, Miriam I. Rosenberg and Claude Desplan SCIENCE vol. 329 no. 5989 July 16 2010 page 284) It’s our old friend RNA again. It turns out that there are tiny bits of RNA that are so small they cannot code for a protein, only for a few amino acids. But they are sufficient to change the expression of genes.
So I am desolate. I am reminded of one of my favorite cartoons out of Punch magazine. The detective and the bobby are standing in what looks like a study or maybe a séance room over the body of an oddly dressed man with a rat like face holding a letter and lying with an exotic dagger in his chest with a bottle of poison beside him while a large spider dangles in one draped corner of the room, and a snake is coiled in another corner, a shadowy figure is passing by the window and there are arcane posters on the walls. The detective is saying, “You know, I don’t think we’re ever going to get to the bottom of this.”
Methylation I thought I could eventually learn to like. But I despair of figuring out this new business. The paper is clear enough on what they are discussing. But I cannot at this point figure out how to hijack the subject to have it account for what I want to discuss.
There have been 4,711 visitors counted to far.