RNA epigenetics:
Acids, of course, react with bases. If you were to take some bicarbonate of soda on your tongue and then a sip of vinegar, you would foam merrily at the mouth. Don’t bother; I just did it. It wouldn’t be good for your teeth, so if you are going to need those teeth for much longer, forbear.
There are various kinds of sugar, which you can easily look up – including one called ribose – and there are various nucleic acids; ones containing ribose are ribonucleic acids or RNA. Pluck an oxygen out of the molecule and it’s DNA. Both RNA and DNA contain bases.
DNA pretty much just sits around being managed by other molecules and occasionally getting copied in whole or in part. RNA is more versatile. Traditionally we refer to 3 kinds. There is transfer RNA, tRNA, that copies information from DNA in the nucleus and brings it out to the cytoplasm where it may encounter a ribosome, made of rRNA, along with transfer RNA which picks up a specific amino acid, and the whole conglomeration works together to make a string from amino acids called a poly peptide, which gets folded and combined to form a protein.
Obviously this classical description has a gaping hole. Suppose somebody were to describe how the brain works and described only nerves coming away from the brain, controlling muscles and glands and such like. You would reasonably ask just how the brain manages to decide which muscle to contract. Maybe not; there are amongst us those new age faithful who think of the brain as less of a computer than that of a receiver, but most of us notice that we hear and see and so forth, so we are pretty well convinced signals travel in toward the brain. Well the body must have some way of noticing things like, “Oh, dear. He just ate his way through a chocolate cake. Better fire up the insulin.” Myriad such events happen, particularly during growth and development.
I suppose the best understood mechanism of control is methylation. Methane is one carbon with four attached hydrogens, cooking gas. Pull a hydrogen group off leaving an open bond, make an open bond on your target, stick them together and you have methylated your target, be it chlorine giving you methyl chloride or a polar bear giving you methyl polar bear. Methylation of DNA or its attendant protein and you alter the function of the DNA. Surprisingly to me, though long known, is that methyl groups and such like are known to decorate tRNA. People are now learning (Cassandra Willyard, A New Twist on Epigenetics Nature vol. 542 no. 7642 February 23, 2017 page 406) that these markers can alter the function of the mRNA. They can do such things as have the mRNA clip off a bit of the polypeptide it is making and turn it to some other use.
The selective advantage of this is that it makes it possible to make a new kind of protein at least in part by sticking together bits and pieces already available, and of course whatever can change those markers on the mRNA can affect what the final protein is. But such a system is probably not amenable to the generation to generation variation that is needed for kin recognition, so is unlikely to regulate fertility … I think … but I’m way over my head here.
What has been shown is that bacteria can carry something called N6-methyladenine – a base with a marker – that helps them distinguish between their own DNA and other DNA … hmm … or between kindred and only distantly kin?
There have been 28 visitors over the past month.