Silent DNA, the sleeper in our midst

The discoveries in genetic science are coming thick and fast. The protective coding of genes is being revealed as an ingenious set of interlocking codes that determine what is copied, what is activated and what is switched off at any time. In the article below, our genetic material is compared to a cookbook, a repository of recipes for particular biological and behavioural patterns. This explains why when geneticists look at our DNA, they see so many silent DNA represented, which up until recently they've considered to be junk, like all the other genetic material they couldn't decode.


Thinking about our genes like a recipe book is useful, because it allows us to understand that a particular biological process requires certain ingredients and a certain process to be expressed. A different combination of those same resources will lead to a different result, rather like the difference between using flower to make pancakes or scones.

For behavioural patterns the environment plays a big part. Recent research out of Kings College in London, cited previously in this blog, has revealed that behavioural responses to stress, like anxiety, require certain gene sequences within the DNA to be latent, but not necessarily switched on. Exposure to specific stimuli from the environment, like bullying, then activates the latent gene. This combination then produces the anxiety response, which feeds back to the gene and keeps it switched on.


I read some interesting research recently which talked about how patient the HIV virus is. When a subject is infected with the HIV virus, the virus inserts itself into the host's cells and then patiently and diligently attempts to break the protective codes of the cell's DNA, until it literally splices itself into the gene and is then able to infect many systems and impair the immune system. It literally hijacks the cell. 

This hijacking may take ten years or more to achieve, which explains why HIV takes so long to manifest as AIDS. The HIV virus can also make itself invisible, so that it is not attacked while its cracking the code. Researchers compared the HIV virus to a software program, whose specialty is code cracking.


This makes me wonder what else within us is silent, waiting to be activated by specific environmental influences. US quantum biologists are postulating that photon storms, predicted to start bombarding the earth again from 2012, coincide with all the major evolutionary leaps on the planet - literally waking up silent genes and mutating others.


These are indeed interesting times. Enjoy the latest article on the subject of genetics from Science Daily...

Mystery Solved: How Genes Are Selectively Silenced

ScienceDaily (Oct. 18, 2010) — Our genetic material is often compared to a book. However, it is not so much like a novel to be read in one piece, but rather like a cookbook. The cell reads only those recipes which are to be cooked at the moment. The recipes are the genes; 'reading' in the book of the cell means creating RNA copies of individual genes, which will then be translated into proteins.

The cell uses highly complex, sophisticated regulatory mechanisms to make sure that not all genes are read at the same time. Particular gene switches need to be activated and, in addition, there are particular chemical labels in the DNA determining which genes are transcribed into RNA and which others will be inaccessible, i.e. where the book literally remains closed. The biological term for this is epigenetic gene regulation.

"One of the great mysteries of modern molecular biology is: How do methyltransferases know where to attach their labels in order to selectively inactivate an individual gene?" says Professor Ingrid Grummt of the German Cancer Research Center (DKFZ).

Grummt has now come much closer towards unraveling this mystery. She has focused on studying those text passages in the genetic material which do not contain any recipes. Nevertheless, these texts are transcribed into RNA molecules in a controlled manner. "These so-called noncoding RNAs do not contain recipes for proteins. They are important regulators in the cell which we are just beginning to understand," says Ingrid Grummt.

In her most recent work, Grummt and her co-workers have shown for the first time that epigenetic regulation and regulation by noncoding RNAs interact. The scientists artificially introduced a noncoding RNA molecule called pRNA into cells. As a result, methyl labels are attached to a particular gene switch so that the genes behind it are not read. The trick is that pRNA exactly matches (is complementary to) the DNA sequence of this gene switch. The investigators found out that pRNA forms a kind of plait, or triple helix, with the two DNA strands in the area of this gene switch. Methyltransferases, in turn, are able to specifically dock to this 'plait' and are thus directed exactly to the place where a gene is to be blocked.

More than half of our genetic material is transcribed into noncoding RNA. This prompts Ingrid Grummt to speculate: "It is very well possible that there are exactly matching noncoding RNA molecules for all genes that are temporarily silenced. This would explain how such a large number of genes can be selectively turned on and off."