06.28
"Junk DNA" Courtesy Crystal Links.com 2009
By Amy Price PhD
Not so many years ago we were told as students that a very small part of the genome coded for genes and the rest was ‘Junk DNA”. The questions why? followed by what if come quickly when I am faced with such literal statements. The answer they are junk because no one knows what they do brought cause for alarm in my view because I don’t know what a good portion of the human race does yet I would not relegate them to junk. I countered with I want to know what happened when you took them all out…turns out that was not doable and I was relegated to the divergent thinker category and lectured on the KISS (Keep It Simple Stupid) principle.
I later found a few people such as McClintock who saw this DNA may have value in the 1940s and worked tirelessly to explore the DNA as a regulatory source for determining which genes are turned on and when they were activated (McClintock, 1965) Around the same time Britten and Davidson agreed and further speculated the junk DNA plays a role in generating different cell types and different biological structures, depending on where in the genome they insert themselves (Britten & Davidson, 1969).
Recently, scientists from Princeton and Indiana Universities studied the genome of a pond organism and found that junk DNA or transposons may perform functions that are central to the existence of an organism. Apparently these genes jump from location to location rearranging the genome in a way that initiates growth just as McClintock thought.
These genes are labelled transposons. In and during development, the transposons appear to first influence hundreds of thousands of DNA pieces to regroup. Then, when they are no longer needed the organism can erase the transposases from its genetic material, paring its genome to about 5 percent of its original load.
“The transposons actually perform a central role for the cell,” said Laura Landweber, a professor of ecology and evolutionary biologyat Princeton and an author of the study. “They stitch together the genes in working form.” This research appeared in the May 15 edition of Science. (MacPherson, Princeton, 2009)
We are just now finding the science that existed in the mind of a researcher over sixty years ago and can watch revelation unravel as science begins to explore how extensive the role of junk or as sometimes coined selfish DNA plays in the circle of life….Sometimes just as in life it is those quietly working without accolades that are holding it all together who are the real stars!
Britten, R. J., & Davidson, E. H. Gene regulation for higher cells: A theory. Science 165, 349–357 (1969)
McClintock, B. Components of action of the regulators Spm and Ac. Carnegie Institution of Washington Year Book 64, 527–536 (1965)
MacPherson ,2009 http://www.princeton.edu/main/news/archive/S24/28/32C04/ accessed june 27, 2009)
