Letter writer's claims about DNA inaccurate
I am currently a Ph.D. student at Vanderbilt University in the Department of Pathology Microbiology and Immunology. Every once in awhile, I like to check out my hometown newspaper to see how the good old sunny Yuma is doing. I was distraught when I read a recent letter to the editor by Stan Lenihan titled “Nothing new in DNA information.”
At my institution, I have attended lectures by world-renowned faculty specialized in the field of structural DNA and mRNA biology. However, the information described by Lenihan is something that a student with basic knowledge of DNA to mRNA transcription and mRNA to protein translation can tell you is incorrect.
I think Lenihan is getting his terms confused. The mRNA (messenger RNA) and the microRNAs are two completely different concepts. DNA is transcribed to mRNA, which is then translated to protein. MicroRNAs are small mRNAs (average of 22 base pairs) with regulatory capacities.
MicroRNAs are actually being studied because of their contribution to cancer, development defects, certain immunoregulatory disorders, etc. The “junk DNA,” which is a scientifically archaic term and more accurately should be described as non-coding DNA, are DNA sequences (introns) which are excised prior to mRNA translation and are absent in protein.
Initial and rudimentary screening of total DNA suggested that these sequences served no purpose. However, further research has shown that they can encode regulatory sequences, parts of introns, telomeres, scaffold regions and also microRNAs.
A perfect analogy would be to think of a PowerPoint slide where the coding DNA would the letters and the message being displayed, the non-coding DNA or junk DNA would be the background color, slide size and even the light of the projector delivering the message. All of these things are part of the non-coding DNA.
Nothing else in Lenihan's letter is scientifically accurate. Muscles do not get bigger because stronger proteins get incorporated into your muscles. Muscle growth — scientifically referred to as sarcomere hypertrophy and sacroplasmic hypertrophy — is the enlargement of intracellular proteins that control the ability of muscles to contract (actin and myosin). These intracellular proteins become larger and better capable of sustaining more weight as muscles are placed under intensity training exercise.
I would also like to address the third portion of Lenihan's letter where he tried to draw a parallel between equality of races and DNA content. I am deeply ashamed that my hometown newspaper would publish such nonsense. This kind of discussion has no room in scientific discourse.
The study that editor Terry Ross wrote about in his column titled “New discovery about DNA flips view on life” is an accurate description of recent results in the field of non-coding DNA biology.
A collaboration project between a large number of laboratories and academic institutions yielding six high-impact publications suggesting non-coding DNA is very active and changes in these small non-coding DNA can have great impact in human health.
This can in turn lead us to develop drugs that are not necessarily targeting the end products of DNA (the letters in the PowerPoint slide), but the non-coding DNA regions (the background color and projector).
Roman Covarrubias
Nashville, Tenn.
