Reasons to Believe

New Research Suggests Two Overlooked Functions of Junk DNA

Life scientists continue to identify new functions for so-called junk DNA. Recently, a researcher from the US Centers for Disease Control and Prevention pointed out two overlooked “junk DNA” functions: (1) serving as a nucleoskeleton that establishes the volume of the cell’s nucleus; and (2) acting as a mutational buffer that protects the genome from mutations resulting from transposon and retroviral DNA insertion activity. Such results help undermine the argument that junk DNA must be leftovers of evolutionary processes, not the creation of an intentional Designer.

If you cannot be open-minded, then you do not possess your ideas, your ideas possess you.

Bryant McGill

DNA is a remarkable molecule—its double helix design displays a certain beauty and, in biochemical terms, its structure and function are no less pleasing to behold. As I discuss in my book The Cell’s Design, DNA is structurally optimized to carry out its chief function: storage of information used by the cell’s machinery to generate life’s building blocks and direct the cell’s operation. (For an example of the optimized structure-function relationships found in DNA, see “DNA Soaks Up Sun’s Rays.”)

Yet there is more to DNA’s purpose than information storage. Recently, biologist Claudiu Bandea of the US Centers for Disease Control and Prevention argued that DNA sequences assume noninformational roles that biologists have often overlooked.1 These noninformational functions help account for the existence of abundant junk DNA in the genomes of humans and other organisms.

Nucleoskeletal Support

First, Bandea shows that DNA plays a skeletal role by helping to establish and maintain the size of the cell’s nucleus. This function is called the nucleoskeletal hypothesis. According to this idea, the amount of DNA in a cell dictates the nuclear volume. The size of the nucleus is not arbitrary, however, but must be maintained within tight limits. The cell will die if the ratio of the nuclear volume relative to overall cell volume deviates too much. Presumably, the nucleoskeletal role of DNA can account for the vast amount of junk DNA within genomes and helps explain the C-value paradox. Larger cells require a larger nucleus and, consequently, a greater amount of junk DNA in their genomes to maintain an adequate nuclear volume. (For more, see “TNRTB Classic: Junk DNA and the Nucleoskeletal Hypothesis.”)

Mutation Shield

Bandea also asserts that junk DNA may serve as a mutational buffer. He notes that the human genome (and the genomes of other organisms) consists of a significant fraction of mobile DNA pieces called transposons. These pieces of DNA move around the genome and, presumably, insert at random into different locations. (Some transposons also possess the capacity to duplicate in the process.) If insertions occur in coding or regulatory regions of the genome, mutations result.

Retroviruses pose a similar problem. When viruses invade a cell, retroviral DNA inserts into the host’s genome. Again, these insertion events can be disruptive if they occur within functional sequences.

But Bandea posits that high levels of junk DNA can make genomes more resistant to the deleterious effects of insertion events. If insertion events are random, then the offending DNA is much more likely to insert itself into “junk DNA” regions instead of coding and regulatory sequences—thus, protecting information-harboring regions of the genome. To say it another way, junk DNA sequences could serve as buffers against mutations that arise from transposon and retroviral DNA insertion events.

Solving the C-Value Paradox

If junk DNA functions as a mutational buffer, then it could also help account for the C-value paradox (which observes “that genome size does not correlate with organismal complexity”).2 It could be that the varying genome sizes are not arbitrary, but instead correlate with the amount of protective DNA. Genomes with higher transposon activity could require a greater buffering capacity and, consequently, more junk DNA.

When it comes to understanding genomes (human or otherwise), the evolutionary paradigm has continuously restricted the view of many people in the scientific community by compelling them to classify, noncoding DNA as the leftover vestiges of evolution. But, as Bandea’s research shows, a narrow focus on DNA’s informational role has interfered with the acknowledgment of junk DNA’s important noninformational functions. Such discoveries help open up the possibility for nonevolutionary interpretations of genome content, including the notion that these tiny pieces of DNA stem from an intelligent Mind.

Subjects: Biochemical Design

Dr. Fazale Rana

In 1999, I left my position in R&D at a Fortune 500 company to join Reasons to Believe because I felt the most important thing I could do as a scientist is to communicate to skeptics and believers alike the powerful scientific evidence—evidence that is being uncovered day after day—for God’s existence and the reliability of Scripture. Read more about Dr. Fazale Rana

References

  1. Claudiu I. Bandea, “On the Concept of Biological Function, Junk DNA and the Gospels of ENCODE and Graur et al.,” bioRxiv, published electronically November 18, 2013,  doi: 10.1101/000588.
  2. “C-value enigma,” Wikipedia, last modified June 30, 2013, http://en.wikipedia.org/wiki/C_value_paradox