A team of researchers has found that diet can impact the composition of an organism’s genome. The team studied groups of parasites and noticed that variations in the concentration of dietary nitrogen had effects on their DNA. The details are in a paper that was just published in the journal Genome Biology.
Genes consist of DNA building blocks called nucleotides. There are four nucleotides that make up a DNA strand; adenine, thymine, guanine, and cytosine. These compounds are partially composed of nitrogen and when DNA is replicated, a source of nitrogen is required to construct new nucleotides. Animals can get nitrogen from their diet. Different species consume completely different diets with varying levels of nitrogen, however. Researchers weren’t sure if these dietary differences could impact the genome. Many other factors have effects on DNA, including ultraviolet light and chemical pollution. This led a team of scientists to design an experiment to study the effects of diet on the genome.
Researchers from the University of Oxford studied simple parasites that consume different levels of nitrogen. The team chose organisms that had simple genomes and were easy to study: Kinetoplastida protists and bacterial parasites called Mollicutes. Although the species eat very different diets, they evolved from a common ancestor and have some genomic similarities. The researchers analyzed their genomes to determine whether or not diet played a role in their genetic makeup.
The team found that the parasites with low nitrogen diets used nucleotides that required less nitrogen during construction. Parasites with high nitrogen diets used nucleotides containing more nitrogen atoms, even when they were encoding the same gene. This shows that metabolism can play a role in genome evolution; animals that consume less nitrogen evolve to use nucleotides that don’t require as many nitrogen atoms.
The findings suggest that an organism’s diet can change how their genome evolves. Organisms that lack dietary nitrogen may evolve to require less of the chemical to construct nucleotides. The study provides new insights into how metabolism may affect DNA.
Emily A. Seward, Steven Kelly. Dietary nitrogen alters codon bias and genome composition in parasitic microorganisms. Genome Biology (2016).