In a study on eukaryotic and bacterial parasites, a duo of researchers at the University of Oxford has detected differences in DNA sequences that could be attributed to the composition of their food.
Trypanosoma cruzi, a parasite of the order Kinetoplastida. Image credit: Myron Schultz / CDC.
“Organisms construct their DNA using building blocks they get from food. Our hypothesis was that the composition of this food could alter an organism’s DNA,” said study co-author Dr. Steven Kelly, from the Department of Plant Sciences at the University of Oxford.
“For example, could a vegetarian panda have predictable genetic differences from a meat-eating polar bear?”
To test this hypothesis, Dr. Kelly and his colleague, Emily Seward, a doctoral candidate in Oxford’s Department of Plant Sciences, picked simple groups of parasites — eukaryotic parasites (Kinetoplastida) and bacterial parasites (Mollicutes) — to use as a model system.
These parasites share a common ancestor but have evolved to infect different plant or animal hosts and eat very different foods.
“We found that different levels of nitrogen in a parasite’s diet contributed to changes in its DNA,” Dr. Kelly said.
“Specifically, parasites with low-nitrogen, high-sugar diets had DNA sequences that used less nitrogen than parasites with nitrogen-rich, high-protein diets.”
The results, based on novel mathematical models developed by the team, reveal a previously hidden relationship between cellular metabolism and evolution.
They provide new insights into how DNA sequences can be influenced by adaptation to different diets.
Furthermore, the authors found it is possible to predict the diets of related organisms by analyzing the DNA sequence of their genes.
“It has been unclear why very closely related organisms can look so different in their genetic makeup,” Seward said.
“By bringing together two fundamental aspects of biology — metabolism and genetics — we have advanced our understanding of this area.”
“It’s a difficult question to answer, because there are so many factors that can influence the DNA sequence of an organism,” she said.
“But our study explains a very high percentage of these differences and provides evidence that we really are what we eat.”
“We are now looking at more complex organisms to see if we will find the same thing.”
The team’s findings were published in the Nov. 15 issue of the journal Genome Biology.
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Emily A. Seward & Steven Kelly. 2016. Dietary nitrogen alters codon bias and genome composition in parasitic microorganisms. Genome Biology 17: 226; doi: 10.1186/s13059-016-1087-9
