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A single mutation of the mitochondrial DNA common in animals could play a role in obesity and other health problems badociated with a high carbohydrate diet.
This is one of the consequences of the research conducted by UNSW scientists who examined the impact of different diets on fruit fly populations. The researchers observed a surprising difference between two groups of Drosophila melanogaster fruit flies when feeding them with alternate diets high in protein and carbohydrate.
Fruit fly larvae with a noted mutation in mitochondrial DNA (mtDNA) showed a marked increase in their development with a diet rich in banana carbohydrates, but stagnant under a protein diet of pbadion fruit enriched with proteins.
In contrast, fruit fly larvae without the tdD mutation thrived on a high protein diet, but their frequency dropped when administered with carbohydrates.
UNSW School of Biotechnology & Biomolecular Sciences, Bill Ballard, professor responsible for the study, said the research was a rare demonstration of positive selection at work in evolution.
"What is unique about this study is that we have identified a mutation in the mitochondrial genome. Having a specific diet is advantageous and leads to an increase in the frequency of flies in a population cage, "he says.
"Then, when you swap the diet for a high-protein diet, flies with the mutation decrease in numbers and other flies without the mutation increase."
Selective advantage
This study, an exhaustive six-year collaboration between authors from Australian, American and Spanish research institutes, challenges the neutral theory of molecular evolution, according to which species-level changes molecular are random and are not caused by natural selection. no advantage or disadvantage for the species.
Sam Towarnicki, Ph.D. student at UNSW, who is also the first author of the paper, explained why this mutation was more than a random and neutral mutation.
"The selective advantage is that the larvae with the mutation fed on a high carbohydrate diet grow up early and become adults before the others with the protein diet. [also with a mutation]," he says.
"And we've seen a difference in development of 10% in one generation between these two groups, which is huge.
"And as we have followed 25 generations, these increases combine with time, resulting in much larger numbers and a huge selective advantage."
Involvement for the human
Given that humans share 75% of the same genes as fruit flies and that they own the same mtDNA genes, it is certainly intriguing that the same mutation inherited from human mtDNA could metabolize carbohydrates in the same way.
Professor Ballard stated that while confirmation of this would be "another NHMRC grant and years of research and testing," the idea deserves to be explored.
According to him, knowledge of a person's "mitotype" could help explain why a diet high in carbohydrates can lead to obesity and diabetes in some, but not others.
"But the news is not all bad for people with the mutation," he says.
"Of course, you will need to manage your carbohydrate intake when you are younger, but if you are unlucky enough to develop Parkinson's disease, a high carbohydrate diet will help you maintain your weight.
"One of the consequences of our study is therefore to open a new field for the development of specific diets and drugs to treat Parkinson's disease."
Know your & # 39; mitotype & # 39;
And far from fighting disease and reducing health problems, this knowledge could help people plan and make life choices.
"The most obvious implication of our work is that people should start managing their diets so that their genotypes match their specific goals. This is the expanding field of 'Nutrigenomics', says Professor Ballard.
It uses the badogy of the different physical demands of a football team: some players need speed, some have to get fat while others may need fat layers.
"Knowing the mitotype of a person will help each person optimize his diet to achieve these goals, but also to choose the type of function for which it is best suited."
"A second example is that our energy goals change over time and that the food we feed for our body should also change. For some, the goal may be to increase fertility, while increasing longevity may be the goal of older people.
"So knowing our mitotype will help us determine the best diet to satisfy life choices."
The document, Genotype to Genotype: Mitochondrial Diet DNA Haplotype Interactions, Inducing Metabolic Flexibility and Fitness, is published today by PLOS Genetics.
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