You know the expression, ‘You are what you eat’? It’s not just an expression: what we eat can actually change how our DNA functions.
That’s what Professor Ryszard Maleszka from The Australian National University has discovered, with some help from his on-campus colony of bees.
Professor Maleszka and his team have shown that the gene expression of the honey bee changes depending on what they eat.
All larvae in a bee colony start out with the same DNA code. But if a larva eats honey, they develop into a sterile, short lived worker bee. Whereas if they eat large quantities of an amazing food fittingly called royal jelly, they actually become a fertile, long-lived queen.
When it comes to metabolism, humans and bees have a similar biochemistry, so does this mean the meal you eat at lunchtime could turn you into royalty? No, but it does show that the type and quantity of food you eat will affect your physiology.
Research on changing dietary habits in human populations has developed scientists' understanding of how nutrition contributes to our health and disease. However, it’s only recently that scientists have begun unravelling how genomes interplay with diet, and what that means for many health disorders.
“So many people thought the genome was like a filing cabinet,” Professor Maleszka explains. “You open it up and all the information is sitting there waiting for us.
“It turns out it’s much more complicated because an animal’s DNA code is used in a complex manner that is highly dependent on environmental cues.”
This genome-environment interface and its impact on an organism’s biology is the focus of a field of study called epigenetics.
Professor Maleszka explains that epigenetics is “concerned with changes in organisms caused by modification of gene expression, rather than alteration of the genetic code itself.”
In the case of honey bees, “the queen-worker developmental divide is a striking example of how a diet can generate two different organisms from the same genetic blueprint, thanks to epigenetic mechanisms.”
The signals from the royal jelly affect DNA methylation, a chemical modification that has the capacity to alter the expression of some of the genes and not others without changing the underlying genetic sequence. That’s how queens end up looking and behaving completely differently to worker bees.
To prove that the DNA methylation is involved in redirecting the honey bee’s developmental trajectory towards queen phenotype, Professor Maleszka used a technology called RNA interference to silence a gene that adds a methyl group to DNA.
“When we applied this technology to disrupt DNA methylation in growing bee larvae, we saw that the majority of treated larvae developed into queens, in contrast to control larvae that developed into workers.”
This elegant experiment proved that interfering with the expression of a gene responsible for DNA methylation mimics the effect of royal jelly on queen development.
This research highlights that environmental factors like diet, climate and stress could have more of an effect on human development that has been thought previously
“Although the honey bee is not to be misjudged as a model for a specific human disease, its unique biology offers unmatched experimental power to investigate changes in epigenomic settings,” Professor Maleszka says.
It seems we’ll be hearing a lot more buzz from the humble bee.
Image courtesy of Brian on flickr.