Honey Bees Reveal Link Between Sugar Sensitivity And Metabolic Disorders
Scientists studying the genetics of honey bees found they reveal some insights into the link between sugar sensitivity, diabetic physiology and carbohydrate metabolism that may also be relevant to humans.
Lead author Ying Wang, a research scientist, in the School of Life Sciences in the College of Liberal Arts and Sciences at Arizona State University (ASU), and colleagues, write about their findings in a paper published on 28 June in the open access journal PLoS Genetics.
Honey bees offer a useful model for studying what influences food-related behavior, such as the role of taste sensitivity in making choices between foods rich in carbohydrate and food rich in protein (for bees this is choosing between nectar and pollen).
A young bee's sensitivity to sugar predicts what she will forage for later in life, as Wang explained to the press:
"A bee's sensitivity to sugar reveals her attitude towards food, how old the bee is when she starts searching for nectar and pollen, and which kind of food she prefers to collect."
To study the processes that influence this, Wang and colleagues successfully inactivated two genes in the "master regulator" that controls the bees' food-related behavior.
When they did this, they discovered a possible molecular link between sweet taste perception and the state of internal energy.
"By suppressing these two 'master' genes, we discovered that bees can become more sensitive to sweet taste. But interestingly, those bees also had very high blood sugar levels, and low levels of insulin, much like people who have Type 1 diabetes," said Wang.
One of the genes they suppressed is called vitellogenin, which codes for a protein in the bee's fat cells and is similar to a human gene called apolipoprotein B. The other gene is called ultraspiracle, which partners with an insect hormone that has some functions in common with the human thyroid hormone.
The bee lab at ASU is run by the paper's senior author Gro Amdam, an ASU associate professor, who also runs a bee lab at the Norwegian University of Life Sciences.
Amdam said if they can use the bees to understand how taste perception and metabolic syndrome are linked, it could be a very useful tool for research. Metabolic syndrome is a cluster of risk factors that together increase the risk of developing cardiovascular disease and diabetes.
"Most of what we know about deficits in human perceptions is from people who are very sick or have had a brain trauma. We know shockingly little about people in this area," said Amdam.
Amdam explained that taste perception evolved in humans as well as bees, as a survival mechanism to help distinguish between foods that might be poisonous (which tend to be bitter) and foods that might be rich in calories (which tend to be sweet).
In all animals, from insects to humans, a communication goes on between the internal energy state and taste perception that regulates food intake and maintains normal life functions in the body. Without this, poorly functioning taste perception can spur unhealthy eating behaviors and metabolic diseases such as diabetes and obesity.
Amdam said this study has helped them realize they can use honey bees to understand how food-related behavior interacts with internal metabolism. The findings also give them insights into how to manipulate these behaviors in order to control metabolic disorders.
The team is now planning to find out how the absence of the two genes in the master regulator enhances bees' sensitivity to sweetness.
They have a hunch that it could be to do with the "fat body" in bees. This is the most metabolically active tissue in bees, it helps store nutrients and make energy, much like the liver and abdominal fat in humans.