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Ever bite into a luscious-looking apple only to be rewarded with, ugh, a chunk of mealy pulp? Turns out that other creatures - including B. J. Leiderman, who does our theme music - associate the texture of food with taste, and that includes fruit fly maggots. Science reporter Ari Daniel explains.
ARI DANIEL: The persimmon was Nikita Komarov's favorite fruit when he was growing up in Moscow.
NIKITA KOMAROV: When they are properly ripe, they're delicious and sweet and soft.
DANIEL: Just before that, though, they're wretched. Komarov, who's a neurobiology Ph.D. student at the University of Fribourg in Switzerland, says taste signals take a bit of time to register in the brain.
KOMAROV: Whereas with physical attributes of food, for example, texture, this is an instant form of feedback when we put something in our mouth before we even perceive what we're tasting.
DANIEL: This sense of mouth feel...
KOMAROV: Is it crunchy? Is it soft? Is it chewy? Is it gooey?
DANIEL: ...Gives important information about food safety and quality, helping avoid eating something that might be dangerous. But actually, very little is known about how animals perceive food texture. So Komarov and his colleagues turn to study the phenomenon in a species that's easy to manipulate - fruit flies, specifically the larva.
KOMAROV: It eats constantly. So it really, really, really cares about food.
DANIEL: The question was, which aspects of rotting fruit do these maggots like and dislike? First, Komarov engineered larvae without their taste organ while leaving everything else about them untouched.
KOMAROV: We gave the animals a choice between a harder and a softer substrate.
DANIEL: Normal larvae prefer to eat the softer substrate, the one that most resembles rotting fruit.
KOMAROV: They are very, very picky.
DANIEL: But the larvae without the taste organ ate both offerings.
KOMAROV: They suddenly stopped caring.
DANIEL: The only difference in the food was the texture. So Komarov suspected an intact taste organ also allows a larva to detect that delicious, not too hard, not too soft, rotting fruit texture, kind of like human tongues.
KOMAROV: In the maggot, what was thought to be an exclusively taste organ is actually also a texture organ as well.
DANIEL: Texture, it turns out, is as important a signal to the maggot as how bitter or toxic a food is. Komarov then examined one of the neurons within the taste organ. He found it responds to sugar, acid, salt and texture.
KOMAROV: Seems to be a neuron that sort of does a little bit of everything.
DANIEL: Not all neurons, in other words, respond to just one thing and relay it up to the brain. It's way more complex.
KOMAROV: The maggot perceives the food in this multidimensional space.
DANIEL: The research is published in the journal PLOS Biology.
DEVASENA THIAGARAJAN: The study could help us understand what drives pests to different crops and then how maybe that can be used to manage their influence on agriculture.
DANIEL: By creating texture-based traps, says Devasena Thiagarajan, a neurobiologist at the Max Planck Institute for Chemical Ecology who wasn't involved in the research. She adds that the findings go beyond just fruit flies.
THIAGARAJAN: Our understanding of what fly larvae does is crucial in also, at some point in the future, understanding how more complex organisms execute similar functions.
DANIEL: That's a point Nikita Komarov agrees with. He hopes the work might one day provide insights into eating disorders among people.
KOMAROV: Understanding the function of sensory cells is important in then evaluating how we perceive things and how that perception can go wrong.
DANIEL: And on the flip side, how to tweak the texture of foods - healthy or otherwise - to make them more palatable.
For NPR News, I'm Ari Daniel.
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