Nav: Home

The value of nutrition and exercise, according to a moth

February 22, 2017

Quick! Name the top-performing athletes in the animal kingdom. Cheetah? Try again. Blue whale? Nope.

Here's a clue: If you take a walk in the desert on a moonlit night, you might see them, darting from flower to flower and hovering in midair: moths of the hawkmoth family (Sphingidae).

Nectar-feeding moths, pollinating bats and hummingbirds are masters in sustaining the most intense exercise of all animals. To extract nectar from a flower, they must hover in front of the flower before darting off to the next one. But how can these organisms perform such feats on a diet that's mostly sugar?

New research by University of Arizona biologists not only offers an explanation, but also suggests that these animals stay healthy not despite, but because of, their sugary diet.

Oxygen, while necessary for life to exist, is a double-edged sword. The more we engage in intense aerobic exercise, such as hovering, the more oxygen reveals its ugly side in the form of reactive oxygen species -- small reactive molecules that wreak havoc on cells.

Researchers in the lab of Goggy Davidowitz in the Department of Entomology in the UA's College of Agriculture and Life Sciences discovered that hawkmoths (also known as Manduca moths) have evolved a strategy that helps them minimize the muscle damage inflicted by the oxidative stress generated during sustained flight. The results are published in the journal Science.

'Like Drinking 80 Cans of Soda'

"If you wanted to consume the equivalent amount of sugar that a moth takes up in one meal, you'd have to drink 80 cans of soda," says Eran Levin, who led the research as a postdoctoral fellow in Davidowitz's group. "It's amazing that an animal can process such an amount of sugar in such a short time."

Nectar-feeding moths and hummingbirds don't take up any antioxidants with their diet, which begs the question of how they deal with the oxidative damage their muscles are suffering during the moths' nightly foraging flights.

Two sophisticated pieces of equipment set up to work in tandem made it possible to study in great detail the metabolism of Manduca moths during sustained flight. The team found that the insects actually use the sugar in their diet to make their own antioxidants. They accomplish this by shunting the carbohydrates they consume to a metabolic pathway that evolved early on in the evolution of life: the pentose phosphate pathway.

Humans, too, have this pathway, but it cannot, on its own, produce all the antioxidants needed, which is why athletes drink antioxidant-laced sports drinks and parents tell their children to eat their veggies. Fitting this pattern, migrating birds often are observed eating berries and fruit -- both rich in antioxidants -- during stopovers.

"Manduca is a well-suited model system to study this metabolic pathway, which is the same for bacteria and sequoia trees," Levin explains. "If we understand how the moth is doing it, you can find out how we do it. And we can learn about what goes wrong with our sugar consumption."

'Impossible' Data Lead to Discovery

During the flight experiments, the researchers noticed something strange: The measurements tracking how much oxygen the moths consumed and how much carbon dioxide they produced didn't add up.

"If you burn all the sugar you're eating, you expect the same ratio of carbon dioxide exhaled to oxygen consumed," Levin says. "This is normal when you feed on carbohydrates, but we obtained results that shouldn't have been possible according to the scientific literature."

Reluctant to trust the data their moths were generating, Davidowitz contacted the manufacturer of the flight measurement apparatus. The CEO of the company came out, and after much troubleshooting, tinkering and adjusting, the readings still did not change.

One day, a colleague suggested flying a bumblebee in place of a moth, because bumblebees are known to burn only carbohydrates during flight. Sure enough, the machine spat out the expected values.

"That told us our data were correct," Levin says. "They indicated that 40 percent of the carbon in our moth flight experiments had to come from something other than carbohydrates, so we looked for an explanation, and the only such pathway that would produce those results is the pentose phosphate pathway."

While flying, it turned out the moths were not only burning carbohydrates, but fat as well. As soon as they rested, within seconds, they shunted their metabolism to the pentose phosphate pathway.

In addition to solving the issue of the higher-than-what-theory-allows measurements, the results provided the answer to the mystery of how a nectar-feeding organism avoids killing itself from oxidative stress.

"On our flight apparatus, moths fly about three miles a night on average," Davidowitz says. "We don't know how much they are actually flying in the wild."

When moths burn lipids during intense exercise, they produce more reactive oxygen species that pose further danger to their flight muscles.

"We think the tissue repair occurs when they rest, but we haven't measured that," Davidowitz says.

If You Rest, You Rust

Moths that were frequent and intense flyers were found to have less oxidative cell damage than those that did not, which seemed counterintuitive, Levin says.

"There is this common notion out there where we tend to think that all animals that feed on sugar are very active and fast-living creatures," he says. "But our experiments suggest that this is actually not the case. In fact, there is much more energy to be gained by burning fats, so we suggest these high-performing animals consume a sugar-heavy diet to protect their muscles from damage."

Levin says he thinks the principles observed in Manduca moths apply to all animals, as similar respiratory values have been measured in marsupials, mammals and birds.

"But because they seemed to contradict theory, those measurements usually didn't make it into the paper, or they were ascribed to lipid synthesis," Levin says.

Adds Davidowitz: "We think the ability to shunt glucose through an ancient metabolic pathway has allowed animals that only feed on nectar to embark on long migrations, such as monarch butterflies, hummingbirds and bats."
-end-
The co-authors on the paper are Giancarlo López-Martinez at New Mexico State University in Las Cruces, New Mexico, and Bentley Fane, in the UA School of Plant Sciences and the UA's BIO5 Institute.

University of Arizona

Related Diet Articles:

Diet may help preserve cognitive function
According to a recent analysis of data from two major eye disease studies, adherence to the Mediterranean diet - high in vegetables, whole grains, fish, and olive oil -- correlates with higher cognitive function.
Diet quality of young people in US
This observational study used national survey data from young people up to age 19 to estimate the overall diet quality of children and teens in the United States and to explore how diet quality has changed from 1999 to 2016.
The keto diet can lead to flu-like symptoms during the first few weeks on the diet
A ketogenic diet can lead to several flu-like symptoms within the first few weeks on the diet.
Reconstructing the diet of fossil vertebrates
Paleodietary studies of the fossil record are impeded by a lack of reliable and unequivocal tracers.
Your gums reveal your diet
Sweet soft drinks and lots of sugar increase the risk of both dental cavities and inflammation of the gums -- known as periodontal diseases -- and if this is the case, then healthy eating habits should be prioritized even more.
Poor diet can lead to blindness
An extreme case of 'fussy' or 'picky' eating caused a young patient's blindness, according to a new case report published today [2 Sep 2019] in Annals of Internal Medicine.
New research on diet and supplements during pregnancy and beyond
The foods and nutrients a woman consumes while pregnant have important health implications for her and her baby.
Special issue: Diet and Health
Diet has major effects on human health. In this special issue of Science, 'Diet and Health,' four Reviews explore the connections between what we eat and our well-being, as well as the continuing controversies in this space.
Should you eat a low-gluten diet?
When healthy people eat a low-gluten and fiber-rich diet compared with a high-gluten diet they experience less intestinal discomfort including less bloating which researchers at University of Copenhagen show are due to changes of the composition and function of gut bacteria.
If your diet fails, try again; your heart will thank you
Risk factors for cardiovascular disease closely track with changes in eating patterns, even only after a month or so.
More Diet News and Diet Current Events

Trending Science News

Current Coronavirus (COVID-19) News

Top Science Podcasts

We have hand picked the top science podcasts of 2020.
Now Playing: TED Radio Hour

Listen Again: Reinvention
Change is hard, but it's also an opportunity to discover and reimagine what you thought you knew. From our economy, to music, to even ourselves–this hour TED speakers explore the power of reinvention. Guests include OK Go lead singer Damian Kulash Jr., former college gymnastics coach Valorie Kondos Field, Stockton Mayor Michael Tubbs, and entrepreneur Nick Hanauer.
Now Playing: Science for the People

#562 Superbug to Bedside
By now we're all good and scared about antibiotic resistance, one of the many things coming to get us all. But there's good news, sort of. News antibiotics are coming out! How do they get tested? What does that kind of a trial look like and how does it happen? Host Bethany Brookeshire talks with Matt McCarthy, author of "Superbugs: The Race to Stop an Epidemic", about the ins and outs of testing a new antibiotic in the hospital.
Now Playing: Radiolab

Dispatch 6: Strange Times
Covid has disrupted the most basic routines of our days and nights. But in the middle of a conversation about how to fight the virus, we find a place impervious to the stalled plans and frenetic demands of the outside world. It's a very different kind of front line, where urgent work means moving slow, and time is marked out in tiny pre-planned steps. Then, on a walk through the woods, we consider how the tempo of our lives affects our minds and discover how the beats of biology shape our bodies. This episode was produced with help from Molly Webster and Tracie Hunte. Support Radiolab today at Radiolab.org/donate.