UC San Francisco scientists have discovered how fruit bats can consume large amounts of sugary fruit without adverse health effects, offering insights for diabetes research. Their study reveals that fruit bats have evolved specific physiological adaptations in their pancreas and kidneys, enabling efficient sugar processing and electrolyte retention. This research could provide valuable knowledge for developing new treatments for the millions of Americans with diabetes.
A new research study reveals how fruit bats’ unique physiology enables a healthy high-sugar diet, offering insights for human diabetes research.
A high-sugar diet is bad news for humans, leading to diabetes, obesity, and even cancer. Yet fruit bats survive and even thrive by eating up to twice their body weight in sugary fruit every day.
Now, UC San Francisco scientists have discovered how fruit bats may have evolved to consume so much sugar, with potential implications for the 37 million Americans with diabetes. The findings, published today (January 9, 2024) in Nature Communications<em>Nature Communications</em> is a peer-reviewed, open-access, multidisciplinary, scientific journal published by Nature Portfolio. It covers the natural sciences, including physics, biology, chemistry, medicine, and earth sciences. It began publishing in 2010 and has editorial offices in London, Berlin, New York City, and Shanghai. ” data-gt-translate-attributes=”[{“attribute”:”data-cmtooltip”, “format”:”html”}]” tabindex=”0″ role=”link”>Nature Communications, point to adaptations in the fruit bat body that prevent their sugar-rich diet from becoming harmful.
Diabetes is the eighth leading cause of death in the United States, according to the Centers for Disease Control and Prevention, and it’s responsible for $237 billion in direct medical costs each year.
Understanding Fruit Bats’ Unique Physiology
“With diabetes, the human body can’t produce or detect insulinInsulin is a hormone that regulates the level of glucose (sugar) in the blood. It is produced by the pancreas and released into the bloodstream when the level of glucose in the blood rises, such as after a meal. Insulin helps to transport glucose from the bloodstream into the cells, where it can be used for energy or stored for later use. Insulin also helps to regulate the metabolism of fat and protein. In individuals with diabetes, their body doesn't produce enough insulin or doesn't respond properly to insulin, leading to high blood sugar levels, which can lead to serious health problems if left untreated.” data-gt-translate-attributes=”[{“attribute”:”data-cmtooltip”, “format”:”html”}]” tabindex=”0″ role=”link”>insulin, leading to problems controlling blood sugar,” said Nadav Ahituv, PhD, director of the UCSF Institute for Human Genetics and co-senior author of the paper. “But fruit bats have a genetic system that controls blood sugar without fail. We’d like to learn from that system to make better insulin- or sugar-sensing therapies for people.”
Researchers at UC San Francisco have uncovered evolutionary adaptations in fruit bats that allow them to thrive on a high-sugar diet, providing potential insights for diabetes treatment in humans.
Ahituv’s team focused on evolution in the bat pancreas, which controls blood sugar, and the kidneys. They found that the fruit bat pancreas, compared to the pancreas of an insect-eating bat, had extra insulin-producing cells as well as genetic changes to help it process an immense amount of sugar. And fruit bat kidneys had adapted to ensure that vital electrolytes would be retained from their watery meals.
“Even small changes, to single letters of DNADNA, or deoxyribonucleic acid, is a molecule composed of two long strands of nucleotides that coil around each other to form a double helix. It is the hereditary material in humans and almost all other organisms that carries genetic instructions for development, functioning, growth, and reproduction. Nearly every cell in a person’s body has the same DNA. Most DNA is located in the cell nucleus (where it is called nuclear DNA), but a small amount of DNA can also be found in the mitochondria (where it is called mitochondrial DNA or mtDNA).” data-gt-translate-attributes=”[{“attribute”:”data-cmtooltip”, “format”:”html”}]” tabindex=”0″ role=”link”>DNA, make this diet viable for fruit bats,” said Wei Gordon, PhD, co-first author of the paper, a recent graduate of UCSF’s TETRAD program, and assistant professor of biology at Menlo College. “We need to understand high-sugar metabolism like this to make progress helping the one in three Americans who are prediabetic.”
A Sweet Tooth Without Consequences
Each day, after 20 hours of sleep, fruit bats wake up for four hours to gorge on fruit. Then it’s back to the roost.
To understand how a fruit bat pulls off this feat of sugar consumption, Ahituv and Gordon collaborated with scientists from a variety of institutions, ranging from Yonsei UniversityYonsei University is a private research university located in Seoul, South Korea. It was founded in 1885 and is one of the oldest universities in the country. Yonsei is a comprehensive university with a wide range of academic programs and disciplines, including the humanities, social sciences, natural sciences, engineering, business, and medicine. It is consistently ranked as one of the top universities in South Korea and is known for its strong research and international partnerships.” data-gt-translate-attributes=”[{“attribute”:”data-cmtooltip”, “format”:”html”}]” tabindex=”0″ role=”link”>Yonsei University in Korea to the American Museum of Natural History in New York City, to compare the Jamaican fruit bat to the big brown bat, which only eats insects.
The researchers analyzed gene expression (which genes were on or off) and regulatory DNA (the parts of DNA that control gene expression) using a method for measuring both in individual cells.
“This newer single-cell technology can explain not only which types of cells are in which organs, but also how those cells regulate gene expression to manage each diet,” Ahituv said.
In fruit bats, the compositions of the pancreas and kidneys evolved to accommodate their diet. The pancreas had more cells to produce insulin, which tells the body to lower blood sugar, as well as more cells to produce glucagon, the other major sugar-regulating hormone. The fruit bat kidneys, meanwhile, had more cells to trap scarce salts as they filter blood.
Zooming in, the regulatory DNA in those cells had evolved to turn the appropriate genes for fruit metabolism on or off. The big brown bat, on the other hand, had more cells for breaking down protein and conserving water. And the gene expression in those cells was tuned to handle a diet of bugs.
“The organization of the DNA around the insulin and glucagon genes was very clearly different between the two bat speciesA species is a group of living organisms that share a set of common characteristics and are able to breed and produce fertile offspring. The concept of a species is important in biology as it is used to classify and organize the diversity of life. There are different ways to define a species, but the most widely accepted one is the biological species concept, which defines a species as a group of organisms that can interbreed and produce viable offspring in nature. This definition is widely used in evolutionary biology and ecology to identify and classify living organisms.” data-gt-translate-attributes=”[{“attribute”:”data-cmtooltip”, “format”:”html”}]” tabindex=”0″ role=”link”>species,” Gordon said. “The DNA around genes used to be considered ‘junk,’ but our data shows that this regulatory DNA likely helps fruit bats react to sudden increases or decreases in blood sugar.”
While some of the biology of the fruit bat resembled what’s found in humans with diabetes, the fruit bat appeared to evolve something that humans with a sweet tooth could only dream of: a sweet tooth without consequences.
“It’s remarkable to step back from model organisms, like the laboratory mouse, and discover possible solutions for human health crises out in nature,” Gordon said. “Bats have figured it out, and it’s all in their DNA, the result of natural selection.”
Superheroes of Evolution
The study benefited from a recent groundswell of interest in studying bats to better human health. Gordon and Ahituv traveled to Belize to participate in an annual Bat-a-Thon with nearly 50 other bat researchers, taking a census of wild bats as well as field samples for science. One of the Jamaican fruit bats captured at this event was used in the sugar metabolism study.
As one of the most diverse families of mammals, bats include many examples of evolutionary triumph, from their immune systems to their peculiar diets and beyond.
“For me, bats are like superheroes, each one with an amazing superpower, whether it is echolocation, flying, blood-sucking without coagulation, or eating fruit and not getting diabetes,” Ahituv said. “This kind of work is just the beginning.”
Reference: “Integrative single-cell characterization of a frugivorous and an insectivorous bat kidney and pancreas” by Wei E. Gordon, Seungbyn Baek, Hai P. Nguyen, Yien-Ming Kuo, Rachael Bradley, Sarah L. Fong, Nayeon Kim, Alex Galazyuk, Insuk Lee, Melissa R. Ingala, Nancy B. Simmons, Tony Schountz, Lisa Noelle Cooper, Ilias Georgakopoulos-Soares, Martin Hemberg and Nadav Ahituv, 9 January 2024, Nature Communications.
DOI: 10.1038/s41467-023-44186-y
Key collaborators included co-first author Seungbyn Baek, PhD, from Yonsei University (South Korea); co-senior author Martin Hemberg, PhD, from Harvard Medical School; Tony Schountz, PhD, from Colorado State University; Lisa Noelle Cooper, PhD, from Northeast Ohio Medical University; Melissa R. Ingala, PhD, Fairleigh Dickinson University; and Nancy B. Simmons, PhD, American Museum of Natural History. Other UCSF authors are Hai P. Nguyen, PhD, Yien-Ming Kuo, PhD, Rachael Bradley, and Sarah L. Fong, PhD. For all authors see the paper.
Source: SciTechDaily
