Newswise – The giant panda feeds exclusively on fibrous bamboo while remaining plump and healthy. In a study published Jan. 18 in the journal Cell Reports, researchers show that changes in the bear’s gut microbiota during the season when nutritious bamboo shoots become available help the herbivorous bear put on more weight and store more fat, which helps the bear can compensate for lack of nutrients in seasons when there are only bamboo leaves to chew on.
“This is the first time we’ve found a causal relationship between a panda’s gut microbiota and its phenotype,” said lead author Guangping Huang from the Institute of Zoology, Chinese Academy of Sciences. “We have long known that these pandas have a different set of gut microbiota during sprout-eating season, and it is very apparent that they are chubby at this time of year.”
Many animals experience a seasonal shift in gut bacteria as a result of changes in food availability. For example, certain species of monkeys have a different gut microbiota in summer when they eat fresh leaves and fruits than in winter when they eat tree bark. A similar shift can also be seen among the Hadza, who are modern day hunter-gatherers living in Tanzania, as the type of food available changes throughout the year.
The team, led by Fuwen Wei from the Institute of Zoology, has been studying wild giant pandas living in the Qinling Mountains in central China for decades. Most of the year these animals feed on fibrous bamboo leaves. But in late spring and early summer, you can enjoy freshly sprouted bamboo shoots that are rich in protein.
Wei says these wild pandas have significantly higher levels of a bacterium called Clostridium butyricum in their gut during sprout-eating season than during leaf-eating season. To investigate whether altering the gut microbiota could affect a panda’s metabolism, the team performed a fecal transplant of panda feces collected in the wild onto germ-free mice. Then they fed the mice a bamboo-based diet that simulated what pandas eat for three weeks.
The researchers found that mice transplanted with panda faeces during the sprout-eating season gained significantly more weight and had more fat than mice transplanted with faeces from the foliar-eating season, despite eating the same amount of food took. Further analysis revealed that the C. butyricum metabolite, butyrate, could upregulate the expression of a circadian rhythm gene called Per2, which increases lipid synthesis and storage. The seasonal changes in pandas’ gut microbiota synchronize the host’s peripheral circadian rhythm to modulate lipid metabolism.
“For vulnerable and endangered wildlife, we cannot do direct testing. Our research has created a mouse model for future stool transplantation experiments that can help study the gut microbiota of wild animals,” says Huang.
Next, the team plans to map other microorganisms in the panda’s gut and determine what role they play in influencing the animal’s health. “The causal exploration of host phenotype and gut microbiota in wild animals is still in its infancy. Finding out which bacteria are beneficial to animals is very important because one day we may be able to treat some diseases with probiotics,” says Huang.
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This work was supported by grants from the National Natural Science Foundation of China and the Strategic Priority Research Program of the Chinese Academy of Sciences.
Cell Reports, Huang, Wang, and Li et al.: “Seasonal shift in gut microbiome synchronizes host peripheral circadian rhythm for physiological adaptation to a low-fat diet in giant panda”, https://www.cell.com/cell-reports/ fulltext/S2211-1247(21)01707-1
Cell Reports (@CellReports), published by Cell Press, is a weekly open access journal that publishes high-quality articles across the spectrum of life sciences. The Journal contains reports, articles, and resources that provide new biological insights, thought-provoking and/or examples of cutting-edge research. Visit: http://www.cell.com/cell-reports. To receive media alerts from Cell Press, contact [email protected]m.
