We finally know why a panda stays chubby when he only eats bamboo

But what the hell is this? As long as it eats only bamboo, far from the most high-calorie food in the world, and even more so in winter, when the shoots have disappeared and only stems and leaves remain that can be put under the tooth, the giant panda manages to remain plump and healthy all year round.

In a study published Jan. 18 in the journal Cell Reports, Chinese researchers uncover a clue: Microorganisms that inhabit the plantigrade gut (its microbiome) give it “physiological plasticity” by causing seasonal changes in its diet – rich in summer and even more so in winter. – have little effect on the figure. This causal relationship between microbiome and phenotype was first established when panda feces were transplanted into mice.

A study led by a team of biologist Fuwen Wei from the Institute of Zoology of the Chinese Academy of Sciences shows how the panda’s gut microbiota changes in late spring and early summer when many protein-rich bamboo shoots emerge. helping herbivores to gain more weight and store more fat, thereby compensating for the lack of nutrients during the harsh season.

Pandas are far from the only animals whose gut bacteria composition fluctuates with seasonal dietary fluctuations. Some monkeys also have different gut microbiota in summer, when they have fresh leaves and fruits, and in winter, when they have to nibble on bark. In humans, such changes have been observed in the Hadza, a nomadic East African tribe that is one of the oldest hunter-gatherers in the world.

Poop transplant and eureka!

According to Wei, who has studied wild pandas for decades, these animals have significantly higher levels of Clostridium butyricum bacteria in their intestines during shoot season compared to leaf and branch season.

To determine whether this modification of the gut microbiota actually affects foot-to-foot metabolism, his team decided to transplant panda feces collected from their natural environment into mice modified to be free of microbes in their bodies. The scientists then fed the rodents as if they were pandas on a diet rich in bamboo for three weeks. Why such a method? Particularly because it minimizes the anxiety of wild pandas, endangered and fragile animals.

The researchers found that mice transplanted with panda feces during the seedling season gained significantly more weight and stored more fat than those given winter feces, despite all consuming the same amount of calories. Why? As a metabolic product of Clostridium butyricum, butyrate appears to maximize the expression of the circadian rhythm gene PER2, which in turn increases lipid synthesis and accumulation.

Subscribe to Slate Newsletter

In other words, the seasonal changes in the panda’s gut microbiota synchronize with its peripheral circadian rhythm and allow it to modulate lipid metabolism so it doesn’t languish in the winter without resorting to hibernation like most of its bear cousins.

Leave a Comment

Your email address will not be published.