Giant pandas have a digestive system typical of carnivores. However, bamboo is their main source of food. The pandas have developed several characteristics to grasp bamboo and flattened teeth that are suited to crushing it, which allows them to live on plants.
All living organisms have DNA, which stores genetic information in a cell, and RNA, which transports and transfers that information. MicroRNAs (miRNAs) are small non-coding RNAs that play an important role in gene expression, the process of turning encoded information in a gene into a function. Plant miRNAs can be absorbed through food.
Now, researchers in China explored whether plant-derived miRNA can enter the systems of giant pandas and regulate gene expression, thus helping adaptation to a bamboo-based diet.
“We showed that plant-derived miRNAs are present in the blood of giant pandas,” said Dr. Feng Li, researcher at China West Normal University and senior author of the study published in Frontiers in Veterinary Science. “Our study proved that the bamboo used as food for giant pandas affects the shift in the feeding habits of giant pandas.”
A matter of taste
The researchers collected blood samples from seven giant pandas, including three adult females, three adult males and one juvenile female. In those samples, they found 57 miRNAs that were likely derived from bamboo.
“The bamboo miRNA can enter the body of giant pandas through the diet, be absorbed by the intestine, enter the bloodstream, and then regulate when the RNA of the giant panda transfers information, thereby playing a role in regulating the genetic expression of giant pandas,” Li explains.
These plant-derived miRNAs can regulate different physiological processes, including growth and development, biological rhythms, behavior and immune responses.
“The bamboo miRNA is also involved in regulating the olfactory, taste and dopamine pathways of giant pandas, all of which are related to their feeding habits,” Li says.
The researchers believe that as pandas eat more bamboo as they grow, certain miRNAs accumulate, modulate gene expression and help in adapting to the taste of bamboo. These miRNAs may also influence the olfaction of giant pandas and allow them to choose the freshest and most nutritious parts of bamboo plants. Therefore, bamboo miRNAs may facilitate the adaptation of giant pandas from a carnivorous diet to a plant-based diet.
From plants to animals
The researchers also found that pandas of different ages and sexes had different miRNA compositions in the blood. “Only miRNAs that can specifically play a role in regulating gene expression can remain in the body, and those that do not play a role will be expelled,” Li says. For example, some miRNAs regulate reproductive processes and, therefore, can only be found in the blood of pandas of a particular sex or age.
The fact that miRNA can transmit signals from plants to animals may open doors to the study of treatment and prevention of animal diseases. “Plant miRNAs can also participate in regulating the animal immune system, increasing animals’ resistance to diseases,” he emphasizes.
Similarly, the study of changes induced by plant miRNA can also help assess and improve the safety of plant-based foods for animals and humans, the researchers say. However, to draw definitive conclusions about the potential of miRNA in general and the effects it may have on giant pandas, more research is needed.
“The giant panda is a very precious national treasure in our country and blood samples are not easy to obtain,” Li says. “If possible, we hope to collect blood samples from young pandas that have not yet eaten bamboo for the research and perhaps obtain even more surprising results,” he concludes.
