Chapter 50, Problem 2Q

Summary Introduction

To review:

The changes in the gut microbiome of bears during winters and summers.

Given:

The brown bears (Ursus arctos) were taken by the researchers for studying the role of gut microbiota in the digestion of food and in many other aspects of nutrition. Brown bears undergo hibernation when the environment is extreme cold. They analyzed whether the microbiome of the bear’s gut was different before and after fasting. They studied the blood and the fecal samples from 16 free-ranging brown bears during hibernation (February or March) and following hibernation (June). There was presence of different microbe communities in different amounts during different seasons and same was with triglycerides and other nutrients.

The following graphs were plotted after observing the conditions in winters and summers. Graph 1 shows the presence of different composition of the microbiome during different seasons. Also, the differences in the blood levels of triglycerides, lactate, and succinate are depicted.

The effects of the microbiota were also examined after introducing them into germ-free mice. Germ-free mice, unlike normal mice are devoid of gut microbiota and are unable to gain mass when they are kept on a high-fat diet. Fecal transplants from summer and the winter bears were given to the germ-free mice. Graph 2 shows the changes in body mass, fat content, and blood triglyceride levels of the mice after two weeks.

Graph 1: The two graphs showing the differences in the gut microbiome of the bear and the content of blood triglycerides, lactate, and succinate during the summers and winters.

Graph 2: The graph showing the differences in the body mass, fat content, and blood triglycerides level of the germ-free mice taken for the experiments and injected with the fecal transplants of bears.

Introduction:

There are a number of microbes present in the gut of bears. They help in digestion of the food. The more the amount of a particular microbe, the more will be the digestion by that microbe. There is a difference in the amounts of the different microbes in the gut during summers and winters in order to digest different products in the gut.