What Mice Can Tell Us About Obesity and Genetics

Alexandra Sifferlin, TIME
Published on January 9, 2013
http://healthland.time.com/2013/01/09/what-mice-can-tell-us-about-obesity-and-genetics/

Summary
For more than two years, researchers at UCLA have observed and monitored weight gain among lab mice. The effects of high-fat and high-sugar diets on them has shown that risks of obesity are affected by genes. The scientists have identified 11 genetic regions affecting obesity and fat acquisition from the diet, several of which are similar to human genes that have also been linked to obesity. During the study, the mice were put on a normal diet for 8 weeks, then consumed a high-fat or high-sugar diet for another 8 weeks. The build up of fat varied widely among the mice, ranging from 0%-600% increase in body fat over the 16 weeks. The amount of fat gained was connected with changes in the mices' gene activity. About 80% of body fat was found to likely be regulated by genes, suggesting that DNA directed the energy needed for processing food, or their metabolism, and that the amount of food the mice ate was not as much of a factor. The study suggests that the amount of physical activity the mice get and how they metabolize food has a greater impact. This may be true for humans as well. Previous studies have estimated that 50%-90% of obesity is inherited in genes, but these have not been fully identified yet. It is also possible that genes may not be directly responsible for obesity, but are set off in the presence of environmental factors such as stress. Studying the different ways that DNA impacts weight can lead to better ways of fighting obesity, which is an increasing problem in the world today. The scientists are planning to further test the genes they identified in the mice in various lab environments to gain a better understanding of how they influence body fat and behavioral responses like appetite.

Connection
This article connects to the heredity and genetics units. It connects to heredity because certain genes in the mice, their genotype, affect their body fat and metabolism, their phenotype. These obesity affecting genes can be passed on to offspring, which is what causes them to exhibit certain rates of body fat gain. Also, the article connects to genetics because DNA is what causes certain genes to exhibit certain traits. However, human genes may influence obesity only in the presence of certain environmental factors such as stress, which is an example of gene regulation.