Does the Environment Change Genetically Identical Mice?
Student Summary by Hayden Byun
Original Source: Ivana Jaric et al., PLOS Biology, October 21, 2022
Abstract
Background: Scientists often use genetically similar mice to conduct experiments in order to reduce variation. It has been known that the phenotype, or observable traits, of a living thing is often made up of two factors: genotype (genetic makeup) and the environment that the organism grew up in.
Objective: Researchers wanted to know specifically how much the rearing environment (all surroundings, care, and life experiences provided for the organism while growing up) impacted certain phenotypes of inbred, genetically uniform mice.
Method: Researchers cared for and kept mice in five environmentally diverse rearing facilities. Each facility varied in conditions such as bedding, nesting materials, light cycles, and care from humans. Afterward, the mice were all moved to a single testing environment for measurement of traits such as body weight, gut microbiomes, behavior, and neuronal chromatin organization (controls gene activity and brain development).
Results: The scientists found that genetically similar mice raised at five different facilities developed significant differences in gut microbiome, body weight, and molecular characteristics in the brain. Even after the mice were moved to the same testing facility, the observed traits persisted. This shows that the phenotypic traits the mice acquired during their developmental phase lasted well beyond the environment that produced them. The rearing facility accounted for 14.4% of behavioral variation in males, and 12.4% in females. Researchers were able to accurately identify the original facilities in which the mice were raised for 58% of males and 53% of females solely based on their behavior. Random sorting would only be correct 20% of the time.
Conclusion: This study showed that mice that are very similar genetically can still develop significant differences when raised in different environments. With this information, scientists may consider experiment setting more carefully; this could potentially help improve the reliability of studies, benefiting the science community.
