Groundbreaking discovery featured in January issue of Science magazine
BY RACHELLE COOPER
Prof. Elena Choleris, Psychology, has made a groundbreaking discovery that explains how genes work together to form the basis of social recognition.
Choleris's research, which could have implications for better understanding human disorders affecting sociality, is featured in the January issue of Science magazine and was published in the Proceedings of the National Academy of Sciences of the United States of America and the Journal of Neuroendocrinology.
Choleris studied the genetic interactions necessary for one mouse to recognize another.
“If the individuals of one species can't recognize others, it means that can't be a social species, so social recognition is really the basis of all social life,” she says.
Although scientists have known that estrogens — through their alpha receptor and the gene for neuropeptide oxytocin — are involved in the regulation of social recognition in mice, Choleris's studies were the first to show that the most recently discovered estrogen receptor, beta, and the gene for oxytocin's receptor are also needed for social recognition.
Based on her most recent discoveries, she has concluded that, in the regulation of social recognition, these four genes are connected together in what she calls a “micronet.”
“As with a net, if you cut it at any one of these four points, you will block social recognition because all the genes have to work together as a mechanism for social recognition to happen,” says Choleris, who's the lead author of the study that she completed with Don Pfaff of Rockefeller University. “I see this as the core control of social recognition.”
For the study, Choleris put a new mouse into another mouse's cage for five minutes. After a 15-minute break, she put the new mouse back in the cage and repeated this process with the same mice four times.
“By the fourth time, a mouse with normal genes will have figured out that the visitor mouse is always the same, so the social investigation — the interest shown towards the visitor — declines,” she says.
The fifth time, Choleris introduced a different mouse, and the resident mouse immediately recognized it was a new visitor and started the examination process over again.
When she did the same experiment with a resident mouse missing one of the four genes that make up the micronet, or where the gene had been temporarily blocked, the animal spent the same amount of time investigating its repeat visitor and its new visitor, showing that the mouse lacked social recognition skills. She also found that, no matter which gene a mouse was missing, the animal showed the same impairment in social recognition.
The natural breakdown of this micronet in the wild can have serious implications. Choleris and Pfaff, in collaboration with Martin Kavaliers of the University of Western Ontario, have also shown it can lead to mice having a diminished ability to stay away from mice with parasites because socially aware mice distinguish between infected and uninfected males on the basis of odours.
Understanding the genetic basis of social behaviour in mice could also help explain the neurobiological causes of human disorders that affect sociality, says Choleris.
“There are studies suggesting the oxytocin system may be impaired in people who suffer from autism.”
