Researchers identify 'Kevin Bacon degrees' gene in well-connected fruit flies

A team of researchers from the University of Toronto has identified a gene in fruit flies that regulates the types of connections between flies within their “social network.”

Researchers have named the gene “degrees of Kevin Bacon” (dokb) for the prolific star of films such as Footloose and Apollo 13. The board game Six Degrees of Kevin Bacon, in which a random actor's connection to Bacon is traced through a chain of co-stars, reflects the actor's many connections with other actors.

It is common for animals to exist in groups or social networks (for example, a pride of lions or a pod of dolphins) within which a multitude of interactions and relationships exist. Within these networks, individuals and groups have different levels of connectivity.

The researchers studied groups of two distinct strains of Drosophila melanogaster fruit flies and found that one strain had different types or patterns of connections within their networks compared to the other strain.

The researchers then isolated the dokb gene in the first strain, also known as CG14109, associated with this connectivity. When they swapped the gene from one strain to another, the recipients exhibited the connectivity of the other strain.

“There has been a lot of research into whether social network structure is inherited, but this question is poorly understood,” says Rebecca Rooke, who carried out this work as part of her PhD. thesis at the University of Toronto in Mississauga.

Rooke is the lead author of the paper describing the research, titled “The 'degrees of Kevin Bacon' (dokb) gene regulates a social network” and published in Natural communications.

It was thought that rather than inheriting this ability, animals instead learned to interact with other individuals. “But what we have now done is found the gene and proven that there is a genetic component,” she says.

Rooke is a postdoctoral researcher in the laboratory of Professor Joel Levine, located at UTM when this research took place.

“It gives us a genetic perspective on the structure of a social group,” says Levine, currently chair of the Department of Ecology and Evolutionary Biology in the Faculty of Arts and Sciences.

“This is surprising because it says something important about the structure of social interactions in general and the structure of species-specific social networks. It's exciting to think about the relationship between genetics and group in this way . This may be the first time.” times we've been able to do that.”

The researchers measured the type of connection by observing groups of a dozen male flies placed in a container and recorded on video.

Using software previously developed by Levine and postdoctoral researcher Jon Schneider, the team tracked the distance between flies, their relative orientation, and the time they spent in proximity. Using these criteria as measures of interaction, the researchers calculated the type of connection or “betweenness centrality” of each group.

Rooke, Levine, and their colleagues point out that individual organisms with strong betweenness centrality within a social network can act as “gatekeepers” who play an important role in facilitating interactions within their group.

Keepers can influence factors such as food distribution or the spread of disease. They also play a role in maintaining cohesion, improving communication, and ensuring better overall health of their group.

In humans, betweenness centrality can even affect the spread of behaviors such as smoking, drug use, and divorce.

At the same time, researchers emphasize that social media is unbiased and favors neither “good” nor “bad” outcomes. For example, high betweenness centrality in a network of scientists can increase the number of potential collaborators; on the other hand, high betweenness centrality in another group can lead to the spread of a disease like COVID-19.

“The structure of a network doesn’t get good or bad results,” Levine says. “The structure of a network can bring happiness or illness.”

Both Rooke and Levine are excited about the research this discovery opens up.

“I think the most interesting next step is to identify the overall molecular pathway in which this gene and its protein are involved,” says Rooke. “Trying to understand what the protein does and what pathways it's involved in. The answers to these questions will really give us a lot of information about how these networks work.”

And although the dokb gene has so far only been discovered in flies, Rooke, Levine and their colleagues predict that similar molecular pathways between genes and social networks will be found in other species.

“For example, there is a subset of cells in the human brain whose function is related to social experience—what the popular press might call the 'social brain,'” Levine says.

“Going from the fly to the human brain is another area of ​​research. But it is almost true that the things we observe in insects will be found in a more nuanced and more dispersed way in the mammalian brain.”