Friday, November 05, 2021

Researchers uncover protein that governs ants' changing social roles

New research identifies a key protein that governs how ants switch social roles, allowing them to switch between being workers or filling a queen-like role. 
Photo by cp17/Pixabay

Nov. 4 (UPI) -- A single molecule controls the unusual social phenomenon in a certain species of ants that sees members of their colonies switch from worker to queen-like status, a study published Thursday by the journal Cell found.

The protein Kr-h1, or Krüppel homolog 1, responds to socially regulated hormones to orchestrate this complex social transition, called gamergate, in the Harpegnathos saltator species of ants, the researchers said.

It's unusual for members of ant colonies to make this "social" transition, they said.

"Animal brains are plastic -- that is, they can change their structure and function in response to the environment," study co-author Roberto Bonasio said in a press release.

"This process, which also takes place in human brains -- think about the changes in behavior during adolescence -- is crucial to survival," said Bonasio, an associate professor of cell and development biology at the University of Pennsylvania Perelman School of Medicine in Philadelphia.

In an ant colony, workers find food and fight off invaders, while the queen's main task is to lay eggs, and it is rare to see changes in these roles, according to the researchers.

By studying ants, Bonasio and his colleagues wanted to understand how turning certain genes "on" or "off" affects brain function and behavior.

To do so, the team developed a method for isolating neurons from the ants and keeping them alive in plastic dishes in the lab, they said.

This enabled them to explore how the cells responded to changes in their environment, including hormone levels, the researchers said.

Through these efforts, the researchers identified two hormones, juvenile hormone and ecdysone, that produced distinct patterns of gene activation in the brains of workers and queens.

These hormones are present at different levels in the bodies of workers and those who transition to queen-like status, and both influence genes by activating Kr-h1, according to the researchers.

"This protein regulates different genes in workers and gamergates and prevents the ants from performing 'socially inappropriate' behaviors," study co-author Shelley Berger said.

"That is to say, Kr-h1 is required to maintain the boundaries between social castes and to ensure that workers continue to work while gamergates continue to act like queens," said Berger, a professor of cell and development biology at the University of Pennsylvania Perelman School of Medicine.

The findings reveal important roles for socially regulated hormones and gene regulation in the ability of animal brains to switch from one genetic mode and social caste to another, the researchers said.

"The key message is that, at least in ants, multiple behavioral patterns are simultaneously specified in the genome and that gene regulation can have a great impact on which behavior that organism carries out," Berger said.

"In other words, the parts of both Dr. Jekyll and Mr. Hyde are already written into the genome; everyone can play either role, depending on which gene switches are turned on or off," she said.

The implications may go much farther than understanding behavioral plasticity in ants and other insects, given that similar proteins may have comparable functions in humans, according to the researchers.

Identifying similar proteins in human brains may enable scientists to discover ways to restore plasticity -- the ability to grow and change -- to brains that have lost it, including aging brains.

In future studies, the researchers said they plan to explore the role of Kr-h1 in other organisms, including humans, and learn how, if at all, the environment impacts brain plasticity and behavior.

"We had not anticipated that the same protein could silence different genes in the brains of different castes and, as a consequence, suppress worker behavior in gamergates and gamergate behavior in workers," Bonasio said.

"We thought that these jobs would be assigned to two or more different factors, each of them only present in one or the other brain," he said.

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