From workers to queens: the fight for the throne in the kingdom of ants
“The brains of animals are plastic; that is, they can change their structure and function in response to their environment ”, he explains. Roberto Bonasio, cell and developmental biology expert at Perelman University Pennsylvania School of Medicine.
Bonasio is the author of an article that under the title Kr-h1 maintains distinct caste-specific neurotranscriptomes in response to socially regulated hormonesis published this week in the magazine Cell, and in which the discovery of a protein called Kr-h1 (Krüppel homolog 1) responsible for a complex social transition in which ants of the species Harpegnathos saltator they can go from being simple workers to a queen state known as “gamergate”. A gamergate is a worker ant that will develop as a female and that can reproduce sexually, that is, lay fertilized eggs.
“This process is crucial for the survival of these ant colonies, but until now the molecular mechanisms that controlled it were completely unknown,” continues Bonasio. “In fact, these kinds of changes also take place in humans; think about the behavioral changes that take place during adolescence. What we have now determined is that in ants of the species Harpegnathos saltator a protein called Kr-h1 is responsible for slowing down the plasticity of the brain by preventing inappropriate genetic activation. “
Ants, hormones, hierarchies and social castes
Bonasio and his colleagues wanted to understand how the activation or deactivation of certain genes affects the function and behavior of the animal brain, something for which the adults of Harpegnathos were shown as ideal candidates for study, since they can go from being workers to ants queens. In a community of ants, the workers maintain the colony by finding food and fighting off invaders, while the queen’s main task is to lay eggs. However, the genetic instructions that give rise to these very different social roles and behaviors are the same in both cases.
To find out the molecular alterations underlying this role change, the research team, led by the study co-authors Janko Gospocicand Karl Glastad, developed a method to isolate neurons from ants and keep them alive in the laboratory. This allowed the team to explore how cells responded to changes in their environment, including hormone levels.
Among the results of the experiments, the authors found that specifically two hormones, youth hormone and the ecdisona, present at different levels in the bodies of both the workers and the gamergates, produced distinct patterns of genetic activation in the brains of the two castes. However, the biggest surprise of all was that both hormones influenced cells by activating a single protein, Kr-h1..
“This protein regulates different genes in workers and gamergates and prevents ants from engaging in ‘socially inappropriate’ behaviors,” says Berger. “I mean, yese requires Kr-h1 to maintain boundaries between social castes and to ensure that workers continue to work while gamergates continue to act like queens. “
“We had not anticipated that the same protein could silence different genes in the brains of different castes and, as a consequence, suppress the antagonistic behavior in workers and gamergates, specifies Bonasio for his part. “We think that these roles would be assigned based on two or more different factors, each of them only present in one or the other brain, however, Kr-h1 is the only factor involved,” he adds.
Dr Jekyll Mr Hide and the genes
The findings reveal important roles for socially regulated hormones in ants and the implication of genetics in the ability of animal brains to change social caste. “The key message is that, at least in ants, multiple patterns of behavior are simultaneously specified in the genome and that genetic regulation can have a major impact on what behavior that organism performs,” Berger explains. “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 genetic switches are on or off. “.
The parts of both Dr. Jekyll and Mr. Hyde are already written into the genome; everyone can play either role, depending on which genetic switches are on or off
The researchers believe that the implications of their study may go far beyond understanding the plasticity of behavior in ants and other insects. “It’s tempting to speculate that related proteins might have comparable functions in more complex brains, including our own. “, Bonasio adventure. “The discovery of these proteins could one day allow us to restore the plasticity of brains that have lost it, for example, aged brains.”
The discovery that a single factor can suppress different sets of genes and behaviors in different brains raises important questions about how the dual function of this protein and others like it might be regulated. In future studies, the researchers plan to investigate the role of Kr-h1 in other organisms, and say that they would also like to explore how the environment impacts genetic regulation at the epigenetic level, through the presence or absence of certain chemical tags. in DNA, and how this, in turn, affects the plasticity and behavior of the brain.
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