Mutant Ants Created for the First Time
Scientists have successfully genetically engineered mutant ants, in order to better understand their behaviour through their genes.
Earlier this week, two independent research teams described their work deleting ant genes, reports The Washington Post. The two papers appeared in the journal Cell, alongside a third study that altered ant behaviour using an insect brain hormone.
Author of one of the studies, Claude Desplan, a New York University biologist, believes that as far as he could tell, the ants are “the first mutant in any social insect.” Ants have complex social roles, despite members of a colony are genetically very similar.
Daniel Kronauer, author of the other mutant ant study, and Rockefeller University, explained, “There’s a lot of interesting biologic questions that you can study with ants that you can’t study with fruit flies or even mice.”
“Ants are amazing because with the same genome you can be a queen, or a worker, or another class of worker, or a soldier,” Desplan added.
The research group focused on a species of jumping ant found in India, the Harpeganthos saltator, because all of these ants are potentially fertile. On the other hand, Kronauer and his colleagues, led by Rockefeller University graduate student Waring Trible studied the clonal raider ants, the Ooceraea biroi. Unlike most ants, the raider ants reproduce asexually, through parthenogenesis. This is usually called virgin birth, a phenomenon seen in some snakes, lizards and sharks. As a result, the offspring end up as clones of the females. For both species, the desired result of genetic alteration was the same, creating mother ants tat gave birth to future generations of mutants.
Both groups used the CRISPR-Cas9 technique, with bacterial molecules acting like scissors to snip out genes, the scientists were able to knock out a crucial component of the ant’s odour receptors.
Pheromones are the odours by which ants communicate, and this is their social medium. Hundreds of olfactory genes exist within ants, deleting one particular gene, called orco, for odorant receptor co-receptor, effectively renders almost the entire ant olfactory system useless. Removing every individual odour gene would be “essentially impossible,” claimed Kronauer. However, the power of orco to “take out the whole family” of olfactory genes makes it an obvious candidate for manipulation. The insects lost about 90% of their olfaction, Desplan added.
As a consequence the behaviour of the mutants changed dramatically. The Indian jumping ants wandered away from the colony and wouldn’t forage. Similar to the Ooceraea biroi mutants became antisocial. Kronauer commented, “Suddenly these ants aren’t really social any more. They wander off, they don’t join the colony. They just walk around.”
Now scientists are able to alter the behaviour of ants through their genes, Kronauer plans to study the way colonies divide their labour. Desplan on the other hand, is interested in the way ants alter their longevity, as well as sensory perception.