Mutant ants provide insights into social interaction

Ant study by ASU researchers, colleagues could help identify genetic mechanisms involved in human social communication


August 10, 2017

Ants genetically engineered to lack their “sense of smell” became unable to communicate, forage or compete to be a queen, as their antennae and brain circuits failed to fully develop. For the first time, researchers successfully shut down a crucial portion of the ant’s olfactory system by using the CRISPR-Cas9 technology.

This finding, stemming from a recent study conducted by Arizona State University scientists and their colleagues from New York University, University of Pennsylvania and Vanderbilt University, was published online today in the journal Cell Harpegnathos worker ants interacting. Photo by Jürgen Liebig/ASU Download Full Image

“While ant behavior does not directly extend to humans, we believe that this work promises to advance our understanding of social communication, with the potential to shape the design of future research into disorders like schizophrenia, depression or autism that interfere with it,” said corresponding author Claude Desplan, professor at New York University’s Department of Biology.

“We found that a species of ant may be the first model to enable in-depth functional analysis of genes that regulate social interaction in a complex society,” said study co-author Danny Reinberg, a professor with the NYU School of Medicine and investigator for the Howard Hughes Medical Institute.

Jürgen Liebig, an associate professor with ASU’s School of Life Sciences and expert in social insect societies, is also encouraged by the results.

“Having studied the behavioral plasticity, colony organization and chemical communication of the ant Harpegnathos saltator for more than two decades, I am happy to see that this charismatic species is finally maturing into a genetic model,” co-author Liebig said.

Smell talk

The current results are based on the fact that ants communicate through pheromones, secreted chemicals that trigger responses. Such odors are used to spread alarm as a predator approaches, leave a trail to food, indicate social (caste) status and signal readiness to mate, all within cooperative societies that achieve complex tasks. Ants can receive such signals because they have proteins called odorant receptors on their antennae, with each protein the right shape to bind to a specific odorant chemical. 

For any odor or pheromone to be processed in an ant’s brain, however, past studies had shown that both the right odorant receptor protein and a shared, common partner protein called Orco must be present. The current team successfully engineered the genetic loss of Orco protein, which resulted in ants that could no longer perform some, if not all, pheromone-based social interactions.

Specifically, the altered young ants, unlike their nestmates without the changes, spent much of their time wandering out of the nest. They failed to interact with other members of the colony and were unable to forage and bring food back to the nest. Furthermore, mutant females no longer groomed males, a pre-mating behavior.

The current study focused on the Indian jumping ant, Harpegnathos saltator, which is unlike many ant species in which only the queen can mate and pass on genes to the next generation. Any Harpegnathos female adult worker can be converted into a queen-like state in the absence of the queen or other queen-like workers.

This is because the queen secretes a pheromone that suppresses the ability of workers to mate and lay eggs. If the queen is removed, the most aggressive females, after winning a series of antenna duels, undergo this transition, and can go on to produce progeny, which is essential for colony survival.  

The current study found that, without Orco, the females cannot process pheromones, which makes them much less likely to engage in dueling.

“This ant system allows dissecting the organization of a society in which social interactions of all individually marked colony members can be tracked easily,” Liebig added.

Harpegnathos worker ant tending to larva. Photo by Jürgen Liebig/ASU

 

Another study result proceeded from the fact that each neuronal cell (odorant receptor neuron) capable of processing the presence of a given pheromone on the surface of an ant’s antennae sends out extensions that converge in a specific blob-like brain structure called a glomerulus. Information about that odor is processed there.

Past studies have suggested that, in solitary insects like mosquitoes, fruit flies and moths, the connections between odorant receptors and glomeruli are “hard-wired,” i.e. their neural development is independent of receptor activity. To the contrary, mammals appear to have odorant receptor cells with extensions capable of homing in on the correct glomeruli based on which odorant receptors they express. This makes the function activity-dependent in mice (and humans), in contrast to the hard-wired context of flies, say the study authors.

The new research suggests that Harpegnathos ants may also have evolved to have flexible, activity-based patterning of nerve connections, which has led to their expanded repertoire of olfactory receptors for detecting pheromones. This flexibility is required for communication based on the pheromone sensitivity and resultant activity of their olfactory neurons, say the authors. Accordingly, the loss of the Orco gene left female ants, on average, with just 62 of the 275 glomeruli that they would normally develop to process pheromone sensing. 

 

The study was supported by Howard Hughes Medical Institute CIA and HCIA 2009005, and in part by National Institutes of Health grants R21GM114457, EY13010, F32AG044971, and DP2MH107055.

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Pat Tillman Veterans Center welcomes new students to ASU


August 10, 2017

Teamwork is essential in the U.S. military, and the Pat Tillman Veterans Center wants new student veterans at Arizona State University to know that there is a diverse team of people here also to help them succeed.

New student veterans looking to learn about their new team and the different resources to be successful at ASU can attend one of the Veterans Welcome events scheduled for Aug. 14 on Tempe campus; Aug. 15, West and Downtown Phoenix campuses; and Aug. 16, Polytechnic campus.   Veterans at ASU New students attend a previous year's Veterans Welcome Orientation. Download Full Image

The Pat Tillman Veterans Center organizes the welcome events every fall and spring as part of its mission to empower and support the veteran and military community as they pursue academic and personal success, said Matt Schmidt, assistant director of outreach for the center.

“Our new student welcome is critical to the short- and long-term success of our students, because the new relationships that are started here and the opportunity for incoming students to get a clear idea of the resources available to them will aid in empowering them to take ownership of their future at ASU,” Schmidt said. 

The Veterans Welcome will introduce students to military advocate Michelle Loposky along with other Pat Tillman Veterans Center staff members. Attendees will also learn about the Department of Veterans Affairs benefits through the VetSuccess on Campus program managed locally by Troy Rundle.

“In order to understand the complexities of VA benefits, come to these sessions,” said Marisa Von Holten, Air Force veteran and student. “The experts can answer your questions in person, and you’ll start opening doors and making connections before classes even start.”

There will also be opportunities to speak with other student veterans who’ve been here and can provide firsthand accounts of the ASU experience, as well as give valuable advice on various topics.  

Schmidt also has some key advice to veterans just starting their ASU journey.

“Seek opportunities to help fellow students,” he said. “If you are known as someone that is always there for other people, other people will be there for you when you need it most.”

He also encourages all students to ask questions and be curious.

“There are a lot of opportunities at ASU,” Schmidt said. “The more curious you are about finding out what is available, the more likely you are to find that ‘thing’ that really inspires you.”

Von Holten, who is pursuing a bachelor’s degree in justice studies and has been at ASU since 2015, also has beneficial, practical tips that apply to all students, not just veterans.

“Remain open to every encounter, learn something new from a stranger every day, and don’t skip reading the syllabus,” she said. “Jot down your due dates at the beginning of the semester and have a plan. Most importantly, save ‘me’ time weekly to forget work, school and life stresses. Stick to your hobbies and balance life.”

 

The fall semester will bring to campus and online a total of about 7,000 veterans and military-affiliated students, including family members. This makes ASU one of the public universities with the highest military-affiliated student enrollment per capita in the nation.

ASU is an attractive choice for students because here they can earn their degree and much more. The Pat Tillman Veterans Center is constantly seeking to create and connect veterans to opportunities, said Steve Borden, the center’s director.

“We want them to think about not just earning their degree,” Borden said. “For example, what would it be like to take that degree and add to it undergraduate research opportunities, an internship, a specific kind of study abroad, a work-study program to help them get some experience in the career field they want to use their degree in after they graduate?”

Many other universities are solely focused on veteran retention and graduation but not thinking about how to expand the education opportunities for veterans, Borden said.

“We’re trying to take an innovative or different approach to getting vets to think about the full scope of what they can do here,” Borden added.

For more information about the Veterans Welcome events, including time and locations, go here

Jerry Gonzalez

Media Relations Officer, Media Relations and Strategic Communications