Nav: Home

New insights into how genes control courtship and aggression

April 28, 2020

LA JOLLA--(April 28, 2020) Fruit flies, like many animals, engage in a variety of courtship and fighting behaviors. Now, Salk scientists have uncovered the molecular mechanisms by which two sex-determining genes affect fruit fly behavior. The male flies' courtship and aggression behaviors, they showed, are mediated by two distinct genetic programs. The findings, both published in eLife on April 21, 2020, demonstrate the complexity of the link between sex and behavior.

"Courtship and aggression seem to be controlled somewhat separately by these two genes," says Kenta Asahina, an assistant professor in Salk's Molecular Neurobiology Laboratory and senior author of the two papers. "Having behaviors controlled by different genetic mechanisms can have some benefits in terms of evolution." In other words, he explains, a fly population that is under evolutionary pressure to compete more--perhaps due to limited resources--can evolve aggressive behaviors without affecting courtship.

Male fruit flies' aggression is primarily toward other males, while their courtship behaviors--which involve a series of movements and songs--are toward female flies. Both behaviors are reinforced by evolution over time, because the ability of male flies to compete with other males and attract females directly affects their ability to mate and pass on their genes.

Researchers already knew which neurons in the brain are important for controlling aggression and courtship. In general, studies had suggested that specialized brain cells called P1/pC1 neurons, promote both courtship and aggression while Tk-GAL4FruM neurons promote aggression specifically. They also knew that the two sex-determining genes fruitless (fru) and doublesex (dsx) played key roles in this behavior. But the connection between the genes and the behaviors hadn't been clear.

In the new study, Asahina and his colleagues raised Drosophila fruit flies that contained light-activatable versions of the courtship and aggression neurons. The team could turn the neurons on at any time by shining a light on the flies. The researchers next altered the fru or dsx genes in some of these male flies. They then developed an automated system using machine-learning to analyze videos of the flies and count how often they carried out aggressive or courtship behaviors.

"We made a computer system to capture aggressive behaviors and courtship behaviors to more quickly and accurately count actions," says Salk postdoctoral fellow Kenichi Ishii, co-first author of both of the new papers. "Getting the program to work was actually difficult and time-consuming but in the end, it made it easier for us to get good data."

The team found that dsx was required for the formation of courtship-inducing neurons: when the fruit flies had the female version of dsx, the courtship neurons were no longer present. On the other hand, fru played a different role--without this gene, flies could still be coaxed to perform courtship behaviors by activating courtship neurons but the courtship was directed at both males and females, suggesting that fru was required for flies to differentiate between the sexes. For aggression, however, the findings were the opposite: fru but not dsx was required for the activation of aggression neurons to cause fighting in male flies.

"This is an important example of the neurobiological differences between sexes and what kind of approaches we can use to study sexually-linked behaviors," says Asahina, who holds the Helen McLoraine Developmental Chair in Neurobiology.

"I think the interesting part of this is understanding that sex is really not a binary thing," says UC San Diego doctoral student Margot Wohl, co-first author of both of the new papers. "A lot of factors come together to control behaviors that differ between the sexes."

Since sex determination in flies is very different than in humans--fruit flies don't have sex hormones, for instance--the new findings don't carry over to how biological sex may impact behavior in people. But Asahina says his approach--the combination of optogenetics and sex-linked gene manipulation--may be useful in understanding behaviors that vary by sex in other animals.
-end-
Andre DeSouza of Salk was also an author on one of the two papers.

The work was supported by grants from the National Institute of General Medical Sciences (GM119844); the National Institute on Deafness and Other Communication Disorders (DC015577); the Naito Foundation; the Japan Society for the Promotion of Science; the Mary K. Chapman Foundation; and the Rose Hills Foundation.

About the Salk Institute for Biological Studies: Every cure has a starting point. The Salk Institute embodies Jonas Salk's mission to dare to make dreams into reality. Its internationally renowned and award-winning scientists explore the very foundations of life, seeking new understandings in neuroscience, genetics, immunology, plant biology and more. The Institute is an independent nonprofit organization and architectural landmark: small by choice, intimate by nature and fearless in the face of any challenge. Be it cancer or Alzheimer's, aging or diabetes, Salk is where cures begin. Learn more at:
Salk Institute

Related Neurons Articles:

The first 3D map of the heart's neurons
An interdisciplinary research team establishes a new technological pipeline to build a 3D map of the neurons in the heart, revealing foundational insight into their role in heart attacks and other cardiac conditions.
Mapping the neurons of the rat heart in 3D
A team of researchers has developed a virtual 3D heart, digitally showcasing the heart's unique network of neurons for the first time.
How to put neurons into cages
Football-shaped microscale cages have been created using special laser technologies.
A molecule that directs neurons
A research team coordinated by the University of Trento studied a mass of brain cells, the habenula, linked to disorders like autism, schizophrenia and depression.
Shaping the social networks of neurons
Identification of a protein complex that attracts or repels nerve cells during development.
With these neurons, extinguishing fear is its own reward
The same neurons responsible for encoding reward also form new memories to suppress fearful ones, according to new research by scientists at The Picower Institute for Learning and Memory at MIT.
How do we get so many different types of neurons in our brain?
SMU (Southern Methodist University) researchers have discovered another layer of complexity in gene expression, which could help explain how we're able to have so many billions of neurons in our brain.
These neurons affect how much you do, or don't, want to eat
University of Arizona researchers have identified a network of neurons that coordinate with other brain regions to influence eating behaviors.
Mood neurons mature during adolescence
Researchers have discovered a mysterious group of neurons in the amygdala -- a key center for emotional processing in the brain -- that stay in an immature, prenatal developmental state throughout childhood.
Connecting neurons in the brain
Leuven researchers uncover new mechanisms of brain development that determine when, where and how strongly distinct brain cells interconnect.
More Neurons News and Neurons Current Events

Trending Science News

Current Coronavirus (COVID-19) News

Top Science Podcasts

We have hand picked the top science podcasts of 2020.
Now Playing: TED Radio Hour

Processing The Pandemic
Between the pandemic and America's reckoning with racism and police brutality, many of us are anxious, angry, and depressed. This hour, TED Fellow and writer Laurel Braitman helps us process it all.
Now Playing: Science for the People

#568 Poker Face Psychology
Anyone who's seen pop culture depictions of poker might think statistics and math is the only way to get ahead. But no, there's psychology too. Author Maria Konnikova took her Ph.D. in psychology to the poker table, and turned out to be good. So good, she went pro in poker, and learned all about her own biases on the way. We're talking about her new book "The Biggest Bluff: How I Learned to Pay Attention, Master Myself, and Win".
Now Playing: Radiolab

Invisible Allies
As scientists have been scrambling to find new and better ways to treat covid-19, they've come across some unexpected allies. Invisible and primordial, these protectors have been with us all along. And they just might help us to better weather this viral storm. To kick things off, we travel through time from a homeless shelter to a military hospital, pondering the pandemic-fighting power of the sun. And then, we dive deep into the periodic table to look at how a simple element might actually be a microbe's biggest foe. This episode was reported by Simon Adler and Molly Webster, and produced by Annie McEwen and Pat Walters. Support Radiolab today at Radiolab.org/donate.