PHOTO: 123RF
the fruit fly
PROPOSITION
Sanne Ettema – Medische Wetenschappen
If you keep your face towards the sun, the shadows will fall behind you. (Helen Keller)
PHOTO: HENK VEENSTRA
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‘In fruit fly world, sex stands for a high chance of offspring’
TEXT: LIEKE VAN DEN KROMMENACKER
What can other living creatures teach us about spring fever and the power of attraction? We asked UG Professor of Neurogenetics Jean-Christophe Billeter, who is researching the genetics and social and sexual behaviour of fruit flies. ‘Once a female fruit fly has mated, she will always choose a
higher-quality male for her next mate.’
Female fruit flies excel in choosing their mates. As they only live for a few days in the natural environment, reproducing is an urgent priority, so monogamy is not in their vocabulary. Furthermore, genetics has equipped the females with a mechanism that makes them initially less choosy. This has everything to do with pheromones: aromatic substances produced by organisms to influence the behaviour of others.
Female fruit flies have a pheromone receptor in their nose. This is particularly sensitive in virgin flies, making them easily aroused when they detect the pheromones of the other gender. A glass of wine or beer also helps. In fact even vinegar can make a fruit fly feel fruity. ‘It’s the yeast that does it,’ Billeter explains. ‘This is an aphrodisiac for fruit flies: a stimulating agent that they can also use to feed their offspring.’
Get it on more quickly
Salient detail in the reproduction process: while mating, the sperm of the male fruit fly furnishes the female with another pheromone, which interferes with their pheromone receptor. In fruit fly world, sex stands for a high chance of offspring. Billeter: ‘So once a female has mated, the next male she chooses is of a higher quality: a fit and healthy fly that produces a lot of pheromone.’
In short: first, she mates as quickly as possible, and then she closes her doors until something better comes along. Can we humans learn anything from this? More alcohol? More promiscuity? Billeter laughs. ‘Of course we have an urban myth saying that foods like oysters and chocolate work as an aphrodisiac. We’re not sure if this is actually true. But the mechanisms by which men produce sperm and women produce eggs are the same as in fruit flies. And in humans too, the activation of certain genes generates differences between men and women. The details are different, but the logic is the same. So in that sense, we could perhaps learn a lot from fruit flies.’
Maybe follow your spring fever instincts, before it turns cold again? Billeter: ‘Fruit flies don’t mate in the winter. Ever. This is when they conserve their energy.’
For many animals and plants: as the spring develops, so does their sexual power of attraction. ‘The thing that fascinates me,’ says Jean-Christophe Billeter, ‘isn’t that it happens, but why it happens.’ As Professor of Neurogenetics at the UG, he is researching how genes influence the brain, and therefore behaviour. Which is how fruit flies flew into his career. ‘They really are model organisms. They’re cheap and largely devoid of ethical problems. We understand their entire genome, which is very similar to that of humans. They have senses, organs, and a day and night rhythm. We know exactly how all their 120,000 nerve cells connect with each other and which information they pass on to the brain.’
Anything but monogamous
Fruit flies reproduce most actively in the summer months; the warmer temperatures and greater availability of food increase the chances of their offspring surviving. By studying both their genes and their mating habits, Billeter learned that only the males in the species display courting behaviour.
‘The gene responsible for courting behaviour is activated in the male brain, but not in the female,’
he explains. This gene also controls aggressive behaviour. ‘So if the gene is not activated, you’re a
non-courting, non-aggressive fly. In other words: a female.’
PHOTO: 123RF
of the fruit fly
Sanne Ettema – Medische Wetenschappen
If you keep your face towards the sun, the shadows will fall behind you. (Helen Keller)
PROPOSITION
Female fruit flies excel in choosing their mates. As they only live for a few days in the natural environment, reproducing is an urgent priority, so monogamy is not in their vocabulary. Furthermore, genetics has equipped the females with a mechanism that makes them initially less choosy. This has everything to do with pheromones: aromatic substances produced by organisms to influence the behaviour of others.
Female fruit flies have a pheromone receptor in their nose. This is particularly sensitive in virgin flies, making them easily aroused when they detect the pheromones of the other gender. A glass of wine or beer also helps. In fact even vinegar can make a fruit fly feel fruity. ‘It’s the yeast that does it,’ Billeter explains. ‘This is an aphrodisiac for fruit flies: a stimulating agent that they can also use to feed their offspring.’
Get it on more quickly
Salient detail in the reproduction process: while mating, the sperm of the male fruit fly furnishes the female with another pheromone, which interferes with their pheromone receptor. In fruit fly world, sex stands for a high chance of offspring. Billeter: ‘So once a female has mated, the next male she chooses is of a higher quality: a fit and healthy fly that produces a lot of pheromone.’
In short: first, she mates as quickly as possible, and then she closes her doors until something better comes along. Can we humans learn anything from this? More alcohol? More promiscuity? Billeter laughs. ‘Of course we have an urban myth saying that foods like oysters and chocolate work as an aphrodisiac. We’re not sure if this is actually true. But the mechanisms by which men produce sperm and women produce eggs are the same as in fruit flies. And in humans too, the activation of certain genes generates differences between men and women. The details are different, but the logic is the same. So in that sense, we could perhaps learn a lot from fruit flies.’
Maybe follow your spring fever instincts, before it turns cold again? Billeter: ‘Fruit flies don’t mate in the winter. Ever. This is when they conserve their energy.’
“
‘In fruit fly world, sex stands for a high chance of offspring’
PHOTO: HENK VEENSTRA
For many animals and plants: as the spring develops, so does their sexual power of attraction. ‘The thing that fascinates me,’ says Jean-Christophe Billeter, ‘isn’t that it happens, but why it happens.’ As Professor of Neurogenetics at the UG, he is researching how genes influence the brain, and therefore behaviour. Which is how fruit flies flew into his career. ‘They really are model organisms. They’re cheap and largely devoid of ethical problems. We understand their entire genome, which is very similar to that of humans. They have senses, organs, and a day and night rhythm. We know exactly how all their 120,000 nerve cells connect with each other and which information they pass on to the brain.’
Anything but monogamous
Fruit flies reproduce most actively in the summer months; the warmer temperatures and greater availability of food increase the chances of their offspring surviving. By studying both their genes and their mating habits, Billeter learned that only the males in the species display courting behaviour.
‘The gene responsible for courting behaviour is activated in the male brain, but not in the female,’ he explains. This gene also controls aggressive behaviour. ‘So if the gene is not activated, you’re a
non-courting, non-aggressive fly. In other words: a female.’
What can other living creatures teach us about spring fever and the power of attraction? We asked UG Professor of Neurogenetics Jean-Christophe Billeter, who is researching the genetics and social and sexual behaviour of fruit flies. ‘Once a female fruit fly has mated, she will always choose a higher-quality male for her next mate.’
TEXT: LIEKE VAN DEN KROMMENACKER