Fruit fly larvae and wasp
What’s the News: Fruit fly larvae have unusually high alcohol tolerance, which scientists used to think was because they happen to feed on yeast in rotting fruit. Turns out they’re in it for the alcohol, too—as medication. According to a new study*, alcohol protects them from the wasp parasites that lay eggs in fruit fly larvae.
What’s the News: When prions or amyloids make the news, it’s usually because they cause mad cow disease or Alzheimer’s—prions, after all, cause any proteins they touch to become as misfolded as they are, and amyloids, which are large clumps of wadded-together proteins, can jam the workings of cells.
But a new study in Cell suggests that a prion-like protein that forms amyloids has a normal, vital function in the brain. Far from being a memory destroyer, this protein, called CPEB, is necessary for long-term memory in fruit flies.
These psychedelic images come from one of two studies in the journal Nature Methods, which present similar but slightly different ways to color the connections between neurons in a fruit fly. The projects build upon similar research from 2007 that achieved this “brainbow” effect in mice, and they could allow for new ways to track the formation and purpose of brain cells.
The researchers gave the insects genes for a red, a green, and a blue fluorescent protein. The genetic control system they devised spurs each cell to make a different amount of each of the three proteins. Like the red, blue, and green pixels on a TV screen, the combination of the three proteins causes each cell to glow a unique color. [ScienceNOW]
The inserted genes come from naturally glowing jellyfish. They allow not just individual cells to be seen, but also connections:
Imagine taking a course of antibiotics and suddenly finding that your sexual preferences have changed. Individuals who you once found attractive no longer have that special allure. That may sound far-fetched, but some fruit flies at Tel Aviv University have just gone through that very experience. They’re part of some fascinating experiments by Gil Sharon, who has shown that the bacteria inside the flies’ guts can actually shape their sexual choices.
The guts of all kinds of animals, from flies to humans, are laden with bacteria and other microscopic passengers. This ‘microbiome’ acts as a hidden organ. It includes trillions of genes that outnumber those of their hosts by hundreds of times. They affect our health, influencing the risk of obesity and chronic diseases. They affect our digestion, by breaking down chemicals in our food that we wouldn’t normally be able to process. And, at least in flies, they can alter sexual preferences, perhaps even contributing to the rise of new species.
Not Exactly Rocket Science: You are what you eat – how your diet defines you in trillions of ways
Not Exactly Rocket Science: An Introduction to the Microbiome
80beats: Scientists Peer Into the Brain of a Fruit Fly in Mid-Flight
80beats: Alcoholic Fruit Flies Don’t Know When to Say When
Image: Wikimedia Commons
In today’s edition of far-out science, researchers have found evidence that the wafting aroma of food has an effect on an organism’s lifespan–and they’ve demonstrated that interfering with a fruit fly’s sense of smell causes it to live a longer, healthier life. While there’s no guarantee that the trick would work for humans, optimistic researchers suggest that certain odors—or drugs that block us from sensing them—might one day help prevent disease and extend lives [ScienceNOW].
In the past decade, scientists have established a clear connection between extremely low-calorie diets and extended lifespans; studies have demonstrated that yeast, fruit flies, mice, and monkeys on these diets live longer than their peers. While the exact mechanism at work isn’t yet clear, researchers suspect that a near-starvation diet causes an organism’s metabolism to slow down, and triggers other changes that evolved to help organisms survive in times when food was scarce. Now scientists say it may not be just what a creature eats, but also what it smells that has an effect on how long it lives.
In one 2007 study, molecular biologist Scott Pletcher and his colleagues found that completely eliminating fruit flies’ sense of smell caused them to live nearly 20 percent longer than normal flies. They also found that wafting the smell of yeast, a tasty treat for fruit flies, towards flies that were on a low-cal, live-extending diet hastened the death of those flies. This led the scientist to hypothesize that specific odors might be influencing the flies’ lifespans. Luckily, other scientists had identified a receptor in a group of neurons that enable fruit flies to smell carbon dioxide, which signals the presence of a good meal of tasty yeast [ScienceNOW]. So, Pletcher and his team set out to find if the CO2 had anything to do with the duration of the flies’ lives.
In leafcutter ants and honeybees, it’s survival of the fittest sperm. Biologist Boris Baer, for a study out this week in Science, investigated these two species because of their peculiar sexual practices: In one day, the queen acquires all the sperm she’ll need to fertilize her eggs over the course of her lifetime. But in the race to be the top genetics-spreader, the males have evolved a dirty trick. Their seminal fluids actually do battle within the female’s reproductive tract.
To test out the idea, Baer and colleagues exposed the sperm of the bee and ant males to their own seminal fluid, and also to that of other males of the same species. The seminal fluid killed more than 50 per cent of the rival sperm within 15 minutes. “The males seemed to use the seminal fluid to harm the sperm,” says Baer [New Scientist]. When the team studied other organisms whose lifestyle didn’t depend on this kind of polyandry, they didn’t see the same effect.
Thanks to a little technological ingenuity, we may soon get a look at what exactly is happening in the flying brain. In the journal Nature Neuroscience, Caltech researchers document how they managed to monitor the brain activity of fruit fly in flight.
“The challenge was to be able to gain access to the brain in a way that didn’t compromise the animal’s ability to fly, or to perform behavior,” said study researcher Michael Dickinson of Caltech. “We couldn’t just rip the brain out of the body and put it into a dish” [LiveScience]. Researchers have previously studied activity in the tiny brain of a living fruit fly, but only when it was restrained. Dickinson’s team created a way to look inside while the bug was flying around.
Despite their tiny size and short lifespan, fruit flies are familiar test subjects in labs because they can show us a lot about ourselves, particularly in terms of genetics. And in a study for Current Biology, a team led by Anita Devineni found that the insects have another thing in common with people—they like alcohol, sometimes a little too much.
The scientists started by giving their test subjects a choice. Flies held inside vials could sip from thin tubes holding either liquid food spiked with 15 percent ethanol or plain liquid food. The researchers measured the descent of the liquids inside each tube to get a readout of which food the flies preferred [Science News]. It was no contest: The flies preferred the alcohol-spiked food, and the more they had it, it seems, the more they craved it—the flies’ tipples grew more frequent over time [National Geographic News].