Tag Archives: fruit fly

Social isolation can lead to overeating and under-sleeping — if you’re a fruit fly

New research on fruit flies provides the first reliable animal model for studying our bodies’ reactions to loneliness.

Image credits Mohamed Nuzrath.

Social isolation; we’re all probably more intimately familiar with the term, given these past two years, than we’d like to be. But we’re not the only ones who suffer when we’re separated from our group. New research on fruit flies shows that they as well sleep too little and eat too much when deprived of social interactions. The paper also reports on changes in gene expression, neural activity, and behavior seen in the flies.

The findings are of interest to all of us today, as they point to novel ways of understanding the effects loneliness has on our bodies. They’re also relevant to scientists directly studying fruit flies, or those whose work involves fruit flies, as accounting for these effects would go a long way to improving the reliability of our conclusions.

Flyin’ solo

“Flies are wired to have a specific response to social isolation,” says corresponding author Michael W. Young, the Richard and Jeanne Fisher Professor and head of the Laboratory of Genetics at Rockefeller. “We found that loneliness has pathological consequences, connected to changes in a small group of neurons, and we’ve begun to understand what those neurons are doing.”

It’s not a stretch to say that most of us have had trouble maintaining our pre-lockdown sleep schedule. Many of us are also overeating, or eating at odd hours, and have gained weight. The team behind this study suspected that the social isolation brought about by the lockdown is, in itself, to blame for this. It seems like their hypothesis panned out, as the results describe how chronic separation from the group can have measurable effects on the body (at least in fruit flies). These effects include changes in gene expression, neural activity, and behavior.

Fruit flies (Drosophila melanogaster) are a very social species. They forage and eat in groups, have complex mating rituals, and even engage in some tiny fights from time to time. However, they spend most of their time (up to 16 hours each day) sleeping — also in groups. They have long been a model organism for researchers in various fields of biology. So, when the team turned to them to test their hypothesis.

“Over and over again, Drosophila have put us on the right track,” says Young. “Evolution packed a great deal of complexity into these insects long ago and, when we dig into their systems, we often find the rudiments of something that is also manifest in mammals and humans.”

“When we have no roadmap, the fruit fly becomes our roadmap,” adds lead author Wanhe Li.

The team first compared how fruit flies behave under various lockdown conditions. Flies were kept together in groups of various sizes, ranging from several individuals to a single fly, for a week. For the most part, the insects didn’t have any problems; even flies who were kept with a single other fly didn’t show any distress. However, those that were entirely isolated from their peers started sleeping less and eating more as the trial progressed.

The team further reports finding changes in the expression patterns of a constellation of genes linked to starvation in the brains of these lonely flies. This, they argue, is the genetic link between social isolation and the observed biological changes. One group of cells known as P2 neurons were involved in changing the flies’ feeding and resting behavior. When the P2 neurons were disabled in chronically-isolated flies, they reverted to more normal feeding and sleeping patterns. Amplifying their activity in flies that were only isolated for one day caused them to exhibit the sleeping and overfeeding behavioral patterns of flies who had been isolated for a full week.

“We managed to trick the fly into thinking that it had been chronically isolated,” says Wanhe Li. “The P2 neurons seem to be linked to the perception of the duration of social isolation, or the intensiveness of loneliness, like a timer counting down how long the fly has been alone.”

While these findings haven’t been replicated in humans, the team is confident that more or less the same biological mechanisms seen in these flies operate in isolated humans as well. It’s not the same as confirming that people who ate more and slept less during the lockdown did so because of their P2 neurons — but it’s a starting point, at least.

“Clinically-oriented studies suggest that a large number of adults in the United States experienced significant weight gains and loss of sleep throughout the past year of isolation precautions due to COVID-19,” Young says. “It may well be that our little flies are mimicking the behaviors of humans living under pandemic conditions for shared biological reasons.”

The paper “Chronic social isolation signals starvation and reduces sleep in Drosophila” has been published in the journal Nature.

Why do men and women store fat differently? The answer might lie with fruit flies

In many species, females store more fat than males — something that applies both to humans and fruit flies. In fact, fruit flies are so genetically similar to our own species that we share nearly 75% of disease-causing genes. Some of these genes may also explain why females store fat differently.

Not only do women generally have a higher percentage of body fat than men, the areas where fat is concentrated also differs among the sexes. Women generally store more fat in the gluteal-femoral region (legs and buttocks), whereas men store more fat in the visceral (abdominal) region of the body.

These differences seem to be mediated by lifestyle and fat metabolism, as well as sex hormones and sex chromosomes.

In the scientific literature, there are hundreds of fat metabolism genes that are influenced in one way or the other by sex hormones and sex chromosomes, but not much is known about which particular genes are responsible for fat storage among the sexes.

In a new study published in the journal PLOS Biology, researchers at the University of British Columbia in Canada focused on the fruit flies’ genome.

Like women, female flies also store more fat than males and metabolize it more slowly. Given the fruit fly’s considerable genetic overlap with humans and the vast knowledgebase on the insect (fruit flies are one of the most studied animals), this made the fruit fly the perfect animal model for this study.

Fruit flies in the lab. Credit: University of British Columbia.

The study identified a gene called triglyceride lipase brummer (bmm) that is involved in the regulation of sex differences in fat homeostasis. Normally, male flies have higher levels of bmm mRNA both under normal culture conditions and in response to starvation. However, when the gene was removed in the lab, male and females stored exactly the same amount of fat.

This discovery might pave the way for identifying other metabolic genes that control male-female differences in other physiological aspects. More importantly, the findings could help researchers understand how metabolic differences between men and women contribute to the risk of diseases associated with abnormal fat storage, such as type 2 diabetes and cardiovascular disease.

Rare genetic mutations and the fruit fly explain how Zika causes microcephaly

In the early part of 2016, the World Health Organization’s Emergency Committee (EC) under the International Health Regulations (2005) (IHR 2005) discussed the clusters of microcephaly and Guillain-Barré Syndrome (GBS) cases that have been temporally associated with Zika virus transmission.

Brazil, France, the United States of America, and El Salvador provided information on a potential association between microcephaly and other neurological disorders with Zika virus. The recent cluster of microcephaly cases was considered a Public Health Emergency of International Concern (PHEIC). Several months later, the WHO confirmed in a scientific consensus that the Zika virus is linked with microcephaly as well as Guillain-Barré syndrome.

Three years and several studies later, researchers at Baylor College of Medicine revealed one way how in utero Zika virus infection can lead to microcephaly in newborns. The team discovered that the Zika virus protein NS4A interrupts the growth of the brain by taking control of a pathway that regulates the generation of new neurons.

Rare genetic mutations helped explain how Zika causes microcephaly

Zika virus protein NS4A interacts with ANKLE2, a protein linked to hereditary microcephaly.

“The current study was initiated when a patient presented with a small brain size at birth and severe abnormalities in brain structures at the Baylor Hopkins Center for Mendelian Genomics (CMG),” said Dr. Hugo Bellen, professor at Baylor, investigator at the Howard Hughes Medical Institute and Jan and Dan Duncan Neurological Research Institute at Texas Children’s Hospital.

This patient and others in a cohort at CMG had not been infected by Zika virus in utero. They had a genetic defect that caused microcephaly. CMG scientists determined that the ANKLE2 gene was associated with the condition.

Several years ago, Dr. Bellen and colleagues discovered in the fruit fly model that the ANKLE2 gene was associated with neurodevelopmental disorders. In a subsequent fruit fly study, the researchers demonstrated that overexpression of Zika protein NS4A causes microcephaly in the flies by inhibiting the function of ANKLE2, a cell cycle regulator that acts by suppressing the activity of VRK1 protein. Since very little is known about the role of ANKLE2 or VRK1 in brain development, Bellen and his colleagues applied a multidisciplinary approach to tease apart the exact mechanism underlying ANKLE2-associated microcephaly.

The fruit fly helps clarify the mystery

This image shows the two lobes of the brain of a fruit fly larva with hundreds of neurons, colored green, and stem cells, colored magenta. 

To figure out how Ankle2 mutations were influencing brain formation, the researchers went back to flies. Normally, Ankle2 works with a series of other genes to control the division of neuroblasts — stem cells that give rise to neurons. These cells are crucial for proper brain development.

Mutations in the Ankle2 gene, though, messed with neuroblast division. Larval flies with the mutation had fewer neuroblasts and smaller-than-expected brains. Further analyses revealed more details about how Ankle2 regulates asymmetric neuroblast division. They found that Ankle2 protein interacts with VRK1 kinases, and that Ankle2 mutants alter this interaction in ways that disrupt asymmetric cell division.

The Zika connection

In the future, a drug that protects this protein could stop Zika’s damaging developmental effects, says Dr. Hugo Bellen.

“For decades, researchers have been unsuccessful in finding experimental evidence between defects in asymmetric cell divisions and microcephaly in vertebrate models. The current work makes a giant leap in that direction and provides strong evidence that links a single evolutionarily conserved Ankle2/VRK1 pathway as a regulator of asymmetric division of neuroblasts and microcephaly. Moreover, it shows that irrespective of the nature of the initial triggering event, whether it is a Zika virus infection or congenital mutations, the microcephaly converges on the disruption of Ankle2 and VRK1, making them promising drug targets.”

Why fruit flies can eat practically anything

They’re a common guest in our houses, and they could teach us a thing or two about our own food preferences.

Drosophila melanogaster — the common fruit fly. Image credits: André Karwath.

Fruit flies are particularly interesting to researchers as they serve as a simplified model for genetic research, and have provided numerous answers about how genes work.

Despite their names, fruit flies don’t necessarily need to munch on fruits. They often pop up around things like banana peel, but they can survive on pretty much anything — in biological terms, they’re called “nutritional generalists.” Another species which falls under the same nutritional umbrella is us humans. However, while our close relatives can also have varied diets, the evolutionary cousins of fruit flies are quite different — they’re nutritional specialists, and can only feed on specific plants.

There is a lot of debate in the scientific world about why animals (and sometimes animals in the same family) have such different nutritional tastes. A new study might shed some new light on this issue.

“Uncovering the differences in the molecular mechanisms between nutritional generalists and specialists can help us understand how organisms adapt to variable nutritional environments,” explain Kaori Watanabe and Yukako Hattori of Kyoto University, who led the study. “In our investigation, we changed the nutrient balance in the food of different Drosophila species and compared their nutritional adaptability along with their transcriptional and metabolic responses.”

To uncover the secrets of the fruit flies’ diet, researchers looked at their larva. They designed an experimental setup to see if the larvae can survive on three experimental diets: high protein, high carbohydrate, and protein-carbohydrate mix.

As expected, the generalists were able to survive on all the types of diets — but the specialist flies couldn’t survive in a carbohydrate-rich environment.

Researchers then tried to figure out why this was happening and came to the conclusion that the most likely culprit is a signaling molecule called TGF beta. TGF beta (or TGF-β) regulates a number of cellular functions, including cell growth and differentiation.

“A signaling pathway known as TGF-β/Activin signaling regulates the body’s response to carbohydrates. In the generalists, this pathway is quite flexible and maintains metabolic homeostasis under different diets. In fact, there are about 250 metabolic genes that are downregulated when their diet is carbohydrate-rich,” they explain.

Essentially, in specialist flies, the genes directing this pathway are more strongly expressed. This means they’re more efficient in deriving nutrients from some foods, but unable to derive enough from others — this increased efficiency comes at the expense of adaptability. Researchers believe that generalists retained their robust carbohydrate-responsive systems through genome-environment interactions, whereas the specialists lost them after living in low-carbohydrate environments.

It’s still early days, but since humans and flies share quite a few of these genes and signaling pathways, this paves the way for a comparative approach regarding the genetic variability of humans in response to dietary intakes.

The study has been published in Cell.

Sparrows.

The ‘forager gene’ of humans and fruit flies works in practically the same way

An international team of researchers reports that a gene humans and fruit flies share has a similar effect on their behavior. The same gene is found in many species across the world, likely acting in a similar way.

Sparrows.

Image via Pixabay.

This might seem ludicrous, but there was a time in which humans couldn’t go to the grocery store to get food. In those dark times, we had to forage our way into a meal. New research shows that one gene with significant impact on foraging behavior in fruit flies (Drosophila melanogaster) has a similar effect on our own foraging strategies.

Will search for food

The team, which includes researchers from Canada, the U.K., and the U.S. has found that a gene known as PRKG1 — which is present in a wide range of species — can dictate whether individuals are “assessors” or “locomotors” when foraging for food.

The team worked with a group of college volunteers, who were asked to play a video game on a tablet. The object of this game was to find as many berries (which were hidden among plants) as possible. Each participant could navigate the environment at will and click on individual berries to pick them up. After playing the game, each volunteer was asked to give a tissue sample for DNA testing.

Some volunteers took a perimeter-first approach, the team reports — these were the “assessors” — while others dove right into the thick of it — these are the “locomotors”. Next, the team looked at the differences in the human equivalent of the PRKG1 — a nucleotide polymorphism genotype called rs13499 — among these participants, and compare them with those seen in fruit flies.

Prior research has shown that one variant of the PRKG1 gene pushes flies towards the “assessor” pattern of behavior, while another makes them “locomotors”. Upon entering an area, assessors are more likely to tour its perimeter first, then move inward. Locomotors, in contrast, make a beeline for the first fruits they see.

If you’re thinking ‘hey, those behaviors seem pretty similar,’ you’re spot on. The team reports finding the same gene variants responsible for instigating locomotor or assessor behavior in fruit flies in their college participants, having the same effect in both species. They further note that the search paths taken by the human volunteers and the sitter and rover fruit flies were nearly identical.

The findings suggest that this gene-induced preference in foraging patterns likely holds for other species as well. The team adds that their findings also suggest the patterns of behavior we employ when pursuing our goals can also be connected with these two gene variants.

The paper “Self-regulation and the foraging gene (PRKG1) in humans” has been published in the journal PNAS.

Scientists image entire fly brain in ungodly detail

No fewer than 21 million images and 7,062 brain slices, all obtained using two high-speed electron microscopes — those are the results of the most detailed digital snapshot of the adult fruit fly brain.

Here (in color), reconstructed the neurons in the fly’s brain responsible for providing odor to a brain region involved in memory and learning. Image credits: Z. Zheng et al. / Cell.

For most of us, fruit flies (Drosophila melanogaster) are little more than a nuisance, buzzing around our over-ripe fruits. But for brain scientists, fruit flies provide an excellent model. Recently, a team of scientists at the Howard Hughes Medical Institute’s Janelia Research Campus in Ashburn, Virginia, managed to map a fruit fly brain in unprecedented detail, identifying the individual synapses (junctions between neurons).

Essentially, they’ve created a visible neuronal roadmap, underpinning the web of connections that underpin specific fly behaviors.

“The entire fly brain has never been imaged before at this resolution that lets you see connections between neurons,” explains  Davi Bock, a group leader at Janelia who reported the work along with his colleagues on July 19, 2018, in the journal Cell.

“We think it will tell us something about how the animal learns – how it associates odors with a reward or punishment,” he explains.

The fruit fly has 100,000 neurons (for reference, humans have 100 billion). Each of those neurons branches out to reach other neurons, forming incredibly dense communication circuits.

Scientists can view these circuits, using a technique called serial section transmission electron microscopy. The technique, which has been developed for brain imaging but can also be applied to other fields, generates high-resolution three-dimensional images from small samples.

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Firstly, researchers dip the fly’s brain into a cocktail of heavy metals which mark the outline of each neuron, as well as its connections. Then, a small block of resin is prepared and ultrathin serial sections (100 nm thick) are cut using a specialized diamond “knife“. Some 7,000 slices are obtained.

The cuts are mounted on the block, where after further preparation, researchers hit the brain slices with a beam of electrons, which passes through everything except the metal-coated areas.

“It’s the same way that x-rays go through your body except where they hit bone,” Bock adds.

They used two electron microscopes which have a much higher resolution than conventional light microscopes.

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Traditionally, this process has been extremely slow. Everything had to be done by hand, and each photo had to be snapped individually. Imagine if you wanted to take 21 million photos — you’d be snapping for decades, Bock says. So he and his colleagues developed new tools to aid in this task, including two custom-built systems to rapidly move tissue samples in eight-micrometer increments, allowing them to quickly capture images of neighboring areas. With this, it only took seven minutes to image a brain slice — which is five times faster than the previous record. Engineers at Janelia also built a robotic loader that picks up and places samples automatically to help Bock’s team.

It’s remarkable how complex the fruit fly’s brain is, with so relatively few neurons.

“They can learn and remember. They know which places are safe and dangerous. They have elaborate sequences of courtship and grooming,” Bock explains.

For instance, Bock’s team followed a neuronal path that reaches out to the so-called mushroom body — a pair of structures in the brain of insects known to play a role in olfactory learning and memory. These cells have been described previously, but the new study allowed researchers to trace their outline more easily and confirm previous findings.

Moving on, there are many other neuronal pathways of interest which researchers will no doubt soon look into. Using the technical capabilities described in this new paper, it seems like researchers will able to move on to more human-like creatures, and that’s where things really start to get interesting.

The fruit fly brain dataset has been released and can be accessed and downloaded at temca2data.org. More than 20 lab groups are already working on the newly released dataset.

Journal Reference: Zheng et al.  “A complete electron microscopy volume of the brain of adult Drosophila melanogaster,” Cell. Published online July 19, 2018.

This photograph shows the head of a fly pupa. The ommatidia of one of the pupa's eyes are yellow and the fat body cells filling the head are visible in red. Credit: Anna Franz.

Scientists show how fat cells help heal wounds in fruit flies [VIDEO]

Fat cells in fruit flies (Drosophila) play a surprisingly important role in healing wounds and preventing infection. According to researchers at the University of Bristol, fat cells propel themselves forward towards the wound, brushing aside debris to be consumed by immune cells. Previously, fat cells were thought to be exclusively immobile, but these new findings suggest otherwise.

This photograph shows the head of a fly pupa. The ommatidia of one of the pupa's eyes are yellow and the fat body cells filling the head are visible in red. Credit: Anna Franz.

This photograph shows the head of a fly pupa. The ommatidia of one of the pupa’s eyes are yellow and the fat body cells filling the head are visible in red. Credit: Anna Franz.

First author Anna Franz was filming fly immune cells (hemocytes) when her attention was turned to large shadows moving across the frame. What objects could have cast such a giant shadow? Franz thought of fat cells “but of course, they shouldn’t be moving, because fat cells aren’t motile,” the scientist recalled. They really were motile, however.

“We had to be sure that they weren’t just drifting and then sort of sticking at the wound site,” said Paul Martin, professor of cell biology and senior author of the new paper, in a statement. “And we had to rule out that they weren’t just being sort of sucked to the wound by fluid coming out of the hole, much like if you tossed a flannel in a bath and then took the plug out.”

This movie illustrates how necrotic cells (bright red nuclei), are swept to the wound periphery by the incoming FBC (green). Elapsed time is in the top right corner in h:min:sec. Scale bars=20μm.Credit: Franz et al./Developmental Cell.

Fruit fly fat cells are large enough that anywhere from one to four cells are enough to plug the wound. Once at the wound, the cells keep bacteria out of the site of injury while it heals. The fat cells stay there until the wound is healed, after which they detach and swim off. “And that’s what this looks like as it moves,” said Martin, referring to fat cells’ mode of migration in fruit flies. Genetically modified versions of fat body cells which deactivated  actin and myosin, the proteins that constrict at the center of the fat cell, no longer moved to wounds. This suggests that the fat cells were actively migrating, rather than being carried along the way by hemolymph — the fluid equivalent to blood in flies.

“One important scientific lesson is “keep your eyes and mind open when doing experiments”; Anna wasn’t initially investigating fat cells; rather she was watching inflammatory cells as they move to a wound and just happened across the fat cells “swimming” to the wound too, and she was smart enough to realise that this was an even more interesting observation, because fat cells were not supposed to be motile,” Martin told ZME Science.

This sort of movement likely isn’t restricted to fat cells. The authors have shown that fat cells in vivo can move without adhering, and perhaps this is the case for other types of cells.

This image is a cross section through the thorax, wings, and legs of a fly pupa. Fat body cells have been false-colored orange. Credit: Anna Franz.

This image is a cross section through the thorax, wings, and legs of a fly pupa. Fat body cells have been false-colored orange. Credit: Anna Franz.

The researchers now want to learn how exactly the fat cells get instructed to the move to the wound. Even when there were no immune cells, fat cells still migrated to the wound where they collaborate with immune cells. Finding the chemical signals that guide the movement of the fat cells could prove extremely important. For instance, if fat cells prove to be motile in mammals as well, then these could be instructed to move around the body for therapeutic purposes.

“We are also fascinated by how fat cells might be utilised to enhance wound healing in patients, and how they might work together with inflammatory cells as a team,” Martin told ZME Science.

No one has shown yet that fat cells can migrate in vertebrates. “But perhaps they do,” he adds. “Now, because of this research, it would be worth looking at them. It’s not crazy to think that they might travel to a wound and do important things when they get there.”

Scientific reference: Developmental Cell, Franz et al.: “Fat body cells are motile and actively migrate to wounds to drive repair and prevent infection.”

 

Personal Space Violation.

Scientists poke at the root of our need for personal space — using fruit flies

Feeling like people are invading your personal space? It’s dopamine that does it, researchers report.

Personal Space Violation.

Image credits Jeff Hitchcock / Flickr.

We’ve all been there. You’re having a chat with somebody one minute, and the next they’re simply too close. You didn’t make a conscious decision about this, didn’t settle on a ‘too near’ line, but you just know it’s being overrun at that exact moment. So you back away, almost by instinct.

You’d think we have a pretty good idea of what’s working in the background of a concept as universal as ‘personal space’ — but not really. That’s why a team led by Anne F. Simon of Western University’s Department of Biology started studying the need for social space and how it can be disrupted. They report that dopamine, a neurotransmitter best known for its role in the reward pathway of the brain, is a key substance in mediating social space.

A-buzz with dopamine

The team worked with Drosophila melanogaster, the common fruit fly, as they come with certain very desirable traits: they develop really fast, lay a lot of eggs, and are dirt-cheap to feed and care for. They’ve seen a lot of use in scientific pursuits, and they’re the insects Gregor Mendel used to lay the foundation of genetics.

Using genetic and pharmacological manipulations, the team tailored the neurons in some of the flies to produce more or less dopamine than those in unaltered fleas.

Their results show that dopamine is a key component in “the response to others in a social group, specifically, social spacing,” and could change how much space the flies need from each other. The effect was “prominent only in the day-time, and its effect varies depending on tissue, sex and type of manipulation.” For example, too little dopamine made male flies seek greater distances from each other, while too much dopamine made them close ranks. In female flies, both too much or too little release of dopamine made them increase social distance.

“Each animal has a preferred social bubble, a preferred personal space,” said Anne Simon.

“If we can connect the dots with other animals including humans — because we all have similar neurotransmitters — we may gain new ways of understanding what’s happening in some disorders where personal space can sometimes be an issue.”

That discovery may, in turn, have implications for better understanding conditions related to dopamine imbalances, such as schizophrenia or the autism spectrum, for example.

Next, the team plans to expand on the findings from the other way around, and find our how social cues influence dopamine release, and to identify the circuitry that regulates it.

“Ultimately, this research could lead us to understand a little better why some people are averse to social contact. It might also help us understand why some people who clearly want to interact don’t interpret some social cues the same way others might,” said Simon.

The paper “Modulation of social space by dopamine in Drosophila melanogaster, but no effect on the avoidance of the Drosophila stress odorant” has bee published in the journal Biology Letters.

Fruit fly.

Neuron cluster which can override sleep identified in the fruit fly brain

Certain neurons in the brains of male fruit flies will suppress the animal’s sleep if they have any female to court nearby.

Fruit fly.

Image credits John Tann / Flickr.

Who here hasn’t had to forgo the sweet embrace of sleep when something important pops up — a paper due in the morning, a book you just can’t put down. Or, if you’re a male fruit fly, because there’a a change you might get some action.

A team of researchers from the Sidney Kimmel Medical College at Thomas Jefferson University found that like humans, fruit flies (Drosophila melanogaster) can keep themselves awake if something important pops up. More specifically, they report that a certain group of neurons in the males’ brains can suppress their sleep so they can court female flies.

Up all night to get lucky

The study started from the observation that although male flies usually spend most of the night awake trying to court nearby ladies, those who have recently mated several times (and thus have a low sexual drive) tend to ignore females and simply go to sleep.

It would suggest that something in the fly’s brains has to (consciously or unconsciously) decide what was more important to the fly at one point — sex or sleep. But nobody knew exactly how this process unfolded, and that’s what the team set out to understand.

“The idea that sleep and courtship might compete with each other is intuitive but had not been studied experimentally, and the underlying neural mechanisms had not been explored. We wanted to know how the sleep drive and sex drive compete to determine behavior,” says Kyunghee Koh, PhD, Associate Professor of Neuroscience, Sidney Kimmel Medical College at Thomas Jefferson University and senior author on the study.

The team zeroed in on a bunch of neurons dubber MS1 (male specific 1) that seem to be at the root of this process. MS1 neurons aren’t part of any previously known groups of neurons which play a part in male sexual behavior, but work by keeping the males awake so they can ply their charm. They release octopamine, a neurotransmitter similar in function to noradrenalin, which will keep male flies awake in a sexual setting. Experiments showed that silencing the MS1 cluster caused males to go to sleep even if there were females around, and artificially activating the neurons kept males awake even in the absence of females.

Interestingly enough, while females have the same bunch of neurons they don’t seem to function the same — activating or inactivating the cluster had no effect on the females’ sleep.

We don’t yet know whether there are similar mechanisms functioning in our brains, but we do know that noradrenalin creates wakefulness in humans. This would suggest that the neurotransmitter plays a key role when we’re trying to consciously suppress sleep, the team notes.

But until we get a definitive answer on that, the team wants to identify which neuron communicate directly with the MS1 cluster, examine how their activation leads to sleep suppression and how MS1 neuronal activity is regulated.

The full paper “Identification of octopaminergic neurons that modulate sleep suppression by male sex drive” has been published in the journal eLife.

Florida quarantines farmlands to contain the Oriental Fruit Fly

Florida’s farmlands are under attack by a highly destructive pest, the Oriental Fruit Fly, and authorities have quarantined some 85 square miles of land and the food grown there in an effort to contain the insect.

The invasive species was first detected a few weeks ago near Miami. Authorities have since banned the transport of most fruits and vegetables from the Redland, — part of Miami-Dade County, named after the pockets of clay that dot the land — one of America’s most productive agricultural stretches of land. Boasting a fertile soil and a year-round growing season due to its tropical climate, farms here produce everything from tomatoes to papaya that are sold all over the country.

Buuzzzzzzzzzz, not anymore, buuuzzzzz.
Image via wikipedia

In recent years, tropical fruit sales have seen a steady rise, with new varieties such as dragon fruit (originally from Asia) or mamey (a Central American crop) becoming available to a much wider range of consumers. Florida has been cashing in on locally growing these exotic treats, the agricultural industry here being valued at a hefty US$ 700 million — but as operations manager at J and C Tropicals Salvador Fernandez walks into one of the six coolers his company operates, that industry seems very close to a dangerous fall.

“It’s usually full,” he says, “especially at this time of year, because we do truckloads of mamey and avocado and passion fruit and dragon fruit.”

The storage coolers are empty, while fruit ripens and rots in the company’s orchards. Two weeks ago, agriculture officials froze production in much of the Redland farming area after they detected the Oriental fruit fly. The quarantine was imposed just as growers were beginning to harvest tropical fruit crops. Fernandez can’t say how much it’s all likely to cost.

“We estimated that we have mamey alone about 500,000 pounds left on the trees,” he says. “[As for] dragon fruit, that leaves 20 million pounds on the trees potentially.”

Florida’s agriculture commissioner, Adam Putnam, has declared a state of emergency and ordered fruit stripped and destroyed in areas where the flies have been found. All kinds of tropical fruit were affected, including sapodilla, guava and passion fruit. Traditional market crops like tomatoes, bell peppers, beans and squash are also in for a rough start, as the quarantine was enforced when the crops should have been planted.

Inspectors have found about 160 Oriental fruit flies so far. But counts have been dropping, which may be a sign the eradication measures are working. But even a population as small as this gives the authorities reasons for concern: what makes the Oriental fruit fly so devastating, Putnam says, is that it affects more than 400 crops.

“[The fruit fly] feeds on the fruit. It pierces it, lays its eggs, causes obviously a very unpleasant condition in that fruit when those eggs are laid in there.”

Past experience with this fly thought the farmers how destructive they can become, but it also left them well equipped to deal with them — Florida has seen 75 fruit fly incursions over the past 90 years, and has eradicated them every time. Paul Hornby with the U.S. Department of Agriculture says scientists and farmers have a great deal of experience with fruit flies, both the Oriental variety and their Mediterranean cousins, and that it’s only a matter of time before the crops recover.

“I’m extremely confident we’ll get our arms around this, and hopefully, within a matter of a few months, we’ll be out of the situation,” Hornby says.

At J&C Tropicals, Salvador Fernandez is working to save some of his tropical fruit by irradiating it before sending it to market. That’s approved by federal and state authorities, but it’s costly. With a drought and another pest that’s hit the avocado crop, it’s been a tough year for growers, and time might be something they might not have. If authorities don’t eradicate the fruit fly soon, Fernandez says there will be serious consequences for the industry.

“There’s a lot of growers that will go bankrupt,” he says. “There’s a lot of people they just don’t have the cash flow to sustain these kind of losses.” Fernandez says he’s already received calls from four growers who told him they want to sell their farms.

Flies feel fear too, but probably not in the way humans do. Drawing: Kim Carlson

Flies feel fear too, but do they have other emotions as well?

Fruit flies experience fear, one of the primary emotions, according to a new research that suggests there’s much more to flies scattering about in the face of a swatter than a mere robotic reflex. But do the flies feel other emotions too? That’s an extremely difficult question to answer, since the researchers themselves aren’t even sure what they’ve been observing is genuine fear. It does, however, bear all the characteristics of fear. The findings are important since the show that other “lesser beings” that have a primitive nervous system like other insects or spiders might also experience fear, and possibly other emotions as well like happiness or sadness. Who knows, maybe love too?

Flies feel fear too, but probably not in the way humans do. Drawing: Kim Carlson

Flies feel fear too, but probably not in the way humans do. Drawing: Kim Carlson

“No one will argue with you if you claim that flies have four fundamental drives just as humans do: feeding, fighting, fleeing, and mating,” lead author William Gibson said in a press release about the study published in the Journal Current Biology.

“Taking the question a step further — whether flies that flee a stimulus are actually afraid of that stimulus — is much more difficult,” added Gibson, who is a Caltech postdoctoral fellow.

Attaching electrodes to the fly’s brain is difficult and likely doesn’t work very well. So, the best method the scientists had at their disposal to gauge whether or not flies feel fear was purely observational. So, in this case, you need to know very well what are the defining characteristics of fear and how the emotion plays out to single out the behavior in the flies. Gibson argues that there are four basic tenets of fear: persistence, scalability, generalization  across different contexts and trans-situational.  These are called emotion primitives.

“If you’re hiking and hear a rattlesnake, your heart is going to pound and you experience fear long after the snake is gone,” said  California Institute of Technology biologist and lead author David Anderson explaining persistence. Scalability refers to the amplification of the emotion. If you see a rattlesnake nest filled with four, five or even ten snakes you should feel more afraid. Generalization and trans-situational refers to responding in a similar fashion, but in different contexts and situations. If you learn to be afraid of gun shots, you might also shiver when you hear the rattle of a pan hitting the floor or a loud clap.

The experimental apparatus used for the study. Image: Current Biology

The experimental apparatus used for the study. Image: Current Biology

The researchers placed hungry flies in an arena and watched how they behaved when a shadow was overcast. When the shadow was cast over the food, the flies would repeatedly scatter away. Sometimes, the flies froze in place – a defense mechanism often observed in many animals, be them rodents or humans. It also took some time before the flies returned to the food source, despite they were starving, suggesting there’s a lasting psychological state and not a momentary escape reflex. The flies moved away each time the shadow was placed, suggesting persistence. When more than one shadow was cast over the food, most flies scattered at a higher speed, suggesting scalability.

This sort of research is important, since it provides a basic foothold for studying how basic emotions are formed, and possibly how these emotions differ across other species. For instance, Gibson and Anderson can never know for sure what’s in the mind of a fly, but by all “verbal accounts” it does seem to feel fear, at least. It’s unlikely, however, that it feels fear in the way humans do (i.e. not as complex). The findings were reported in Current Biology.

“The argument that this paper makes is that the Drosophila (a type of fly) system may be an excellent model for emotion states due to the relative simplicity of its nervous system, combined simultaneously with the behavioral complexity it exhibits,” Gibson explained.

“There are two difficulties with taking your own experiences and then saying that maybe these are happening in a fly. First, a fly’s brain is very different from yours, and second, a fly’s evolutionary history is so different from yours that even if you could prove beyond any doubt that flies have emotions, those emotions probably wouldn’t be the same ones that you have,” he says. “For these reasons, in our study, we wanted to take an objective approach.” –

In the future, the researchers say that they plan to combine the new technique with genetically based techniques and imaging of brain activity to identify the neural circuitry that underlies these defensive behaviors. The ultimate goal is to identify those neural mechanism involved in creating the emotion primitive responses.

Fruit Fly

Mere presence of opposite sex triggers premature aging in fruit flies and worms

Ever found yourself in a hazardous relationship in which your spouse makes your hair go white? Well, if the answer’s yes then you’re not alone. A new study provides new evidence that key aspects of the social environment of some animals significantly influence life span after researchers found that sexually frustrated fruit flies and “haunted” hermaphrodite nematodes died earlier than expected.

Fruit Fly

(c) frankieflowers.com

Environmental cues play pivotal rules in an organisms’ development and health. It’s not only about the space and objects around an animal that influence it however, interactions with other members of the species also have an effect on longevity.  For instance, female fruit flies face a dramatic cut in life expectancy after mating since the male fruit fly’s seminal fluid contains toxins. Now, a group of researchers led by Scott Pletcher, a geneticist at the University of Michigan, Ann Arbor, found that sexually frustrated fruit flies live a shorter life.

An unshared love

Pletcher and colleagues played a most cruel prank on male fruit flies. The researchers genetically modified some male fruit flies to expel female pheromones that typically invite male for mating. To normal flies’ surprise they found they couldn’t mate  with these strange “females”.  This sexual frustration caused the males flies to lose fat, become stressed, and decrease in life span by 10%.

After dwelling deeper into the physiological processes sparked by the psychological sexual frustration, the researchers found that some neurons that signal the production of a certain protein which enable the flies to respond to rewards or mating were destroyed. So, basically living in a delusional world was too much for the fruit life as it never got to have a piece (reward) of what it was expecting (anticipation). Similar results were measured after female flies were modified to release male pheromones; this trickery caused female flies to also live shorter lives.

[RELATED] Promiscuous female mice breed sexier male offspring

Elsewhere,  Anne Brunet, a geneticist at Stanford University in Palo Alto, California, found that nematodes significantly lived less just after sensing the presence of the opposite sex. Now, for this particular nematode species, sex may not be the word to describe them since 99% of all specimens are hermaphrodites (lay eggs and produce sperm at the same time), while only 1% are males.

Simply smelling the opposite sex kills the roundworm

The researchers placed the tiny male roundworms in culture dishes for up to 2 days and then ejected them. In the same dishes, they introduced hermaphrodite worms. Even though the males were gone, the hermaphrodites could still sense them fact which significantly affected their life span. Like in fruit flies, the worms differentiate between sexes using pheromones and in this case, the males’ scent persisted in the dishes causing the hermaphrodites to experience   premature aging—the worms slow down or become paralyzed, and their muscles and internal organs begin to degenerate.  Genetically modified hermaphrodites engineered not to smell pheromones anymore had a normal life span – as in much higher than if they could sense male worms.

“We’ve known for a long time that mating can be harmful,” says Patrick Phillips, an evolutionary geneticist at the University of Oregon in Eugene. But these papers show that “you can have the effects without direct physical contact.”

What about mammals? The researchers say mammals are far more complicated, however I’ve read before of some studies that suggest castration increases lifespan in males. A very interesting  Korean study examined the genealogy records and lifespan of 81 Korean eunuchs to find that their average lifespan is ~14-19 years longer than that of non-castrated men of similar class.  Now, the data range is rather narrow but the life expectancy compared to the control general population is so great that it can only make you wonder. Want to live more? Well… you know what to do now.

fruit fly life cycle

New generation eco-friendly pesticide might work by shutting down insect reproductive system

Farmers, with the help of researchers in the field, have been desperately trying to develop new insecticides that can ward off pests looking to claim their crops. These products work with a varying degree of effectiveness. For one, the insect pests tend to develop tolerance and new solutions have to be developed, and of course there’s always the issue of poisoning to humans and mammals. Spraying chemicals on crops might kill your pests and preserve yields, but if it comes at a compromise to human health, then we’re spelling trouble here.

A new generation of  safe insecticides might prove to be the most efficient, if we’re to judge the latest findings made by an international team of researchers. The team successfully isolated for the first time a neuropeptide named natalisin that regulates the sexual activity and reproductive ability of insects. After blocking this neuropeptide, the researchers found that neither male or female insects were able to reproduce any longer. This neuropeptide is unique to insects and arthropods, so theoretically spraying it over crops won’t affect humans and will in return kill off all pests simply by leaving them no means of reproducing any longer.

fruit fly life cycle

(c) orkin.com

Neuropeptide is composed of short chains of amino acids in the brain of insects and arthropods and is part of their peptidergic system – a genetic network that uses small peptides as neurotransmitters to chemically relay messages throughout the body, particularly those related to sexual activity.

“Natalisin is unique to insects and arthropods and has evolved with them,” said Yoonseong Park, professor of entomology at Kansas State University. “It appears to be related to a neuropeptide called tachykinin that is in mammals and invertebrates. While tachykinin is involved with various biological processes, including the control of blood flow in mammals, natalisin is linked to reproductive function and mating behavior in insects and arthropods.”

The research followed natalisin interactions in fruit flies, red flour beetles and silk moths, each of them insects with four classic stages of development – egg, larva, pupa and adult. Natalisin distribution was manipulated using a genetic tool called RNA interference, or RNAi, which allowed the researchers to see what happens during each development cycle. They found that the absence of natalisin in the brain led to the insects’ physical inability to reproduce as well as reduced their interest in mating.

“For example, we saw that knocking out the natalisin in the fruit fly makes them unable to mate,” Park said. “The female is too busy grooming her body for the male to approach her. The male doesn’t send a strong enough signal to the female to get her attention. We’re not sure if that’s because the male can’t really smell her or because he is not developed enough to signal her.

This neuron knockdown might allow scientists to develop targeted pesticides that would be environmentally safe, because they wouldn’t affect plants, animals or humans. This statement, however, warrants one or a couple of new studies altogether. What effects on the local biosphere would such a pesticide pose? If a large population of insects become sterilized, besides the targeted pests, how would this affect other animals that depend on these for food, for instance? Honeybees always come to mind.These are just a few important questions that need to be addressed.

If anything, however, the study sheds new light on how the brain functions with the neurosystem, and provides more information about the basic biology of the fruit fly, which is the model insect for research. The research was made in cooperation between the Kansas State University, South Korea’s Institute of Science and Technology, Korea Academy and Slovakia’s Slovak Academy of Sciences.

Findings appeared in a paper published in the journal Proceedings of the National Academy of Sciences.

The fly's tendency to perform left or right turns (yaw torque) is measured continuously and fed into the computer. In closed-loop, the computer controls arena rotation (single stripe or uniform texture as patterns on the arena wall). An additional white screen (not shown) covered the arena from above for all groups. (c) Maye A, Hsieh C-h, Sugihara G, Brembs B (2007)

Fruit flies, and most likely other animals, have free will as well

We could go on about what free will is until dusk and still not reach a conclusion. Indeed, philosophers have been theorizing free will for thousands of years, but haven’t we neglected an important aspect? There seems to be a general consensus that free will is entirely a human trait, but what of other animals? An older study, published in a 2007 edition of PLoS ONE, showed that free will and true spontaneity exist … in fruit flies.

The common fruit fly is easy to care for, breeds quickly, and lays many eggs, which is why it has been used for decades in biological research, especially genetics. Actually it was one of the first organisms to be used in genetic research, and a number of advances, especially basic principles of heredity, have been proven and documented with the help of this insect.

Are animals, insects as well, simple robot-like minded organisms that merely respond to external stimuli and thus lack even the smallest hints of free will? This used to be the general understanding, among scientists at least, and when animals were observed behaving differently than expected, even to the same external stimuli,  this variability was attributed to random errors in a complex brain.

An international team of scientists, however, proved that this kind of variability in behavior cannot be due to simple random events but is generated spontaneously and non-randomly by the brain.

 The fly's tendency to perform left or right turns (yaw torque) is measured continuously and fed into the computer. In closed-loop, the computer controls arena rotation (single stripe or uniform texture as patterns on the arena wall). An additional white screen (not shown) covered the arena from above for all groups. (c) Maye A, Hsieh C-h, Sugihara G, Brembs B (2007)

The fly’s tendency to perform left or right turns (yaw torque) is measured continuously and fed into the computer. In closed-loop, the computer controls arena rotation (single stripe or uniform texture as patterns on the arena wall). An additional white screen (not shown) covered the arena from above for all groups. (c) Maye A, Hsieh C-h, Sugihara G, Brembs B (2007)

The scientists placed fruit flies in an environment where its surroundings were of completely uniform white, and recorded their turning behavior. No external stimuli whatsoever was introduced in the chamber – no light, no sound, no vibrations, nothing. Lacking absolutely no input, the fruit flies movement in the chamber should have resembled a random pattern, like the noise the radio makes when its tuned between stations. Using a combination of automated behavior recording and sophisticated mathematical analyses, the scientists found that the structure of the fly’s behavior was very much different from what one would call noise. A myriad of complex random computer models were introduced, but none could adequately model the fruit flies behavior.

 “I would have never guessed that simple flies who otherwise keep bouncing off the same window have the capacity for nonrandom spontaneity if given the chance,” said Alexander Maye from the University of Hamburg, lead author of the 2007 paper.

“We found that there must be an evolved function in the fly brain which leads to spontaneous variations in fly behavior” co-author George Sugihara said. “The results of our analysis indicate a mechanism which might be common to many other animals and could form the biological foundation for what we experience as free will”.

What is free will?

Just recently, another research team, this time from Harvard University, assembled a new experiment to test the fruit fly’s free will. The scientists used isogenic fruit flies – genetically similar from inbreeding, but not identical – which they introduced in a contraption they appropriately name the “FlyVac”. You’ll see why.

Fruit fly free will testing device T maze

Fruit fly free will testing device T maze

The device which the Harvard researchers employed has a T-shaped maze, like a fork in the road, with LEDs at each of the two ends. The end of the fork to be illuminated was chosen on random, and as the fruit fly entered the maze, it had to make a phototactic choice: either it went towards the light making the decision photopositive or move away from it, in which case the decision was photonegative. No matter its predispositions towards light, photons and such, the fly was vacuumed away from the maze rather unceremoniously, and taken back to its initial position. It then started all over again, and again, and again. I didn’t understand from the paper how many times per fly they did this, by I presume a lot – for 17,600 flies!

I bet your curious to find out what they got. Well, for instance one photopositive fruit fly strain chose light about 80% of the time. However, one oddball fly in this group chose light 100% of the time. When verifying other fruit fly strains involved in the experiment, similar results were found. The variability encountered was much grater than that possibly occurring from chance alone. The results were published in the journal PNAS.

 “The question of whether or not we have free will appears to be posed the wrong way,” says Brembs. “Instead, if we ask ‘how close to free will are we”‘ one finds that this is precisely where humans and animals differ”.