The Weirdest Things We've Done to Fruit Flies | Compilation

this slash of compilation video is supported by brilliant as a scishow viewer you can keep building your stem skills with 20 off an annual premium subscription at brilliant.org scishow [Music] fruit flies have been the backbone of laboratory experiments for about a hundred years they're not as charismatic as like monkeys or birds so flies don't often get a lot of our sympathy and it doesn't help that they are also really annoying when they're all over your house if your gut instinct is to start swatting you're not alone but fruit flies face some bigger stranger Fates than just getting killed in your kitchen researchers I really put these little guys through the ringer and it is not just out of spite So today we're bringing you some of the wildest experiments that fruit flies have been subject to and what we have learned from it all first we need to address the fly in the room why are we so fixated on manipulating these particular animals we've done everything from give them cancer to mess with their sleep but Michael has a solid explanation for all these random studies before scientists test new drugs diagnostic procedures and Therapeutics on humans they usually start by evaluating how those things perform in animals but sometimes their choice of animal seems maybe not not that representative of human biology like one common test subject is a fruit fly except fruit flies have been behind some of the most groundbreaking discoveries in physiology and medicine and they're helping us understand everything from inheritance all the way to cancer and sleep in some ways the reason we use fruit flies in the lab are pretty basic like they're cheap to keep and maintain for example but there are also bigger reasons for one the Flies are much easier to study than complex vertebrates especially when it comes to genetics their whole collection of genetic material consists of just four pairs of chromosomes compared to hour 23 that means it's easier to study what genes do and how they interact they're simpler genes and structure also make fruit flies relatively easy to genetically modify which allows us to test what happens when you break things and of course their short life cycle is useful in a research setting too but like here's the key thing fruit flies also have a shocking amount in common with us they have equivalent genes for 60 percent of the human genome they also have a similar Gene for 65 to 75 percent of the human genes that have been linked to diseases like Alzheimer's diabetes and many Cancers and thanks to those similarities they've shown us quite a bit fruit fly research officially began in the early 1900s when the now famous biologist Thomas Hunt Morgan was studying how genes are inherited by this point in history we knew inheritance was a thing but we didn't quite understand how it worked so Morgan was looking into it in his research he found a male fruit fly with white eyes instead of the typical red and he observed how this trait was passed on by breeding different fruit flies together ultimately he discovered that only male flies ever had these white eyes and that the genetic factor that determined eye color was on the same chromosome that determined sex in doing so he was the first to link the inheritance of a trait to a specific chromosome and it not only earned him a Nobel Prize but it opened the door to most of what we understand about inheritance in humans today because we also have traits controlled by our genes on our sex chromosomes one example is red green color blindness which is passed down on the X chromosome that's why people who are x y and only have one copy of this chromosome are more like likely to be colorblind usually men people with two X chromosomes would need to have the gene for color blindness on both of them which is less likely meanwhile one of Morgan's students named Herman Mueller made another revolutionary Discovery using fruit flies that earned him a Nobel Prize he found that X-rays and other ionizing radiation can cause genetic mutations by breaking apart chromosomes this can cause DNA to get deleted duplicated swapped around or just inserted into the wrong place all of which could be passed on to offspring thanks to his work we now take precautions when taking x-rays like using those heavy lead aprons you might wear at the dentist but this work had implications Beyond inheritance too since they had to keep track of all these rearrangements scientists ended up creating records of what sorts of genetic information lived in different parts of the chromosome and that led us to broader discoveries like it taught us more about how embryos developed specifically it let us find one of the signaling Pathways that controls development within an embryo a signaling pathway is how cells communicate with each other this one is called Notch because researchers found it while trying to figure out what made certain fruit flies develop notches in their wings but lots of other animals have it including mammals like us through a lot more research spanning decades scientists not only learned how it communicates with other cells but that this pathway is critical for the development of things like neurons blood cells the heart bones and skin through this pathway cells are told what to become during differentiation the process where they transition from one type of cell to another notch also controls cell multiplication survival and equilibrium that means that any mutations or abnormal signaling can result in developmental disorders and Cancers and really that's only the start of the list the potential applications of fruit flies in biomedical research are far from exhausted they're being used to study wound healing new bioengineering Technologies the effects of new Pharmaceuticals how the brain works and cancer as a whole like in the 2010s the number of cancer studies using fruit flies increased exponentially and they're teaching us about everything from how tumors spread all the way to why cancer cells can resist medication fruit flies have even taught us about sleep it turns out that fruit flies need to rest just like we need to sleep making them a good model for studying the mechanisms and function of sleep because we still don't know why sleep is a thing we need by looking at their genetics researchers have identified genes and signaling Pathways that affect fruit fly sleep cycles as well as the regions of the brain responsible so while these results don't have direct applications to humans yet they could lead to a better understanding of the differences in sleep habits really fruit flies may look Nothing Like Us on the outside but because of their biology and their genes there's a practically endless number of things that they could teach us so the next time you see a bunch of them hovering around your fruit bowl you may want to thank them before getting out the flyswatter those were some of the most famous fruit fly experiments ever conducted but for some reason this next experiment didn't quite get the same accolades nobody gave a Nobel Prize to the scientists who programmed fruit flies to ejaculate On Cue but then again why would anyone want to do that here's the announcement from 2018 when we found out animals need to like sex to keep doing it and having babies but scientists aren't always clear on which aspect of sex is compelling for them like with male fruit flies maybe it was something about cozying up to a female fly or finding a really great grapefruit maybe it was something else and in a study published on Thursday in current biology Israeli neuroscientists found out that male fruit flies aren't all that different from humans because they like to ejaculate too for their experiments they had to get the mail fly to release his sperm without a female in the picture normally this would be a hard nut to crack but oddly enough scientists know which neurons trigger ejaculation in male flies and because of a technique called optogenetics they can genetically engineer certain neurons to turn on in response to light this means researchers can make flies that ejaculate whenever the researchers want just by flashing a light in this case a red light which can pass through a fruit flies exoskeleton and hit those modified neurons the future is now the team put these engineered flies into a box with a red light on one side and then looked to see whether they hung out more in that space if they did it was a sign that they found it rewarding and did the Flies ever they strongly preferred the well-red light district but females and unmodified males wandered around and didn't prefer any particular area activating the ejaculation neurons a lot also increased the amount of a signaling molecule called neuropeptide f which normally Rises after lots of fly sex so that's another sign that the researchers are tapping into a natural reward circuit so team they still can't say for sure whether pleasure comes from activating the ejaculation neurons or from other signals related to releasing seminal fluid but it's clear that flies like it so why well one reason why researchers are so interested in fly sex is because understanding basic reward systems could help us better understand Addiction in fact another clue that flies like to ejaculate is because when they do they drink less alcohol flies normally prefer alcohol-based food to a normal version but that's not the case after a few blasts of red light in humans it's bound to be more complicated than that but researchers hope that they can use flies to dig deeper into the reward mechanisms at play when someone abuses or is at a higher risk of abusing a drug so one day maybe a non-alcoholic toast to fly ejaculation will be in order apparently the fruit flies we're actually having a blast in that experiment so I guess you're welcome fruit flies and while we're patting ourselves on the back here's another great experience we've foisted upon fruit flies space travel space tons of people would spend a lot of money to go into space and here we sent the fruit flies for free here's why from the scishow space Channel 200 years from now it's entirely possible that we will have people living off Earth full time either on another planet like Mars or in some kind of space station by then we'll probably be pros at living in Low Gravity environments we'll have figured out how to solve the problems we have today like how space flight can take a toll on the heart and immune system and when we get to that next big chapter of humanity will have a tiny test subject to thank fruit flies while it may not seem like useful stand-ins for humans fruit flies have more in common with us than you might think many of root light genes mirror the functions of human ones making them useful and understanding what those genes do they also have some characteristics that make them especially great for studies performed in space for one they don't take up a lot of room which is super important in an environment where space is limited thousands of flies can be housed in a container the size of a deck of cards also their lifespan is only about two weeks so scientists can study several generations of them in a month so fruit flies have been sent to space over and over again to test different effects of space flight especially how microgravity affects living bodies and while we still have plenty of questions they are already teaching us a lot for instance in Space the heart acts a little differently like among other things its muscles get weaker since they're not Fighting Gravity we know this is true of other muscles as well but considering how how important the heart is figuring out exactly how it changes in microgravity will be huge for our long-term future in space and these are of course things we're studying in humans but we can only send so many people to the space station at a time which means we can only learn so much about exactly what's happening to the heart and how to combat it so one study published in November 2020 used more than 200 fruit flies as a model for how space flight affects cardiac disease and function the scientists found that flies living in microgravity had smaller hearts that weren't as effective at pumping blood which is similar to what can happen to astronauts the researchers also found the Flies had problems creating the proteins needed to keep the heart working properly so now that's something else for cardiac researchers to keep an eye on and eventually studying these proteins could accelerate the development of new treatments especially for longer missions but as important as our hearts are one area of fly research that's been especially fruitful is studying the immune system astronauts experience a suppress question of their immune system during and right after space flight that makes them more susceptible to infection and flies offer a very specific Advantage for helping us understand how and why see the human immune system has two branches innate and adaptive the innate immune system is something you are born with it's essentially a system of barriers that protect against foreign particles like viruses bacteria and parasites these include physical barriers like your skin and general immune responses like inflammation meanwhile the Adaptive immune system is the part that learns to respond to threats as it's exposed to them using specialized cells and antibodies untangling what each branch does and how it changes in space is somehow even harder than it sounds and that's where fruit flies come in they do not have adaptive immune systems that's limited to us vertebrates so they can allow us to really dial into just how the innate immune system works without the whole other part getting in the way and confusing things the key with the innate immune system is that for it to work your your body has to recognize pathogens as foreign object then it can work on fighting them to do that the innate immune system uses molecules called receptors to bind and recognize other molecules on the surface of infectious agents like bacteria and viruses and when it comes to space flight Studies have found that the immune system can become impaired with communication to these receptors is disrupted like a 2014 study showed that fruit flies born and raised aboard the Space Shuttle Discovery were a lot more susceptible to certain infections compared to flies on Earth but in that study only one of the two receptor systems the researchers looked at was impaired the one that responds to fungal infections the other which responds to certain types of bacterial infection was unaffected they haven't quite figured out why and proposed that it could have something to do with how the specific proteins act in each system but it could mean that the fungal receptor is more sensitive to disruption in microgravity which would suggest that the effects on the innate immune system aren't the same across the board meanwhile the study also found that fruit flies that experienced increased gravity which happens during launch and re-entry had a boosted immune response to fungus again it's not clear why maybe it's that something about the proteins is more stable in hypergravity but maybe somehow intentionally subjecting astronauts to increased gravity could have therapeutic uses on long duration missions or maybe it just means we need to put more time and Research into developing anti-fungal Coatings to extend space fly research even further NASA established the fruit fly lab on board the ISS in 2015. this small long-term housing for the Flies allows more in-depth study than those on the space shuttle such as studying the effects of space flight on the interactions between a microbe and host and results from this lab are still coming in teaching us even more about how our immune systems work in space so it seems weird that we'd use those buzzing nuisances always drowning in your tea to learn about ourselves and even weirder that we would launch them into space taking them to the one place where we can and finally be free of them to do it but researchers are carrying out even more experiments using the fruit fly lab to learn more about immunity and life in microgravity meaning fruit flies still have more to teach us about what living in Space is really like so someday when our first people do move off Earth permanently they'll not only know what to expect but how to stay as healthy as possible okay so maybe the heart problems in the fungal infections weren't the best things for those fruit flies but at least they got to go to space now we are not astrophys or anything but we can teach you a few things about space through brilliant brilliant is an online learning platform that offers guided courses in science computer science and math they keep learning engaging through interactive puzzles and lessons for Learners of all levels their course on gravitational physics takes you through the engineering of space travel even out there where Newton's Laws get a little shaky in this course you'll learn about gravity and orbits without the negative side effects that those flies experienced from actually going to space you can check out brilliant today by by clicking the link in the description down below or heading to brilliant.org scishow as a scishow viewer you'll get 20 off an annual premium subscription and thanks to brilliant for supporting this scishow compilation brilliant can help us understand things a little better in a world where there's so much that we don't understand like for example how anesthesia works you think that we'd have a handle on that because hospitals use it all the time and have been for a long time but here is the fruit fly research that finally showed us what anesthesia is doing to our bodies it's safe to say that general anesthesia has made modern medicine possible so it might surprise you to hear that even though doctors have been using general anesthesia for nearly 200 years they haven't known exactly how it works in the brain to temporarily shut it down we know that anesthesia doesn't just put someone to sleep it's closer to a temporary coma where you don't respond to pain or other stimuli your anesthesiologist can keep you in that state and reverse it when it's time to wake up but what's actually happening in your brain while that goes on has been a mystery until now there have been two main hypotheses for how anesthesia works on a molecular level the first called the lipid hypothesis has been around since the turn of the 20th century that's when scientists observed that the potency of some anesthetics directly correlates with their ability to dissolve in oils our cell membranes are made of oily molecules called lipids and there are several anesthetic drugs that are all oil soluble so it made sense that an affinity for our cell membranes could be the key to how they worked but the lipid hypothesis started to lose support after the membrane protein hypothesis gained Traction in the 1980s that's when evidence was coming to light that anesthetics could bind to proteins in the membranes of nerve cells as opposed to interacting with the membranes themselves we've managed to identify several proteins that bind with different anesthetics and protein binding is how most drugs work still that didn't explain what those anesthetics were doing after they were bound but a June 2020 study has revealed a major Clue Into the mechanism of general anesthesia and in this case it's actually consistent with the lipid hypothesis the study was specifically interested in inhaled anesthetics rather than injected ones it demonstrated that inhaled anesthetics disrupt lipid rafts in nerve cells these are clusters of lipids that form part of the cell membranes of neurons they seem to play a key role in the central nervous system studies suggest that lipid rafts are more tightly packed than the surrounding cellular membrane and have a slightly different chemical composition the researchers used a super high-tech microscope to show lipid rafts expanding and bursting apart like billiard balls in response to anesthetics when the rafts burst apart they spill their contents including an enzyme called pld2 once on the loose the researchers showed pld2 heads over to a protein called Trek 1. once there it binds to Trek 1 and switches it on that causes it to open up and turn out positively charged potassium nerve cells need a certain balance of charged particles including potassium to Fire and do their jobs the potassium increases the charge of the nerve enough for it to malfunction inhibiting the firing of neurons in other words words you're out like a light or so it went in fruit flies to image the rafts the researchers used an advanced microscope that can pick out single molecules lipid rafts are smaller than what you can normally image using visible light a limitation called the diffraction barrier this technology finally provided enough resolution to work around that barrier and actually visualize the lipid rafts which is how they were finally able to propose an answer to such an old question we're still not sure why this mechanism exists obviously it didn't evolve so surgeons could use anesthesia further research ought to shed light on why our neurons do this billiard ball lipid raft thing it could also help scientists better understand how neurons work and may reveal new treatments for nervous system disorders so we finally have an idea for how some kinds of general anesthesia work after over a hundred years of trying to figure it out which is pretty cool and reassuring if you're headed in for surgery sometime soon for all the outrageous things that we do to fruit flies it's nice to know that we can anesthetize them I mean after this next experiment they might be asking for some anesthesia because to get a better understanding of fear scientists designed entire experiments to scare flies so here's the news from 2015 of what a scared fruit fly looks like it's kind of tough to identify emotions in animals like flies because how would you know fly fear if you saw it but a group of American researchers has translated fear into a few basic behaviors so that animal's responses could be studied without assigning them subjective human feelings like Dread or anxiety scientists arrived at behaviors like whether an animal's response was persistent meaning that it lasted for a while or if it was scalable in which case repeated stimuli would cause a greater response they call these traits emotion Primitives sort of like the Primal components of emotions that some animals may have in common to test for those components the team put groups of fruit flies into well-lit containers and then passed an object over them to cast a shadow just like a bird or a rodent would if they were approaching to prey on them then they observed the fly's responses sometimes the Flies just froze a defensive reflex which makes a lot of sense but other times the Flies started hopping around erratically when the Shadows passed over them and the more the shadow returned the more agitated they seemed to become the researchers then tried the experiment on flies as they were feeding and they found that flies not only abandoned their food when the shadow approached but the more often the shadow came by the longer they took to return to their food so the Flies responded to these repeated threats in ways that were both persistent and scalable which to the researchers at least is a lot like what we call fear but other than making everyone feel bad for a bunch of fruit flies what does this accomplish well the researchers want to study the biological and evolutionary origins of fear and since fruit flies and humans have about 60 percent of their genomes in common studies like this can be useful in researching and eventually treating prolonged states of anxiety fear and other emotional disorders in people they might be on to something Shadows can be terrifying sometimes but to abandon your food like that's next level scary I mean food is one of the great joys of life I could sit around and eat all day and I would be happy I'm hungry right now I'm thinking about the pizza that is just two blocks from where we filmed this but eating all the time is not really an option if I want to maintain my functional physique at least for me as a human but here's a news announcement from 2020 that explains how fruit flies could pull it off exercise is an important part of staying healthy but I'm sick of it what if we could get the benefits of working out without actually having to work out it's 20 20. well in a new study in nature Communications researchers report a type of protein that seems to confer the healthy effects of exercise to be more specific having higher levels of this protein improved things like muscle tone and endurance in flies and in mice but the research does have important implications for human health it could help us better understand the exact physiological changes that exercise causes in our bodies and that knowledge could help doctors care for a lot of people just to be clear these researchers were not trying to get me out of going to the gym they were searching for ways to help people stay healthy when they can't exercise say due to the effects of age or illness or injury that work LED them to study a group of proteins called cestrin previous research has shown that sestrin's build up in muscles following exercise but it wasn't clear why or what they actually do so the international research team designed a workout routine for fruit flies they put the flies in vials and then by Shifting the position of those vials the team encouraged the Flies to repeatedly climb up the sides basically a fly treadmill they also used a similar technique to induce flies to fly across the vial and some of these flies were engineered to lack cestrons over weeks of exercise the normal flies experienced several health benefits including a faster metabolism and increased endurance the flies without cestrids saw no such improvements so the researchers tried essentially the same thing with mice and it was the same Story the mice engineered to lack sestrons didn't gain the usual benefits of a workout regimen instead they got winded when they ran on their little wheels all that made it pretty clear that sestrons were required for the benefits of exercise so the researchers tried dialing up sestron levels instead of lowering them and flies engineered to over produce estrogens not only had stronger muscles and more endurance they got buff without doing their workouts the researchers suspect that cestrons are responsible for coordinating the cellular Pathways that underlie the health effects of working out and that might mean they can be used to help people stay toned while they can't exercise for example in a related study published this week in nature Communications researchers found that the muscles of mice engineered to overexpress cestrons didn't weaken an atrophy when kept from moving so it's possible that in the future sestrins could help people who are bedridden keep their muscles healthy but if you're hoping to to go to the store and buy some cestron supplements we are not anywhere close to that yet none of the study animals were fed cestrins to get these effects instead the teams tinkered with their genomes to get them to over produce estrogens where they are normally made ancestryans are large proteins so they may not work well as pills your stomach might just chop them up and digest them like any other protein and if they're absorbed they might not travel to where they're needed besides scientists have a lot more to learn about these proteins and how they work especially in humans since you know we are not flies or mice but with more research we might someday be able to use the knowledge we gain of out cestrons to help people be healthier see some of the fruit fly science isn't so bad we gave them the power to never move and get buff doing it once again the fruit flies are getting quite a lot of benefit out of these experiments and that's an example of how great people are at rationalizing the unusual stuff that we do we can always tell our ourselves that these experiments aren't as bad as what some other animals are doing to fruit flies like we cannot be as bad as the parasitic wasps that Rose is about to describe these days most of us can agree that Contracting a virus is generally a bad thing so you could imagine that in most species parents would want to protect their offspring from viruses but among certain parasitic wasps passing a virus to their offspring is the key to the species survival one of these wasps is a tiny non-stinging insect that lays its eggs inside fruit fly larvae now this might sound like a weird place to put babies inside another creature but it can actually work out great the babies get a safe place to develop with a constant food source as long as they can avoid getting killed by the host's immune system and these wasp eggs can adult wasps turn fruit fly larvae into hospitable hosts by infecting them with a type of virus called a pox virus this pox virus is in the same family as smallpox but it's specific to Insects the wasps and the species are generally all infected by it but it's evolved to be harmless for them fruit flies aren't so lucky though each time a female wasp lays her eggs in a fruit fly larva she also injects the virus into it with her Venom gland inside the larva the virus multiplies and spreads soon it completely overpowers the host's immune system and that's what makes it possible for the WASP eggs to develop in peace under different circumstances the larva's immune system would identify the eggs as foreign objects and kill them but while it's overrun it can't do a thing the Wasps eventually hatch and continue developing inside the larva feeding on their hosts until all its tissue is gone once they're mature they emerge as adults and their host larva dies before ever becoming a fruit fly now even though this symbiotic relationship seems to work out for the wasp and the virus exposing vulnerable Offspring to a dangerous virus still might sound like a bad thing and to be clear it's not like the WASP knows it has a virus or is thinking about whether that virus is good or bad for its babies it's just doing what it evolved to do but fortunately both species have evolved to the point where the virus is harmless to these wasps even the baby ones and oddly enough for the WASP immersing its Offspring in the virus before they're born may be crucial for its survival in a 2022 study entomologists at the University of Georgia found that as the WASP develop and feed on The larva they're in constant contact with virus particles these accumulate on the WASP outside shell also called a cuticle and as the WASP larvae mature and develop Venom glands the virus particles get incorporated into them the authors of this study believe that this is the main way the WASP is able to get enough virus to successfully over overrun a fruit fly larva's immune system as an adult they found that if the outside of the developing wasp was sterilized with bleach after being exposed to the virus they lost their viral infection and wasps without the virus weren't nearly as good at ensuring their offspring had a nice larva to grow up in this unusual relationship with a virus may not just be useful for wasps in the future it could also be useful to us humans that's because the fruit fly hosts of these parasitic wasps can be a major agricultural Pest and parasitoid wasp species are known for helping keep pest populations down in the areas they live it's a reminder of the many ways nature can Inspire solutions to our problems if we make the effort to understand it at least scientists don't infect flies with pox virus lay their eggs inside baby fruit flies and then eat their flesh from the inside out but they do put those things together so that they can study process so I guess they're not entirely blameless either thanks for watching the scishow compilation if you liked hearing about the range of things that people do to fruit flies you will probably enjoy our other video about scientists who injected Venom into them and other animals to see just how dangerous it is that's right we made a very long compilation video about all the weird things we've done to fruit flies and we couldn't even fit all the videos we've made about weird things we've done to fruit flies in it [Music] thank you

Channel: SciShow

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Keywords: SciShow, science, Hank, Green, education, learn, complexly, fruit flies, the weirdest things we've done to fruit flies, what fruit flies taught us about human biology, human biology, biology, new insights into what fruit fly sex is like, the surprising benefits of space flies, space, we finally know how anesthesia works, anesthesia, seasonal genes and the science of fear, science of fear, fear, how to get buff without exercise if you're a fly, exercise, why viruses are good for wasps, wasps, virus

Id: MYzEHuaL3e8

Length: 29min 44sec (1784 seconds)

Published: Thu Jan 26 2023