Mikhail Atallah

Transcription

[music] Jessica (J): Hi everyone we are coming to you live from Purdue University with our "It's a Gene Thing" zipTrip. I'm Jessica, your Purdue zipTrip guide. Now we have students all over the country watching this broadcast. Just take a look at this. Hales Corners Lutheran Middle School are you guys there? [kids yell] GO Rangers! I love to see that pride. Are you guys ready to have some fun today? [kids yell] YEAH! J: Cool OK, We'll be checking in with you periodically throughout the show. And right here in the studio, we have students from right here in Indiana joining us from Southmont Junior High School. Hey Guys! Kids yell "Hey" J: Don't be shy, don't be shy. While we cannot see all of you out there today's zipTrip is interactive and you have the chance for your voices to be heard. Now, if you have a question for any of the scientists you can email them into us here at the show. We're using a new way to send email. It's through our new website. So for all of you teachers out there, on your my zipTrip page in the It's a Gene Thing show you will see a green box on the left side of the screen where you can submit your questions for the show. Just type in the question and hit ask. You can ask as many questions as you want. And don't worry if we cannot get to your question today, a few days after the show is over there will be a link to all of the questions asked with answers from our scientists. And we are also using another great interactive technology today called Purdue Hotseat and let me tell you it is hot, hot, hot! We're using it to take student questions so everyone say hello to our Hotseat correspondent Abbey. Hey Abbey! Abbey: Hello everyone. Hotseat is a social media program that lets us use computers, cellphones and other mobile devices to pose questions and vote on the ones that you students would like to see answered on the show. The hotseat is packed today. Joining me here we have River Valley Middle School, St. Francis and Claire, Hales Corners Lutheran Middle School, St Thomas Aquinas Regional School, Andrew J Brown Academy, Noblesville West Middle School, McDuffy School, Hendersonville Middle School and St. Thomas Moore's School. Now hotseat users, be sure to answer the poll question before moving on to topic #1. J: WOW, we've got a lot of schools joining us today. And thank you Abbey we look forward to hearing from those schools throughout today's program. Now this zipTrip is all about genetics. Do you know what a scientist who studies genetics does? Well today we're going find out. First we are going to meet a young geneticist who's on a team researching the mechanisms that allows some plants to thrive in soil with high levels of poison like arsenic. Then we'll connect with a laboratory right here on campus where something fishy is going on. Finally we will work with Purdue wildlife experts outdoors and indoors to use our scientific inquiry skills to help solve a genetics case about these unique amphibians. So get ready to meet some scientists, have a little fun and learn something too. This zipTrip is all about genetics and the mystery of life. [music] Watson: Come take a look at this Crick. Crick: What is it Watson? [music] Watson: I think we're on to something. What does this imagine of deoxyribonucleic acid or DNA look like to you? Crick: Why, I believe it looks like a long twisted ladder. Watson: Yes, yes, it appears that DNA looks like a double helix. See the two phosphate backbones and the base pairs are like the rungs of a ladder. Crick: Let's build a DNA model with simple materials from the lab. Watson: Totally. Crick: Show the world that DNA, the very building blocks of life, are like a twisted ladder. Watson: This is so exciting. Crick: Yeah! [music] J; This is so exciting. Yeah! Well as we're learning today, DNA is the genetic material that determines a plant or animal's characteristics. Like the color of leaves or for humans the color of a person's hair. Scientists who study DNA and all of the different structures and environments that surround it are called geneticists. There are many geneticists working right here and studying here at Purdue. And joining me now is one of them. Nadia Atallah. Hi Nadia. Nadia: Hi Jessica. J: Thanks for being here today. Nadia: Thank you so much for having me. J: This is your first time with zipTrips so we're so lucky to have you. Now you don't look like a normal scientist so what's your story? Nadia: Well, I'm a scientist and also a graduate student studying plant genetics here at Purdue in the department of Botany and Plant Pathology. J: Very cool stuff. So are studying the genes of plants much different than studying the genes of humans or animals.? Nadia: The fundamentals of genetic research are the same. Going back to basic Mendelian genetics. For instance we all start out learning the Punnett square. Do you all know about the Punnett square? J: Do you guys know anything about the Punnett square? Looks like we may need a refresher. Nadia: Right, so here's a quick example on how a Punnett square works, this one using mice. J: Great, let's take a look. Nadia: The Punnett square is a diagram that is used to predict an outcome of a particular cross or breeding experiment between two individuals. The Punnett square is a visual representation of Mendelian inheritance. Genes are either dominant or recessive and we will represent that by an upper case letter and a lowercase letter. In this Punnett square we will use the letter "B". We will use mice as an example in this Punnett square. The big "B" will mean dark brown fur and the little "b" will mean white fur. There are four sections to this Punnett square with each section representing an outcome of 25%. We have two light brown mice. We'll be determining the probability that the offspring of these two mice will have either dark brown fur, light brown fur or white fur. Both mice have one big "B" which gives dark fur and one little "b" which gives white fur. Mating these two mice gives us one square with two big "B"s. This gives us a brown mouse. We get one big "B", little "b" which gives is a light brown mouse. Then we get a little "b", big "B" which also gives us a light brown mouse. And finally we have a little "b", little "b" which gives us a white mouse. And that's how a Punnett square works. J: Well that was a great quick genetics lesson, but you are a plant geneticist. So can you tell us a little bit about what you're studying? Nadia: Sure. I have two areas of research. The first it focuses on plant development, specifically sex determination in plants. So how the sex of a flower or plant is determined is very important. In humans we know that sex is determined through sex chromosomes. However, plants have a wide variety of mechanisms from sex chromosomes to sex being determined by the environment. J: Wow, the environment. Nadia: So the plant we study is we focus on a fern - pteridophyta. Ferns have been around for a very long time, since even before the dinosaurs. J: So they're like prehistoric. Nadia: Yeah, exactly. So because of this and because seed plants such as the crops we rely on today evolved so much later we can learn a lot about seed plant development by studying more basal groups of plants such as the ferns. So in our lab we use a variety of techniques to study pteridophyta. I use a mix of molecular biology, computational biology and reverse genetics. J: Which is what we are seeing right now. Nadia: So forward genetics is when you have a phenotype and you want to find the gene that is responsible for that phenotype. Reverse genetics however, is when you have the sequence of the gene and then you want to see what that gene does. So we use reverse genetics in our lab in that we have the sequences of the genes and we want to find which of these genes determine sex in pteridophyta. So we do a lot of knock out experiments. So we knock these genes down and then we look at the phenotype. Knock down experiments can tell you a lot about a genes function. For example, if I'm studying a plant that makes purple flowers and I want to know if gene A is responsible for creating the purple pigment I can knock down the expression of gene A and then if the plant starts producing white flowers I know that there's a really good chance that gene A was involved in some way in making the purple pigment. J: So you solved that purple pigment mystery. Nadia: Exactly. J: Awesome. That's really interesting work that you do. So how is what you learned applied to your future work? Nadia: So overall we want to uncover how sex determination occurs in pteridophyta, however then we can apply this research and knowledge to seed plants. So how sex is determined in plants is very important and has profound implications in agriculture and plant breeding because the sex of the plant determines what other plants it can be bred with and in some cases even cultivation. So you see, genetics can unlock a lot of processes for us. It can improve agriculture, it can improve plant breeding and can even lead to the creation of plants with new traits such as drought tolerance or the ability to tolerate toxins in the environment. And that brings me to my next area of research. J: And I see you've brought some plants with you today. Some little friends. So what's their story? Nadia: I'm working on a team of researchers here at Purdue that is studying this fern - pteris vittata. What's neat about this fern is that it has genes that allow it to hyper-accumulate and tolerate large quantities of arsenic. J: Arsenic? Like the poison? Nadia: Yes. Arsenic is a highly toxic element and arsenic contamination is prevalent in many areas of the world in the soil and water. It can be naturally occurring or it can be a result of human activities. This arsenic contamination often leads to arsenic poisoning. So we're studying this plant because it can accumulate and tolerate arsenic. It tolerates 100-1000 times more arsenic than other plants. So the amount of arsenic that this plant will thrive in will kill plants such as this venus flytrap. And quickly kill them. And so we're studying the genes involved in this response because this plant also can literally suck arsenic out of the soil and store it in the fronds here. J: That's so cool. So we can hopefully use these genes and put them in other plants to allow these plants to suck arsenic out of the environment and then we could maybe use these plants to remediate contaminated soils. J: So the fern is basically like a toxic savior, like a super hero. Nadia: Yes. It is a super hero fern. J: That's really amazing. Thanks for telling us all about your work today. Before we let you go, I hear we've got some hotseat questions for you so Abbey what's the hotseat question of the moment? Abbey: The hotseat question of the moment is why does DNA look like a twisted ladder? Nadia: So DNA is a double helix. It has a sugar phosphate backbone and it has complimentary base paring. So it's all about the structure of the DNA, that's why it looks like this double helix. The base pairs you have A pairs with T, G pairs with C and then you have these on the sugar phosphate backbone and it has minor grooves and major grooves and that's why it has this twisted shape. J: Very cool stuff. We also just got an email question that came in for you from Blake. He is at West Middle School in Nobles Indiana and the question is: if the sex of a plant is determined by environment will changing the environment change the sex? Nadia: Yes, absolutely. So in the plant that I'm studying Pteridophyta, the female plants release a pheromone that turns all the developing plants male. So then if you take one of these male plants and plant it by itself, away from these female plants it will revert back to a female plant. J; So will that happen with male plants will they be able to turn a female plant male? Nadia: No not in this species. Only the females have the ability to do that. J: Wow! Go females. Alright. So let's check in with Hales Corners. Do you have any questions for Nadia? Student: Yes we do. In your video you mentioned reverse genetics. So what exactly is that? Nadia: We start with the sequence of the gene. We have the sequence but we don't know what the gene actually does. What we do is we try to figure out what the function of this gene is. One way you can do this is to by lowering the expression of this gene or knocking it down and then looking at the phenotype that we see. It is kind of the opposite of what you normally think of when you think of genetic experiments which is known as forward genetics - when you see a phenotype and you try to see what gene causes that phenotype. J: So total reverse. Thanks for your question. And let's go ahead and check in with our studio audience. Do you guys have any questions for Nadia? Yes, you're right in the center. Student: About how long does it take before you can determine the sex of a plant? J; Good question. About how long does it take before you can determine the sex of a plant? Nadia: That's a very good question. It varies by species. So in the fern I'm studying about six days. However, in some plants such as date palms it can take over a decade. And that's why understanding the mechanisms of sex determination is so important because it's really hard to breed those plants that you don't even know what sex they are for a decade. J: Awesome. Well thanks so much Nadia. We're going to check back in with you at the end of the show so stick around. And if any of you think of more questions just submit them through our website. [music] J: Wait so you mean to tell me we are all mutants? I know I look pretty spooky in that video. Before we go to our next scientist I have a quick genetics activity for us to try. So do this with me. I want you guys to pull on your earlobes. Like this. I want you to see if your earlobe is attached or detached. What about you is it attached? Student: Attached. J: Mine is detached. And now I want you guys to stick out your tongues, I know this is silly. I want you to see if you can roll your tongues like this. Anybody? Some of you? Some can't and some can. OK, so let's go ahead and check in with our hotseat and see what they are saying. Abbey. Abbey: Our poll shows that 75% of our hotseat users have nonattached earlobes while 25% have attached and 75% of our hotseat users can roll their tongue while 25% cannot. J: OK so I guess I'm in the majority with the tongue rolling thing. Now we've learned that thanks to genetics we have physical traits like different eye color or hair color but have you ever thought about why we all have different personalities? Or are more interested in some subjects than others? For example why do some of us like to travel, like this girl right here and some of us don't. Let's take a look at this. [music] Girl 1: Hey how's it going? Girl 2: Great, I'm so glad it's the weekend. Girl 1: Me too. Do you have any big plans? Girl 2: No, not really. I'm just going to stay at home, play some solitaire, maybe hang out with my brother, watch TV, get on Facebook maybe. Girl 2: Well, if you get bored you should call me. A bunch of us have been planning to go to the movies and get ice cream afterwards. Girl 1: That's OK. I really need to get caught up on some TV shows. Girl 2: Tomorrow Sara and I are going to the festival downtown and then maybe go shopping. You should come with us. It would be really fun. Girl 1: I really just like to stay home and hangout on the weekends. I mean, don't you like to take it easy and relax? Girl 2: No way, I like to get out of the house, hang out with my friends and do different things. So if you get bored just give me a call. Girl 1: OK, well there's my mom. Girl 2: See you! [music] J: Well just like humans there are some animals who like to travel and some who don't. A scientist here at Purdue is trying to find out more about fish and what makes them swim in some pretty unique places. Joining us live from his lab in the Lilly Hall of Life Sciences here on campus is fish geneticist Matt Hale. Hey Matt! Matt: Hey Jessica! J: Can you wave hello to everyone who is watching? Matt: Sure, Hey everyone! J: Matt can you tell us a little about where you are? Matt: Sure. I'm in the Lilly building here at Purdue University, the main campus in West Lafayette. Here in the Lilly building is where the department of biology is kept. Here the many different scientists working on answering many different questions in biology. Some people work in cancer, some people work in photosynthesis and some people work in animals. We've got people here working with amphibians, some people work with birds as well as several different scientists who work in fish. Like myself. J: That's really cool. Your lab sounds really cool and very high tech. But you're not always in the lab, right? Matt: That's right. We have a facility about 5 miles to the west of campus the aquaculture facility. Which you guys are seeing some footage of right now. So here there are several different researchers who keep several different species of fish alive and that lets us ask and answer several different questions about the fishes biology or about their behavior. So some of the footage you are seeing now are of one of the two species of fish I work on. These guys are called brook trout. Brook trout are found throughout the Great Lakes region of Canada and North America. And some of the questions we're looking at with these guys is why is it that some of them seem to stay at home whereas others of them migrate. Some of these guys migrate around Lake Superior and Lake Huron before returning to breed. So we can see now some of the footage of some of the fish. We weigh them, we measure them, we can cross them. So we can take the eggs from one fish and the sperm from another fish and cross them to make a new generation of fishes. We can keep looking at these fish and measuring things like their size or their weight and seeing how that changes from generation to generation. J: Very cool stuff. We're learning that scientist are using different animal models to learn more about different types of genetics. So Matt can you tell us of all the animals in the whole world why did you decide to work with fish? Matt: When I was about 8 I got a fish tank for a birthday present from my parents and that kind of started my interest in fish. I had things like guppies and silver-tails. The sort of things you can see now-a-days in pet stores. But I've been interested in migration for a long period of time. Many different of species of animals migrate from birds to mammal and insects. But often it's really difficult to know whether or not an individual has migrated or if it hasn't. With the fish, with the salmon and the trout it's really, really easy to tell if an individual has migrated or not because of the appearance, the size of the fishes are very, very different. J: Gotcha. So they are great creatures to study. Now your job takes you to all sorts of cool places and I hear you have a really cool project going on right now. Can you tell us about that? Matt: Definitely. So the main project I'm involved with here at Purdue is found in Alaska not far from the town of Sitka which you guys are seeing some pictures of now. Matt: This is really, really remote. You can't get there by car. There are no roads so you've got to get there by a float plane. They need some more float planes. What we're doing here is we're looking a different species of trout. We're looking at a species called rainbow trout. But just like the brook trout they have two different types. A type that stays at home and types that migrate. These guys, these big silvery guys they migrate out into the North Pacific for 3-5 years before they come back to spawn. But these smaller colorful guys with the pink band along the center, those are residents. They stay in the streams that they are born throughout their whole lifecycle. One of the cool things about this system is that we can catch the fish as they are coming back. Now you are seeing some of the drift nets we put out. When we put these out right as the fish are coming back from the open ocean to spawn and that lets us catch all the migrate fishes that are trying to get back into the streams to spawn. What we can also do, as you're seeing now, is we can take boats up river and catch some of the resident fish, the ones that don't migrate out into the ocean by just basically using a fly and reel. So just going fly fishing and collecting the fish. J: So you basically have the home-body fish and then you have the thrill-seeker fish. Matt: Yes, you got it. J: So how long were you in Alaska? Matt: I was in Alaska for about two weeks right at the end of May and early June. J: Awesome. How big was your team? Matt: There were about 5 or 6 scientists who were up there pretty much throughout the whole breeding season. So when the first fish start to come back in the middle of May through to about June 20th or there abouts. J: Do you bring back information from the fish in Alaska to your lab here in Purdue. Matt: Yes, definitely. As you saw in some of the footage there we take things like the weight and the length of the fish, but we also take a tiny piece of tissue. We take a little fin clip from each of the fish we sample. J: A fin clip. So just to be sure, that doesn't hurt the fish, right? Matt: No, no not at all. It's just like taking a finger nail clipping it doesn't hurt the fish one bit. J: Awesome. So what do you do with the DNA from the fin clips? Matt: Once we get the fin clips back here to Purdue, the first we do is we extract the DNA and then once we've done that we set up a whole bunch of reactions. I'm going to show you an example of right here. Just make sure you guys can see this. J: Yes, we can see it. Matt: OK great. So we set up a whole bunch of these small tubes. In each of these tubes is the DNA of the fish we are interested in looking at as well as several different enzymes and reagents. So what we do is we set up a whole bunch of these tubes, like 20, 30, 50 depending on how many we want to look at. Then we take these tubes and put them into one of these machines I've got here on my right. So these machines are called polymerase chain reaction machines or PCR machines for short. All we do is put the older samples we're going to look at on this block and then pull the lid across and then we just press go. Like on a DVR machine we just have the little green arrow that we press for go. Then within 2 - 2.5 hours we get many, many millions of copies of that individual gene that we are interested in looking at between the migrants and the residents to see if we can find any differences. J: Wow, millions of copies! That is one serious copy machine you have over there. So what have you learned about the fish so far? Matt: Sure, so one of the most interesting facts we've found out is it doesn't seem that there's only one or two genes that are different between the guys that stay at home and the guys that migrate. It seems there are many hundreds of genes that seem to be associated with this behavior. J: So how will what you are learning impact the future to come? Matt: Sure, so there are two real points. First on a real broad perspective we still don't know how complicated behaviors and complicated traits are inherited. And the example I always like to give of that is human height. We know that tall people generally have tall kids. J: Right. Matt: OK But we still don't know how many genes or which genes are actually determining height in human beings. And its the same kind of thing with migration in salmon. There's lots of genes, but we still don't know exactly which genes and what the identity of those genes are. The second thing that hopefully this research will be able to help with is a conservation angle. So unfortunately in the lower 48 so in Washington, Oregon and California a lot of the populations of the migrant fish aren't doing really well. There numbers keep going down, down, down. It's possible that some of the work we are doing here at Purdue is going to help us understand why that may be. J: Gotcha. Matt, thank you so much for joining us from your lab here at Purdue. You really work in some interesting places doing some interesting stuff. Before you go, I hear we've got a hotseat question for you so let's check in with Abbey. Abbey: Matt the hotseat question of the moment is, do you know which type of fish live the longest, the ones that stay at home or the ones that travel. Matt: In the species I work on the migrants tend to live longer than the ones that stay at home. Migrant fish when they leave the fresh water they tend to be about 2 years of age. Then they migrate out into the North Pacific and spend about 3 years or so basically just swimming around the North Pacific and eating before coming back to spawn. So typically the migrant fish live to be about 5 or 6, it depends a little bit on the population Where the resident fish don't tend to live as long. They tend to live about 3 to 4 years. J: Gotcha. We just had an email question come in for you Matt. This is from River Valley Middle School in Indiana. Are all diseases somehow caused by our genes? Matt: No. Certainly there are a lot of genetic diseases that are caused by mutations in individual genes but there are whole bunch of other diseases that are caused by pathogens so things like viruses, bacteria and fungi that arouse in the environment. So when you catch the common cold for example, that's from a virus. That's from a foreign body in the environment that you ingest and it manifests itself as the common cold. But there are a whole bunch of genetic diseases that are due to mutations in genes. J: So it's sort of a mix.. Matt: It's both, yes. J: OK, Lets go ahead and check in with our school Hales Corners. Do you guys have any questions for Matt? Student: Yes. Is a certain type of fish easier to study than others? Matt: Yes, sure. Some types of fish are really difficult to study. There are loads of species of fish that are found in really deep waters in the oceans. Trying to get samples of those fish is really, really difficult if not impossible. One of the nice things about working with salmon and trout is when they come back to spawn. A lot of times these rivers, as you saw in some of the video from Alaska, are not very deep. So it's really easy for scientist like myself to catch a large proportion of those fish that are coming back to spawn. J: Let's go ahead and check in with our studio audience. Do you guys have any questions for Matt? Yes, you sitting on the floor. Student: Have you found any dominant genes that like when the migrating fish and resident fish mate have you found a dominant gene that will find if the off spring is going to be a resident or a traveling fish. J: Did you hear that? Matt: Yeah, I did and that's an excellent question. So some of the work that we are doing here in Alaska is there seems to be some dominant genes that seem to be associated. And the reason we think that is when we do crosses, you saw some footage there of us doing some crosses, we get the eggs from one fish and the sperm from another fish. If both your parents are migrants, you're more likely to grow up to be a migrant fish than you are a resident fish. But that association is not 100%. J: Gotcha. Matt; So even though you have two migrant fish a male and a female when they breed they still can produce and do produce a resident fish. So we think it is a mixture of both dominance and also co-dominance that's kind of explaining this variation in behavior. J: Very interesting. Great question. Alright. Let's check back in with Abbey in our hotseat to see what question you have for Matt. Abbey: Matt the question is, if you can breed fish and one would be a fresh water fish and the other parent would be a salt water fish would it's offspring be able to live in both environments? Matt: That's a good question too. And that kind of gets at the question just now. So when the migrants come back we can do that, we can spawn resident fish and migrant fish and see what the proportion of the offspring are going to turn into. Will they go back out into the ocean or will they stay in fresh water. And like with the previous question it seems to be a mix. You seem to get some individuals that stay in the fresh water, while others will migrate. It's definitely a mix of the different sort of genetic traits and it's also the environment that is important. If you warm the fish, if you turn the temperature up on the fish as they're eggs you get a higher proportion staying resident than you do migrating out to the ocean. J: Gotcha. So it's sort of like humans, some people are more like their moms, some more like their dads, some like both. We just had an email question come in for you, and this one is from New Bridge Middle School, I'm sorry St. Patrick's School in Indiana. Does the sex of the fish determine whether they migrate? Matt: That's a good question. So potentially. In our population in Alaska what we're seeing is that more females make the choice to migrate versus the males who that decide to stay at home. That is really, really population specific. If you look at other populations it can be 50%-50% male- female, if you look at different population the higher proportion seem to be male. But in our group, our population in Alaska it seems that mostly the girls are deciding to migrate versus the boys that stay at home. J: Gotcha. Let's go to our studio audience again. Any more questions for Matt? Yes, you. Student: Like my friend said with the dominance say you get one that migrates farther away from the other one, they have two different migrating paths, if you breed them is it more dominant to go one way as a parent or will they make a new migrating path? Matt: If I understand it right, the question was if you have one that migrates further and you cross that with one that doesn't go so far what will the offspring do? J: Yes, what type of migration path do they have? Matt: OK, that's a great question. Unfortunately we still don't know exactly where these migrants go once they leave the stream that we work on. We know they go around the North Pacific up to the Aleutian Islands and then across Eastern Russia and into Japan but we don't know how far one individual fish goes and we don't know how far your parents go if that will determine how far you go. If that makes sense. So for example, imagine if your mom went to Japan and back, that doesn't necessarily mean that her kids are also gong to go to Japan and back. They go somewhere in the North Pacific but exactly where we are still not sure. That is a really interesting question. We would love to find that out. J: Wow! We've had so many questions come in for you and we're going to have more at the end of the show. So thanks Matt for your segment and we'll see you in just a little bit. Matt: Sounds great, thanks Jessica. J: Thanks. [music] Narrator: Science is fun. It helps you to learn. You discover the marvelous inter-relations between all living things. You find out what makes things tick. Everything from a molecule [music] to a living organism. In the study of sciences found the most useful and satisfying knowledge of man. Why study science? Study science because you and Betty and the Nancy's and Bill's and Joe's and Jane's all over the country will find in the study of science a richer more rewarding life. [music] J: Wow that was pretty cool. An animal's genes and heredity are determined by its parents. Now that goes for dogs, humans, fish and even salamanders. Get ready because we are going to solve a salamander puzzle. With us here today are Purdue wildlife geneticists Andrew DeWoody and Rod Williams. Hey guys! Andrew: Hi Jessica. Rod: Hey. J: Now Andrew can you tell us what it means to be a wildlife geneticist and what kind of work you do? Andrew: Sure, wildlife geneticists are biologists who generally go out in the field and collect some sort of tissue sample from an animal, maybe a fin clip like you just heard from Matt, or maybe it's a hair sample from a bear. Bring those back to the laboratory, get DNA from them and use that DNA to study different aspects of their biology. We do a lot of work on eagles as you can see here. J: They're so cool. Andrew: Yeah. So we collect naturally shed feathers from the eagles, get DNA from those and then from those feathers alone we can determine the sex of the donor eagle. We can attach a DNA fingerprint that's unique to that individual bird, then we can monitor populations over time and figure out whom mates with whom and if the population is growing or shrinking or so forth just from studying the feathers and the DNA in those. And so wildlife geneticists use DNA to study secretive animals. J: Awesome, secretive animals. So you guys also study another mysterious or secretive creature and that is the salamander. Right? Rod can you tell us about salamanders? Rod: Sure. First there's a lot of different species of salamanders. Over 600 worldwide. While they can be very similar they also have some very striking differences. I actually brought three species with me today to show you some of these differences. J: Great! Rod: This first animal is a museum specimen so it's not alive. This is a small salamander, one of the small ones. This is an eastern redback salamander. It's a woodland salamander, it occurs in forests and woodlands through the eastern United States. It's a fully terrestrial salamander. So it spends it's entire life on land. J: And that's fully grown. Rod: That's fully grown. J: OK. Rod: Other species can be quite different. This is a North America's largest salamander. This is an eastern hellbender. This particular species is fully aquatic. It spends its eniire life from a juvenile all the way up through an adult in the water. J: Awesome. We some of your work there. Who else do you have with you? Rod: This last species is as an eastern tiger salamander. J: It's alive! Rod: This is a species that spends part of its life in the water as a juvenile and part of its adult life on land. They only go back to water in the spring to try to find a mate and lay their eggs in the water. J: Very cool. So if they are so secretive how do you guys actually find them? Rod: Well, it depends on which species you are talking about. If you're talking about the terrestrial woodland salamanders you go into the woods you sort through the leaf litter, you roll over logs. They're very secretive and cryptic and hide under structures. Hellbenders as you saw in the video you have to put a mask and snorkel on and swim under water and try to find them under rocks. This particular species you can intercept them on their way to migrations again to find a mate and lay their eggs in the water during breeding season. J: Awesome. So you guys know a lot about them so I have to ask, what are you trying to find out about tiger salamanders exactly? Andrew: Well, we do know a lot about them but there's still many things we don't know about salamander biology in part because as Rod mentioned many species lay their eggs in ponds that are often really murky. All of breeding biology occurs in situations that are very hard to observe. So what we can do is use genetics to figure out questions like whose coming to breeding ponds, whose breeding with whom and determine things like parentage. J: Parentage. So can you define parentage for us? Andrew: Yes, intuitively we know that everybody in this room and out there watching has a mother and father and its the same why for virtually all wild animals. What we don''t know is the pedigree of these animals. Who was the salamanders mother, who's its father and how did they choose their mates in the wild. We can use genetics to try and sort that out. J: So why does determining parentage matter? Andrew: It matters in part because mating systems and parentage determines the genetic variation in populations. The genetic variation is important because it helps determine how populations can respond to changing environment. Everything from pathogens, like Matt mentioned earlier to things like climate change. So genetic variation of population allows it to evolve in response to changing environment. Parentage can help determine that. J: This little guy was trying to steal the show for a second there. Andrew: He was. J: So how do you guys actually collect your data? Rod: I think we have a video of Andrew and myself along with some of our graduate students out in the field trying to collect some of the data we are going to talk about a little later in the show. J: Awesome. So let's take a look. [music] Rod: The Purdue Wildlife Area is used for a large number of different research projects. One project in particular is a project examining how tiger salamanders, which are amphibians, breed. [music] So what you're looking at here is a drift vent. This is a technique by which we can intercept amphibians on their migration towards a breeding pond. So many amphibeans will over-winter in grasslands or in forests and every spring they'll leave their over-wintering site and migrate to a pond which you see behind me. We'll dig a trench, we'll take the fence, we'll bury the fence in the soil, cover the soil back up. Salamanders and other amphibians will walk down the fence, not see the pit fall trap fall into the traps and they're captured and held there until researchers can come along and pick them up. Salamander: Look out! Rod: Researchers will come every morning and every afternoon to check the traps to be sure the animals aren't held in a trap longer than necessary. [music] So there are several ways of getting DNA from a salamander. One of the ways that you can get DNA is to take the tail and take a small tail snip from the tail. The tails will regrow or regenerate and it's relatively painless for the salamander. [music] Andrew: So this is a tiger salamander egg mass. If you look closely you can actually see the individual embryos within this egg mass. We can take a small tissue sample from these embryos in addition to the tail snips from the adults back to the lab, extract DNA and then conduct the parentage analysis. [music] J: Cool. Well now that we have the DNA from the salamander's tail and their eggs we need your help in figuring out the parentage of these salamanders. So Andrew you're going to take us through a Punnett square activity to help us determine who the parents are. Andrew: You bet. We've got a video to help us with that. So here we've got a cartoon that illustrates we've captured all of these adult salamanders that have migrated to the breeding pond. We caught them in the pitfall trap and took the tail snip. We've also got all the egg masses and the embryos in those and we extract DNA from all these individuals. Then we assign a genotype to them. As you can see here we've got six different embryos that have been genotyped. Half of them are CC's and half are CD's. Then we can compare that to all the adults. And you can see that their genotypes have been determined and added in there. Then we can go through all the possible combinations of parentage. So every possible male and every possible female. So he's the first example. We had a dad who was AA and a mom who was AA. And as we learned earlier with the Punnett square this gives rise to embryos that are all AAs. That's not what we saw in this egg mass. J: That's not a match. Andrew: That is not a match. That is not the mom and the dad. We can then do that for every successive parent pair until ultimately we find out who were the parents. In the case we see here we've got a dad who was CC and a mom who was CD. Our Punnett square shows half the offspring should be CCs and half should be CDs. And that's exactly what we saw in our egg mass. So, those are consistent with parentage of the embryos in that particular egg mass. J: Yeah! We have a match. So let's talk about those results then. What did you guys find out in your salamander parentage study? Rod: So this is a great example to show how wildlife geneticist can use genetics to unlock mysteries of secretive species like salamanders. And we've actually learned quite a few things new about them using genetics. First is we've learned that females will lay their eggs in many different locations in those wetlands that you saw in the video. And within those egg masses that are distributed all throughout the wetlands they may have many different dads within that egg mass. And more importantly those different dads are chosen by the females based on their size. Females tend to prefer males that have long, taller tails. J: So how does this guy fare? Rod He's going to do very well. J: Such a go getter. I'm so proud of you. So I have to ask you guys how did you guys decide to study salamanders? Don't you find them a bit creepy to work with? Andrew: No, not at all. I don't think they're creepy and they're a great example of a secretive species where it's hard to know much about their biology because of their way of life. DNA offered a great opportunity to learn more about their biology. J: Very cool. Out of our studio audience I want to know who does not find a salamander creepy? Anybody? Anybody want to come touch it? You, come on up here. What's your name? Student: Austin. J: This is Austin. Rod: Hold your hand out here Austin. So I want you touch the tiger salamander. How does it feel? Austin: Slippery and wet. J: Slippery and wet. Do you like the look of it? Austin: Yeah. J: I think it's pretty cute. So, so, so cute. Thanks Austin. Now let's go ahead and check in with Abbey to see what's happening in the hotseat. Abbey. Abbey: Hotseat users would like to know how do you extract DNA out of hair or feathers? Andrew: Well, it's much like Matt talked about the process of PCR involving different enzymes. So we can take that hair sample or feather sample or fin snip back into the laboratory. We can incubate it at fairly high temperatures and use some enzymes to disrupt the cell membranes and release all the DNA that's in the nucleus and then basically we chop everything else up. All of the carbohydrates and lipids and everything else until we are just left with the DNA. J: OK. We just had an email question come in for you from St. Francis and Claire School in Indiana. If the tiger salamander was migrating where would you catch it? Rod: They actually have a very wide range of habitats in which they live. They can migrate from a forest setting, a grassland, and you just put up a fence like we showed in the video and intercept them on warm, rainy nights in the spring which hopefully we'll have here in the next couple of weeks in Indiana. They'll migrate in mass numbers. They're aggregate breeders, means hundreds of those guys will migrate to the pond to breed. J: Awesome. Now let's check in with Hales Corners. Do you guys have any questions for our scientists? Student: Yeah, can some salamanders be poisonious and will it affect the research? J: Can some salamanders be poisonious and will it affect the research? Rod; Many species of salamanders will secrete a slight toxin from their body and they use that to deter predators. So yes, there is a level of toxicity of those secretions varies from species to species. J: Alright, and let's go ahead and check in with our studio audience. Do you guys have any questions for Andrew and Rod? Yes, you all the way back there. Student: How long would it take to take some, find out the DNA inside a feather? Like, how long would it take? J: How long would it take to find out about the DNA from a feather? Like one of the eagles. Andrew: Not too long. It takes really just a few hours to take the DNA from the feather and then the actual genotyping part that is necessary for a Punnett square maybe takes a few more hours or another day. So within two days you can learn just about everything there is to know genetically about a feather. J: Awesome. You guys do great work and we're glad to have you. We'll see you at the end of the show. Remember if you think of more questions out there you can submit them through the It's a Gene Thing page on the website. [music] Host: Hi everyone. Welcome back to the show. Our next guests have a big, big question to answer. Say hello to male and female tiger salamanders, Sal and Amanda. Sal: Thanks. Amanda: Nice to be here. [audience booing in background] Host: So what brings you here today? Amanda: We're here to learn if Sal is the father of my embryos. Sal: I'm not. I'm not! Host: Here's a shot of the egg mass in question. Amanda: See they look just like him. Just like him! Sal: No they don't, no they don't. Amanda: You don't know me. You don't know me. Host: Well we've run the genetic test to determine the parentage of these embryos. Let's see the results. [drum roll] Sal, the genotype doesn't match. You are not the father. [Amanda crying and Sal cheering} J: That cracks me up. Now we hope you've had a great time meeting some real life geneticists here at Purdue University and have learned some things too. Remember how animals can have different characteristics because of mutations, like the mice with different coat colors. Also geneticist travel all over the world to learn more about what causes animals like fish to move from place to place and you can use scientific inquiry to solve important heredity questions about animals like salamanders out in the wide. Now we do have time for some more of your questions for all of the scientists in today's show. So first lets go to the hotseat. Abbey. Abbey: Hotseat users have a question for Andrew and Rod. They want to know if you breed a venomous salamander and a non-venomous salamander what would happen? Rod: Well to my knowledge there are no venomous salamanders. The toxins that we were talking about earlier are species specific so you can't really interbreed those different species. J: Gotcha. We just got an email question come in for you Nadia. This is from New Bridge Middle School in North Carolina. Hey North Cakalaki! Why do plants have different colors even different colors on the same plant? Nadia: Well, there's a lot of different ways that can happen. First of all plants make a lot of secondary metabolites and a lot of different compounds in plants. So purple a lot of times comes from a chemical called anthocyanin. So you have a lot of compounds like that and then sometimes the different patterns you see on plants can even be caused by what people refer to as "jumping genes". They're called transposable elements and they can move from one place to another. Actually cause the different colors in kernels you see in corn and even different patterns on leaves. so there's a lot of different ways it can happen. J: That sounds really interesting. J: Now let's check in with Hales Corners. Do you guys have any questions for any of our scientists? Student: What made you want to get into genetics? J: Who want to take that? What made you want to get into genetics? J: Anybody. Andrew: I'm happy to say that I think it's just a great technique for somebody like me who likes to study wildlife it's sort of the latest, greatest technology. You can go around and collect these samples, bring it back to the laboratory and answer questions that we really had no idea about until the advent of genetics. Just like salamander parentage, nobody really knew that female partitioned their clutches. They didn't know they mated with multiple males or that the females were really interested in tail height and tail length to the extent that they are. J: Right and now we do and you'll continue to learn more and more about things you don't know about right now. Andrew: We hope so. J: And what about our studio audience. Do you guys have any questions for our scientists? How about you? Student: Mine is for Nadia. With the square, I forget the name of it, how big normally does that get for one species of plant, human or animal. Nadia: for the Punnett square? Student: yes. Nadia: OK, so it depends on the question you're asking. So some traits that you're looking at maybe you'll have only big "A" little "a" traits. Or big "A", big "A". But you can also have traits that have multiple genes that go into the phenotype and then your square gets bigger. So it depends on whatever, what question you're asking really. J: Cool. Alright then let's go back to our hotset. Abbey. Abbey: Hotseat users have a question for Matt. Do you study any animal other than fish? Matt: Right now I'm only studying fish. In the past I have studied different species of fish as well as birds, insects and even pine trees. I've studied a whole bunch of different organisms. But currently, right now my research is really fish oriented. J; Is that your favorite? Matt: Yeah! [laughter] J: Alright and let's go check in with Hales Corners. Do you guys have any questions for our scientists? Student: How many places have you gone to work to study fish. J: OK. That's for Matt. How many places have you gone or traveled to study fish? Matt: There's the work I've done in Alaska, as well as work I'm doing in the Great Lakes with the first species you saw in the first video, the brook trout. I've also gone up to Lake Oneida in New York with Andrew actually working on lake sturgeon which is a project I did here at Purdue before I started work with salmon and trout. So those are the three main places I've been to working with fish. J: Awesome. Well, for the questions we were not able to get to today, we will be sending out an email with the most frequently asked questions from todays show for teachers to review with their students. And for future zipTrips keep checking those emails and the zipTrips website for updates. Thanks to our students here in the studio and our scientists. For all of our zipTrips crew I'm Jessica Jackson. See you next time. Bye. [music]