How to get rid of head lice

I am going to start a series of blog posts on lice. I thought I would write a little bit about their biology and how to get rid of them, for all the parents out there.

Figure1Pediculushumanus

Head lice have not been found to transmit disease. They do not infect dirty people more than clean people and some really old studies found that lice will actually leave a sick person for a healthy person, fortunately we don’t do those types of experiments on people anymore. Head lice do not survive if they fall off the host (yep that’s you), in fact most head lice will be dead within 9-14 hours. Lice cannot even move round unless they are on hair.  This means they are not likely to be in your bed, on your floors, on your stuffed animals or anywhere in your house except on your kids heads. Studies that have looked for lice in hats, bedding, combs etc. have found almost no evidence that lice are transmitted this way.  In fact, the worst and most common issue with head lice is the itching caused by the bite from the louse.

Although they can infect anyone, lice are most common on children aged 3-12 and are widely spread throughout our school systems. Because lice move from head to head we have essentially set up a system that is perfect for these little buggers. We put a bunch of little people who don’t have any personal boundaries into a small area. Have you ever watched kids in a playground? They jump all over each other. If you are a parasite that spreads when people put their heads together this is the ideal system.

According to the World Health Organization, it is thought that around 10-20% of children are infested worldwide. In the United States alone, approximately 6-12 million infestations occur every year. Although these data are really hard to get so these numbers are estimates.

Parents have attacked this problem using every method from shaving their child’s head to covering the entire scalp with petroleum jelly, vinegar, and even toxic chemicals like kerosene. We have been evolving with lice for millions of years, and we are still struggling to understand and eradicate these parasites.

How to get rid of them?

There are a number of options. Many chemicals are available you can buy to put on your kids heads. As unappealing as this sounds it is a very common method. Unfortunately, lice around the world are evolving resistance to these pesticides so there is a chance it will not work, and the more we use them the more we promote resistance in these lice.

Manually removing the lice is an option. In fact the term “nit-picking” actually refers to doing just that. Nits are louse eggs so the term comes from picking lice and their eggs off peoples heads.  This can take a long time and requires much patience. Missing a single louse may cause the infection to return. Lice tend to stay close to the base of the scalp, and the eggs are glued onto the hairs, using a louse comb and carefully going through small sections of the hair is the best method. If the eggs are found far from the base of the scalp (on longer hair) these are likely a hatched eggs that do not have a louse in it anymore or are not viable because they need the heat from the scalp to be incubated.

My most recent favorite method is the Louse-Buster. This is a machine that essentially blows hot air on the lice and dries them out until they die. It works on lice and eggs and it is unlikely they will be able to evolve resistance to being dried out. This has to be done by a trained professional so there is a company that will come out and blow-dry your kids heads for you.

Dung Beetles Have Right of Way. Addo Elephant National Park, South Africa

Dung beetles have the right of way

DungBeetleSignIn South Africa there is a place called Addo Elephant National Park. This park is amazing, not only having over 500 elephants, but there are also countless other mammals including lions, hyenas, buffalo and black rhinos.  One year I was fortunate enough to go to the park and while we were there we ran across a sign that said “Dung Beetles Have Right of Way”. I was immediately intrigued.  Does this mean that if there are dung beetles crossing the road we will all stop and let them go?  This seemed incredible and as I looked into it turns out there is an endangered species of dung beetle that only lives in this one area in South Africa. Therefore, in this park it is actually illegal to run over dung beetles and even elephant dung because there might be beetles in it.  It was incredible to see all the cars driving around piles of elephant dung throughout this park. I kept thinking how awesome it was to be in a part of the world where dung beetles have the right of way.

I thought I would write a post about dung beetles mostly because I really love them for some reason. There are about 35,000 species of dung beetles around the world. Dung beetles, as their name suggests, eat dung some species eat other things but many eat dung. Some will even roll it up into a large ball and roll it away where they will bury it to store for either food or to lay eggs in it. Because of this dung beetles are dependent on large animals to make the all important dung.  One interesting thing is that when the large marsupial mammals in Australia went extinct in during the Pleistocene so did many species of dung beetles.

After the loss of these species of dung beetles in Australia an important nutrient cycling process was lost. Because these beetles move and bury dung they move nutrients around which is important for these ecosystems. They have recently introduced a numberof species of dung beetle for this purpose.

100_1941.Dung.Beetle

One final cool fact about dung beetles. They are famous for being able to use the milky way to orient themselves. They are the only animal that has been found to do this. Think about how light pollution from street lights might affect these species.

 

 

Marie Dacke, Emily Baird, Marcus Byrne, Clarke H. Scholtz, Eric J. Warrant. Dung Beetles Use the Milky Way for OrientationCurrent Biology, 2013; DOI:10.1016/j.cub.2012.12.034

There is no confusion about climate change

In the wake of hurricane Sandy reeking havoc on one of our most famous and loved areas of the country I thought I would write about climate change and the current literature behind it. The big question here is did climate change cause Sandy? But along those lines our real question is… can say that any specific weather event is due to climate change?

First, before I start let me say that there is no confusion among scientists about climate change. They no longer ask if climate change is happening, rather they ask how is it going to happen. By 2004 all major scientific bodies in the United states had made statements to the effect that climate change is occurring due to humans increasing green house gasses. This is because there is massive amounts of scientific evidence that support human caused climate change.

In a nutshell: climate change (as caused by humans) is essentially our world getting warmer because we are releasing greenhouse gasses (like carbon dioxide) into the atmosphere. These gasses trap heat and therefore increase the temperature of the planet. Maybe someday I will write a blog on the science behind this issue, but for now if you want a fantastic overview of the science watch Al Gore’s “An Inconvenient Truth” which is online streaming for free. He deservedly won the Nobel Peace prize for his work in this area and the movie is an excellent overview.

There have been a number of extreme weather events occurring. For example, the increase in droughts in North America, Europe, and parts of Asia and heat waves in many of these same areas. Similarly, there have been a number of hurricanes to hit North America and countries in the Caribbean, and these storms have been gigantic. One thing I have noticed while traveling and talking to people about the weather is that everywhere I go people say something to the effect of “last year the weather was strange”. Although this is not data collected in a rigorous way this is how we function as scientists, by noticing a pattern and then forming a testable hypothesis about this pattern. In this case it would be something like has the weather been different from normal?

What do we predict to happen if our planet were to get warmer? Models show that an increase in extreme weather events like hurricanes, record breaking heat and droughts are predicted. That seems to be what is happening. The number of hurricanes that form in the Atlantic has doubled in the last century(1), and that the intensity of those storms is increasing(2). There have been major droughts across North America, Africa, and Asia in the last few years. If you have been watching what is happening due to the African drought it is really heartbreaking. The drought this summer in North America caused our crop yields to be the lowest in 18 years, with huge economic consequences. Hansen (2012) just published a study finding that with “near certainty” the Texas and Russian and European heat waves would not have happened without human caused increase in green house gasses. Dai (2010) found that the warming is most likely the cause of droughts in Africa, Asia and North America. More and more scientists have been able to link specific weather events to climate change.

So what about hurricane Sandy? It is a little too soon to be able to determine if Sandy would have occurred without human caused climate change. However, it fits with the trend of increasing powerful hurricanes that are predicted from models of climate change. This hurricane season there have been 19 named storms (the average is 12) ending another “above normal” season according to the National Oceanic and Atmospheric Administration. We are in a period of high-activity and that combined with warmer oceans are causing these hurricane seasons to be deadly.

Unfortunately, the scientific evidence is overwhelming. Climate change is real and is already affecting lives not only here at home but across the globe. So what do we do? Do we put up sea walls to protect New York , and New Orleans? Do we do something about the greenhouse gasses in the atmosphere?

What do you think?

References:  1. Holland et al. 2012. PNAS  2. Webster et al. 2005. Science  3. Hansen et al. 2012. PNAS  4. Dai A. 2010. Climate Change

Primate DNA tells us about the history of an African rainforest

We know that all animals are dependent on their environment. They need resources like food and mates. If their habitat changes, we expect that to have an impact on their population. For example, if their forest expands, we expect that their population will grow. Alternatively, if their habitat shrinks, then their population will likely shrink too. Because of this, if we know the size of an animals population in the past, we can make hypotheses about what has happened to their environment in the past.

One of the amazing things we can learn from DNA is how animals have fared in the past. For example, we can tell from DNA if a population has gone through a bottleneck (declined rapidly) and even when this bottleneck occurred. This can not only give us insight into what has happened with this population but, more to the point, it can give us insight into what might have been going on in its environment at that time.

Can we figure out how animal populations have changed in the past to understand how their environments have changed?

This was what we wanted to know when we started this project. We wanted to know how the population of a group monkeys changed over time — to understand more about the forest they live in. We studied Red Colobus monkeys, which are one of the most endangered primates in the world. They live in forests along the equator in Africa. Almost everywhere you find Red Colobus, their populations are threatened, endangered and in some cases extinct. The reason they are so endangered is that they are very sensitive to changes in habitat, which is what is happening in many places around the world. If their forests start to get cut down, the Red Colobus are one of the first species in the forest to start declining.

However, there is one place in Africa with a huge population of Red Colobus, Kibale National Park in Uganda. There are estimates of around 30,000 monkeys in this forest. This is one of the only places in the world where the Red Colobus are not declining. This National park is rather spectacular. It has 351 species of trees, 335 species of birds and 13 species of primates. It is is one of the most diverse areas in the world for primates. For this project we wanted to know how about the history of these monkeys to see what we could figure out about the forest itself.

We took DNA from 85 monkeys throughout the park, amplified pieces of DNA called microsatellites. These sections are known to evolve rapidly, so rapidly in fact that we can tell differences between individuals in a population. These genetic markers are the same ones used to identify fathers of humans and other organisms, and they can tell us about the population as a whole. If a population is large, we expect there to be more genetic diversity conversely if a population is small, we expect there to be less. Therefore, depending on the level of genetic diversity, we can make predictions about the size of a population and even how that population size has changed in the past.

We found something completely unexpected. We found that this population of monkeys has been stable for at least 50,000 years, meaning that the population size of this group of red colobus has not changed for a very long time. So what does this tell us about the forest?  Does this mean that the forest itself has been stable for that long as well?  Although this is an obvious question, just because the population has been stable in time it does not necessarily mean that it has been stable in space (i.e. in this same forest the whole time).

Right now, however, this is the simplest explanation for our result, because other possible scenarios are much less likely. For example, one possible scenario is that the population was in another forest and then moved into this forest. However, when animals move most of the time only a few individuals move and that leaves a strong genetic signature of a population decline. In this case for that scenario to fit our result the entire population would have had to move en masse to this forest without any population size change. Although not impossible, it is much much less likely. Therefore our data led us to propose the hypothesis that this forest may have been stable for quite some time.

There have been many changes in East Africa over the last 50,000 years. For example, we know there was a huge drought ~18,000 years ago during the last glacial maximum, and many changes happened to forests and areas around Lake Victoria, in Uganda. Our results suggest that Kibale forest was stable during that period and buffered this group of Red Colobus from these environmental changes and therefore likely buffered many other species during that time period as well. This suggests that the forest may have been very important in maintaining species diversity in this area. This hypothesis needs to be tested further, but it is rather exciting.

What other ways could we go about testing this hypothesis?

Here is the link to our article it is available online free for everyone.

Thanks to Caroline Roper for making the video of me talking about this project. Caroline is interested making science available for everyone and has created a number of videos highlighting research from the University of Florida. For more videos like these go here.

Life Finds a Way

I was talking to a friend of mine about the influence we are having on the planet, by doing things like spraying pesticides everywhere and putting up buildings and parking lots. My friend quoted the now famous line from Jurassic Park “Life Finds a Way”, making the point that life will survive and continue on no matter what we do. This got me to thinking, and I often wonder what people see when they look at a city or an apartment building or a corn field.  When a biologist looks at these things we see habitat loss, we see areas where other species used to live that no longer do.  Of course, it is hard to understand what used to be in these places, especially if we did not see them before they were changed. Furthermore, it is easy to see how we could think that ‘life finds a way’ because when we look at these places we find animals living there… so yes, life finds a way but lets think about what that means for the local species.

When we change an area by putting up a building usually we have changed the habitat so drastically that the native animals can no longer live there. Instead what we have done is create suitable habitat for other species.  Usually these species are exotic – meaning they were not originally in these areas. Here are a few examples of some of the really successful city dwellers.

The common pigeon also known as the “rock dove” is found in every major city in the world. When we think of big cities like Rome we often think of peoples standing in large plazas feeding huge flocks of pigeons. It is thought that one of the reasons pigeons do so well in cities is because naturally they nest on cliffs, and buildings resemble cliffs making a ton of suitable habitat available for these pigeons. Because there are so many buildings and many food sources that are now available to pigeons, they are one of the most successful city animals in the world. However, as you move outside of the cities into the more natural areas pigeons disappear and you find many other species of birds like blue birds, wrens and warblers.

Other really common city dwellers are black and brown rats. These two species are now almost every where in the world. These guys are fantastic at finding food in dumpsters and other places, they can burrow into buildings and live in walls where they create their nests, and they have also done extremely well at moving from city to city on boats and other things.  However,  as you move away from the cities these city dwellers get replaced with many other species of the native rodents. For example in the Great Basin desert where I used to work we would commonly find six different species of rodents, including the Kangaroo rat –probably the cutest animal ever.

Of course, I am not trying to say that rats and pigeons are not fascinating in their own right. I study lice so…who am I to talk?  What is happening is that in cities we find species that do really well but we have lost native species that used to live there.  Because we are making some species really common in cities and losing native species in those areas, globally we are losing species diversity when we alter these habitats.

As cities grow bigger and bigger the habitat for exotic species grows and that for native species shrinks, and in some areas they are gone completely. The large changes in the animals that we see around us are not trivial, and we do not yet completely understand the impacts those have had on the ecosystems they live in.  So.. yes life finds a way, but at what cost? Perhaps we could change the saying to “Some Life Finds a Way”.

“The science you do not understand looks like magic” – sometimes true even if you understand it -by Judit Unvari-Martin

Science majors in college, in the last years of the undergraduate degree, suddenly realize the value of “experience”. But what is this elusive “experience” that all job applications talk about, without specifying what they actually require you to know? How do you get it? There are basically no entry-level science jobs out there; everyone wants you to already have “experience”. It is scary, when you first realize, that to be able to do anything with your degree, you need to already work in your field, and have all kinds of skills that nobody taught you in class. That is what “experience” is all about. Your classes, your grades do not really matter in the long run, you need to be able to DO things.

So, basically, experience equals doing. Doing science! Well, hopefully that sounds like a lot of fun to a science major, assuming that the reason behind choosing this major was because they like it. I sure did some exploring in different fields, before I settled with my major, and even then one was not enough, and I ended up picking a second major two semesters before graduation. They were both science though, because I love the exploration, the hunt, the quest. Science allows you to ask questions that interest you (and perhaps others as well), and then go ahead and find an answer. Then writing about science is an attempt at convincing others regarding the answers found. It is a never-ending challenge. Hmmm, never-ending, that may make it sound not that attractive for all, but it may just be a special motivation knowing that there is always something else out there that you can pursue.

But I digress, back to experience. So, I realize that I want to DO science. Where to start? Here is how I did it, and would recommend doing it. The easiest way to get started is the departmental list of labs and graduate students. With luck, you just contact them, and you will find a herd of people, eager to get help from you. Manpower is what you can first provide, and you will get skills in exchange, and you will find out whether you really like DOING this. I was already working on a project with birds, running around on campus. Then during the nights, I helped my bird-mentor sort through samples of powder that contained lice collected from birds in the tropics. That is how I met Julie. Since Julie is into lice… she likes them a lot. We started talking about host-parasite coevolution, and what we could do with all the lice that we found. She mentioned that they were looking for somebody in the lab who could help out with a project on Anoplura (those are sucking lice; I had no idea either…). Paying job!!! That is the best way to get the elusive “experience”. Finally, becoming a professional, and getting paid to work on science. This meant a lot of autoclaving, solution making, but also learning: DNA extractions, PCR, a bit of cloning. Part time position, so it allowed me to keep on chasing birds around on campus. It was perfect.

Once I had the basic lab skills down, I started working on the project of Red Colobus (those are monkeys; I had to look them up – way cuter than lice…). Same skills, just different organism, different questions too.  Julie was great at guiding us through troubleshooting, and there was a lot of trouble. Lab work seems to have its own black magic. You can do everything according to the book, follow the recipes, and you just do not get anywhere. Staring at blanks. However, once you get the hang of things, get rid of contamination, make new primers, new water, freshly autoclaved tubes, pipette tips, recalibrated pipetter, fresh dye, fresh TAQ, and the right constellation of stars comes together, then, finally, it is really rewarding to load your samples into those 96 tiny wells on the tiny plate. Magic is necessary. I am not complaining, I am just describing how I gained “experience”; and learned the magic of troubleshooting. It is similar to your computer misbehaving, and the best solution being unplugging and plugging it back in. Simple magic.

The TV shows out there really glorify labwork. Everything works so quick, you load a sample, and out comes a printed sheet with results on it that help you identify the victim, catch the criminal, diagnose the disease, isolate a compound. With “experience” you learn though, that it is not that easy. It is a challenge, it is a leap of faith, and it can be frustrating. It can also be glorious, and rewarding. The reality of first working in a lab as an undergraduate is mostly figuring out what you like, and what you do not like. You have a mentor, or sometimes even more than one. Your mentor(s) guide you, reward you, discipline you, teach you, and if you are lucky like me, they become your best friends. Friends for life.  Because the skills you pick up while getting experience, they stay with you for life. Every time I have to deal with troubleshooting, I think of Julie, my labwork-mentor, and all the things she taught me; but I also remember the shrine of trinkets from all over the world proudly displayed on and around the thermocycler, to please the machine, to give an offering to the forces that allow the primers to sit down in the right places and make your sample DNA elongate. Nobody teaches you that in class…

I still do labwork, and with “experience” I have learned, that I enjoy chasing birds a lot more. It is not enough though, I want the magic of the invisible, the answers hidden in the genes, the things I can only find if I work in the lab. It allows one to look deeply. Deep in time even. Doesn’t that sound like magic?!

Judit Unvari-Martin is a PhD student at the University of Florida. She studies the genetics of birds that live in the Amazon. To do this she spends 6 months of every year in Peru trapping birds and hiking around the rainforest. 

Are all homophobic politicians gay?

Doesn’t it seem that every time we hear a politician rant about how we should deny rights to the gay community, he turns out to be gay? From Phillip Hinckle in Indiana to Mark Foley in Florida, time and time again politicians with anti-gay voting records frequently get caught engaged in homosexual activity.  As scientists, we are taught to notice patterns and then pose scientific questions. This is a good example of a pattern that begs for a scientific question. In this case, the question would be “Are all homophobic politicians gay?”

On the surface it seems difficult to answer this question because we need to know politicians’ actual sexual orientation which may differ from what they say it is. Only then can we contrast their sexual orientation with their speeches and voting records on bills that provide equal rights to members of the LGBT community.  A recent NY Times article reported on a study that attempts to answer this question.

Here is the idea behind the study. Dr. Weinstein and colleagues wondered if parents who are homophobic or are not supportive of their children honestly expressing their true attitudes, will have children who demonstrate “reaction response” in which they adopt behavior that is opposite to how they really feel (like being really homophobic to hide their homosexuality).  This response is an attempt to protect themselves from being disowned by their parents or from backlash in the community.

How do you come up with a scientific experiment to test this idea?  How do you figure out what someone’s actual sexual orientation is.  Here is what Dr. Weinstein’s team did. They conducted what is called a reaction time test to determine an individual’s sexual orientation.  Men and women were asked to place words or pictures into one of two categories–homosexual or heterosexual.  The words were “gay, straight, homosexual and heterosexual” and the pictures were of gay and straight couples.  They then measured the time it took the participants to respond. However, immediately before participants began the task, the researchers subliminally flashed either “me” or “others” onto the screen. The research theory was that homosexual participants would take longer after they see the word “me” to put things into the heterosexual category. Similarly, if they are heterosexual, it will take them longer to put things into the homosexual category after seeing the word “me” on the screen. The researchers then asked them questions designed to indicate how their parents feel about homosexuality, how they feel about homosexuality and of course their own sexual orientation.

The results were really interesting.  There was no correlation between participants’ measured sexual orientation and what they said their sexual orientation was unless their parents attitudes towards homosexuals were added to the mix . For people whose parents were not homophobic and were open to their children expressing themselves, measured sexual orientation matched their stated sexual orientation. For people whose parents were outwardly homophobic, measured sexual orientation only matched their stated sexual orientation if they were straight.  However, if their measured sexual orientation was gay or lesbian, they were more likely to say that they were straight. This suggests that people are taking on behaviors that are the opposite to how they really feel if they do not think they are supported by their parents.

More importantly, researchers found that if participants’ measured sexual orientation did not match their stated sexual orientation, they were more likely to be homophobic.  This could explain why our politicians often get caught in homosexual activities when they have extensive anti-gay voting records. They might be trying to hide their sexual orientation to protect themselves from perceived risks such as constituent backlash or parental rejection. This research helps us to not only understand the motivations behind certain behaviors but also brings up other interesting questions. What could we learn about school yard bullies who pick on other students for being gay? What are their parents thoughts about equal rights for the gay community and how does this impact their children’s behavior? Ultimately this research suggests that homophobia might be gay…

When I Grow Up…. by Lisa Barrow

“Many people don’t know what they want to be when they “grow up”, and I am no exception.  When I started college, I decided to study Biology because I was fascinated by things I had learned about the natural world, about the diversity of life, and about the way organisms have adapted to succeed in their environments.  I had no idea what I could do as a biologist, and had vague thoughts about being a wildlife veterinarian, or perhaps working in conservation.  Then I stepped into the Reed Lab at the Florida Museum of Natural History, and was introduced to a world of research I never knew existed.

During my first summer in the lab, I was trained on molecular techniques including DNA extraction from a bit of tissue, amplification of pieces of DNA using PCR, visualizing PCR products using gel electrophoresis, and sequencing those pieces of DNA for use in phylogenetic analysis that would tell us something about the evolutionary relationships and histories of the organisms in question (in this case, humans and their head lice!).  I have never quite gotten over my fascination with the idea that, in such a short time, I can go from a tiny piece of tissue to data that answers questions about the history of life! (so much so, that 6 years later I find myself in graduate school using many of the same tools (and new ones that continue to be developed) to answer ever more interesting questions about ever more interesting systems).

But molecular work was not all I found in the Reed Lab.  During my 3+ years there I was able to help the graduate students with fieldwork including catching bats in Puerto Rico, and the Florida mouse nearby.  My time in the lab opened up opportunities like studying marmot behavior in the Colorado Rockies, and rainforest birds in the Peruvian Amazon.  I also had the opportunity to complete my own project for an Honors Thesis, in which I studied the genetic relationships of pocket gophers across geographic space using historical museum skins.  Most importantly, I found myself being part of a lab, a group of people who teach you, encourage you, and criticize your work, all contributing in some way to your development as a scientist.  And of course they are there at the end of the day for some cervezas or Argentinian wine-tastings to help you relax and de-stress!

Now here I am in grad school, gearing up for a field season that will take me all over the Southeastern U.S. to study the genetic structure of frogs, also eager to get back to the pile of sequence data that will hopefully be waiting for me to analyze and write up with my advisor and undergraduate co-authors when I return.  As the semesters roll by, it becomes more and more clear that there is another decision somewhere in the distance – what to do next?  Post doc in another research institution?  Teach at a community college or primarily undergraduate institution?  Work at a wildlife agency, conservation non-profit, or natural history museum?  Well, I’ve got a couple more years of catching frogs, teaching, and mentoring to think about it.

So I still may not know exactly what to do when I grow up, but I’ve sure found a pretty fantastic way to appreciate life (and hopefully contribute a little something to our knowledge about it!) while I figure that out.”

Lisa Barrow finished her undergrad degree in Biology and is now a graduate student at Florida State University, where she runs around studying the genetics of frogs.  Here she writes about her experiences doing research as an undergraduate.

The Black Death

How does one study an ancient disease? How do you study something that is no longer around? What kind of information do we want and how do we get it? As a geneticist I always want to look at DNA because DNA is an excellent source of information. It can tell us things like was it a virus or a bacteria?  Is it closely related to bacteria that are around today? What made it become an epidemic? The real question though, is how do you get your hands on DNA of an ancient disease?  Well,  you rob graves of course.

The Bubonic plague is probably one of the most famous epidemics of all time. It was also called the Black Death and killed ~25 million people which was around 30 – 50% of Europe’s population in the 1350s. The disease has many symptoms but two of the most famous were the swelling of lymph nodes (ew) and where the tissue in the extremities (like fingertips, arms and nose) would get gangrene and this rotting tissue would turn black (double ew). This symptom is what gave the disease its lovely name the Black Death.  Apparently these symptoms would occur within just a few days of getting the disease and people would die a very painful death soon thereafter.

The disease is thought to have been caused by a bacteria called Yersinia pestis. Although there have been reports of the plague occurring more recently it has been debated whether it is actually the same strain of bacteria as what caused the major epidemic ~600 years ago. One of the things we could do with the ancient DNA is to find out if the plague is still around, of course to find this out we need to get our hands on some of its DNA.

Bos and colleagues took a really interesting tactic to getting this DNA. They wanted to know how its DNA changed to make it go from a regular old bacteria to one that is capable of killing millions of people. To figure this out they had to get DNA from the actual bacteria that was killing people in the 1350s to see what it looked like. So where to find it?  Well, one of the big problems they had during the epidemic in the 1300 hundreds was what to do with all of the bodies, and one of the things they did was to create mass graves just for victims of the Black Death (awesome). Bos and colleagues took advantage of that and went to one of these old gravesites and actually dug up bodies and took teeth from five individuals and got DNA of the bacteria from those teeth (I wonder what they said they wanted to be when they grew up?).

What does the ancient DNA tell us, well to understand this we need to know a little bit about bacteria genomes.  Bacteria have really cool genomes, they have one circular chromosome (different from our 23 pairs of chromosomes) and they have other little pieces of DNA called plasmids. Plasmids are little circles of DNA that can be easily passed from one bacteria to the next.  These plasmids have been really important in the evolution of bacteria. For example, if a gene that makes a bacteria resistant to an antibiotic is on a plasmid and that plasmid gets transmitted to new bacteria then the new bacteria is instantly resistant to antibiotics. This is thought to be one of the reasons we have so many problems with antibiotic resistance.

The genome of Yersinia pestis has one large bacterial chromosome and two plasmids. Boss and colleagues found that the DNA from the ancient strain of bacteria is different from the strains of Yersinia pestis that are around today, but that it is likely that all of the strains that are around today are descendants of the ancient bacteria.  What is even more interesting is that they did not find any single spot on the chromosome or on the two plasmids that could explain why the bacteria became so infectious.  Instead they suggest that there were a lot of other things going on during that time period that added to the problem of this disease, like maybe people were more susceptible to getting sick, and the conditions were just right for spreading the disease.

It is fascinating to think about the issues around diseases and that many times other factors must fall into place for a disease to be really successful (and not necessarily just a genetic change), things like sterility, medical applications and knowledge, human health, and how the disease is transmitted. It may be that some bacteria or virus could be completely capable of causing a huge epidemic but we have other things in place that prevent those things from happening. The recent Cholera epidemic in Haiti is a good example of this. We have known what Cholera is and how it is spread since the days of John Snow, but we still were unable to prevent this problem in Haiti because the conditions were right for the disease to be spread.

 

Paper Referenced: Bos et al. 2011. A draft genome of Yersinia pestis from victims of the black death. Nature 478: 506-510.

The Real World by Lauren Long

“As soon as you enter University the pressure is on to figure out what you want to do with your life and to gain as much knowledge and experience as possible in those four short years before you enter “the real world”.  I have always known that I wanted to do science; I was fascinated by the natural world around me.  So, the hard part was figuring out what really interested me (the natural world is quite a big place) and how I was going to get any real experience to figure it out.

First semester sophomore year, I was lucky enough to have a fantastic biology TA.  She made biology lab extremely interesting, and best yet, she got me in touch with her advisor about getting some lab experience!  I was finally going to start getting some practical experience so I could start the process of figuring out where my interests lie.  I found out that the lab mainly researched lice (umm…pretty sure that’s not where my interests lie) but that the research was actually using the evolution of lice to look into human evolutionary history (way cool!).

After hours of pipetting tiny amounts of liquid into tiny tubes to the musical sounds of the PCR machine, I had decided that molecular lab work wasn’t for me.  That doesn’t mean I didn’t love every minute (nearly) of it though!  There is something extremely satisfying about putting in a lot of hard work and time to turn on the ultraviolet light and see the genes you were looking for amplified on the gel.  Just knowing that I contributed to research that could shed light on how humans evolved makes me feel pretty important.

So the moral of the story is to take every opportunity you can in college to learn and experience new things.  Even if what you are doing doesn’t directly lead you to your dream job, you still might find yourself involved in something that could change how we think of the world.”

Lauren Long was a former student at the University of Florida. She currently lives in Auckland, New Zealand where she works on public policy issues for the Auckland Council.  Here she writes about her experiences working in research as a college student.