Ask a Scientist: Does cracking your knuckles cause arthritis?

By: Kylia Goodner

We all crack our knuckles (or at least know someone who cracks theirs), but each time we hear the characteristic “pop” of a joint cracking we have a slight moment of panic. Were our parents correct? Will cracking our knuckles cause arthritis?

Before I answer the question, I want to explain what is causing the characteristic “pop” associated with knuckle or joint cracking. Surrounding all of the body’s joints is a liquid called “synovial fluid” that helps your joints move smoothly. When oxygen and other gasses are brought into this area, large gas bubbles are formed. When you move or extend your fingers this lengthens the space between your joints and decreases the pressure formed by the fluid. This sudden decrease in pressure causes the large gas bubbles to “pop” and form into extremely tiny bubbles. Over the course of the next fifteen minutes the space between your joints returns to normal, which allows for another round of popping.

But does this repetitive cracking cause arthritis?  Although there have only been a handful of studies examining knuckle cracking, the prevailing answer is no.  A study examining 215 patients, found no increase in the amount of arthritis between knuckle crackers and non-knuckle crackers.  Another study examining 300 patients found the same result. However, this doesn’t mean its good for you or your hands. This same study found that knuckle cracking is associated with increased hand swelling and decreased grip strength.

As in every scientific study there are critiques. To date, there hasn’t been a single study to examine knuckle-crackers under the age of 45. Now, although it is probably safe to assume that people cracking their knuckles at age 45 have been doing it for most of their lives, a study examining knuckle cracking over time hasn’t been performed.  But for now, whenever you hear that characteristic “pop” you can quiet the terrified voice in the back of your mind and know that it is unlikely to cause arthritis! 

 

Some future kids will have three parents to embarrass them

By: Helen Beilinson

In each cell of our bodies, DNA is stored in two places. The nucleus contains nearly all of our genetic material, storing information that ranges from our hair color to how quickly we can break down the food we eat. A few genes are stored in an organelle called the ‘mitochondrion’, known more colloquially as ‘the powerhouse of the cell’. Mitochondria are predominantly in charge of generating their cell’s supply of chemical energy (hence their nickname), but are also involved in a variety of other tasks, such as cell growth and cell death.

Despite being involved in so many functions, mitochondria only have 37 genes (as opposed to the 25,000 in the nucleus). This may sound insignificant, but these genes are critical in ensuring that cells are happy and function properly. Consequently, defects in the function of mitochondria can have major effects on our health, resulting in a set of disorders called mitochondrial diseases. These include Leber’s hereditary optic neuropathy (LHON), which causes loss of vision at early ages and progressive loss of vision due to optic nerve degeneration, and mitochondrial myopathy, a muscle tissue disease. Fifteen percent of mitochondrial diseases are caused by mutations in mitochondrial DNA (the remaining are due to nuclear DNA mutations or other causes).

Mitochondrial diseases are treatable. However, current therapies are predominantly directed toward alleviating symptoms and in order to provide more comfort to the patient. These therapies don’t actually eliminate the cause of the symptoms— particularly mutated mitochondrial DNA. Why is it so hard to target the cause of mitochondrial diseases? Mitochondria are incredibly abundant; nearly half the space inside of heart muscle cells is taken up by mitochondria, and each liver cell contains up to 2000 individual mitochondria. So to target the cause of mitochondrial disease, one would need to eliminate the problem in the original mitochondria that gave rise to the lifetime supply present in all the cells of our bodies. Luckily, scientists have found a trick to do just that.

All of this potentially mutated mitochondrial DNA is inherited from our mothers, because the female egg, unlike sperm, contains all the mitochondria that the offspring will inherit. If a woman’s eggs contain only unhealthy or mutated mitochondria, the egg will usually be killed before it can further develop into a fetus. This is a common protective strategy used to eliminate fertilized eggs with any number of defects that could cause disease in the fetus. There are rare cases where the fetus will continue to birth with such inherited diseases. Luckily, accumulated knowledge about mitochondrial diseases and advancements in cellular biology have led to an invention that helps prevent infertility in women with defective mitochondria and protects their children from inheriting mitochondrial diseases.

This method, called three-parent in vitro fertilization (TPIVF), is essentially a twist on in vitro fertilization, where an egg is mixed with a sperm in a dish, outside of a body, and this fertilized egg is then implanted into a woman’s uterus. Unlike traditional in vitro fertilization, however, fertilized eggs generated through TPIVF contain DNA from three parents (hence the name). In this method, the nucleus from an egg with healthy mitochondria is removed and replaced by the nucleus from an egg with unhealthy mitochondria. This egg, composed of the mitochondrial DNA of parent A and the nuclear DNA of parent B, is then fertilized by sperm of parent C. In this way, a woman whose eggs contain mutated mitochondria is still able to conceive a child whose nuclear DNA is half her own.

At the beginning of February, the United Kingdom became the first country to legalize this method of in vitro fertilization. As early as January of next year, children will be born with three biological parents. As wonderful as this method is at preventing disease and infertility, it raises a lot of ethical issues, which are the predominant reason as to why TPIVF hasn’t been legalized in countries other than the UK.  Allowing for such extreme genetic modification of offspring opens the door to acceptance of “designer babies”. The idea of designer babies is that with advancements in basic cellular biology, people may start wanting to manipulate the genetic make up of their future children to personally select for features such as blue vs. brown eyes, curly vs. straight hair, etc. To my knowledge, in vitro fertilization, be it two or three parent, has thus far only been used to allow couples experiencing infertility or those whose offspring have a high risk of debilitating disease to give birth to healthy children. However, there will always be the question of whether such manipulations will lead to something more extreme.

TPIVF is an incredible advancement that highlights how far cellular, genetic, and developmental biology have come. Nevertheless, with great power comes great responsibility (thanks, Voltaire). It will definitely be interesting to see where our new abilities to genetically modulate offspring will lead.

Ask a Scientist: Can we eradicate diseases like Ebola and HIV/AIDS?

The world can be a scary place, especially when new and dangerous diseases seem to spring out of nowhere and cause enormous worldwide death tolls. Therefore, it’s no surprise that both the public and scientists are united on getting rid of these diseases as fast as possible. But what exactly is disease eradication, and are scientists even able to eradicate diseases like Ebola and HIV in the future?

Well first, according to the Centers for Disease Control and Prevention (CDC), eradication of a disease is defined as the “permanent reduction to zero of the worldwide incidence of infection”. This means that there must be zero new infections worldwide for a disease to be labeled as “eradicated”. Three guidelines are used to identify diseases that have the potential for eradication:

1) There must be an effective intervention to stop transmission of the disease. This can be a quarantine of all sick patients or administration of a vaccine to healthy people. Essentially, this is anything that will stop a new infection from occurring. 

2) There must be tools to identify when someone is infected. This is usually something like a cheek swab or a blood/urine test to determine whether someone is actually infected with the disease-causing virus or bacteria (aka pathogen).

3) The pathogen must rely on humans for its life cycle.  This means that if a pathogen can survive without a human, it cannot be eradicated.

If these three conditions are met, then a disease has the potential to be eradicated.

So how does Ebola virus measure up against these criteria?

1)    Prevention of transmission:

Although quarantines are effective in blocking human-to-human transmission, humans can also get Ebola from animals, like fruit bats. Therefore, quarantines will not be 100% effective in preventing the spread of Ebola. Another great way to stop people from getting a new infection of Ebola is a vaccine. Unfortunately, there are no vaccines available for public use, but there are many in the clinical trials pipeline. So the first condition isn’t met, but could the virus be eradicated if an effective vaccine were available?

2)    Tools for detection:

Yes! There are currently lab tests that measure infection.

3)    Dependence on humans:

Unfortunately, Ebola can survive in fruit bats without a human. Therefore, even if an effective vaccine were developed, it would be possible for a mutated form of the current Ebola virus to evolve in bats and be resistant to the developed vaccine. So unfortunately, eradication of Ebola is unlikely under the lens of these criteria.

Don’t be too discouraged, though, because eradication of HIV/AIDS is a different story. Returning to the three conditions required for eradication:

1)  Prevention of transmission:

Currently, the only interventions against HIV transmission are education and use of protection during sex. These are obviously not 100% effective to stop transmission of HIV. The creation of a vaccine would be ideal, but like Ebola, there are no currently available vaccines targeting HIV. There are a few vaccines being tested in clinical trials, however. But, when scientists are able to create an HIV vaccine, will eradication be possible? The answer is yes, because HIV meets both the second and third requirement set forth by the CDC:

2) Tools for detection:

There are tools that can accurately detect HIV infection and,

3)    Dependence on humans:

Yes! The life cycle of HIV depends on humans.

So now you know: eradication of Ebola is unlikely, while eradication of HIV/AIDS is definitely possible! However, a common theme among both of these diseases is that vaccines are desperately needed in order to be able to stop human-to-human transmission. Trust in vaccines is dwindling in today’s society, and although the safety of vaccines is a topic for another day, I will say that I fully support the creation and distribution of vaccines, new and old. They are a necessary part of our society if we want to be serious about eradicating diseases.  And I don’t know about you, but I definitely want to eradicate HIV as quickly and effectively as possible.

 

 

 

Seeing the Future of African Science

This is Durban, South Africa. Aside from being a surfing mecca, a thriving center of Zulu culture, and the largest port on the African continent, Durban (located in KwaZulu-Natal province) is the global epicenter of the HIV and tuberculosis (TB) epidemics. TB is the leading cause of death amongst South Africa's HIV-infected population, which is the largest of any country in the world. And a huge proportion of South Africa's affected population resides in KwaZulu-Natal. 

I extremely fortunate to have been able to study these infections in the laboratory and the classroom as an undergraduate. But when it comes to infectious diseases, some of the hardest questions can only be answered by studying them in hard places. This was, in large part, the motivation for the founding of the KwaZulu-Natal Research Institute for Tuberculosis and HIV in Durban, and was also my motivation for moving thousands of miles away from home for two years to conduct research there. I wrote about my experience for a new magazine about science and society, called Method. Check out the excerpt below, and read the full story here. And be sure to read all of the other great content that Method has to offer. 

Between 2005 and 2006, an outbreak of extensively drug resistant tuberculosis (XDR-TB) killed all but one patient at the Church of Scotland Hospital in Tugela Ferry, South Africa. The median survival time following diagnosis was a mere 16 days, and of the patients tested, all were co-infected with HIV. The situation was desperate, the fatality rates unprecedented, and the community unprepared for an outbreak of this magnitude. Though this calamity sent shockwaves through the TB and HIV research communities, the situation was not unique. XDR-TB had been detected in all of South Africa’s nine provinces, all of its neighboring countries, and dozens of other countries across the globe. HIV was fueling the TB epidemic, and Africa was the only region of the world in which TB incidence was on the rise. No new TB drugs had been discovered in nearly 40 years. Effective vaccines against HIV or TB infection remained a dream.

More than 8,000 miles away, in Chevy Chase, Maryland, American researchers at the Howard Hughes Medical Institute (HHMI), the largest private funder of academic biomedical research in the United States, were meeting to discuss their international program. At this meeting, Dr. Bruce Walker, an HHMI investigator who leads an HIV research lab at Harvard Medical School, proposed using a model similar to what has historically worked for HHMI in the United States: investing in individual investigators who were doing great work in biomedical science.

“But,” Dr. Walker recalls, “In a place like Africa, truly transformative support would require establishment of critical infrastructure and a critical mass of investigators.”  Indeed, this meeting identified two important and intricately related problems in the developing world: the desperate need for cutting edge biomedical research, and the rarity of sites in which to conduct such research...Read more

Reprinted with permission from Method Quarterly.

Ask a Scientist: Does smoking marijuana cause as much harm to your lungs as smoking cigarettes?

By: Kylia Goodner

Marijuana is all over the news: being decriminalized, legalized, and sold in an ever-growing number of states around the country. But as its legal presence grows larger, it is important to consider the safety of smoking marijuana before you light up (legally, of course). 

Both tobacco and marijuana plants are made of carbon, which, if you remember back to your high school chemistry class, makes up all living organisms. So what happens when you burn carbon? Well a variety of harmful chemicals are released into the air, and these chemicals can hurt your lungs when you inhale them. But this is true for burning anything that was once living, including wood for a bonfire, or grilling a steak on a hot summer’s day. 

So if burning anything with carbon creates harmful chemicals, then why is tobacco smoke so bad for you? Well mainly, it is harmful because it is addictive, which means that people who smoke tobacco inhale a lot of smoke, usually in the form of cigarettes. Further, cigarette companies add an additional 600 chemicals to these cigarettes, compounding the harmful effect on your lungs. Typically, people are not sitting around a bonfire multiple times a day, every day, for years on end inhaling harmful smoke in the same way that people smoke cigarettes. 

But this response is supposed to be about marijuana, and its effect on your lungs. It’s been known since the 80s that marijuana and tobacco smoke contain many of the same chemicals. Therefore, you would think that smoking marijuana would have the same effect on your lungs as smoking cigarettes, but surprisingly this isn’t the case. 

A study looking at over 5,000 people over the course of 20 years found no association between smoking marijuana and the development of lung cancer. A separate study focusing on lung function in marijuana smokers found that there was no decrease in lung function up to 20 joint years (1 joint year = 365 joints). However, they did find a slight decrease in function for smokers above 20 joint years. On the other hand, long-term marijuana smoking has been found to increase cough, phlegm and wheeze. 

Unfortunately though, researching marijuana has been made difficult by laws restricting access to the plant and the chemicals it contains. Therefore, we don’t know much about its effects on other bodily functions, including other cancers and heart disease. We do know, however, that inhaling burned carbon often is not good for your overall health. So when marijuana is legalized in your state, be cautious, responsible, and consider safer ways of inhalation. 
     

 

Cheaters never prosper, not even bacteria

We all know that cheating is wrong, but some people do it anyway. I know I had my fair share of classmates growing up who would try to copy my homework (perils of being a nerd). Big or small, cheating has consequences. If you’re caught peeking at someone’s answers while taking a test, you’ll probably get a zero.

The existence of consequences for cheating makes sense in the context of social cooperation— rules and laws facilitate our happy coexistence, and thus need to be enforced. It turns out that the phenomenon of social cooperation isn’t unique to humans. Biologists have also observed that animals living in groups can have complex social structures that are regulated by rules to prevent cheating, and “police” who enforce the rules. In ant colonies, for example, worker ants are policed (link) by occasional violent attacks to prevent individual workers from cheating. In this case, cheating means a single worker ant reproducing more than would be good for the colony as a whole. By policing these cheaters, the overall harmony of the colony is maintained.

While scientists have long known that animals exhibit cooperative behavior, a recent study published in Proceedings of the National Academy of Sciences showed that bacteria do the same thing. A team led by Dr. Peter Greenberg from the University of Washington studied social behavior in a species of bacteria called Pseudomonas aeruginosa. All social groups need a means of communication. Humans use language, among other things, to communicate with one another. In P. aeruginosa (and, in fact, all bacteria), communication is mediated by a process called quorum sensing.

In a legislative body, quorum refers to the minimum number of members that must be present at a meeting to make its proceedings valid. Bacteria are able to sense quorum, or how many bacteria of the same species around them, by sending out molecules that can then be recognized by special receptors on other bacteria. If you’re an individual bacterium, these receptors tell how many of your buddies are nearby by detecting the concentration of these quorum sensing molecules. When quorum sensing is intact, the entire population of bacteria benefits by being able to coordinate their behavior. If there’s a certain valuable resource around, like a nutrient, the whole population benefits if the nutrient is equally shared. In order to make sure they share equally with each other, the bacteria need to be able to sense how many other bacteria are around, which they accomplish through quorum sensing.

Unfortunately, this system is subject to cheating. After all, these nutrients are really yummy to the bacteria, and they don’t always want to share. It’s like if you brought a bunch of cupcakes to school to celebrate your birthday, but then realized that the cupcakes are delicious and you’d actually just rather sit at home and eat them all yourself. P. aeruginosa is able to cheat when it loses the ability for quorum sensing. This occurs by random a mutation event, but subsequently allows an individual bacterium to take up nutrients and reproduce independently of its buddies. This is great for the cheater (the bacterium that loses the ability for quorum sensing), but bad for the population as a whole, so the population needs a way of controlling this cheating behavior.

 It turns out that cooperating P. aeuroginosa, those that don’t cheat and maintain the capacity for quorum sensing, police the activity of the cheaters by producing a toxic molecule called cyanide. The same gene that mediates quorum sensing is also implicated in the detoxification of cyanide. So cheaters are punished for their behavior by losing the ability to break down cyanide produced by cooperators. The cheaters die, the cooperators prosper, and all is right with the world. 

Ask A Scientist: Why do you crave greasy food when you have a hangover?

By: Kylia Goodner

We’ve all been there: hungover and craving cold pizza the morning after a fun night out. But why do we crave pizza and greasy foods, instead of a large bowl of lightly seasoned quinoa and grapes? Biology has the answer in a little peptide called Galanin.

Galanin is a neuropeptide, which just means that it’s a very small protein that resides mainly in the nervous system, including the brain and spinal cord. Neuropeptides control many aspects of our day-to-day life. They tell us to move our hands when we’re touching a hot stove, and help us to remember our route to work. Although the main function of galanin is unknown, scientists have found exposure to fatty foods and ethanol causes more of it to be produced.

In laboratory rats, injection of galanin into a specific area of the brain, called the paraventricular nucleus, increased food intake in the hour after injection. Further, when scientists created mice without the ability to produce galanin, they found that they ate less fat and subsequently gained less weight than mice with galanin. So even without alcohol, if you eat fatty foods you’re going to produce galanin, which is then going to encourage you to eat fatty foods more often.

But what happens when you add alcohol? Unfortunately for us, the consumption of alcohol also increases the amount of galanin in our brains. Researchers have found that if they give ethanol to rats, through ethanol injections or by adding it to their water, the amount of galanin the rats produce increases compared to rats not receiving ethanol. Scientists further confirmed the relationship between galanin and alcohol by injecting mice with galanin and then observing how much ethanol they voluntarily drank after the injection. They found that after injection of galanin, the rats voluntarily drank more ethanol than the rats that did not receive an injection.

So, eating fatty foods and consuming alcohol both cause your body to produce more galanin, which in turn drives you to eat more fat and drink more alcohol. It’s a vicious cycle, which can lead to numerous cold-pizza hangover binges. Luckily, scientists may have identified a way out. Recent research has found that properties in the ginseng berry may act as an anti-hangover agent by getting rid of some of the harmful chemicals, called free radicals, which cause hangovers. So, next time you’re feeling the ill-effects of a night out, grab some ginseng berries instead of the cold pizza. You’ll thank yourself for decreasing your galanin production and escaping the vicious cycle it causes! 

Starting this week: Ask A Scientist!

Do you have a scientific question you've always been curious about? Heard some scary science "news" on television and want to know whether it's legitimate? Read something on Wikipedia and want to know if scientists really think it's true? Think the world is ending and want to have scientists weigh in on the subject? 

Starting next Tuesday, March 12, our newest contributor, Kylia, will be answering your questions about all things science! Submit questions on our Ask A Scientist page, and check back on Tuesdays for the answers. 

Male Odor Bride

By: Ross Federman

If you have ever been sexually attracted to someone, you likely know how powerful a feeling it can be.  You may have also made the discovery that the person you’re attracted to smells really great.  And while you find that they smell amazing, your friends may not always react the same way.  Why is this? The answer is surely a laundry list of factors that we don't understand fully and plenty that we don't even know exist yet.  However, some of how this process works has been studied, and indeed much of what you’re smelling are pheromones—chemicals secreted in sweat and other bodily fluids that have purportedly evolved to attract mates. Several studies have found a fairly significant link between how attractive a potential partner’s pheromones are and how well their combined genetic codes would render their offspring in fighting disease. Evidence really does seem to suggest that one is more attracted to those that will make their future children together healthier.

Although we are very adept at battling infections in general, one of the most powerful aspects of our immune system is its ability to adapt and focus its power on a very specific virus, bacteria, fungus, or toxin that has invaded the body, and to remember that same target if it ever shows up again.  There are two analogous molecules in mammalian immune systems known as the Major Histocompatability Complexes one and two (MHC I/MHC II) that allow little bits and pieces of these pathogens to be "presented" to other components of your immune system.  Under the right confluence of events these bits and pieces of proteins presented by MHC I and II trigger your adaptive immune response to know what to look for.  For example, if some punk kid in a red t-shirt sneaks into a black tie charity gala to get free food and drinks, the MHCs would basically show the red t-shirt to other cells, training them to look for it amongst the crowd.  I can't underscore enough how incredibly important the activity of MHC I and II is to your immune system.

The MHC proteins are made by various genes in the HLA family, and these HLA genes are the most diverse in the entire human genome.  That is to say, within the human population, there are many more varieties of MHC proteins than any of the other proteins that your genome codes for.  Each MHC has its own unique ability to present various types of peptides (which are chopped up bits of larger proteins) to your immune system.  In this case, these peptides are considered "antigens" by your immune system, small molecular signatures that allow for specific recognition, much like the red t-shirt on the moocher in the example above.  And while each unique MHC can present a wide variety of peptides and antigens, no single MHC can do this for all possible peptide antigens.  To answer this, we have evolved to each have several copies of HLA genes instead of just one.  This gives us the ability to try to cover as wide a range as possible in what our immune system can recognize and mount an attack against.

At the population level, this variety is crucial.  It ensures that the human race will have a spectrum of susceptibility to any given pathogen, so that even the worst mega pandemic virus will find some humans whose MHC molecules will present the viral antigens so efficiently that they will (hopefully) survive.  Essentially, evolution has given us the ability, as a whole species, be more suited to survive these horrible occurrences like the plague, the 1918 flu, and countless other similar events that undoubtedly occurred before recorded history.

But back to you and the awesome kids you'd have with that person that smells delicious and you’re finding yourself attracted to.  You and your partner each have a unique set of HLA genes creating a unique blend in ability to present various different antigens.  When you and your mate have very different MHC molecules, your offspring will ultimately get an even greater variety, and since HLA diversity has been so evolutionarily beneficial to our immune systems, our bodies seemed to have developed the ability to pick up on this as a cue.  Thus, we find a far more attractive scent or odor from a potential mate whose HLA genes differ from our own.  So it appears that our senses have been evolutionarily tuned to help us find sexual partners that will give our offspring a survival advantage when it comes to fending off disease, though it is still mysterious as to how this phenomenon occurs at a molecular level.

So take a second to forget about all of the crazy things going on in your head and your body when flirting, dating, or just meeting someone for the first time.  If you find yourself drawn to their scent, it could very well be nature's way of saying, "Hey if you two have kids, they'll have well equipped immune systems to fend off disease."  And with the lower and lower numbers of parents vaccinating their children recently, it might not be such a bad idea to keep this mind.

8 Science Facts That Will Blow Your Mind!

By: Erin Heim

1. Ok we’re going to start out with a kind of funny one. Hepatitis C is caused by, wait for it, Hepatitis C virus (HCV), which infects more than 3% of the world’s population. There are a handful of drugs on the market that are effective against HCV. Yay! Well just this week, scientists finally found out how some of these drugs may work—they stop the virus from replicating. So you Hepatitis C havers have been taking drugs that just happen to work, but no one knew why until now. Hilarious! Source

I thought scientists did the science BEFORE making the drug.

I thought scientists did the science BEFORE making the drug.

2. Great news for mice these days! They get cured of different cancers left and right! This time it’s AML (acute myeloid leukemia). To make a long story short, AML is caused when two factors that normally facilitate DNA replication (let’s call them Factors 1 and 2) get mutated, and prevent each other from working. So not just one, but two factors that normally help DNA replicate end up doing the turkey-tango with each other instead of DNA to cause AML, oh the drama. Scientists have found another protein (…Factor 3) that can interact with Factor 2. When Factor 3 interacts with Factor 2, Factor 2 no longer interacts with Factor 1, and Factor 1 is free to hang out with its’ true love, DNA, and AML doesn’t occur. Jeez, this reads like my middle school diary. Source

And then Factor 2 was all "No he didn't!" and Factor 1 was like "Uh yeah he diiiid."

And then Factor 2 was all "No he didn't!" and Factor 1 was like "Uh yeah he diiiid."

3. Scientists have finally proven what we all knew to be true - our cells are essentially the moving staircases from Harry Potter. And factors (like those same ones from above) are only able to replicate DNA when the stairs get them to the right spot and the entire castle is in the right orientation. And magically (just like in Harry Potter) the cells know how to move around all of their DNA to be at the exact right place at the exact right time and catch the bad guy mid-action! So, what I mean by all of this is that there is now strong evidence for how much the DNA organization gets remodeled and shuffled about in stem cells. This moving about happens to a SIGNIFICANT extent, and helps determine what the stem cells turn into. Like maybe if that one staircase hadn’t moved at that one point time, Harry would have been a Slytherin and Snape never would have killed Dumbledore. But that staircase knew what it was doing and Harry will forever by a beloved Gryffindor. Source

Wow. Stem cells in action. Wow.

Wow. Stem cells in action. Wow.

4. So I’m going to keep going with this stair thing. It actually seems like the way the stairs are organized in the very first cell of a tumor determines the entire cancer-ness of the tumor. So now scientists can use math and things to determine which cell started the tumor and what the stair shape was…. But… ermm… now what do we do with this information? Source

 

Who knew Will Smith's kid was the origin of the tumor?

Who knew Will Smith's kid was the origin of the tumor?

5. It is widely accepted in the science worlds… and hopefully the health worlds… that fat around your mid-section is really bad for you. Fat around your thighs isn’t actually all that bad (Sir-mix-a-lot knew what was up). Unfortunately for dudes, dangerous stomach-fat statistically tends to accumulate in the bad spots for men more often than for women. Well, good news guys! This new study…. totally just proves that point even further using data from over 200,000 individuals. Sorry to get your hopes up, I’m awful. Source

 

Everything seen above is perfectly normal and healthy.

Everything seen above is perfectly normal and healthy.

6. Know what works well to counteract fat? Muscle. Let’s talk about muscle. But before we talk about muscle, let’s talk about things scientists don’t know enough about. Like muscle. And RNA. So RNA is kind of like DNA, but it’s the messenger between what your DNA tells the cells to make and the actual protein that the cells make. There is WAYYYYY more RNA made than is needed to actually make proteins (98% of DNA doesn’t code for proteins), and for a long time scientists called these extra RNAs “non-coding” because they don’t code for proteins. Well within the past couple of years, many groups have found that this just isn’t true. Those non-coding areas do often code for proteins. The proteins are just small and adorable and tiny, so like the bullies that we are, we’ve been ignoring them all along. Well scientists have just found that one of these itty-bitty weakling proteins that we’ve previously ignored are actually able to slow down the ability to build muscle. Mice without this puny protein have an improved exercise performance. So, some RNA that we didn’t know makes proteins actually makes an itty-bitty protein that slows down our exercise performance. How’s that for the moral of a story? Just get rid of the puny weaklings, and you can grow stronger and get rid of fat! Source

 

And then the explorer broke all his body parts and could never get big and strong again. Stupid tiny penguin.

And then the explorer broke all his body parts and could never get big and strong again. Stupid tiny penguin.

7. I really, truly love when scientists come up with clever solutions to problems. When a virus wants to get into a cell, it attaches to a receptor on the cell surface, and essentially fusing itself into the cell. One problem with trying to cure HIV is that if you try to block it from accessing the receptors on the cell it wants to enter, the virus mutates to be able to bind those receptors anyway and then HIV does its thing and you get AIDS (that is a very long process summed up- please forgive the scientific semi-inaccuracies all of you nerds out there that just got mad at that summary). Well, clever scientists were like, wait, why try to block HIV? Let’s give it exactly what it wants! And they attached the receptors that HIV likes onto free-floating proteins  that aren’t actually attached to cells. So HIV is all “Whee! Look I am attaching to a receptor and am under no evolutionary pressure to mutate!” and the decoy receptors are like “Teeheehee, jokes on you, I’m not a cell!” Clever. Source

 

If Morgan Freeman thinks it, it must be true.

If Morgan Freeman thinks it, it must be true.

8. Human papillomavirus (HPV) is no good. It can cause warts and cancers and skin lesions. Did you know scientists still have very little clue about how HPV gets from outside the cell to inside the cell to cause infection and warts and everything? Well, these INSANELY smart (like, seriously, REAL smart) scientists found that HPV uses a unique type of trafficking to get from outside the cell to inside the nucleus of the cell by hijacking the cell’s natural processes and using a new signal to tell the cell “Sort me! Sort me!” SERIOUSLY SMART SCIENTISTS, AND LIKELY ATTRACTIVE AND NICE TOO! Source

 

Sorry guys, I'm obnoxious, my labmates wrote this paper and I'm just so proud.

Sorry guys, I'm obnoxious, my labmates wrote this paper and I'm just so proud.

Sisterhood of the Traveling Genes

By: Helen Beilinson

Unlike humans, bacteria reproduce asexually (yet another reason why I’m happy I’m not a bacterium). This means that one bacterium splits itself into two, giving rise to two daughter cells. The two asexual offspring have the same genome as their one parent. Although keeping the same genome as your parent has a lot of benefits (moms always know best), it can also lead to problems; the lack of new genes sometimes makes it hard for bacteria to adapt to changing environments. Luckily for them, bacteria have found lots of ways of acquiring new genes to survive new environments. One such strategy is getting genes from other bacteria through a process called ‘horizontal gene transfer’ (as opposed to ‘vertical gene transfer’ where parents give genes to their offspring). Horizontal gene transfer doesn’t just occur between bacterial species—it has also happened between bacteria and eukaryotes, which are much more complex organisms. And recently, scientists from the University of Washington found that horizontal gene transfer has brought bacterial genes into animal genomes.

The researchers, led by Joseph D. Moungos, published a study in a recent issue of Nature. They found a bacterial gene called Tae that has repeatedly entered eukaryotic lineages through horizontal gene transfer. Many bacteria have Tae proteins, which function as antimicrobials to kill other bacteria. To do this, Tae breaks down the layer of protection that surrounds the bacteria, called the cell wall. The bacteria that Tae targets actually have two cell walls—an inner wall and outer wall. Tae goes in between the two walls and breaks down a sugar-rich structural protein called peptidoglycan. By targeting peptidoglycan, Tae essentially makes the two cell walls collapse in on each other, killing the bacteria. This group found that at least six times in history, eukaryotes have gotten this gene from bacteria to use as their own. When they looked at the animal versions of the proteins, termed Dae, they discovered that their function in animals is the same as in bacteria; Dae proteins are antimicrobial agents that target peptidoglycan.

The experiments initially showing that Dae has antimicrobial function were performed in a test tube, outside an actual organism. To investigate whether Dae has antimicrobial function within organisms, this study looked at an animal that got Tae from bacteria—the deer tick. Deer ticks can spread the bacteria that cause Lyme disease, which results in fevers, headaches, and rashes, and can lead to more serious symptoms if untreated. Borrelia burgdorferi is one bacterium that can cause Lyme disease in humans. It moves from person to person by living in ticks and transmitted through tick bites. To see if Dae works as an antimicrobial in deer ticks, the scientists removed the Dae protein from the deer ticks and looked for changes in the amount of B. burgdorferi. Turns out that without Dae, deer ticks have more B. burgdorferi. Dae restricts the population size of B. burgdorferi can get in the deer tick by killing the bacteria.

 Collectively, bacteria harbor heaps of antimicrobial peptides. This group looked at one such protein in a defined animal species. If one protein has been transferred to eukaryotic genomes six times in the species that they looked at, this implies that with the thousands of other antimicrobial peptides and thousands of other animals, it is highly probable that many other bacterial genes have been transferred into animals. Who knows, maybe it wouldn’t be so bad being a little bacterial.

Roses are red, violets are blue, frogs are icky, but may be good for you

By: Zuri Sullivan

Sorry, kids, but if you kiss a frog, it’s highly unlikely that he’ll turn into a prince. The most you’ll probably get out of it is some icky frog skin slime on your mouth. That may sound terrible, but a new study published in Antimicrobial Agents and Chemotherapy suggests that some components of icky frog skin can have some unexpected benefits for our health.

As you might imagine, frogs are pretty distantly related from humans, and consequently, their immune systems work quite differently from ours. One thing we have in common, however, is that we both produce molecules specialized for killing bacteria, called antimicrobial peptides (AMPs). Humans produce lots of AMPs in their guts— last week, I wrote a story about how the helpful bacteria in our guts manage to survive in the face of these harsh molecules, while dangerous bacteria don’t. Unlike humans, frogs and other amphibians produce AMPs in their skin. To a certain extent, you could say they wear their immune systems on their backs.

Scientists haven’t quite figured out all of the ways that AMPs actually kill bacteria, but if the bacteria are susceptible to them, they work incredibly well. So from the bacteria’s perspective, AMPs are pretty nasty. From biomedical scientists’ perspective, however, this means that AMPs from a variety of species may be able to be used to treat bacterial infections when our own AMPs are inadequate.

This was the focus of the study I mentioned above, led by principal investigator David Craik at the University of Queensland in Australia. His research group wanted to know whether frog AMPs could be used to treat Staphylococcus aureus infection. You may know of Staphylococcus aureus by its more colloquial nickname, Staph. Staph infections are a major problem in hospitals, and the widespread use of antibiotics has led to the emergence of antibiotic resistant staph, also known as MRSA (for methicillin resistant Staphylococcus aureus). Antibiotics are great, but when misused or overused, they can promote the emergence of antibiotic resistant bacteria, necessitating the development of new antibiotics. It’s a vicious cycle, but AMPs could be new weapons in our anti-bacterial arsenal.

Can you really take AMPs from frog skin and use them to treat a staph infection? In mice, the answer seems to be yes. Dr. Craik’s group isolated AMPs from frogs, and studied their chemical structure. If they’d had to run out and catch a frog every time they wanted to do an experiment, the study would have taken forever, so they synthesized molecules that were very similar to the frog AMPs. These synthetic AMPs were then used to treat Staph-infected mice. Surprisingly, they worked! And not only that, but when they tested the compounds to find out if they were toxic to the mice, they seemed to be safe.

This doesn’t mean you should go out and lick a frog next time you’re feeling sick. As Helen and I tried to illustrate before, findings in mice need a lot of work to be extrapolated to humans. We know that a drug’s effect on mice is not always the same as its effect on humans, so clinical trials, despite being absurdly costly and tedious, are really important to make sure our drugs have the effects we want them to. AMPs are also expensive and difficult to synthesize, and scientists will need to find easier ways of making them if they want to try to use them to treat human infections.

Don’t give up on frog AMPs yet, though. With time, scientists may be able to turn them into real treatments for human infections. And in the meantime, you can put them to good use by applying the old Russian method of dipping a frog in unpasteurized milk to keep it from spoiling.

Mycobacterium tuberculosis: Man’s Best Frenemy

By: Zuri Sullivan

Modern humans arose in Africa around 200,000 years ago. For an estimated 70,000 years of our history, we have co-existed with a bacterium called Mycobacterium tuberculosis (M. tb). M. tb is most notable for being the causative agent of tuberculosis (TB) disease, which kills 1.5 million people each year. However, this is only the tip of the iceberg when it comes to the ways that M. tb has influenced our biology.

We’ve developed an intimate relationship with M. tb over the last 70 millennia of our coexistence. The bacteria live inside immune cells in our lungs, and rely on us for survival. Our immune systems work to control the growth of M. tb when we become infected. If this immune response is unsuccessful, we can die from the infection.

In short, our survival and the survival of M. tb are deeply intertwined with one another, with each species attempting to subvert the other’s efforts to kill it. This arms race between a host (humans) and a pathogen (M. tb) is sometimes referred to host-pathogen co-evolution, and in the case of M. tb, it’s been going on for quite a long time.

Fighting off M. tb isn’t the only thing humans have been doing for the last 70,000 years, however. We migrated out of Africa, learned agriculture, formed nations, fought wars, made major technological advances, and fought lots of other pathogens. A history class can teach you how these and other events throughout human history have affected us as a species, as smaller populations, and as individuals. A new study published in Nature Genetics explores how major historical events have influenced our old frenemy, M. tb.

The study of human history often relies on primary sources, like ancient texts stored in archives. Unfortunately, bacteria haven’t learned to write, and scientists have only known about them for a few hundred years, so researchers studying the history of bacteria need to rely on other sources of information.  This is where deoxyribonucleic acid (DNA) comes in. You can learn more about DNA here, but the bottom line is that DNA is how information is stored in biology.

How did the researchers use this information to study the history of M. tb? When DNA is passed down from one generation to the next, small changes, or mutations, occur. It works a lot like the game of telephone, which lots of people play in elementary school. One person comes up with a silly message, and whispers it in the ear of the person next to them. That person whispers what they heard to the person next to them, and so on, until it gets back to the original message sender. The fun of the game is in seeing how much the message has changed, or mutated, as it traveled around the circle. Mutations in DNA accumulate in a similar way, but unlike the game of telephone, geneticists can quantify the changes and estimate when in history they occurred. This allowed the researchers in this study to read the DNA of M. tb like a historical text.

The team of researchers, representing 45 institutions on six continents, collected the largest assembly of a single strain of M. tb ever described: 4,987 samples from 99 countries. Using this massive collection, they traced the history of this M. tb strain over the last 6,000 years. The researchers looked at the similarities between the different bacterial samples to find out how related they were to one another. They identified seven distinct groups within the strain of M. tb, kind of like seven different families descended from one ancestor. They were able to plot the seven different groups, called clonal clusters (CC), on a geographic map because they knew exactly where each sample had come from.

Their map showed that this particular strain of M. tb had arisen in East Asia, and that certain CCs had spread to the islands of Polynesia and Micronesia, while others spread westward to Russia and Eastern Europe. The timing of this spread suggests that these CCs were likely transmitted along the Silk Road. Some CCs were present only in East Asia, the United States, and South Africa, suggesting that they were spread by immigration, rather than transmission along trade routes.

So the information in M. tb’s DNA showed how human migration has influenced the bacteria—what else can we learn from it? In addition to identifying the seven CCs of closely related bacteria, the researchers also tracked periods of overall expansion and contraction in the bacterial population. As in their first analysis, they looked at mutations in DNA. Because they occur at quantifiable rates, researchers can estimate when mutations occurred by comparing the number of observed mutations to the known mutation rate. In doing so, they generated a timeline for the expansion and contraction of this strain of M. tb.

Our close relationship with M. tb would suggest that this bacterial timeline would look a lot like the timeline of human history, and indeed, this is what the researchers found. The first major expansion in the bacterial population occurred around 200 years ago, coinciding with the Industrial Revolution. This was a time of major expansion in the human population as well, so a concomitant expansion in M. tb makes sense. The second M. tb growth spurt coincided with World War I, when people from different corners of the world were interacting with each other and likely spreading the bacteria. After this expansion, they noted a major drop in M. tb population around the 1960s, the period when the use of anti-M. tb drugs became widespread. For the first time in our history, humans had a secret weapon against the bacteria, and the findings from this study show that we were winning. Unfortunately, this downward trend was recently interrupted.  With the onset of the global HIV epidemic, the researchers observed a renewed growth in the M. tb population, reflecting the known positive influence of HIV on M. tb transmission.

 Part of the reason that we study human history is that the lessons from the actions of previous generations can inform our own decision-making. Studying bacterial history may be able to help us in a similar way. And because M. tb remains a major public health threat in many parts of the world, understanding how our actions impact its spread may help us to save the millions of lives that are affected by it.

The Cold and A Cold: Do they really go hand-in-hand?

By: Helen Beilinson and Zuri Sullivan

Biology is complex—very, very, very, very, very complex—and because of this, simplification is incredibly important. Many experiments are conducted by breaking down a complex system and studying its constituent parts, manipulating specific components (or “variables,” in science slang) to understand how they impact the system as a whole. For example, to understand how viruses replicate within their animal hosts, scientists often study how the virus replicates in animal cells grown in an incubator, instead of the whole organism. As a consequence, scientific knowledge accumulates in tiny increments—each study answers a small, but specific question. When we amass sufficient answers to simple questions, we learn something new about a complex biological system. 

This strategy of deconstruction and reconstruction has led to a number of important scientific discoveries, but it comes at a cost. Findings made in smaller systems can’t always be extrapolated to the larger system. Sometimes, these findings are really exciting, and they tempt us to jump to conclusions because of their potential impact on the larger system. This presents a major challenge to science reporters: keeping a story exciting at its beginning while resisting the temptation for overstatement. Some stories in the media meet this challenge better than others, but like all news, science news should be taken with a grain of salt—a scientist’s interpretation of his or her findings and their potential impact on society can vary widely from the interpretations of reporters.

As a case study for this idea, we investigated a recent high-profile story about the relationship between temperature and catching the common cold. The original study, published last month in the Proceedings of the National Academy of Sciences by a team of investigators headed by the laboratory of Akiko Iwasaki, an investigator of Howard Hughes Medical Institute and Professor of Immunobiology at Yale University, investigated the effect of temperature on protective immune responses to rhinovirus, the predominant causative agent of the common cold.

“It’s been known since the 1960s that the virus replicates better at nasal cavity temperature, which is around 33 to 35 degrees Celsius,” said Dr. Ellen Foxman, a post-doctoral fellow at Yale University who was the primary author of the study. Core body temperature for humans is 37 degrees Celsius (98.6°F), but inhaling cool air brings the temperature in our noses down to about 33-35 degrees Celsius (91.4-95°F)—the temperature at which rhinovirus grows best. By exploring the role of specific immune responses in a cell system, the study found that the temperature difference in viral replication was caused by a temperature-dependent difference in immune responses. Turns out, key immune responses against rhinovirus don’t work as well at 33-35 degrees as they do at core body temperature, so the virus is able to replicate more.

Given the implications of these findings (particularly that we should always listen to our moms and bundle up in cold weather), this study was covered widely by the media, with such headlines as “Common cold ‘prefers cold noses’” and “Common cold really is triggered by cold weather”.

“Some of the headlines went further than we did in our study,” says Ellen. “We didn’t actually study weather at all. Or people going out in the cold.” This was apparent in the original research findings, but many journalists bit into the cold weather/cold virus relationship. “To really make that claim, in terms of a clinical research study, you’d need to have two groups of people, normalize them, put some people in the cold…all that we didn’t do. So some people took it a bit further than we would have.”

This study wasn’t conducted in humans or in animals for that matter. It was done in a system where cells that live on a dish in an incubator in a lab are infected with the virus and are grown at different temperatures. Organisms are a lot more complicated than cells in a dish, making it difficult to extrapolate the findings from the study to a complex organism like a human. The relevance of these studies in humans is not currently known. This was seen as a limitation in other mainstream articles that covered the study, but was never fully discussed. On another note, the study looked at temperatures of 33-35°C compared to 37°C. The temperature of the human nasal cavity during winter could reach far below 33°C. Studies exploring how the immune responses functions below 33°C have not been done. Far from invalidating their results, however, the controlled system in which the experiments were performed is a major strength of the research. It demonstrated that the slight shift in the temperature dampens the immune response to the virus. Because inhaling cold air results in cooling of the nasal cavity temperature, the study implies that the cold weather could lead to more virus replication in human nose.

“After we isolated the primary cells, everything was identical about them, except for a few hours of incubation at different temperatures. So, it’s not the same as studying it in a person…but in a person, there are so many variables that you can’t control, that you can’t analyze. That’s the advantage of doing something in a laboratory. You can control everything except for one variable at a time and see how this variable affects the immune response, and thereby the infection.” This high degree of control is an indispensable component of the scientific method—without it, results are extremely difficult to interpret because outcomes cannot necessarily be attributed to a single variable. In order to show cause and effect, scientists need to ask straightforward questions under tightly controlled conditions. This control allowed for the discovery of what Ellen sees as the most important implication of the study.

The Other Sputnik: The First Known Virophage

By: Helen Beilinson

For every organism on earth, there are a multitude of viruses that can infect it. Every. Single. Organism. There are viruses that infect everything from bacteria to fish to humans, and anything in between. I’m going to tell you about one of my personal favorite viruses, Sputnik.

But first, let me introduce our host, the amoeba. Amoebae are single celled organisms, more closely resembling our cells than those of bacteria. Unlike humans, they don’t have an extensive immune system that protects them from harmful pathogens in their environment. Their main mechanism of protection is ‘eating’ things in their environment and breaking them down, in a process called ‘phagocytosis’. Although this defense works great often enough, there is not much the amoeba can do to protect itself once it’s infected with a virus.

One such virus is the Mamavirus. Mamavirus is a HUGE virus at around 750 nm in diameter. This may seem small, but that’s about half the size of the bacterium E. coli and it’s almost eight times as large as the infamous influenza virus. You can even see it under a regular light microscope, the kind of microscope used in many high school science labs, compared to most other smaller viruses that you need a high powered microscope to see them. It was first found almost seven years ago living inside amoeba in a cooling tower. Mamavirus lives and replicates in the cytoplasm of amoeba, where it sets up a “replication factory” that takes over the cell. This replication factory is where the virus replicates its DNA genome and makes the proteins necessary to build the outer shell in which it keeps its genome. Once Mamavirus replicates to a high degree, the viruses break down the amoeba cell, a process called ‘lysis’, to be released. As I’m sure is clear, this isn’t a great fate for the amoeba who has little defense against the virus once it starts replicating. That’s where Sputnik comes in.

Sputnik is a very small DNA virus, only about 50 nm in size, about fifteen times smaller than Mamavirus. It became fairly famous after its discovery as the first known virophage, a virus that infects viruses. That’s right—Sputnik is a virus that infects viruses. In fact, it infects Mamaviruses. Although Sputnik can infect amoeba on its own, it’s not that great at replicating by itself. However, when the amoeba is also infected with Mamavirus, Sputnik replicates like crazy. It takes over Mamavirus’ replication factory, which is a perfect little nook for the smaller virus to replicate. Although it might sound kind of unpleasant to be infected with two viruses at once, it’s actually a benefit for the amoeba. By hijacking the Mamavirus’ machinery, Sputnik reduces the ability for the big virus to replicate and make proper virions (or virus particles). It can reduce the Mamavirus load up to 70% and decreases amoeba lysis by threefold. Turns out the old proverb “the enemy of my enemy is my friend” really is the case with the amoeba and Sputnik.

Since the discovery of Sputnik, many more virophages have been discovered, which predominantly attack the large viruses that infect amoeba and zooplankton (a marine microorganism). Virophages have increased our knowledge of the deep complexity of the microbial world. As these critters are essentially brand new to our understanding, there is still a lot to learn about how they influence our ecosystems. There has been an ongoing battle amongst scientists about whether or not viruses are living things. Without getting too much into the details of things, the major point of contention is whether we can consider something living if it has to live within another organism’s cells to replicate. Maybe we need to reconsider whether we should classify viruses are living organisms or not. If they can also be infected with viruses, just like us and our pets and the bacteria that live in our guts—why can’t they be alive?

Why don’t we kill our microbiota?

By: Zuri Sullivan

If you didn’t already know that humans are colonized by trillions of bacteria, that these bacteria make up much more of our bodies than our own cells, and that they play an important role in our physiology, health, and disease, then you probably didn’t read Helen’s piece about the microbiota and defense against viruses. The “microbiota” refers to the collection of microorganisms that live in and on our bodies. A search for “microbiota” returns close to 14,000 academic papers. To call this a current hot topic would be a massive understatement. Why are scientists so excited about the microbiota? First, major technological advances have allowed scientists to begin unraveling the complex community of bacteria, fungi, and viruses that colonize our bodies. Additionally, mounting evidence suggests that the microbiota can influence nearly every aspect of our physiology, which raises important questions about its interactions with other cells and tissues in our bodies. 

There’s a lot to be learned about the microbiota and its functions, but one of the biggest unanswered questions in the field is why all of these bacteria are overlooked by our immune system. Most of us know the immune system as the mechanism by which our body eliminates disease-causing agents, or pathogens. These pathogens are bacteria, viruses, and fungi—the same organisms that make up the microbiota. One of the biggest unanswered questions regarding the microbiota is why our immune system doesn’t eliminate our own microbial population, but does eliminate those microbes that are pathogenic. The initiation of an immune response against an invading species relies on the detection of pathogen associated molecular patterns (PAMPs). PAMPs are molecular structures that are present in microorganisms, but not in host cells. For example, a particular sugar-like molecule, lipopolysaccharide (LPS) is present on the surface of some bacteria, but absent from mammalian cells. Thus, by targeting attacks against cells that have LPS, the immune system can efficiently target a wide array of bacteria without risking damage to host cells. In addition to being distinctly non-mammalian, another critical feature of PAMPs is that they are conserved amongst microbes. This means that PAMPs tend to be molecules that serve critical functions for microbial survival, and thus they are seen in an array of microbial species, including pathogens (microbes that make us sick) and commensals (microbes that have neutral or beneficial effects on our health). This raises an important conundrum: if the immune system recognizes PAMPs that are common to all microbes, why don’t we attack commensals?

A paper published last week in Science provides an exciting clue to how our commensal bacteria survive some of the host’s innate defenses. They looked at antimicrobial peptides, which are chemicals made by immune cells that can directly kill bacteria. They’re like antibiotics made by your own body, and they are an important innate defense mechanism against bacterial infection. The team of researchers asked whether commensal bacteria might be resistant to antimicrobial peptides, which would allow them to survive in the host. Their hypothesis was that commensal bacteria that are adapted to live in our bodies might have evolved mechanisms to tolerate antimicrobial peptides, while pathogens have not.

They found that a common commensal species, Bacteroidetes thetaiotamicron  (B. theta) was more resistant to a particular antimicrobial peptide than pathogenic bacteria. Next, they identified the B. theta gene that was responsible for antimicrobial peptide resistance, a gene called LpxF. They then asked what role this gene played in the ability of this commensal organism to survive the host immune response to a pathogenic bacteria.

This was an important question, because it illustrates an important principle about how the microbiota helps us protect ourselves from pathogenic bacteria. When we’re infected with an intestinal pathogen, gut immune cells detect the infection and induce many defense mechanisms, one of which is the secretion of antimicrobial peptides. These antimicrobial peptides need to be able to target the pathogen, while sparing the commensals that provides other benefits to the host. Thus, by having a gene that confers resistance to antimicrobial peptides, the commensal has an advantage over the pathogen in the context of an immune response.

This was borne out in an experiment wherein the researchers added two different bacterial strains to the intestines of germ-free mice (mice who are raised to not have their own microbiota): wild-type (normal) B. theta or B. theta that were lacking LpxF (a mutant strain), and therefore lacked resistance to antimicrobial peptides. They then infected these mice with a known pathogen, Citerobacter rodentium. They found that while the LpxF mutant strain of B. theta was outcompeted by the pathogen, the wild-type B. theta survived the immune response.  

The findings of this study illustrate two important principles. First, they provide a mechanism that explains how a commensal bacterium survives a host defense mechanism that is directed against all bacteria. Second, they show that this survival mechanism helps commensal microbes compete with pathogens for colonization of the gut. These principles are relevant to both the continued understanding of the role of the microbiota in host defense, and in understanding the co-evolution of the immune system and commensal microbes. This co-evolutionary relationship, whereby our evolved mechanisms for eliminating bacteria are resisted by commensals that have evolved to live in our bodies, is important for the continued study of the microbiota and its impacts on our health. 

I Kid You Not, A Disease Exists That Makes You Drunk, Constantly

By: Ross Federman

A bar I used to frequent serves a delicious frozen drink known as a “Constant Buzz.”  It sounds like an appealing concept, a nice basal level of ongoing intoxication, but did you know that in some incredibly rare cases, individuals find themselves in this situation without any choice?  Auto-Brewery Syndrome (or gut fermentation syndrome) is a disease whereby patients literally brew alcohol in their guts.  Imagine not taking a single sip of beer, wine, or liquor, yet still constantly registering above the legal limit on any manner of blood alcohol or breathalyzer tests.  This is the unfortunate case for those rare few that find themselves with this disorder.

How does it happen?  It was a mystery for years.  In fact, it’s likely that some may have been incarcerated, fired from jobs, suspended from school, you name it, all because they were drunk against their will with no explanation to offer as to their erratic behavior.  Recently, we have gained significant insight into the nature of our gut microbiota and the profound role that it plays in human health.  The microbiota is usually discussed in terms of the species of bacteria that comprise it; yet other microorganisms are present, as well.  In most healthy microbiota, a small population of the commonplace fungal yeast species Saccharomyces cerevisiae lives in your gut with all the other microorganisms.  S. cerevisiae is also known as “Baker’s Yeast” and is the species often simply referred to as “yeast” in the majority of baking and beer brewing applications. You and everyone around you likely have some S. cerevisiae hanging around in your guts, and the amount of it is largely kept in check by your immune system, other microorganism species, and competition for nutrients.  However, in some rare cases, this population is not kept to the proper minimal levels and grows wildly out of control. 

At the heart of this phenomenon is the fermentation process.  It is found in both yeast and bacteria, though the specific fermentation products differ.  In both cases, sugars or carbohydrates are broken down to carbon dioxide in order for the microbes to produce energy in an environment lacking oxygen (such as our guts).  For bacteria, lactic acid is the second byproduct along with carbon dioxide, but in yeast, ethanol is produced in lieu of lactic acid.  Thus by increasing the ratio of S. cerevisiae to bacterial species in the gut, greater amounts of ethanol are produced, and past a certain threshold, the ethanol metabolic product seems to reach levels where it is in a great enough concentration to equate to imbibing ethanol in the form of an alcoholic beverage.  It should also be noted that this same fermentation process is used to achieve the alcohol content in said beverages, though this, of course, does not take place directly in our stomachs.

Even with a greater understanding of the microbiota, the precise nature of why these yeast populations can grow so large and lead to ongoing intoxication remains unknown. Cases are so rare that really everything we know about this disease is almost entirely anecdotal.  Perhaps the patients ate an absurd amount of sourdough after taking antibiotics that would have wiped out many of the bacteria just prior to yeast colonization?  Whatever oddball circumstance lead to this, the end result?  Enough yeast in your gut to lead to fermentation levels that are actually sufficient enough to influence blood alcohol levels.  Sounds pretty awesome if it only lasts for the three days you spend at Coachella, but week in and week out, it would probably get old pretty quickly.

DNA: delicious.

By: Zuri Sullivan

It has come to our attention that many people are concerned about deoxyribonucleic acid (DNA) in their food, and that more than 80% of Americans support “mandatory labels on foods containing DNA,” according to a study conducted by the Oklahoma State University Department of Agricultural Economics. The study found that more people supported mandatory labeling on foods containing DNA than supported a tax on sugared sodas, a ban on the sale of marijuana, a ban on the sale of foods with trans fats, or a ban on the sale of unpasteurized milk.  

Ilya Somin, a Professor of Law at George Mason University, discussed these findings in a recent blog post on washingtonpost.com. In his post, Somin addresses the dangerous intersection of widespread ignorance about science with mistrust of public policy amongst the American electorate. Our purpose here is to address some of the scientific misinformation leading to these concerns.

DNA is a molecule that stores all the information necessary for life. Along with a related molecule, ribonucleic acid (RNA), it is one of a group of macromolecules, or building blocks, that make up all known living organisms. Other groups of macromolecules include proteins, carbohydrates, and lipids (or fats). The information encoded in DNA, however, is required for building all of these molecules. In short, DNA is essential for life.

All living organisms, from single-celled bacteria to large, complex, multicellular organisms like us, are built from cells that contain DNA. Even fossils, like this 400,000 year-old skeleton contain DNA. All of the food that we eat, provided that it came from a living organism, contains DNA. Vegetables, fruits, meats, dairy, pizza—all of it contains DNA. The only thing in your refrigerator that doesn’t contain DNA is the refrigerator itself. If we were to label all foods containing, DNA, therefore, we’d need to label every single food. Not only would that be wasteful, but it would also be meaningless. In fact, I’d be in support of labeling any foods that don’t contain DNA. I’m not sure what that would be, maybe rocks or something? 

The purpose of Because Science is two-fold. First, we think science is awesome and we want everyone else to think science is awesome, too. But more importantly, we want to help people to better understand the science that impacts their daily lives. While we felt a bit of an imperative to write this quick piece about following the publication of this study, we are always open to suggestions based on concerns or misunderstandings about science. So if there’s a scientific topic you’d like to know more about, send us an email and let us know!