BioQuakes

AP Biology class blog for discussing current research in Biology

Author: kysquared

Identical Twins, Identical Lives, Different Disease

Jack and Jeff Gernsheimer are identical twins. Jack has Parkinson’s disease, and his twin Jeff does not. Up until recently, because they have identical genomes, it would have been a mystery as to why Jack could develop Parkinson’s but not Jeff. However, with the discovery of epigenetics, scientists know that genes alone cannot explain why some people get Parkinson’s and other do not. While there are some genetic mutations linked to Parkinson’s, 90 percent of cases are “sporadic”, meaning that the disease did not run in the family. Even twins often do not develop Parkinson’s in tandem. Naturally, if genes don’t explain the development of Parkinson’s, scientists look to environment. There are several environmental factors that are known to link to the disease. People who were POW’s in WWII, for example, have a higher rate of developing Parkinson’s. But, and here’s the interesting part, Jack and Jeff have lived almost identical lives. For almost all of their lives, they have lived less than half a mile apart. Throughout their lives, they have been exposed to the same air, water, pesticides, etc. When they grew up, they built homes five minutes apart (by walk) on their father’s farm in Pennsylvania. Then, when they entered the professional life, they co-founded a design firm, working with their desks pushed up against each other.

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This anomaly, where a pair of humans exist with the same genetics and the same environment yet only one of them got sick is a research “bonanza” for scientists. All expected variables are being held constant, thus whatever is left must be deeply linked to the origins of Parkinson’s. However, there was a small difference in their lives that could provide insight into this anomaly. in 1968, Jack was drafted into the army and Jeff was not. This led to a series of unfortunate events in Jack’s life: first he served two years stateside in the military, got married, had two children, became involved in a long divorce, and suddenly his teenage son died. After this traumatic event, Jack went on to develop Parkinson’s, glaucoma, and prostate cancer, none of which Jeff has.

Jeff and Jack have been more than willing to undergo several studies in hope of finding something that could alleviate Jack’s Parkinson’s. The first study involved collecting embryonic stem cells from the twins. The benefit of stem cell cultures is that they act similarly to how they would in the body even though they are in a petri dish. The mid-brain dopaminergic neurons grown from Jack’s cells created abnormally low amounts of dopamine. Jeff’s produced normal amounts. Surprisingly, even though Jeff showed no signs of Parkinson’s, both twins had a mutation on a gene called GBA. This gene is known to be associated with Parkinson’s. As a result, both of their brain culture cells produced half the normal amount of beta-glucocerebrosidase, an enzyme linked to that gene. Instead of answering questions, this study only raised more to the fascinating case of Jeff and Jack.

I want to add a bit about how Jack’s son died, because it is unimaginably tragic and can show you just how much Jack had to face. Especially if we are considering Jack’s trauma as a contributor to his development of Parkinson’s, it is important to know the story. When Gabe, Jack’s son, was 14 in 1987, he became fascinated with the Vietnam War. Like any good father, Jack rented his son some movies on the war. One of those being The Deer Hunter, in which there is a scene where two prisoners of the Viet Cong are forced to play Russian Roulette. Gabe told his friend that if it were him, he wouldn’t just sit there. He would rather just get it over with. With that conversation, Gabe got his dad’s pistol, that he knew was hidden in the closet drawer, put one bullet in the chamber, put the gun to his head, and shot.

Jack rarely shows emotion. This “pressure cooker” way of dealing with things could explain his illness. Jeff thinks that the parkinson’s is a physical manifestation of how Jack deals with stress, rather how he doesn’t deal with stress. The connection between stress and disease is a very active research topic. And while their lives were very similar, if compared, Jack’s is by far the life with a more stressful environment. Some research might suggest that this stress differential can have a relation to Parkinson’s disease. In 2002, neuroscientists at UPitt subjected rats to stress, and they found that the stressed rats were more likely to experience damage to their dopamine-producing neurons than the non-stressed rats. This led to the term “neuroendangerment”, which means “rather than stress producing damage directly and immediately, it might increase the vulnerability of dopamine-producing cells to a subsequent insult.”

Another hypothesis as to what caused Jack’s Parkinson’s is that it could be linked to chronic inflammation.  Chronic inflammation is the mechanism by which stress can create neurodegeneration. Evidence that suggests this could be the case in Jack and Jeff is presented in their skin. Jack has psoriasis, a condition linked to chronic inflammation, and Jeff does not.

To this day, the search for what caused Jack’s Parkinson’s continues. Last year, NYSCF scientists conducted a study on the twins’ stem cells. They found a few functional differences between their cells. After finding the GBA mutation, they searched harder for other clues as to what might differentiate their brains. They screened 39,000 SNV’s, single nucleotide variants, which are instances where a single nucleotide in the human genome has been altered (either switched, deleted, or duplicated). They found 11 SNV’s, nine of which are linked to Parkinson’s disease. However, all 9 were found in both twins, meaning that this did not explain why Jack was sick and Jeff wasn’t.

Finally, they were able to uncover a relevant difference. Jack had high levels of MAO-B, which is involved in the breakdown of dopamine, whereas Jeff’s levels were close to normal.This hypothesis supposed that there exists a possible molecular mechanism by which stress could lead to neurodegeneration. What’s nice about this finding is that it could present a possible treatment for Parkinson’s. MAO-B inhibitors exist and are actually drugs currently on the market. They were given to Jack, and while it’s too soon to see the effects and to recommend them as treatment for Parkinson’s disease, it’s definitely a start.

Source: http://nautil.us/issue/21/information/did-grief-give-him-parkinsons

Biologists grow real human muscle

Scientists at Duke University recently announced that they have successfully bioengineered a human muscle that expands and contracts just like the real thing. Scientists see vast opportunities for this new advancement. It could become a powerful tool for studying diseases like muscular dystrophy. Not only could it help understand these diseases, but the engineered muscle could help scientists develop drugs to treat these diseases without the need to test on human beings. Dr. Grace Pavlath, senior vice-president and scientific program director for the Muscular Dystrophy Association,  says that the discovery will most benefit from testing cures to diseases without the risk of human life.

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To create the muscle, the scientists extracted special muscle “precursor” cells from human bodies and then multiplied then up to 1,000 times. Then they mixed the cells with a special gel and placed it in a 3d mold, which stimulated the growth of this muscle. When they stimulated the muscle with electric shocks and a number of different drugs, the scientists were delighted to find that the muscle reacted just like human tissue would, contracting and expanding as the impulses hit the muscle. This breakthrough holds large implications for improving research and testing of cures to many muscular diseases.

 

Source: http://www.huffingtonpost.com/2015/01/15/lab-grown-muscle-first-contracting_n_6471398.html?utm_hp_ref=science

Why do we actually care about celebrities?

Celebrities are a huge facet of many people’s lives. They fill the news and occupy hours of thought from millions of people who don’t even know them on a personal level. Why is there such a huge fascination with celebrities? It turns out that it all links back to our primal nature.

All primates experience the competition for resources within their ecosystem. Granted, some experience this more fiercely than others, but there’s no doubt that it exists in all primates. Let’s look at the savannah baboon, for example. The most defining factor in the life of a savannah baboon is its societal rank in a sex-specific dominance hierarchy. These baboons are constantly observed stealing glances at the most dominant of their pack. Social status is always on their minds. This ranking system is not an anomaly for the savannah baboon. It makes sense. With the hierarchy in place, there’s less fighting, the distribution of food is more orderly, and mates are chosen more easily.

In humans, things get a bit more complex. We simultaneously belong to several hierarchies, valuing most the one we rank highest in. Despite the complexity, the general idea remains the same as that of the savannah baboon. Over the course of our evolution, this hierarchy of social dominance has remained deeply ingrained in our brains. Psychology professor Nicholas Rule found that humans could correctly identify whether a face was of high or low social status in a mere 40 milliseconds. A study by Lotte Thomsen of Harvard shows that ten-month-olds are already accustomed to the idea of dominance and social hierarchy.

To find out more, scientists are looking at brain scans. When subjects evaluate social status from faces, they are using the “fanciest, most recently evolved part of the brain, the frontal cortex.”(http://nautil.us/issue/5/fame/on-the-origin-of-celebrity) Caroline Zink of the Lieber Institute for Brain Development found that if a subject observes two people  flip-flopping in their standing on the social ladder, the amygdala is also activated, which is responsible for processing fear and anxiety.

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Looking into the lives of celebrities entrances people because most often, celebrities hit the news because they did something foolish or embarrassing. For that one instant, we feel like we are on even footing with the “alphas” of our society by being able to gossip and joke about them. Caring about celebrities is literally part of our brain, and shows that we have a common ancestor with primates.  As someone who has never taken a big interest in celebrities, maybe it’s time to get my brain checked out.

 

Where Does Language Come From?

Somewhere in Britain, there is a family where each member has varied speech difficulties. Some members can’t say words like “hippopotamus”, others have trouble reciting words that begin with the same letter. This family, known as the KE family, was subject to research by Oxford University in the early 2000’s to find that they had a rare gene mutation. The subtle mutation took place in the FOXP2 gene, where only one nucleotide was misplaced. However, this research has opened up the world to the search for the so called “language gene” in our bodies.

 

There are approximately 6,900 languages in existence today.

For a while, scientists thought that the FOXP2 gene was the “language gene” in our bodies. But further tests show that the gene has much broader capabilities in humans and other animals, such as mice. This evidence suggests that there is no one language gene but instead it relies on a much broader neural support system. With the existence of a language gene being much less concrete, understanding where language originates from becomes much more difficult. A 2010 study by neuroscientist Aldo Faisal showed that what led humans from making stone flakes to axes was a shift in cognitive capacity, not an improvement in physical coordination. Researchers believe that as toolmaking became more common in the world, humans may have acquired the mental capacity for language. Liverpool archaeologist Natalie Uomini says: “A lot of people would say that toolmaking came [before language], I would just say that they co-evolved.” 

Liverpool archeologist Simon Kirby takes a different perspective on the origin of language, arguing that the human brain alone is not enough to explain language and that we must look at the evolution of human culture as well. Through several experiments with fictional languages, Kirby has found that as a language passes from one person to the next, it develops a unique structure and evolves in such a way that participants could guess words that they weren’t even trained to know. This shows that there is a lot more than just brain function in the evolution language. There is a huge social component, and this makes the discovery of language’s origin even messier than originally thought.

The fact that such an integral part of our society is still relatively unknown biologically is fascinating, and many breakthroughs in this topic have been made within the last 5 years. What’s fascinating about the search for language is that it shows that as modern science progresses, we may not find the answer to the question that we asked, but instead find a whole new set of questions that we would never have thought to ask. What do you think about the origin language? Did it come to fruition before or after toolmaking? Leave your thoughts in the comments section below, thanks for reading!

 

Source: http://nautil.us/issue/17/big-bangs/the-family-that-couldnt-say-hippopotamus

 

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