Fishy Diets – What Are You Really Eating?

In 2007, several people in the US sat down to what they thought was a harmless dinner of monkfish. Little did they know that this particular Chinese import was actually a toxic puffer fish that had entered the country under the cover of a more innocuous name (1). This scare began to draw more attention to the regulation of the fish market and labs began to investigate whether this incident was an aberration or a frequent occurrence. In the United States, most consumers are completely trustworthy of food labels and believe that a misrepresentation of a food product is extremely rare or nonexistent. This year, multiple labs investigated this assumption and did not like what they saw. Some of these labs included associates of Oceana (an environmental group), Consumer Reports Magazine, private lab companies like ACGT, Inc, and the Food and Drug Administration (FDA). Their results showed a massive problem in our country’s seafood regulation.

Seafood is a staple food in cultures around the world. It is commonly considered a healthy alternative to many other food groups and there are multiple delicacies found in oceans, rivers, and ponds. The FDA recognizes 45 species-specific market names for fish (4) and retail companies must legally identify their fish with these market names. Unfortunately, it is believed that 20-25% of seafood samples throughout the world are actually mislabeled, oftentimes as a more expensive species (3). In fact, the FDA port inspections speculate that a third of seafood sold in the U.S. is mislabeled. One reason for this may be that 86% of seafood eaten in the U.S. is imported and only about 2% of these imports are inspected (2). This deception costs consumers millions of dollars each year when they are under the belief that they are actually buying a more expensive fish (1). It also may cause health problems similar to the toxic puffer fish or allow endangered fish to be sold illegally, thus enabling the decimation of certain species.

During the occurrence of the puffer fish incident in 2007, fish samples were verified through protein analysis, or isoelectric focusing (1). Each fish species contains slightly different proteins in its body and this test identified the proteins by their electric charge differences. This older test was limited by its inability to determine the accuracy of the sample’s identity if it had been processed or cooked because these processes affected protein structures. This rendered the test useless in many different circumstances. The next step in seafood regulation was to determine a more efficient and reliable way to regulate seafood.

So what is the new technique that was developed to identify these species? The answer is simple; scientists are now able to use a DNA barcode to identify different fish species. Every living organism has a DNA sequence that is unique and contains the individual’s genetic information. A single species will have individuals with varying DNA sequences, but there will exist certain genes in common that are only usually found in that particular species. A gene is a stretch of DNA that codes for a protein, so this basically analyzes the same information as the old test, but at an earlier stage. DNA is not as easily affected as proteins by any processing done to the fish. Comparing DNA barcodes is easy to do and relatively inexpensive. It compares the sample’s DNA to a known database and matches the sample to its correct species (1). There is currently a global effort to finish a Consortium for the Barcode of Life (CBOL), which is a sequence reference library for every species of fish on earth for the specific gene, cox1 (4). It currently contains the gene sequencings for cox1 in most seafood species. If a lab needs to identify a species, they are able to do so by comparing their sample’s DNA to this library. This analysis requires only a gram of the sample and is able to identify the sample whether it is raw, frozen, steamed, or deep-fried (1). In fact, DNA barcodes could be extremely helpful for the FDA in many cases of food-related illness or economic fraud investigations. In order to begin testing on a regular basis, the FDA recently installed DNA-sequencing equipment in nine of its laboratories across the country in order to decrease seafood substitutions. This technology will allow the United States to take the next step in food safety and help ensure that regulations are upheld in order to decrease economic fraud, harmful substitutions, and a great threat to endangered species.

This shows a comparison of genes (or stretches of DNA) in different tuna species. The rows indicate the genes being analyzed from the different species and the columns indicate the specific nucleotide being looked at. Nucleotides make up DNA similar to how atoms make up different molecules. Highlighted boxes show specific nucleotides that cause a gene to be unique for a single species.

Works Cited

1. “Specious Species: Fight against Seafood Fraud Enlists DNA Testing”. Scientific American. November 10, 2011. <http://www.scientificamerican.com/article.cfm?id=dna-testing-for-seafood-fraud&gt;

2. “Fake Fish: Experts Say Mislabeling of Seafood is Risky Business”. ABC News. May 27, 2011. <http://abcnews.go.com/US/fake-fish-experts-mislabeling-seafood-real-problem/story?id=13706266#.TsIE2XPb_fE&gt;

3. “Mystery fish: The label said red snapper, the lab said baloney”. Consumer Reports Magazine. December 2011. <http://www.consumerreports.org/cro/magazine-archive/2011/december/food/fake-fish/overview/index.htm&gt;

4. Lowenstein, Jacob H., George Amato, and Sergio-Orestis Kolokotronis. (2009) The Real maccoyii: Identifying Tuna Sushi with DNA Barcodes – Contrasting Characteristic Attributes and Genetic Distances. PLoS ONE 4:4-14.

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Why Can’t I Breathe?

Environmental allergies are one of many ways allergies can inhibit our day-to-day lives. (http://www.allergydruginfo.com/images/allergy-medication.jpg)

Whether it is a runny nose, itchy eyes, or a skin rash, many of us have faced the systems of an allergic reaction at some point in our lives. They are a determining factor in the places we go, the pets we have, and even the food we eat. The Asthma and Allergy Foundation estimates that allergies affect 50 million Americans, making it the fifth leading chronic disease in the country. Despite the frequency of allergies in the population, few individuals really understand how allergies occur (1).

A healthy body’s immune system is set up to constantly identify invading pathogens by identification of self vs. non-self. While one definitely should not be upset that the body has this skill, things can become problematic when the body cannot differentiate what non-self entities are harmful or harmless. Allergies are induced when the body begins to strike against non-harmful entities (5).

The above picture describes the process of eliciting an allergic response. An allergen causes B cells to release IgE, which bonds to Mast cells or Basophils. When allergens interact with these antibodies, the cells they are attached to lyse and release chemicals that cause allergy symptoms. (http://microbiology2009.wikispaces.com/Histamines--What+They+Do+%26+What+Anti-Histamines+Do+to+Stop+Them)

When an allergy is induced, the body identifies an allergen, inducer of the allergic response, as an invader. An allergen may be anything individuals are exposed to in day to day life (2). In order to remove this invader, the body elicits a response to destroy it. T-cells and B-cells, two types of White Blood Cells, play an important role in eliciting this response. When these cells are presented with a foreign substance, T-cells either recruit more White Blood Cells or directly attack whatever invader is present. B-cells release antibodies, which are also engineered to fight off the specific invader. IgE is the antibody specifically associated with allergic reactions. It bonds to basophils and mast cells, eventually causing them to release their contents, including a protein named histamine (5).

Histamine influences the body by causing inflammation. When an area of the body is inflamed, blood vessels become less dense, allowing an increase in the number of blood cells able to enter the site of histamine release. This increase in blood cells causes swelling at the site of the allergic reaction (4). These additional blood cells may also trigger the allergic response, causing the reaction to become worse with continued exposure. Histamine also causes smooth muscle to contract (6), which leads to breathing difficulties frequently associated with an allergic reaction.

There are several ways a person may try to deal with allergies. Some simply try to avoid allergens that tend to cause an immune response. Sometimes, allergens cannot be avoided, so allergy treatment drugs are provided. One common way to treat allergies is to use anti-histamines, such as Claritin and Allegra. They work to inhibit the ability of histamine to bond with other molecules that cause the allergic response (4). In severe allergic reactions, some individuals require an epinephrine injection. Epinephrine causes blood vessels to contract, inhibiting the allergic response (3). In severe cases, immunotherapy may be used. Immunotherapy forces the patient to be exposed to the allergen that normally elicits a response. While it is not always effective, in some cases it causes the body to release IgG, a blocking antibody that improves a subject’s response to an allergen (5).

While some of these ways of dealing with allergies are achieving a reasonable amount of success with sufferers, a larger question remains. How do we prevent allergies from developing in the first place? Research from the University of Copenhagen claims allergies tend to develop more prevalently in individuals who are not exposed to many types of bacteria in the first six months of life (7). This is why infants born via cesarean section have a much higher tendency to develop allergies than those born naturally (7). Naturally born children are much more heavily exposed to the mother’s bacteria in the birthing process. Some researchers suggest this reasoning is also why children raised in rural environments are less prone to develop allergies.

Though we still have a lot that we may learn about allergies, the information we see indicates that an increase in allergies is being caused by modern medicine. By not allowing bacterial exposure early in life, we are forced to face alternate medical consequences. Hopefully, researchers will develop a fuller idea of how to prevent both illness and allergies, but, in the meantime, we are left to take our Claritin, fear our bees, and exhibit caution in the presence of peanuts.

Works Cited

1. “Allergies – PubMed Health.” Web. 09 Nov. 2011. <http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0001815/>.

2. Cunha, John P. “Allergic Reaction Symptoms, Causes, Signs, Treatment and Prevention by EMedicineHealth.com.” EMedicine Health. Web. 09 Nov. 2011. <http://www.emedicinehealth.com/allergic_reaction/article_em.htm>.

3. “Epinephrine Injection: MedlinePlus Drug Information.” National Library of Medicine – National Institutes of Health. Web. 09 Nov. 2011. <http://www.nlm.nih.gov/medlineplus/druginfo/meds/a603002.html>.

4. “Histamine.” Biology @ Davidson. Web. 09 Nov. 2011. <http://www.bio.davidson.edu/courses/immunology/Students/spring2000/lamar/mfirp.htm>.

5. “HowStuffWorks “How Allergies Work”” HowStuffWorks “Science” Web. 09 Nov. 2011. <http://science.howstuffworks.com/environmental/life/human-biology/allergy.htm>.

6. Schmidt D, Ruehlmann E, Branscheid D, Magnussen H, Rabe KF.  1999 Aug.  Passive sensitization of human airways increases responsiveness to leukotriene C4.  European Respiratory Journal 14(2): 315-319.

7. Hans Bisgaard, Nan Li, Klaus Bonnelykke, Bo Lund Krogsgaard Chawes, Thomas Skov, Georg Paludan-Müller, Jakob Stokholm, Birgitte Smith, Karen Angeliki Krogfelt. 2011. Reduced diversity of the intestinal microbiota during infancy is associated with increased risk of allergic disease at school age. Journal of Allergy and Clinical Immunology 128 (3): 646 -652.

When Art meets Science

When you are snapping off a picture, exposing a film, uploading an album onto your Facebook, did you ever think about what makes it possible for you to do all of these?

Pretty as it is, what behind these photos is the hidden science.

How can we see the image?

The word “photography” came from “drawing with light”. The light reflected from a subject is processed by our eyes and brains to provide sense of sight. The difference in wavelengths results in a variety of colors. Jumble of light reflected from points on subject is controlled by the iris in intensity and by the stretching and compressing of lens in focus to form an image.
One characteristic of light is that its path is bent as it passes between mediums of different density, for example from air to glass. This principle is used to construct a converging lens. Such a lens takes the jumble of light from one point on the subject and converges these rays to one point of focus. The lens is moved backwards or forwards to focus, that is to create a sharp image. The image formed by a lens or pinhole is upside down.

Please click to see larger view

Both the shape of the lens and the density of the glass alter the light bending power of the lens. The ‘focal length’ of a lens is a measure of its light bending power. For a simple lens the focal length is the distance between the lens and where the light rays are brought into focus.

For the same subject a shorter focal length lens produces a smaller image than a long focal length lens.

Please click to see detail of a long focus lens

The image quality of a simple lens is poor, that is why compound lenses are used in most photographic equipment. Within a compound lens barrel there are several positive and negative lens elements, each with their own focal length. A good quality lens will produce a bright, sharply focused image without aberration.

A ‘standard’ lens is used to produce an image that is roughly equal to the human eye’s view of the scene. A standard lens has a focal length that is approximately equal to the diagonal of the film format. For example the standard lens for 35mm film is about 50mm however for the larger medium format film it is almost 80mm.

The focal length of a lens, in conjunction with the aperture setting, determines how much of the view is in focus. The amount of the view, from near to far, which is in sharp focus is called the “depth of field”. The shorter the focal length of a lens the greater the depth of field.

So next time, when someone ask you what will happen when Art meets Science, you should give them the definite answer “MAGIC!”.

http://www.ted.photographer.org.uk/photoscience_form.htm

Secrets of Air

        Air is one of the most mundane substances around us. It is colorless, odorless and amorphous, yet everywhere – we cannot escape from it. On the small scale, air consists of multiple types of molecules, some of which are crucial for the organisms on earth; while on the large scale, air forms the atmosphere of earth, which essentially is the reason why lives can exist on earth. Today, let’s look at air from different prospective and on the way unfold some secrets of air that you may not know.

1. 21, 78, 3, 3, 94

        If you have taken some high school chemistry, this array of numbers may look familiar to you – at least for me, I used this recipe to cram for my chemistry exams. This array stands for the proportions of each kind of gases that consists air. A common mistake that the general public may make is that, air is made of “air molecules”. In fact, the commonly used term, air, refers to a collection of gases including oxygen (denoted by O2), nitrogen (N2), carbon dioxide (CO2), argon (Ar), and some other kind of gases. By volume, air contains approximately 21% oxygen, 78% nitrogen, 0.03% carbon dioxide, 0.03% other gases, and 0.94% noble gases, of which primarily is argon.

2. The weight you cannot bear

        Air seems to be weightless. The situation does not usually happen where you have to make tremendous efforts to just stand up because the air on your shoulders is too heavy. However, air does have weight, and it IS heavy. Let’s verify this argument through some simple math. The air pressure, defined by the force exerted on a unit area, is about 105 Newton per square meter. The area of your shoulders is about 15 cm * 40 cm = 6 *10-3 m­­2. This gives the force on your shoulder by air, F = 6 *10-3 * 105 = 600 Newton = 135 pounds! Well, apparently you do not feel this weight every time you stand up (in addition to your own weight, of course), so how come? The magic spell is that, air is everywhere! This is saying that, while there is 135 pounds of force on your shoulder, there is also the same amount of force from below that “lifts” you, as long as there is air that you “stand on”. Therefore, you should now understand why the suction cup can “stick” your GPS receiver on your wind shield – there is practically no air in the suction cup, so the atmospheric air pressure keeps it there.

3. Refund!!! There is “water” in my bottle of compressed air!

         Some of you may have used compressed air to blow off the dust on your laptop. When you shake the bottle, you will typically hear the sound of “water” pounding on the interior of the bottle. Why there is “water” in the bottle? In fact, the “water” is actually air! Air does not necessarily have to be in the gaseous state, and it can change from a gas to a liquid or even to a solid when you, for example, compress it to a very high pressure. In this case, the pressure forces the molecules to stay closer to each other, and air appears to be a liquid. (Actually, this is the ultimate difference between a liquid and a gas – the molecule spacing.) In practice, this is how people usually store gases – in a steel, high-pressure bearing tank – so that it would be volume efficient.

4. Wind – a troublemaker but also a blessing

        When there is a pressure difference of air between two regions, maybe caused by the different temperatures, air will flow from the high pressure region to the low pressure region. This process creates one of the most common natural phenomena – wind. In a hot summer day, a breeze is almost bliss. However, you do not want the wind to blow too hard; too fast the wind might be detrimental. Tornado is a wind of this kind. Wind is also one of the reasons that accounts for a phenomenon called ocean current. Ocean current is a continuous, directed movement of seawater. The constant winds in the high seas (far away from shore) direct the surface sea water to move along with the winds due to friction, so ocean current forms. Ocean current is a very important phenomenon – it is a dominant factor in determining the climate of many regions! The most striking example is the Gulf Stream, an ocean current originates at the tip of Florida and extends towards Europe. The consequence is that, due to the Gulf Stream, northwest Europe is actually much more temperate than any other region at the same latitude. The famous Peruvian anchoveta fishery is also a result of ocean current, where ocean current brings abundant nutrition to the area.

5. Epilogue

        Although air is so unnoticeable, it affects our lives in nearly every aspect, either directly or indirectly, just as its universal presence. It protects all the organisms on earth surface from serious cosmic radiation, and retains heat on earth so that the temperature on earth surface would not vary dramatically. I would like to end our investigation of air with a question: air is an important industrial raw material. What is air making?

I spy with my little eye….

How many people can remember their mom telling them not to read in the dark?  Probably many.With all this new technology, there are many new problems to consider. Nintendo recently gave the warning that children under the age of six shouldn’t use the new 3D feature of their 3DS and computer vision syndrome is becoming much more popular.

The warning from Nintendo has raised a lot of questions about the effects of 3D technology on eyes and in particular developing eyes.  The concern Nintendo has is that before age six, it is believed that eyes are in a critical period of development.  Experiments have shown that if a young child cannot see out of one eye after a few years they will not be able to see out of the eye even if the problem is fixed. On the other hand if the same thing happened in an adult, when the problem causing the blindness in one eye is fixed they will be able to see normally again. This is because of how the brain processes the visual information.  The two eyes see slightly different images and then process the information into essentially a column of cells.  When both eyes work, the columns should alternate which eye the information came from by cell. But when only one eye works or is heavily favored then the columns only have information from that eye.  When vision is returned to the eye, the brain doesn’t know how to make the columns start alternating if they haven’t done it before.  It is more than just blindness that can cause one eye to become dominant over another though.  If the two eyes are misaligned or if they focus at different distances, then one eye will generally become dominant to prevent double vision.

In order to begin research on the effects of watching 3D on young eyes, Dr. Tychsen did research on baby Rhesus monkeys. While not a guaranteed indication that the effects observed will carry over to humans, it is very likely that the effects will be similar.  In Dr. Tychsen’s research, he had monkey’s watch 3D films throughout each day for three months.  The monkeys who watched the films had no difference in their visual development compared to those who did not watch the films. In fact, some researchers believe that the only potential concerns for have more to do with how much information the brain has to process and the fatigue that comes from that.

Surprisingly, it turns out that the 3DS may actually have visual benefits in the sense that it could have doctors diagnose issues that may result in learning difficulties in children at an earlier age.  Many vision problems can be treated much easier if they are detected early. The 3DS is essentially showing each eye a slightly different image, so when they combine you get the 3D effect.  Therefore, if one eye is dominant over another, there will be issues when viewing the 3D content as the information will not combine correctly and will not give the correct 3D effect.  When using the 3DS there are 3 signs that you need to get a comprehensive eye exam by an ophthalmologist because there may be an issue.  They are dizziness, discomfort, or lack of depth.

So what about computer vision syndrome?  We’ve all had those days where we’ve stared at the computer for way too long and before we know it, we’re rubbing our eyes, can’t focus and that nagging headache is building up, but why does it happen? Part of it is because of how the computer screen works.  When you stare at an unchanging object, the computer screen is not actually unchanging.  The screen is actually constantly refreshing itself and forcing you to refocus your eyes every time it refreshes.  Another cause is an underlying vision problem that is aggravated by the computer. And as you age, your eyes are changing anyways. So watch out baby boomers…computer vision syndrome is coming with carpal tunnel syndrome for those of you who are on the computer all day.

Proper work place set up.

So what can you do to prevent it? Well you have some options.  The easiest thing is to blink and take breaks more often.  If you blink more frequently as you work, it will help prevent dry eye and breaks will give your eyes time to refocus.  Also make sure you work station is set up properly. The diagram to the right shows the recommendations of the American Optometric Association.  You want the screen below your eyes and just over two feet away from your eyes.  Finally, do your best to reduce the glare on the screen either by changes in lighting or by adding an anti-glare screen.

For more information on these topics, here are some good articles:

  1. http://www.hhmi.org/senses/b410.html
  2. http://www.aoa.org/x17309.xml
  3. http://bits.blogs.nytimes.com/2011/01/05/eye-specialists-question-nintendos-warning-on-3-d-technology-and-children/
  4. http://www.aoa.org/x5253.xml