November 2010 Archives

Depending on where you live, you may find that even local corner stores have sections that are kept under lock and key. Over-the-counter drugs and even toys often end up under "please ask for assistance" supervision. It can be frustrating to have to get a clerk to help you get your cold medicine, batteries, or the newest pack of trading cards, but it makes sense. From surveillance technologies to exploding ink security tags to simple lock-and-key access, businesses are doing what they can to protect their goods and their customers—and to help cut down on incidences of petty theft.

A Scientific Approach

In the Netherlands, local businesses have adopted a crime-prevention system that puts science on the front line of both deterrence and tracking. Fast food restaurants like McDonalds are among the businesses that have installed DNA mist systems. When activated, the system silently alerts police to criminal activity and "marks" the thief with an invisible mist of DNA. Businesses using the system post signs that indicate the presence of DNA systems: "You Steal, You're Marked."

This mist, visible only under ultraviolet light, is so fine that someone being sprayed may not even realize that he or she has been "marked." The mist, however, contains DNA markers that link it to the specific location of the spray system—making it possible to link a criminal to a specific crime based on DNA markers. If apprehended, a simple UV wand may reveal the tell-tale mist. A suspect's presence at a crime location can then be confirmed by matching the mist DNA to its unique location.

For the science-minded—or the armchair detective—the mist-based system raises questions and many "what-ifs." What if the thief goes straight to a public bathroom and changes clothes? What if the thief takes a shower? What if a bunch of bystanders are sprayed? What if the spray doesn't adhere to certain substances or kinds of clothing? There are plenty of questions, any of which you could turn into the beginnings of an independent science project, but reports suggest that businesses using the DNA mist systems have seen a decrease in criminal activity. In part, authorities suggest, the success of the DNA mist system is that its presence alone works as a deterrent.

Why DNA?

DNA mist systems are in use in a handful of European countries, and media coverage suggests they may appear in the US soon. Reading about this system brings up one obvious question: why use DNA? Why not use some other synthetic chemical? The answer lies in the versatility and configurability of DNA. Not only is it inexpensive to make large quantities of synthetic DNA, but DNA can be "programmed" to contain an unlimited number of unique tags. Every store in a city could have a unique mist-system with DNA markers that could lead the police straight to their door if a suspect showed up covered in mist linked to their location. This kind of widespread site-specific and distinct crime marker wouldn't necessarily be possible with other chemicals. Plus, forensics labs are also accustomed to handling and analyzing DNA. The systems are already in place to read and evaluate DNA.

And would-be criminals know it, which increases the power of the warning: "You Steal, You're Marked."

Understanding DNA

Students interested in DNA and curious about the properties of DNA, and the infinite customization possible with DNA's 4 base pairs, can get an introduction to understanding DNA fragments in this Science Buddies project idea:

• What Makes a DNA Fingerprint Unique? (Difficulty: 4-6 )

• Who Done It? DNA Fingerprinting and Forensics (Difficulty: 8-10)

Do you wrinkle up your nose at the taste of something bitter? That's partly what your taste buds do—help warn your body against something that is bitter and could be poisonous.

While your tongue may or may not like the bitter taste of foods like radishes and dandelion greens, your lungs might react differently! A team of researchers from the University of Maryland and Johns Hopkins recently discovered that the lungs have "taste receptors" (like the ones on your tongue). That was a surprise, but the bigger surprise was that rather than contracting and withdrawing from bitter substances, the lungs appear to respond positively to bitter substances—the airways expand and open up, which makes it easier to breathe.

An Accidental and Surprising Discovery

Scientific discovery doesn't always go as planned. In fact, discovery often involves following the trail of experimental results even if they lead away from the initial experiments—or fail to support initial hypotheses.

Researchers were studying the human lung muscle receptors responsible for regulating how our airways contract and relax when they realized that taste may not be all in the mouth. When the team of researchers realized they had stumbled upon a strange scenario—taste buds in the lungs—they could have thought their data was wrong. They could have just shrugged and continued with their initial course of research. After all, taste buds were not what they were looking for! They could have just assumed the presence of taste receptors was an odd and unimportant artifact of human evolution....but instead, they investigated.

A Wrong Hypothesis

The team continued experimenting and testing, hoping to determine how taste receptors in the lungs "work." Further experiments confirmed that the taste receptors are receptors for bitter substances, just like the receptors found on the human tongue.

It is thought that bitter taste receptors on the tongue evolved as part of the body's self-defense system against harmful or poisonous substances, many of which have a bitter taste. If you taste something bitter, you are more likely to spit it out and, as a byproduct, save yourself from being poisoned.

Initial guesses were that the taste receptors in the lungs would respond to "bitter" in the same way the tongue does... with a shiver and a shake! Speculation was that the presence of these "bitter" receptors in the lungs was again related to self-defense. Researchers guessed that when confronted by a bitter substance, the receptors would react and cause the airways to constrict, thus letting in less potentially contaminated air.

But they were wrong.

The taste receptors behaved exactly the opposite of what researchers expected. The presence of the reactors does, indeed, seem related to the body's self-defense mechanisms. But instead, of constricting the airways, bitter substances caused the lung muscles to relax the airways, increasing the air flow.

Understanding "why" the taste receptors work differently in the lungs compared to on the tongue required formulating a new hypothesis, their original one regarding the behavior of the taste receptors already disproven. The researchers now believe that the bitter taste receptors are present in the lungs because they can help detect bacteria that cause lung infections like pneumonia.

Bacteria often secrete compounds that are "bitter." If the taste receptors in the lungs sense these bitter compounds, they may give orders to help open up the airways, helping the patient breathe more easily—and potentially helping the patient survive the infection. This is the direction their research is taking as they track down how "taste" in the lungs really works.

A Result that May Help Millions Breath Better

Will eating extra bitter foods help you fight off an illness? Probably not. But this research may help open up new possibilities in the development of better and more effective asthma medications.

The team's findings were certainly unexpected, but now that the bitter taste receptors have been identified and their behavior tracked, drug companies can use these findings to develop asthma drugs that will target these receptors, thus allowing asthma patients to breath more easily during an asthma attack.

Student Research

Students interested in exploring questions related to taste receptors or breathing can tackle projects like the ones listed below from the Science Buddies Project Ideas directory.

Projects related to taste receptors:

• Do You Love the Taste of Food? Find Out if You're a Supertaster! (Difficulty: 1-3)


• Do You Have the Willpower to Taste Something Sour? (Difficulty: 2-3)


• Old Salty: Does Age Affect the Ability to Detect Salt? (Difficulty: 5)

Projects related to lungs and breathing:

• Ewww, Dog Breath! Does Active Play Take Your Dog's Breath Away? (Difficulty: 1)
• Breath of Life: Does Exercise Increase Vital Capacity? (Difficulty: 6)
• Lung Capacity and Age* (Difficulty: 6)

Smallpox, typhoid fever, bubonic plague, cholera... These may be health problems you know best from history class—or even from novels in your literature class. In a world in which super-bugs lurk on the medical fringe and new viruses like H1N1 and SARS have threatened to explode to pandemic proportions, it's sometimes easy to discount diseases, viruses, and bacteria that have proven epidemic in the past.

But many of these bugs from "long ago" haven't ever completely disappeared. A bit of research on health crises through the years shows a number of repeat offenders, outbreaks that have returned on an epidemic scale, time and again and around the world.

For example, high incidence of Cholera showed up in 2007 and 2008 in Vietnam, and in both India and Iraq in 2007. In recent months, cholera has reared its head in mass numbers, sweeping through both Haiti and Nigeria.

Can You Catch It?

An infection that attacks the small intestine, cholera is caused by the bacterium Vibrio cholera. Luckily, cholera is not an airborne disease—unless picked up and spread by a natural disaster like a tornado or hurricane. The disease is transmitted primarily through contaminated water or food, and in impoverished conditions, poor sanitary conditions and inferior (or nonexistent) sewage removal systems contribute to the spread and risk.

What's in the Water?

Water is an essential staple for life. But the water we drink and use day to day has to be safe. If it isn't purified, water may contain compounds we don't want to drink (like salt or toxic elements like lead), or it may contain pathogens, like the bacteria that causes cholera.

To learn more about testing and purifying water, check the following Science Buddies project ideas:

• Solar-Powered Water Desalination (Difficulty: 6-7)
• Learn How to Disinfect Contaminated Water (Difficulty: 7-9)