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Effect of environmental toxins on GATC methylation in E. coli May 3, 2011

Posted by ljsteele in Biology, Chemistry, Ecology, Environment/Conservation, Evolution, Genetics, Health, Marian University curriculum, Physiology.
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With the end of the semester drawing near it is becoming that time again when the results are piling in from research you have been working on all semester. As we speak, the final data collection and analysis is taking place in biochemistry, a team of student researchers are exploring of environmental toxins of DNA methylation  in the bacterium E. coli. 

The Bacterial Genome

Bacteria exist throughout the world and can survive in almost any climate . Bacteria are unicellular and can consist in a wide range of environments such as a pond all the way to soil.  One unique attribute of the bacterial genome is that it contains adenine methylation , opposed to mammalian organisms which contain cytosine methylation at GpC islands.  Adenine methylation is when a methyl group becomes attached to the adenine nucleotide on the DNA. When a methyl group is donated from SAM to form a covalent attachment, it is made on the adenine which can cause steric hindrance of transcription factors and differential effects of DNA binding proteins, which can contribute to a change in gene expression.  In previous studies  it has been shown when E. coli is exposed to different carbon sources (ie glycerol or glucose).  Some areas of the genome become demethylated.  In the bacteria E. coli almost every adenine (A) in the GATC sequence is methylated.  To block the methyation at the GATC sequence, a protein must be present to inhibit the DAM methyltransferase from depositing a methyl group on the adenine.

What does Methylation do?

Adenine methylation has many roles in bacteria. Methylation can effect gene expression, cell cycle, virulence, and how proteins interact with the DNA. For the research we are performing, we are concerned with what effect the environment has on changing adenine methylation on the GATC repeats. There are about 20,000 GATC repeats in the E. coli genome and under normal log growth conditions almost every single repeat is methylated. It has been found that when bacterial cells are in a log growth phase there are 6-10 sites which are not methylated. These nonmethylated sites lie up and down stream of promoters of different genes. The lack of methylation may allow DNA binding proteins to modulate their function to allow a functional change in gene expression.

Pollutants and the Genome

In the study we are performing we wanted to see how three classes of chemicals pollutants commonly found in the Midwest affect adenine methylation at the GATC site. We choose three pollutants to represent chemicals that fit into the families of common water pollutants, which are heavy metals, chlorinated compounds and nitrogen rich compounds.Gel Electrophoresis

The above families of compounds will be compared to samples collected from different areas around the campus of Marian University, Indianapolis, IN. Supplements will be added to all the samples to generate a rich liquid media that will facilitate bacterial growth.  With 6 different test groups and 2 controls we are going to seek to determine if any of our known compounds or a compound present in our environmental sample has an effect on the methylation.  The determination of methylation can be done by using restriction enzyme digest with endonuclease selecting specifically for the nonmethylated site.  The enzyme we have chosen was MBO and AVI.  When all the genomic DNA from the bacteria is extracted and digested, then it will be ran on a gel to be imaged to determine if the bands of digested DNA differ depending on the chemicals present during growth.  This is a time efficient way to examine if any changes in methylation levels have occurred.

What Does It All Mean?

For conclusion, the relevance of this study includes a few things.  This study will provide evidence to show if environmental toxins have an effect on bacterial DAM methylation. One role bacteria play in an ecosystem is influencing the flow of nutrients which support plant and algae growth. The results of our proposed study may display that toxins have an effect on methylation patterns which could lead to an increase the mutation rate of the bacteria genome itself.   Destructive mutations may decrease bacterial populations leading to a disruption in the ecosystems nutrient flow, hence disruptions in plant and algae growth with effect additional aquatic and terrestrial organisms.

Mystical “Catnip” May 3, 2011

Posted by mhostetler099 in Behavior, Biology, Chemistry, Health, Physiology.
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So what is it about “catnip” that makes cats crazy, mosquitoes fly away and at the same time has seemingly no effect on human beings?  In actuality, the better question is what are the distinguishing factors allow different organisms to interpret “catnip’s” chemical signal differently or not at all.

The 6th Sense (the vomeronasal organ in cats)

It is well documented that all mammals posses 5 senses (sight, taste, touch, smell, hearing); BUT could mammals have a 6th sense?! Some scientists would say YES and pinpoint this sense to be related to the mysterious vomeronasal organ located above the roof of the mouth.  This sensory organ is attributed to sensing chemical signals from other organisms and the environment known as pheromones.  The vomeronasal organ is present in most mammals and is considered a chemoreceptor organ which exists as a separate entity than the nasal cavity.  Chemoreceptors detect chemical signals from the organism’s environment and transduce a physiological response accordingly. Studies indicate that nepetalactone (the chemical produced by “catnip”) is responsible for eliciting a psychosexual response in cats by mimicking a sex pheromone and interacting with the feline vomeronasal organ.  Although human beings and felines are both mammals, they react to the chemical in “catnip” much differently than one another.  “Catnip” elicits no response in human beings and a rather strong response in felines.  The distinction between these responses can most likely be attributed to a physiological difference in the feline and human sensory system.

The Vomeronasal Organ in Humans

The function of the vomeronasal organ in human beings is actually quite controversial.  Studies on human embryos have indicated that the vomeronasal organ does correspond to the vomeronasal organ in cats and other mammals.  Although the vomeronasal organ is common in both feline and human species, the organ in humans was thought by scientist to be vestigial (or no longer functioning).  The vestigality of the vomeronasal organ in human beings may explain why humans do not react to chemicals in “catnip” however this is an unlikely explanation because studies have shown human beings can react to pheromones.  Another explanation to the differing reactions could potentially be attributed to the physiological differences in the organs themselves (show left). 

 So Why are Mosquitoes Repelled?

So why are mosquitoes seemingly repelled by some essential oils extracted from different plants and herbs (including “catnip”)?  This question is a little more difficult to answer directly because little is known about insect sensory system.  Studies have shown that mosquitoes are more attracted to people with high concentrations of steroids and cholesterol on the surface of the skin.  Mosquitoes are attracted and repelled by certain pheromones.  More than likely, the chemical nepetalactone in “catnip” is able to mimic a pheromone that triggers a chemical signal causing the insect to become repelled (acting as an insecticide).

It is truly amazing that the same chemical can signal different responses in different organisms.  The responses to chemical signals in the organism’s environment are evolutionarily beneficial; whether it be to attract a mate or flee from impending danger.  According to a news report conducted by NPR the CDC is working on natural repellant consisting of extract from cedar tree.  This substance is completely environmentally friendly and actually acts as an insecticide.  It is able to kill the mosquitoes by blocking receptors on their nerve cells (absent in human beings).  Although the chemical found in “catnip” is not known to be an insecticide, the similarity between natural extracts (from “catnip” and cedar tree) may certainly explain insects natural repulsion from them.

Carbonic Acid: Not Just for Coca-Cola Anymore. April 30, 2011

Posted by tsublett in Chemistry, Climate Change, Ecology, Environment/Conservation, Policy.
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We sit at an critical point in time with the looming threat of global warming. The world is being changed, but the exact extent of that change is now coming to fruition. Ocean Acidification is one facet of global change that is not being addressed at the same level as, say global warming. Nevertheless, oceanic acidification is going to become a global concern in the next twenty years because its effects are very damaging.

How bad is Ocean Acidification?

Oceanic acidification is not a new phenomenon. According to a February 2009 article in Scientific American:

Oceans naturally absorb the greenhouse gas; in fact, they take in roughly one third of the carbon dioxide released into the atmosphere by human activities. When CO2 dissolves in water, it forms carbonic acid, the same substance found in carbonated beverages. New research now suggests that seawater might be growing acidic more quickly than climate change models have predicted.

"Present day" (1990s) sea surface pH

This article explains that the ocean is responsible for the bulk of the work in recycling atmospheric gases. The problem, though, occurs in the rate of carbonic acid formation. “Research at the University of South Florida has shown that in the 15-year period 1995-2010 alone, acidity has increased 6 percent in the upper 100 meters of the Pacific Ocean from Hawaii to Alaska,” according to an article on Ocean Acidification from Plumbot.com

The carbon cycle is a popular topic today. We talk about emissions and about the amount of CO2 given off by an SUV versus a Prius, but what we do not talk about is how detrimental CO2 can be to oceanic processes. The ocean recycles CO2 by converting it into carbonic acid via the reaction:

CO2 + H2is in equilibrium with H2CO3

Is There a Consensus?

Representation of the carbon cycle.

Carbonic acid is not necessarily a bad thing, but concentration influences its danger. I can drink a can of soda and I won’t see any detrimental effects. The sugar may cause problems, but not to a level of lethality. In the ocean, though, the stakes are higher. According to Jason Hall-Spencer, a researcher at the University of Plymouth, “Many of the marine species having calcium carbonate based external skeletons, including corals and mollusks, are affected because, as water becomes ever more acidic, calcium carbonate concentrations in the water decrease, leaving them with little resources to build their skeletons on.” Also, “Marine ecologist J. Timothy Wootton of the University of Chicago…and his team discovered that the balance of ecosystems shifted: populations of large-shelled animals such as mussels and stalked barnacles dropped, whereas smaller-shelled species and noncalcareous algae (species that lack calcium-based skeletons) became more abundant.” This trend is also true of herring populations. According to an articlein the Seattle Times, “For example, computer models suggest that, if acidification reduces one type of plankton eaten by herring, herring populations may go down. But if acidification hits a different plankton species, the number of the fish could in fact increase. In another hypothetical scenario, potential declines in invertebrates such as urchins and sea cucumbers might be less than first expected because their predators — sea stars — decline, too.” Dr. Busch is saying here that the effects of Ocean Acidification are so complex, that it will be difficult to really predict what will be affected.

How Does this Affect Me?

It is clear that, though we would not necessarily be directly affected by ocean acidification, the organisms that feed fish we use commercially could decline, resulting in a detrimental effect on the fishing industry in general. That alone may spark much interest into determining the root cause of oceanic acidification and move individuals into steps geared at remedying this problem. According to Cheryl Logan, in an article from BioScience: “Changes in ocean chemistry will probably affect marine life in three different ways: (1) decreased carbonate ion concentration could affect the calcification process for calcifying organisms (e.g., corals); (2) lowered pH could affect acid-base regulation, as well as a variety of other physiological processes; and (3) increased dissolved COcould alter the ability of primary producers to photosynthesize.”

But I Live in Indiana!

The research that was done here, though it has many implications for the future, does not necessarily focus on the problem of fresh water resources. The ocean, by far, is the largest CO2 sink due to its size, but not much research has really been put into freshwater testing of acidification, other than the testing of acidification by direct dumping. The research that Maria Solis and I performed this year at Marian University attempted to test this theory, that freshwater resources would experience the same process of acidification.

Though we did not definitively prove any new groundbreaking theories about acidification, we think that we are on the right track. For us, the ideas about ocean acidification do not hit very close to home in land-locked Indiana, but we know that lakes are commonplace. We wanted to do something that not many have done before, look at natural acidification based on dissolved CO2 compared with chemical dumping.

For our experiment, we wanted to observe the effects of high and low CO2 concentrations on plant growth rate and snail shell formation. When looking at plant growth rate, we hypothesized that the increasing levels of CO2 would increase the growth rate in plants at lower CO2 levels. The rate would increase to a point, until acidification would lead to a decrease in plant metabolic functions. Testing photosynthetic rate, or in our case growth rate, is a good measure of CO2 metabolism. Photosynthesis depends on sunlight and CO2, so increasing the level of substrates would definitely increase the level of metabolism in the plants that we chose to use. We chose to use three types of plants to get a range of growth rates. We used a common aquarium plant, Egeria densa. For a secondary plant species, we chose Elodea densa.  Finally, for use as a invasive species control, we chose to use Vallisneria, a freshwater species of eelgrass. Eelgrass is an invasive species, that according to Gabriel Garche in his article entitled “Water Acidification Process Reveled by Marine Life,” “seagrass exploiting the excess of carbon dioxide seems to be thriving.” Also, to test the effects of carbonic acid on benthic organisms, we also included mystery snails (a species of Pomacea bridgesii).

A direct image of tanks used during our experiment

To establish an effective experiment, we obtained six, ten gallon tanks, into which we placed plants into the first three. We placed around 4-5 snails into each of the six tanks. We wanted to simulate the effects of dissolved CO2, so we placed stone bubblers into four of the tanks, into which we bubbled varying amounts of CO2. For two of the four tanks, we used stone bubblers that had room air bubbled into them. So, in total, we had three tanks with plants, all six with snails, four with CO2, and two with room air bubblers. See Photos below:

We were unable to measure dissolved CO2, so we used Vernier dissolved O2 sensors to measure the change in dissolved oxygen as a function of time. Also, we used pH probes to measure the change in acidity as a function of time. To measure photosynthetic rate, or rather metabolic rate, we measured all plants prior to experiment starting time, to develop a before-and-after measurement that would confirm growth rate. Also, we weighed all snails as a function of tank, measuring all by mass and volume to determine shell growth  rate. These measurements gave us a benchmark from which we would determine the level of growth as a function of tank. The experiment was carried out for several days.

Low CO2 (Snails and Plants)

Unfortunately, due to time constraints. We were unable to conclude much from the experiment itself.

Due to the fact that the water we used was fresh water, the pH sensors, based on their configuration for measuring ions, did not register much of a pH change. We will need to find a better method for measuring pH in non-alkaline solutions. An interesting effect we observed was in the snail populations. We observed that all snails in the high CO2 environments died, most likely due to the lack of oxygen. This result was not in keeping with our hypothesis of reduced shell growth, but does speak to the effects of a high CO2 environment on snails. The snails in the tank with low CO2 and no plants died as well. We saw some die in the tank with low CO2 that included plants, but not all died. This seems to indicate that the plants in the tank were able to utilize enough of the CO2 as to provide the snails with oxygen. The tanks with air bubbled in showed all living snails. 

The dissolved O2 sensors were sporadic at best. They needed water movement to best determine the dissolved O2. We ran out of CO2 early in the experiment, so without movement, our sensors were unable to register consistent measurements of dissolved O2. We will, in the future use bigger CO2 tanks to get a more prolonged test, so that our O2 sensors may become more effective in giving us detailed results. We also observed plant growth in all tanks. So, we were not successfully able to quantitatively determine what we set out to determine, i.e. pH and dissolved O2, the death of our snails and the growth of our plants gave us a qualitative result that demonstrated that the plants grew in this environment, but that the snails were unable to thrive.

The experiment, if it could be carried out for a longer period of time, would likely demonstrate a trend. This trend would show that the tanks that had high CO2 bubbled into it with plants would show a slower trend of dissolved O2 trending toward a higher CO2 rate. The plants would show growth at a rate higher than the control tank that had room air bubbled into it. The snails would probably not show much change in size, but would most likely thrive better in the tanks that contained the plants that had room air bubbled into. The rate of CO2 bubbling would need to be scaled back, so that our snails would have a chance to thrive in the high CO2 tanks. That way we would be able to measure relative growth rates based on mass and volumetric displacement. The high CO2 tank that contained snails that had no plants would most likely show death of snails, if no growth rate at all.

With these results, we would prove that acidification of freshwater can occur, but most likely not to the level observed in the ocean. This is due to a lack of calcium carbonate in the water itself, a molecule that interacts with CO2 to form carbonic acid.

With an understanding of the crisis that awaits us if CO2 is continually added to the water supply, we must begin to take steps to mediate acidification. One way to do this is to stop adding more CO2, allowing the algae and other CO2 metabolizing organisms to work to reduce the oceanic concentration. Hopefully, with the boom in growth rate that would be observed, the rate of acidification can be slowed to a degree that would diminish detrimental effects. Only time will tell if acidification of both the ocean and freshwater resources will be as detrimental as projected, or if mankind can do something about it. This crisis will affect all of us, if not directly. We need to think and act now.

Crazy for “Catnip” March 14, 2011

Posted by mhostetler099 in Behavior, Biology, Chemistry, Fun, Health, Uncategorized.
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“Catnip,” a feline favorite, is a perennial herb in the mint family

Nepeta cataria, more commonly known as “Catnip” is a perennial herb that belongs to the mint family.  This herb packs a powerful punch to cats by provoking a state of euphoria usually lasting several minutes (video).   Many times herbs are utilized for medicinal purposes , but “catnip” obviously doesn’t affect human beings in the same way that it does cats.  What is it about “catnip” that provokes a euphoric response in cats but not in human beings?

The chemical component responsible for the effects of catnip

Studies suggests that the chemical nepetalactone found in “catnip” is primarily responsible for triggering the response in cats.  Nepetalactone evokes a psychosexual response in both male and female cats by mimicking a sex pheromone found in cat urine.

Bugs aren’t so crazy for “catnip”

The chemical nepetalactone may attract felines, but does quite the opposite to some insects.  Researchers at Iowa State University found that the chemical nepetalactone is a successful repellent of mosquitoes, flies, and cockroaches.  Particularly, the research team at Iowa State found that a solution of catnip extract is comparable in effectiveness to a ten times more concentrated solution of DEET.  Research in finding alternatives to repellents or pesticides, such as DEET, is very important because chemicals contained in most pesticides pose a serious threat to human health and the environment.  Unfortunately, the essential oils in “catnip” are extremely volatile and have a potent, but short lived repelling effect.  Further research in reducing its volatility is essential before such repellents can be used by the general public.

Catnip’s properties are multifunctional

Interestingly, researchers at the Max-Planck Society found that birds that used different types herbal plants in their nests produced offspring that were less prone to infestation of mites.  This study indicates that other herbs may have the same insect-repelling power as “catnip” and that organisms other than humans are using this characteristic to their benefit.


In the future, the active ingredient, nepetalactone, may be found in the bottle of repellent you spray on yourself or the pesticide you sprinkle on your plants.  You can be sure that the product you are using is much safer than the products of old, but if you have cats you must beware!  Such products will still provoke the same euphoric response caused by “catnip” sold in pet stores.


Survivor? Or Starvation? March 4, 2011

Posted by abueno526 in Biology, Chemistry, Nutrition.
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Outwit. Outplay. Outlast.

Survivor. A show with the motto above,  “Outwit, Outplay, Outlast.” Contestants are put on a deserted island with meager food, shelter, and comforts to compete in a series of challenges as they try to become the ‘Sole Survivor”.  Although the glory of winning the title is great, what is physically happening to contestants’ bodies as they put themselves under these extreme conditions?  Some, like Russell Swan from Survivor:Samoa, get fatigued earlier than others, having to be removed from the game for medical reasons.  When this shut down occurs, what is happening?  How far can they really be pushed until they move into a starvation-like mode?

How does it all start?

Typically, glucose is the major energy provider to the body.  Fats can be a precursor to glucose, and ample amounts of them in the body lead to proper function and metabolism.  When one is in starvation mode, the liver is the first to sense this.  Because the body is unable to convert fats into glucose, it biochemically makes a shift to harness more of its energy from ketone bodies in order to save the muscles from deterioration via protein breakdown.

And the downward spiral begins

This switch to the use of ketone bodies is also vital to supplying energy to the brain cells, which is a top metabolic focus for the body no matter its state. In this protection mode, and use of a new fuel source by the brain, blood glucose levels drop dramatically.  This way of living will continue until all fatty acid energy stores have been used up.  Metabolic function will switch from using ketone bodies to its last

resort of proteins for energy.  Final stages of starvation such as these can result in heart arrhythmia, liver failure , and a discontinuation of muscle functioning, ultimately leading to death.

What would you do for a million dollars?

So, when a Sole Survivor is picked at the end of 39 days, what sort of condition are they in?  Although perhaps a few sizes smaller, the contestants will not have reached a true starvation mode due to the time frame of the show and availability of some food for nourishment.  Although they can do it, it’s definitely not recommended unless you’re playing for the million dollar prize!

Cramming: A Student’s Best Friend? March 4, 2011

Posted by ljsteele in Behavior, Biology, Chemistry, Health, Medicine, Science & Culture, Uncategorized.
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The night flies by…

As a senior undergraduate student, slowly over the past four years I have realized the importance of cramming before a test. Simply put, by this stage in my academic career, it has become routine to stay up all night before a test to study.  In classes where there are multiple choice tests, it appears to be easier to stay up all night cramming, as is the belief that if you at least can recognize the question, ruling out the different choices for the answer becomes quite simple.  It has been shown that over a third of students cram the night before a test.

Equal Justice?

However, although many students utilize the practice of cramming, whether or not it helps students is up for debate. There are different levels of cramming, and each appear to cause different results when it comes to grades and GPA.  The issue that is starting to be seen is that although cramming may help in terms of short term memory, the retention of that information weeks after the course ends seems to be up in the air.  Of course, when cramming is being utilized, it only makes sense that the information storage would be contained in the frontal lobe of the brain, while long term memory, which would be associated with studying that has taken place over numerous days or weeks, would be stored over multiple parts of the brain.

Green highlighted area represents the frontal lobe of the brain

Many different universities have brought to light the health implications that one may bring upon him or herself when cramming. But, it is also shown that certain periods of acute stress are positive for the human body, which cramming would appear to fall under the category of acute stress. During acute stress, the body increases its fight or flight response (epinephrine and norepinephrine), shuts down digestion, reproductive systems, and boosts metabolism. Vasoconstriction and vasodilation also take place, therefore pumping blood into certain areas of the body and brain that during a normal day’s activities may not get stimulated very often.  Especially during the fight or flight response, one becomes more attentive, which would seem to help with say, studying for a huge test.

Are there more effects than just retaining information?

Although cramming may not be ideal for certain people, research needs to continue in terms of stress and cramming, and even learning styles.  Certain people are exposed to more stress than others, so possibly stress levels are compromised, leading to a decreased ability to study and cram the night before a test.  Students continue to cram because results are obtained on tests and finals.  Quite possibly cramming could do more than just get a student a good grade on a test-it could also help to train the body for different stress activities that otherwise may not be achieved.


Healing a “Broken” Heart March 4, 2011

Posted by Kyle in Biology, Chemistry, Health, Medicine, Physiology.
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Irreparable Harm

The majority of those reading this have probably experienced some sort of injury in their lifetime.  Injuries such as cuts and broken bones will soon heal with proper care, but there are certain tissues that if damaged, cannot repair themselves. Heart tissue and brain tissue are two examples that come to mind. This may be the case for most of us adult humans, but new research out of The University of Texas Southwestern Medical Center at Dallas is pointing out that some newborn mammals have the ability to heal completely when it comes to heart damage. The only problem is, at some point along the line, as we age, the heart loses this ability to heal itself. Still, this is a very important discovery for a society that suffers greatly from heart disease, which kills thousands of Americans every year.

Studying a Broken Heart

Researchers found that in newborn mice, when sections of heart were removed, the heart had completely healed within three weeks. The hearts then functioned as normal with no signs of damage. Understanding how this works and why the heart stops doing it after a certain amount of time is now the next step for researchers. Unlike when you tear a hamstring, damage to cardiac tissue after a heart attack doesn’t just heal with time. So for those who suffer from heart problems, a discovery like this brings them one step closer to a healthy heart in the future.

Of Mice & Men

Obviously mice, which help us a lot more than most people realize, and humans are a little different from each other, but seeing results like this in another mammal is still promising. If nothing else, it is definitely a huge step in the right direction for researchers looking to cut down on the number of heart related deaths. For now though, it is important for people to remember that they only have one heart, and taking care of it should be a priority.


Taking a Radioactive Drag: Polonium 210 and Cigarettes March 3, 2011

Posted by tsublett in Chemistry, Health, Medicine, Physiology, Policy.
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Radioactive Smoke: A Dangerous Isotope Lurks in Cigarettes

The Unknown and Known Dangers of Smoking

Many of us know the dangers of smoking. We see many friends and loved ones diagnosed with cancer and know of many who die from it each year. We have seen the warning labels on cigarette packages, but what is actually in that smoke? Research says, it’s polonium-210, a radioactive isotope found in fertilizers. The problem is, tobacco companies knew about this, a while ago. According to a 2011 article in Scientific American, “The tobacco industry has known about polonium in cigarettes for nearly 50 years.” Facts like these are disconcerting on many levels.

A Tobacco Plant

Ways We Are Exposed to Polonium 210

How exactly this isotope gets into the tobacco leaf is not entirely known, but it is thought to be a “daughter isotope of uranium 238 found in fertilizers. When the fertilizer is spread on the soil, it begins to decay into either an airborne isotope, such as radon 222, or into lead 210 in the soil. Both of these products enter through the roots or into the leaves and eventually decay into polonium 210. The leaves are then processed normally and eventually end up in cigarettes.

The History of Polonium 210 Detection

Now, then, there seems to be a problem. See, polonium 210 was detected first in the 1960s. This should be a BIG problem, because we are now considering its dangers even though it has been known about  for 50+ years! Through a series of papers published during the 1960s, namely a paper published in 1964 by Radford and Hunt, scientists demonstrated how polonium 210 can enter the soil.  Subsequently in a paper published in 1974, by John B. Little and William O’Toole, proved that smokers can develop “hot-spots” on their lungs where polonium 210 accumulates. The hot spots can cause mutations due to alpha decay . The problem is, tobacco farmers and cigarette manufacturers are not removing this isotope. The good news is… they may start doing so soon.

How much polonium do we get when we smoke?

Here is an excerpt from a New York Times article:

A fraction of a trillionth of a curie (a unit of radiation named for polonium’s discoverers, Marie and Pierre Curie) may not sound like much, but remember that we’re talking about a powerful radionuclide disgorging alpha particles — the most dangerous kind when it comes to lung cancer — at a much higher rate even than the plutonium used in the bomb dropped on Nagasaki. Polonium 210 has a half life of about 138 days, making it thousands of times more radioactive than the nuclear fuels used in early atomic bombs.

We should also recall that people smoke a lot of cigarettes — about 5.7 trillion worldwide every year, enough to make a continuous chain from the earth to the sun and back, with enough left over for a few side-trips to Mars. If .04 picocuries of polonium are inhaled with every cigarette, about a quarter of a curie of one of the world’s most radioactive poisons is inhaled along with the tar, nicotine and cyanide of all the world’s cigarettes smoked each year. Pack-and-a-half smokers are dosed to the tune of about 300 chest X-rays.

 

Is there any relief?

Maybe we should stop smoking, it’s likely the best approach. If you can’t quite kick the habit, the FDA may help. Recently the FDA has taken over the regulation of cigarettes in the wake of the Family Smoking and Tobacco Control Act passed in 2009. With the FDA’s help, the exact content of polonium 210 in cigarettes may soon be published. On a side note, one quick fix may come in tobacco leaf preparation. Simply washing the leaves after harvest may eliminate a large portion of the polonium 210 found in the air.

 

The Largest Preventable Cause of Death in the World.

It seems like a radioactive isotope found in smoke is just one of many carcinogens that continue to contribute to tobacco being the largest preventable cause of death in the world. According to Scientific American:

The World Heath Organization has made clear that smoking is the most avoidable cause of death. It estimates that 1.3 million people die of lung cancer worldwide every year, 90 percent because of smoking. If polonium has been reduced through methods known to the industry, many thousands of those deaths could have been avoided. The industry, many thousands of those deaths could have been avoided. The industry’s lawyers made the conscious choice not to act on the results of their own scientists’ investigations. But it is the customers who have had to live with-and die from- that decision.

So, cigarettes are bad, but how bad they may be for us is still up in the air. Perhaps we can make them a little less dangerous in the future by removing these dangerous isotopes. Hopefully, with the FDA regulating cigarettes, this dangerous vice will soon be put to rest.

Mysterious Melatonin December 18, 2010

Posted by Kyle in Biology, Chemistry, Health, Medicine, Neuroscience, Nutrition, Physiology.
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I am sure everyone has already heard of a little compound known as melatonin. Melatonin is a hormone that can be found in many different organisms including plants, although most people know melatonin for its actions in mammals. In humans, melatonin is produced in the brain by the pineal gland. Circulating melatonin levels have been found to be high at night and low during the day, which is consistent with research that has shown that light suppresses melatonin. Because melatonin plays a role in controlling the circadian rhythm, it has received much interest for its use as a treatment for various sleep disorders. Because melatonin is a hormone, supplementing melatonin can present some issues.

Many people have used melatonin supplements to help them sleep at night. If you take a trip to your local drug store you are likely to find melatonin on the shelf. The first time I came across melatonin supplements I couldn’t help but think about the potential negative aspects to selling melatonin over the counter, unregulated. As many of you know, the human body likes to maintain homeostasis. When this delicate balance is interrupted, the body will react to return to homeostasis. I started to wonder what happens when someone takes melatonin supplements. The first thing that comes to mind is a decrease in the amount of melatonin receptors or a decrease in the production of melatonin itself, or both. I also wondered about possible side effects of increasing melatonin levels. As we have seen with many other hormones, multiple pathways and mechanisms can be influenced by a single hormone. So someone taking melatonin to help them sleep could inadvertently throw off other pathways, like those involved in reproduction for example.

Melatonin has been shown protect against reactive oxygen species, which can wreak havoc inside cells. This could potentially be an obvious benefit to taking melatonin supplements, especially if it helps an individual sleep at night. While sifting through the literature, I was unable to find any studies specifically looking at the negative effects of taking melatonin supplements, if any. But just because it isn’t proven that something is bad, doesn’t mean the potential for bad isn’t there. Also, other countries have taken action to stop over the counter sale of melatonin. Of course, there is also the question, do melatonin supplements even work?  How much of the melatonin present in a melatonin pill is denatured by stomach acids or excreted in urine before it even has an effect?

I am skeptical of melatonin supplements, if you haven’t noticed yet. To each his own, but I don’t think I will be purchasing or taking any melatonin supplements in the near future.  Good luck to everyone on their upcoming finals. Make sure to get plenty of sleep, although if your to-do list looks like mine, that won’t be happening.

Stress and the GI Tract December 17, 2010

Posted by ljsteele in Behavior, Biology, Chemistry, Ecology, Environment/Conservation, Health, Neuroscience.
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The mechanics of stress and the gut.

Stress is shown to have a huge effect on the body, whether or not it is experienced as an acute or chronic stress.  A major topic of interest is what effects stress has on the gastrointestinal tract in organisms.  According to a multi-part scientific paper entitled “Stress and the Gastrointestinal Tract”, there are many different stressors that can be examined within a variety of organisms.  Examples of the stressors explored include food deprivation, fearful sounds, weather changes, and water avoidance ( an acute stressors explored in lab organisms such as mice, rats, and guinea pigs).  It has also been shown that acute stressors in humans, such as pain exposure, anger, fear, and intense exercise can cause gastrointestinal shut down.

From the stressors listed above, research has explored how stress influences gastro muscles to slow contraction,  thus inhibiting the processing of food.  An interesting reaction to this slowing of peristaltic movement is the fact that many organisms lose control of their colon, showing defecation in response to certain stimuli such as fear and water avoidance.  Corticotropin releasing hormone, also known as CRH  (or CRF, as identified in the aforementioned paper), is released from the hypothalamus, and blocks the effects of the vagas nerve, while also traveling through the solar plexus, and attaching to receptors in the stomach.

Stomach ulcer

Once bound, this hormone has been shown to inhibit gastro movement, and thus preventing emptying of the stomach. The difference between the stomach and the colon is that the stomach requires contraction of the muscles to push food through, whereas the colon requires contraction to keep bowel movements inside the body.  With the effect of CRH binding to the receptors, relaxation in gastrointestinal muscles occur, which is why the release of the colon sphincter results.  However, the results explored here were in response  to short term stressors.  The effects of long-term stressors have yet to be studied.

Stress and Ulcers

What does this research mean to you?  Well, the results we glean from research like this offer powerful implications for human medicine and today’s society.  Many people not only experience acute stress, but chronic stress as well.   Short term affects of acute stress include accelerated of heartbeat and an increase in metabolism, but it is only natural to ponder the long term effects of chronic stress.    We can extrapolate from the results of  acute stress that it would make sense that we, as humans, would not want these effects to be long lasting.  Major problems would arise with the decrease of gastro movement.  Problems manifest from a build up of bile and stomach acids in the stomach.  Since gut motility is decreased when stressed, less movement would mean that more bile, which is highly acidic, would sit in the stomach longer and could lead to stomach or intestinal ulcers.

Sympathetic Nervous System

Chronic stress can also lead to a decrease in the immune system of the organism as well as a decrease in the second messenger systems within the body.  An example of this effect on a second messenger system is the attachment of CRH to CRH-receptors in the solar plexus.  The binding of these receptors causes the effect of the decrease in gastro movement.

How much stress is too much stress?

Lastly, with chronic stress and chronic stimulation of the CRH/CRF system, we might see a scenario in that the more that these receptors are activated, the more desensatized they can become. This could cause problems for people and their response to stress.  If the are “desensitized” this may mean that these people have a problem when trying to   properly responding to an acute stressors when needed.