Tag Archives: science

Do you have an “Appetite for Life?”

The University of North Carolina Nutrition Research Institute (NRI) hosts regular events as a part of a program they call “Appetite for Life.” It’s an initiative to “unlock the promise of personalized nutrition for proactive health management.” In other words, their mission is to show people how to eat for their health, specific to individual genetics and environmental experiences.

zeisel-afl

The speaker at the event on September 13 is Steven Zeisel, MD, PhD, and Director of the NRI. Zeisel is world-renowned, a pioneer in the field of personalized nutrition. A nutrient you’ve probably heard of, called choline, is essential for human health, especially concerning pregnant women, and Zeisel is the scientist credited with this discovery.

“I’m not going to tell you what to eat today,” Zeisel says as he begins his talk. Tonight’s event is called “Genetics and Health: Your nutrition needs are as unique as you are,” and the venue, local eatery Restaurant 46, is packed with members of the local community and employees from the neighboring North Carolina Research Campus (NCRC), a 350-acre research center located in Kannapolis, North Carolina.

Zeisel goes on to describe the true meaning of personalized, or precision, medicine and the past, current, and future studies the NRI has in place to make personalized medicine a reality for everyday people concerned with their health.

“Diet can be changed to bypass nutrient deficiencies depicted by the genetic code,” Zeisel goes on. He starts by breaking down the specifics of nutrition science, starting with genetics. He describes single nucleotide polymorphisms (SNPs), common genetic variation that occurs uniquely in all humans, as “spelling errors” in the DNA. Considering that a majority of the audience have a limited understanding of current genetics, Zeisel presents his description of SNPs in an accurate yet simplified manner. After all, what’s the point of talking about bringing personalized medicine to the public if the lay people can’t understand what you’re talking about?

img_0500

Zeisel and his colleagues at the NRI are preparing for the future of genetic testing, a technology they predict as being able to sequence an individual’s genetic code to provide a complete record of specific “spelling errors” in the DNA that might make the individual at risk for certain nutrient deficiencies. Being aware of nutrient deficiencies would then allow the individual to change their diet to eat more or less of a certain type of food.

There are companies that exist now, like 23andMe, that can provide genetic information from a DNA sample. However, the product a 23andMe customer gets in return for their money and a cheek swab is just pages and pages of combinations of “AGTC” that’s essentially meaningless unless the customer also happens to be an expert in nutrigenetics with a lot of free time.

Zeisel goes on to talk about choline, folate, and other studies from the NRI and other institutions concerned about health and nutrition. He leaves plenty of time for community members to ask their own questions, many about their health and the health of their loved ones.

The NRI’s story is far from over, but after a while questions subside. For now, people head home with a new perspective on individualized nutrition. The next Appetite for Life event is now something to look forward to, a talk by NRI scientist Stephen Hursting on October 18.

img_0496

Images from UNC NRI and Kara Marker

Advertisements

The Truth About Sunscreen and SPF

The CDC lists increasing exposure to UV light as “the most preventable cause” of skin cancer, the most common cancer in the United States. This includes natural sunlight or artificial sunlight from tanning beds. Since we can’t wear full-body protective suits every day to prevent unwanted sun exposure, we use sunscreen to protect our skin from harmful rays of sun. I have studied a series of videos produced by Huffington Post where Dr. Neal Schultz discusses various elements of sun protection. He debunks several sunscreen misconceptions of which you should be informed! Luckily for you, I have compiled the most important information here. Read on!

Image Source: ClipartPanda
Image Source: ClipartPanda
“SPF,” the acronym you see on all sunscreen products, means Sunburn Protection Factor. It’s a relative measurement that describes how much sun is required to cause a burn considering the current amount of sun protection on your skin, compared to the amount of sun required to cause a burn on skin without any protection at all (FDA).

The important thing to realize about SPF is that it’s directly related to the amount of sun you are exposed to, not the time you are in the sun (FDA). Time and amount are not always interchangeable; the sun is more powerful at noon than it is at 10AM. For example, you can ingest the same amount of alcohol by taking a shot of liquor that you can by drinking one whole beer. SPF is relative in the same way. The FDA lists other factors affecting the relationship between SPF and the power of the sun including skin type, the amount of sunscreen applied, frequency of reapplication, and the fact that “greater solar intensity occurs at lower altitudes.” All of these things must be taken in to consideration when using sunscreen.

Another important question we ask when picking out a sunscreen to use is this: what SPF should I use? It’s vital to understand how protective each SPF number is, and first you must understand that SPF values are not linear. Get this: a sunscreen labeled 15 SPF gives you 88% protection from the sun. Moving up to 30 SPF, you increase your sun protection to 95%. However, when you move up to 60 SPF, you are only getting four more percent protection from the sun.

“Part of this numbers game is drive by consumer demand,” Dr. Schultz points out.

Our advice: save some money and use 15 or 30 SPF sunscreen, and reapply often to account for sweating and rubbing off in the water when swimming. You are wasting your money on sunscreens labeled 60, 70, and 100 SPF. Plus, when using such high value SPF sunscreen, people may incorrectly assume that applying enough sunscreen and reapplying later are less important. If you don’t use enough sunscreen, the SPF value greatly decreases, and you leave yourself very vulnerable to harmful rays of sun.

Another issue I looked into was that of spray vs. lotion. I am personally guilty of taking the easy way out, choosing a spray sunscreen over lotion to cut down on time spent applying sunscreen and to prevent my hands from getting sticky/sandy/etc. FutureDerm.com tested it and concluded that spray sunscreen is less effective than lotion. This result is derived from the fact that SPF is only as powerful as the amount of sunscreen that you use on your skin. What I mean by that is this: FutureDerm discovered that when people apply spray sunscreen, they end up using much less than if they applied using a lotion. Like I discussed earlier, not using enough sunscreen drastically decreases the value of SPF protection. So, if you’re going to try and save some time by using spray sunscreen, make sure to spray a generous amount on your skin, or you’ll be making up the time saved by rubbing aloe on your burnt skin 8 hours later.

Lastly, keep in mind that UV-A rays, the dangerous rays of sun that cause skin cancer and premature aging, don’t diminish in the winter. It’s always important to wear sunscreen on a daily basis. Also, sunscreen SPF is not additive. If you wear moisturizer that provides 15 SPF protection and foundation makeup that also has 15 SPF protection, you don’t get a combined protection of 30 SPF. You get the SPF protection of the first thing that you put on your skin. If you can, make sure that the first layer is sunscreen, not foundation.

My hope from doing this research and from writing this blog post is that you’ll change your habits based on learning the facts. Take care of your skin!

Check out Dr. Schultz’s videos for yourself here:

http://videos.huffingtonpost.com/tech/how-to-choose-the-right-sunscreen-266799626

Gluten: The Protein, The Trend, The Choice

In the five years since her rheumatoid arthritis diagnosis, Bailey Brislin can attest to the increase of gluten’s appearance in public discourse and on social media. A poll I conducted asking 34 random participants various questions about gluten revealed a lot about public opinion and knowledge surrounding the gluten-free trend. Collectively, it seems like these are the two opposing misconceptions about gluten:

  1. Gluten is an unhealthy component of food and should be avoided by everyone
  2. The gluten-free diet is entirely a conspiracy; no one should have to avoid gluten

Although a strong majority of the participants did not actually follow a gluten-free diet themselves, 90% knew at least one other person who did. Two-thirds of these people known to be gluten-free either had celiac disease or another gluten intolerance. Other participants listed their gluten-free friends as simply following the fad or trying “to be healthy.”

“I think people who are gluten free by choice with no medical need for it just don’t understand the science of gluten very well.” Becky Turner, a senior biology major at UNC-Chapel Hill, has often pondered with me the cause behind the growing popularity of the gluten-free diet. “Your diet is your choice, but uninformed choices are causing those who don’t have a choice to suffer from the subsequent bad reputation of being gluten-free.”

Although true gluten-free individuals like Brislin may receive criticism from a few skeptics, at least the growing trend in the gluten-free diet is increasing the number of gluten-free products on grocery shelves. In 2014, the U.S. Food and Drug Administration (FDA) defined “gluten-free” as products containing less than 20 parts per million of gluten (FDA, allergens). However, since this labeling is voluntary, there has been an increase of marketing products as “gluten-free” even though their contents have always been naturally absent of gluten (example: hummus).

Rebecca Houser, a weight-loss consultant with a degree in nutrition science from North Carolina State University, predicts the future of the gluten-free trend: “Unless you have an actual sensitivity to gluten, the hype will die down and we will move on to the next fad diet.”

So, after all of this clarification on what gluten is and who is truly impacted by it, how do we ascertain how the craze began? Ultimately, the beginning of the focus on gluten when talking about nutrition cannot be pinpointed to one study or one patient. However, it is possible and reasonable to think that technology and research have enhanced in the past decade to the point where disorders like celiac disease and rheumatoid arthritis are better understood. I hypothesize that it is this increased understanding that has led to a new light being shined upon gluten as a harmful product. When scientists were able to pinpoint gluten as a cause of illness, people with celiac disease and other gluten intolerance disorders begin to eat gluten-free as instructed by their doctors. Friends and family who heard about their lifestyle change may not have connected the aversion to gluten to become healthier with a unique medical condition. Hence, the association of “gluten” with “unhealthy.”

This, my friends, is an example of a classic health misconception. The bigger picture lesson here: ask why. If someone (not a doctor) tells you gluten is bad, do not take their word for it. Do the research yourself – be informed! And if eliminating gluten from your diet makes you feel better, that’s great! Shrug off any criticism. You know how you feel better than anyone else.

Autoimmune Disorders and Gluten Intolerance

Some medical conditions require a patient to eliminate gluten from their diet.

Celiac disease, which affects about 1% of the population of the United States (Mayo Clinic), is an autoimmune disorder based on an intolerance of gluten proteins. Autoimmune disorders occur when the immune system attacks particles that are normally not harmful to the body, either ingested food proteins or the body’s own cells.

Celiac disease occurs when the immune system attacks the body’s own cells after gluten is ingested. Specifically, the cells of the small intestine are targeted. Celiac disease-related attacks on the small intestine damage the cells that absorb nutrients during digestion (Celiac Disease Foundation).

Celiac disease is hereditary, meaning it runs in families. The pattern of inheritance is unknown (NIH). However, 95% of people with celiac disease have the same gene specific for celiac disease predisposition (Medscape, Genetics of Celiac Disease).

Rheumatoid arthritis is another autoimmune disorder relating to gluten intolerance. However, gluten is only one of many potential signals that can lead to an autoimmune attack. Rheumatoid arthritis causes inflammation of the joints – resulting in swelling, pain, and decreased movement ability (Arthritis Foundation).

Bailey Brislin, a UNC-Chapel Hill sophomore biology major preparing for medical school, was diagnosed with juvenile rheumatoid arthritis during her first year in high school. “My ankle had been swollen for months. We went to multiple doctors that couldn’t tell me what was wrong,” Brislin recalls of the time before her diagnosis. Finally, an ankle specialist ordered an MRI and referred Brislin to a rheumatologist after blood test results indicated Rheumatoid factor (RF) in her system. RF is an antibody characteristic of rheumatoid arthritis patients as well as people with other autoimmune disorders (Medscape, Rheumatoid Factor).

The next step to calculating Brislin’s proper treatment was a 5-week series of food sensitivity testing. Although the cause of rheumatoid arthritis is not fully known, potential factors triggering joint inflammation are food proteins, pathogens, female hormones, obesity, stress, and other environmental factors (Arthritis Foundation).

The results of Brislin’s sensitivity tests showed intolerance of gluten and dairy: typical occurrences among rheumatoid arthritis patients. After a while, Brislin realized that eliminating gluten from her diet had a much stronger impact on reducing  her joint inflammation than eliminating dairy.

“After a month off of gluten, I felt better. I was able to stop taking pain medication just by eliminating gluten alone,” Brislin says, “but I should be dairy-free too.” Many years later, Brislin still regularly takes immunosuppressant drugs to improve her condition.

After many years of maintaining a gluten-free diet to ensure her joint inflammation does not return, Brislin has also gathered an opinion on the growing trend of a gluten-free diet. Brislin compares people going gluten-free for no necessary reason to people trying a vegetarian diet just to see if they can do it. “There are people glorifying the gluten-free diet. It’s just bread,” Brislin says, in response to people going gluten-free for supposed “just to be healthy” reasons.

“So gluten-free becomes this very popular trend… and I get all of this criticism for being gluten-free. My rheumatologist always talks about how you don’t have to find the specific scientific data you want, just work with what has been proven in your own case,” Brislin says as she describes her encounters with gluten-free skeptics. Brislin experienced the growth of the gluten-free trend from a very unique perspective. She understands the necessity of eliminating gluten from the diet in certain circumstances but is also critical of the diet in other instances.

Her evaluation below perfectly sums up my goal in writing this series on the growing obsession with gluten:

“There are a lot of people who are very healthy who also eat gluten. I don’t think there’s anything inherently wrong with gluten – it’s not an evil food. Not eating a lot of bread is probably a good thing, but stopping eating bread and replacing it with gluten-free bread doesn’t make much sense… I’m not sure what dietary benefits people think that’s providing…”

Stay tuned for my third and last segment of my series on the gluten-free trend. This last post will contain further analysis on the development of the gluten-free trend, data from a poll of opinions about it, and an interview with Raleigh allergist Dr. Vaishali Mankad.

What is gluten?

Contrary to what you may have heard, gluten is not harmful for most people to ingest.

(0:44)

Let me set the record straight. Gluten refers to a specific set of proteins. Proteins are large molecules made up of amino acids that perform a vast range of actions necessary for life in all living organisms. In this case, gluten proteins contribute to vital life functions for the plants of wheat, barley, and rye.

The word “gluten” comes from the Latin word for glue, and rightly so. Gluten proteins are responsible for the qualities in bread such as elasticity, chewiness, and shape1. When baking bread and other products containing these proteins, the mixture thickens and rises because of thousands of gluten proteins sticking together as the temperature increases.

Foods containing gluten:

(Not a comprehensive list)

  • Pasta
  • Bread
  • Crackers
  • Baked goods
  • Cereal and granola
  • Pancakes and waffles
  • Flour tortillas
  • Beer
  • Milkshakes

While reflecting on this list, it may seem that going gluten-free could be a way to reduce fat intake and lose some weight. After all, beer and bread are notorious for contributing to weight gain. Avoiding these foods could help you lose weight, but gluten is not at all the only ingredient contributing to this circumstance. If you choose instead gluten-free substitutes for the food items listed above, you are not improving your chances at weight loss. In fact, you are more likely to gain weight by changing your diet to eating the gluten-free form of these foods.

In a study done last year in Spain, scientists looked at the nutritional differences between gluten-containing products and their gluten-free alternatives.2 Gluten-free bread was found to contain less protein, but two times the amount of fat (a lose-lose situation). Similarly, gluten-free pasta exhibited these changes, and in addition it contained more sodium and less fiber (more bad news). Cereal bars and flour followed this same trend.

Although it has been shown that food altered to be gluten-free is less nutritious than its natural form, fortunately there are plenty of naturally gluten-free options to choose from for people suffering from Celiac disease, rheumatoid arthritis, and other conditions in the realm of gluten intolerance. Fruit, vegetables, rice, corn, and potato are all naturally gluten-free options for healthy eating.1

Now that I have established what gluten is, what food it is found in, and the nature of gluten-free substitutes, hopefully your opinion of gluten has been fine-tuned. In the next part of this series about gluten, I will discuss Celiac disease as well as rheumatoid arthritis – and why people living with these conditions live a gluten-free lifestyle.

References:

  1. Gluten-Free Diet – Celiac Disease Foundation. (n.d.). Retrieved June 9, 2015, from http://celiac.org/live-gluten-free/glutenfreediet/
  1. Miranda, J., Lasa, A., Bustamante, M.A., Churruca, I., and Simon, E. March 2014. Nutritional Differences Between a Gluten-free Diet and a Diet Containing Equivalent Products with Gluten. Plant Foods for Human Nutrition. 69(410).

Image source:

berrycart.com/blog/wp-content/uploads/2014/08/gluten.png

Special thanks to Christine Rardin for the video reference!

How should you dry your hands?

One of my passions surrounding “biological awareness” so-to-speak is proper hand-washing behavior (see my BuzzFeed article – http://tinyurl.com/BacterialResistance). The perspective I want to take today, however, is actually the practice of drying hands after washing them. What is the best way to dry your hands post-cleansing? *My perspective of “best” = most sanitary*

Let’s look at some common options:

  1. Hand dryer
  2. Paper towels
  3. Cloth towel

Let’s go ahead and knock out that last option. Cloth towels are infamous for quickly becoming cesspools of germs like Coliform bacteria and Escherichia coli (1). E. coli is an infamous pathogen known for playing a role in cases of food-poisoning. Coliform bacteria are a group of bacteria commonly transferred by fecal contamination. These bacteria alone are not highly pathogenic, but their presence indicates a high incidence of other more dangerous germs that are similarly transmitted.

Poor hand-washing techniques exacerbate the colonization of these microorganisms. When microorganisms colonize, they are growing into communities of germs that are derived from a common ancestor and are increasingly resilient as they grow into larger numbers.  If one person does not adequately scrub their hands with soap and remove all dangerous infectious agents while washing, these leftover germs are transferred to the cloth towel. Also, since hand towels will realistically remain moist during the majority of their existence, essentially the perfect environment is created for many bacteria to grow and thrive until the next person comes along to dry their hands. Little does this person know, all progress made moments ago at the sink are erased (and potentially made worse) by re-infecting your hands with the germs harbored by the towel.

Our next option: utilizing hot air and friction (by rubbing your hands together) under an automatic hand dryer. This may seem like the best option because often you do not have to press a button or touch anything else after cleaning your hands. The preferred hand dryer is motion-activated and effectively dries your hands in 45 seconds. UNC Chapel Hill pharmacy student and science enthusiast Tim Angle is convinced that the warm air from these dryers is generated from a place swarming with bacteria. “Air dryers distribute bacteria due to their moist, warm environment that is prime for growing bacteria,” Angle explains. However, back in 2000, scientists showed that the air emitted from hand dryers is in fact just as sanitary as paper towels (2). In addition, in 2012, a group of researchers found that the air leaving a hand dryer actually had fewer microorganisms than the air entering it (3).

Nevertheless, Angle is still correct about the capability of warm air hand dryers to spread bacteria. This seemingly flawless method of using air to dry just-washed hands is still, in some ways, faulty. According to an article by three scientists comparing the hand-drying efficacy of various methods, warm air dryers and jet air dryers are more likely than drying hands with paper towels to spread potentially infectious droplets to the environment (4).

Dr. Christy Esmahan, a molecular biologist, brings up another flaw of warm air hand dryers. “It takes so long that people tend to leave with their hands still moist — a magnet for fresh germs.” Just like a wet cloth towel provides a fruitful breeding ground for germs, still-wet hands provide the same environment, especially when people leaving a restroom are highly likely to touch door handles and cell phones within seconds.

Considering my strictly sanitation focus, paper towels could very well be the best method for hand drying. One-time use greatly decreases risk of contamination in comparison to cloth towels. In addition, using paper towels includes the same benefit of frictional removal of bacteria as rubbing hands under a warm air dryer, while eliminating the high incidence of spreading potentially contaminated droplets to the environment.

hand drying preferences chart
Image 1: A Random Survey of Hand-Drying Preferences

Indeed, in a study of 47 random participants, a large majority preferred paper towels to warm air hand dryers (Image 1). However, the evidence for the sanitation of paper towels may not be enough to convince the large number of environmentally-concerned citizens to abandon warm air hand dryers and cloth towels. 63% of people preferring hand-drying methods other than paper towels mentioned reduction of waste as the main motivation for their choice. In addition, although the large majority of the surveyed participants did choose paper towels as their hand-drying method of choice, only 25% of those participants mentioned cleanliness and sanitation as their reasoning. 25% rationalized their choice with speed and efficiency.

Therefore, the concluding question seems to be not only “Which method is the most sanitary?” but also “How should the most appropriate method be communicated?” and, thinking holistically, “Should we be more concerned about sanitation or waste reduction?” Those who are biologically biased will likely continue to clash with the environmentally-minded. However, potential future projects that could bring the two fields together could revolve around biodegradable paper towels, for example. Ultimately, the question you should be asking yourself after reading this article is this:

What will it take to change YOUR daily hand-drying habits?

References

  1. Gerba, Charles P., Tamimi, Akrum H., Maxwell, Sherri, Sifuentes, Laura Y., Hoffman, Douglas R., Koenig, David W. 2014. Bacterial Occurrence in Kitchen Hand Towels. Food Protection Trends. 34(5): 312-317.
  2. Best, E.L., Parnell, P, Wilcox, M.H. December 2014. Microbiological comparison of hand-drying methods: the potential for contamination of the environment, user, and bystander. Journal of Hospital Infection. 88(4): 199-206.
  3. Huang, C., Ma, Wenjun, Stack, Susan. 2012. The Hygienic Efficacy of Different Hand-Drying Methods: A Review of the Evidence. Mayo Clinic Proceedings. 87(8): 791-798.
  4. Tayler, J.H., Brown, K.L., Toivenen, J, Holah J.T. December 2000. A microbiological evaluation of warm air hand driers with respect to hand hygiene and the washroom environment. Journal of Applied Microbiology. 89(6): 910-919.

Important Links

https://www.ChristyEsmahan.com

Agrobacterium: A Biological Syringe

Plants, just like humans, fall victim to bacterial infections. Dr. Ann Matthysse, a researcher in the Department of Biology at the University of North Carolina, has studied interactions between plants and pathogens since 1970, when she thought that Agrobacterium tumefaciens might lead to advances with cases of human cancer.

Matthysse initially thought that A. tumefaciens, a Gram-negative, rod-shaped bacterium found in upper layers of the soil, could be a model for cancer because it causes tumors in plants (Figure 1)

She found instead that the cancer-causing mechanism utilized by A. tumefaciens has virtually nothing to do with human cancer. However, continuing studies with the bacterium is still very beneficial due to its unique initial surface reactions with wounded plants as it binds them to begin infection.

Matthysse describes A. tumefaciens as “a biological syringe” because its virulence comes from a transfer of DNA upon infection of a plant wound, a process unique to this specific plant bacteria2. The transferred DNA integrates into the host cell chromosome and transforms the plant’s cells into tumor cells. These transformed cells then make metabolites that only A. tumefaciens is able to utilize as an energy source. The virus essentially taps into the host plant’s energy source in the same way a cell phone charger would pull energy from your car battery. This results in smaller fruit than normal being produced by the plant host, but it is usually not fatal to the plant unless the tumor blocks its main vascular tissue. Additionally, these initial surface interactions involved in DNA transfer will function the same even if non-natural, specifically-selected genes are inserted into the bacterium for transfer into a plant.

Now, Matthysse is interested in manipulating this mechanism to more efficiently develop genetically engineered crops. Some crops have been difficult to engineer, but these problems can be alleviated by identifying restrictions on the host range for agrobacterium. “Because if we knew what [these factors] were,” she proclaims, “it might be possible to counteract them.”2 If A. tumefaciens can be manipulated to bind to these plants like it does to other plant hosts, one could engineer some of these crops. For example, one could transfer genes that resist pathogenic fungi, and there is opportunity to improve nutrient levels in certain foods. “For example, rice that contains a lot of vitamin A, which would be good for people in India that don’t have a lot of vitamin A in their diet, has been made by putting the genes for vitamin A biosynthesis into rice.”

In 2006, the Centers for Disease Control and Prevention (CDC) reported that an Escherichia coli outbreak occurred from the bacteria infecting salad vegetables and causing disease in those eating the vegetables raw (Figure 2). In the numerous studies that were based on the results reported, Salmonella was also identified as a cause of disease through a similar route. E. coli was traditionally used in the lab as a control for the A. tumefaciens experiments because it did not bind to the plant host, so E. coli studies quickly began. Matthysse found that salad leaves and sprouts encountered bacteria in multiple situations:  contamination of irrigation water or equipment, improperly prepared manure fertilizer, and in post-harvest situations. Once the bacteria are bound, they cannot be removed simply by washing; infected sprouts and fruits that are not cooked prior to eating pose the greatest risk for transferring the disease to humans.

It turns out that the signals produced by the plant cell stimulate bacterial binding for A. tumefaciens, E. coli, and Salmonella. There are multiple ways that A. tumefaciens,  E. coli, and Salmonella appear to be binding to alfalfa sprouts and other salad vegetables. However, studies show that there might be a single sensory pathway that could be blocked so the bacteria are unaware of the presence of a plant in their vicinity. Thus, although the bacteria are ultimately unable to be removed once bound to the plant tissue, the sensory pathway approach could bypass this problem and prevent the bacteria from ever binding in the first place (Figure 3). Currently, Matthysse is looking at multiple methods of blocking/changing signals from plants and/or altering signal receptors on pathogenic bacteria. It might be possible to manipulate the environment so that sensory genes are turned on too soon or too late, and thus attachment and infection are not as effective.

The future of these studies remains promising, and Matthysse acknowledges the difficulty and importance of designing the most effective experiments:  identifying which factors matter the most, pinpointing the best incubation time, appropriating growth temperatures, and other conditions are a serious time investment. Practicality also has to be considered in this situation; increasing costs to customers is not a helpful option when considering long-term reduction in E. coli and Salmonella infections in raw salad vegetables. Eating leafy greens has always seemed very healthy and beneficial to the human diet, but these foods are just as prone to contamination as others. It is probably not common to consider the conditions of our salad, given that it is purchased from a seemingly safe grocery store. “We have all gotten so far away from where our food actually comes from,” Matthysse says.

Ultimately, Matthysse’s studies could lead to revolutionary improvements in genetically modified foods, and the possibilities for utilizing the A. tumefaciens gene transfer mechanism are endless. Her experiments to prevent the binding of pathogens like E. coli and Salmonella to salad vegetables could significantly reduce the number of outbreaks of these pathogens. Understanding these complicated interactions will continue to provide a strong foundation for future studies of plant pathogens.

Escherichia coli, a Gram-negative bacterium widely studied in the lab as a model organism and also found in cases of food poisoning
Figure 2: Escherichia coli, a Gram-negative bacterium widely studied in the lab as a model organism and also found in cases of food poisoning
Attachment of Agrobacterium tumefaciens to tomato root hairs. The decrease in binding visible from (A) to (B) is a comparison of wildtype A. tumefaciens (A) to A. tumefaciens without the attachment mediating gene, UPP(B).
Figure 3: Attachment of Agrobacterium tumefaciens to tomato root hairs. The decrease in binding visible from (A) to (B) is a comparison of wildtype A. tumefaciens (A) to A. tumefaciens without the attachment mediating gene, UPP(B).
Dr. Ann Matthysse, Professor of Biology, University of North Carolina at Chapel Hill.
Dr. Ann Matthysse, Professor of Biology, University of North Carolina at Chapel Hill.

References:

  1. Ann G. Matthysse; Frontiers in Plant Science 2014, 5, 1-8.
  2. Interview with Ann G. Matthysse, Ph.D. 9/18/2014.
  3. Update on Multi-State Outbreak of E. coli O157:H7 Infections From Fresh Spinach, October 6, 2006. http://www.cdc.gov/ecoli/2006/september/updates/100606.htm. (accessed September 22, 2014).

Image Sources:

  1. A. tumefaciens and E. coli: Public Domain
  2. Figure 3: Ann Matthysse

This article was previously published in Carolina Scientific Magazine, Fall 2014.