Tag Archives: biology

Rise of the Planet of the Apes — A Scientific Critique

“Rise of the Planet of the Apes” told the story of a researcher who, while looking for the cure to Alzheimer’s, inadvertently created an army of highly intelligent primates (whoops) by developing a virus that allowed brain tissue to heal itself. The scientist, played by James Franco, had personal reasons for developing the cure; his father, living with him at home, was visibly suffering from Alzheimer’s.

Throughout the film, many of the details involving the miracle virus are vaguely expressed, but the film does adequately show a difference in how the chimpanzees and humans are differentially affected by the virus when infected. Thus, this film is a fine representation of the difficulties of applying animal model research in the lab. Moreover, this film uses topical knowledge of the pathogenicity of Alzheimer’s combined with the more widespread knowledge of the visible, debilitating effects of the disease to develop a dramatic science-fiction story with just enough realistic explanation of scientific phenomena to make the story seem plausible in real life.

Alzheimer’s disease is a neurodegenerative disorder occurring in nearly 5% of the elderly population worldwide (Bali et. al, 2010). The disease develops over time as neuron cells die, and ultimately presents clinically with memory loss and cognitive impairment (Castellani et. al, 2010). Current studies in Alzheimer’s therapy revolve around prevention: recognizing particularly susceptible groups and taking steps to slow the onset of the disease. Specifically, amyloid-β treatments are utilized since deposits of these peptides are often visible many years before patients show symptoms of Alzheimer’s (Reiman 2013).

James Franco and his scientist buddies, while looking for a cure to Alzheimer’s, infect chimpanzees with an experimental virus to examine how it impacts brain tissue and intelligence. Promising results show infected chimps succeeding at the so-called “Lucas Tower” – an actual laboratory test called the Tower of Hanoi. This test is used in real life in various studies, and it measures cognitive abilities based on skill learning and mastery (Schiff and Vakil, 2015). In the film, improved intelligence (based on a “good” Lucas Tower score) of the chimps is understood to supposedly highlight potential brain-healing qualities of the drug in humans. However, this mechanism is not particularly explained, just assumed. My critique of this particular detail is this: although new brain cells may develop in chimps infected with the drug and subsequently enable them to perform higher level functions, there is no assurance that this same mechanism will revitalize dead neurons in a human brain plagued with Alzheimer’s.

The scientist’s father shows the accurate signs of Alzheimer’s. He has trouble using silverware while eating, remembering piano tunes, and he is unable to drive. Complications occur in the lab, and the scientist eventually finds himself running unofficial, experimental human trials on his father using the virus. The Alzheimer’s-stricken old man receives an injection before bed and is heard flawlessly playing old piano tunes just a couple of hours later after waking up. Although there is no current complete cure to Alzheimer’s in existence to compare this phenomena to, it is still hard to believe that such a monumental improvement would occur within the man’s brain overnight with such visible effects. Alas, the quick change certainly instills a strong feeling of fulfillment and human victory over misfortune amongst the film’s audience.

In addition after the lab complications, the scientist takes home a baby chimpanzee (Caesar) that is found to have received the virus in utero, his mother being one of the chimps showing increased intelligence after infection with the virus. Although some viruses like HIV and herpes are known to cross the placenta during pregnancy or transmitted during birth, the movie did not provide enough detail about the virus to be able to say whether this transmission would be plausible or not. As the scientist’s father responds to the virus with restored cognitive abilities, the chimp responds to its presence in his body by showing abnormal, high-intelligence behaviors for a monkey: quick learning of sign language, humanistic qualities like holding and drinking from cups, and general adaption to a human environment.

Although the chimp continues to get smarter (and cause more problems), after a while the old man regresses back to showing symptoms of Alzheimer’s. The scientist associates this problem to his father’s immune system producing antibodies against the anti-Alzheimer’s virus. It is unclear in the film how long the virus is effective before the body responds by attacking it. It seems like in order for an immune response to be plausible it would have had to occur within a few days of the man receiving the virus. Another discrepancy is this: another scientist in the lab is accidentally exposed to the virus during a chimp experiment and dies. The infection causes some hemorrhagic disorder that was clearly not present in the old man (although he ends up dying as well since the virus stops being able to cure his Alzheimer’s). Lastly, the chimp infected with the virus neither develops the hemorrhagic disorder nor builds up antibodies against the virus. These discrepancies are strangely not addressed and slightly frustrating to someone with a scientific mind.

Despite the vague details of some biological aspects and the mentioned inconsistencies, the foundation of Alzheimer’s as the scientist’s initial motivation for most of the drama that occurs is powerful and relatable. As the generation of senior citizens increases, there a larger high-risk group for Alzheimer’s, and many people my age and older are likely to experience their grandparents or parents suffering from this unfortunate disease.

The next time you watch a science-fiction movie consider the plausibility of the science discussed in the plot. The majority of science-fiction films you will watch won’t have any scientific basis at all, but one of the coolest parts of this film is that a biologist like myself, however visionary, can see a future in brain-healing Alzheimer’s therapy. I am less convinced that vengeful apes will congregate, learn to speak and take over the world, but… I digress.

Check out the Rise of the Planet of the Apes trailer here:

Note: I originally wrote this review for my Molecular Basis of Disease class at UNC.

References

  1. Bali, Jitin; Halima, Saoussen; Felmy, BoasView Profile; Goodger, Zoe; Zurbriggen, SebastianView Profile; et al. Cellular basis of Alzheimer’s disease. Annals of Indian Academy of Neurology, suppl. Suppl 213 (Dec 2010): 89-93.
  2. Castellani, Rudy J.; Rolston, Raj K.; Smith, Mark A. September 2010. Alzheimer’s Disease. Disease-a-Month. 56(9): 484-546.
  3. Reiman, Eric M. January 2014. Alzheimer’s disease and other dementias: advances in 2013. The Lancet Neurology. 13(1): 3-5.
  4. Schiff, Rachel; Vakil, Eli. 2015. Age differences in cognitive skill learning, retention and transfer: The case of the Tower of Hanoi Puzzle. Learning and Individual Differences. Accessed Online.
  5. Picture Link: http://www.dvd-ppt-slideshow.com/blog/wp-content/uploads/2011/08/rise-of-planet-of-the-apes-4.jpg
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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.