Image Citation: [1]
Written by Hailey Stone ‘28
Edited by Joanna Sohn ‘28
A closer look at magnetic bacteria, emerging theories on migratory animals' sense of direction, and the potential applications of this knowledge in advancing cancer research.
One problematic piece of cancer treatment is the negative side effects the medication or antibiotics have on the recipient's body. Clearly, a more direct route to the tumor that avoids damaging the healthy tissue would be best. One possible solution is the little organisms called magnetotactic bacteria, which sense direction simply through their genetic makeup. Usually, these bacteria utilize this skillful trait to move around in their mud habitat where it’s impossible to know up from down. But what about the complex blood vessels of the human body? Researchers believe that with a little help, these bacteria can transport chemotherapeutic ligands directly to the tumor cells [2].
There are two main options in this process. The first, which is more passive, is called the enhanced permeability and retention (EPR) effect, where certain-sized molecules are more drawn to cancerous areas. In contrast, the active treatment consists of creating a magnetic field that orientates the bacteria towards the tumor or modifying them to have specific tumor cell receptors directly on their magnetosomes (organelles of the magnetotactic bacteria). One crucial note about these bacteria is they are natural rather than chemically made and therefore maintain their magnetized quality even at room temperature [3]. This makes it convenient and less prone to error while being tested in labs or in storage before treatment. Furthermore, magnetotactic bacteria have very strong flagella, allowing for high-speed movement quick enough to move against blood flow. This also requires a highly detailed mapping of the human body and understanding of the time concerned properties of blood flow [4]. However, it could be pivotal in getting to specific spots in the body.
Figure 1: Three different forms of preparation utilizing entire magnetotactic bacteria or the removed magnetosome minerals [4]. | Figure 2: The formation of the chain-structure that optimizes the dipole moment and gives the bacteria their magnetic nature [5]. |
Now, to truly understand this information, it is important to know just how these bacteria biologically work. The interest in researching such organisms and biological processes of magnetism began with the question of how migratory animals know where to go. This question is still not perfectly answered, and there is still plenty of ongoing research.
However, the most concrete example of a magnetoreceptor is in phytoplankton and bacteria. Since their discovery in the 1970s, magnetotactic bacteria have fascinated the scientific community. These curious organisms get their qualities due to having chains of ferrimagnetic minerals like magnetite (Fe3O4) and greigite (Fe3S4). This gives off an extremely large dipole moment, allowing the alignment with the magnetic field [6]. Following this discovery, scientists also concluded that these bacteria do not only thrive on their own but also exist within other creatures. Such species include those inquisitive migratory animals: honey bees, birds, salmon, and sea turtles.
Figure 3: The collection of sea turtle tears for testing of the bacteria’s presence in the nervous system [7]. | Figure 4: Sea turtles miraculously travel thousands of miles every year, returning to the same beach to lay their eggs [8]. |
As mentioned above, these animals are still the subject of many studies to this day. One recent study involves sea turtles and their tears. The question is if these animals are truly working with the bacteria or if it is mere coincidence that they coexist. Assistant Professor Robert Fitak of the UCF Department of Biology has recently put together the data on these bacteria and began a study to answer this question. The focus of the study is on whether the bacteria are present in the nervous system, and therefore may suggest a correlation between the bacteria and the animals’ navigation skills.
Fitak partnered with UCF’s Marine Turtle Research Group to begin gathering data. The collection process is actually quite simple and in high availability during the turtles nesting season. In short, while sea turtles nest on land, they need a way to keep their eyes as moist as they would be in the water. To mitigate this issue, the sea turtles frequently produce goopy tears, which can easily be collected with a swab. Furthermore, it’s a perfect piece of data because tear ducts connect with the nerves–exactly what these scientists wish to study [7].
While this is only the beginning of this fascinating new study, the samples that have been collected already show signs of magnetotactic bacteria. If this new study can decipher the truth behind sea turtles' and other migratory animals’ sense of direction, then there is the possibility of using this information to protect them. By knowing how they navigate and where they might go, scientists can make better decisions and put measures in place to preserve habitats of endangered or protected species.
With this knowledge, new research, and future solutions, there is much to still uncover regarding these mysterious magnetotactic bacteria. Do sea turtles really use them to navigate? Will this be the new treatment for fighting cancer? Definitely something to keep an eye on.
References
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Kuzajewska D, Wszołek A, Żwierełło W, Kirczuk L, Maruszewska A. Magnetotactic Bacteria and Magnetosomes as Smart Drug Delivery Systems: A New Weapon on the Battlefield with Cancer? Biology. 2020 May 19;9(5):102.
Alsharedeh R, Alshraiedeh N, Aljabali AA, Tambuwala MM. Magnetosomes as Potential Nanocarriers for Cancer Treatment. CDD. 2024 Oct;21(8):1073–81.
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Fitak RR. The magneto-microbiome: A dataset of the metagenomic distribution of magnetotactic bacteria. Data in Brief. 2024 Apr;53:110073.
Parks J. Everything to Know About the Secret World of Sea Turtles. Discover [Internet]. 2024 Mar 6; Available from: https://www.discovermagazine.com/planet-earth/everything-to-know-about-the-secret-world-of-sea-turtles
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