“Beware of the Blob! It creeps, and leaps, and glides and slides across the floor! Indescribable…Indestructible! Nothing Can Stop It! The indestructible creature! Bloated with the blood of its victims!” (The Blob, 1958). Physarum polycephalum, nicknamed the “The Blob” after the 1958 classic from Irvin Yeaworth and Russel Doughten, has taken the scientific community by storm. Its impressive repertoire includes spending a summer in space, modeling the early evolutionary history of eukaryotes, and of course, navigating the reproductive scene with over 720 sexes in one organism. Traveling without legs and healing injuries in just under two minutes, this slime mold “belongs to one of nature’s mysteries” according to Bruno David, director of the Paris Museum of Natural History (The Guardian, 2019).
Such a creature shrouded in mystery can commonly be located growing within rotting logs searching for food via a long network of thin tendrils. When the organism encounters food it grows over the object, secreting digestive enzymes to “consume” the decaying vegetation or microorganism. Its intricate structure allows for nutrients to be passed around within the network of the organism.
Toshiyuki Nakagaki, a mathematical biologist, and colleagues observed Physarum polycephalum’s networking capabilities to predict effective city planning. The laboratory placed the mold into a culture mirroring Tokyo’s infrastructure. Upon placing food in the city’s population centers, the organism’s tendrils uncovered pathways nearly identical to Tokyo’s railway system (Wogan, 2012). The research demonstrated Physarum polycephalum’s incredible ability to solve complex problems, such as uncovering the fastest pathway through a maze, despite having no “brain-like” center (Kramar, 2021).
The single-celled slime mold’s ability to make intelligent decisions without a central nervous system, “a memory without a brain,” has sparked intrigue into its real-world applications. Within a medical context, the mold’s early growth could be essential to understanding how tumors supply themselves with blood. Slime molds in their early stages of growth begin as a collection of isolated spores that grow in an outwards direction. Next, the spores gather in smaller groupings which release tendrils that connect with other gatherings nearby. This eventually forms a larger single celled organism that can transport nutrients, fluid, etc within itself. This process is called “percolation transition”, when separate networks become interconnected to form a transport system. Tumors subscribe to a similar process.They produce factors that stimulate the creation of blood vessels that supply the components necessary for their growth (NCI, 2018). This process is a highly active subject of research within the field of oncology. “The Blob” may aid in furthering the field’s understanding of tumors.
Further research on Physarum polycephalum may provide insight into not only understanding but preventing tumor growth. Hans-Gunther Dobereiner, Adrian Fessel, and colleagues from the University of Bremen and Mechanobiology Institute focus their studies on slime mold percolation transition. They observed how the mold’s tendrils grew and joined with one another similar to a subway map system, as seen earlier by Nakagaki. Researchers recorded the connections and discovered that percolation transition always happened when the collection “nodes” of the mold and the tendril lines observed a specific pattern. Regardless of the number of collection “nodes,” there was a constant ratio of tendrils to nodes. Dobereiner hopes that further research into the vascular network formation of the slime mold can lead to techniques of preventing tumor growth using their slime mold-derived mathematical model (Wogan, 2012).
Whether a Mathematician, Puzzle-enthusiast, or Urban planner Physarum polycephalum’s many talents merits many real-world applications. While it may not make a cinema debut quite like its chilling movie-star counterpart, this slime mold is ready for the big screen of the scientific community. What will Physarum polycephalum accomplish next? Certainly something, “Indescribable…indestructible…insatiable” (The Blob, 1958).
Image Credit: https://www.imdb.com/title/tt0051418/
Works Cited
The Blob. (1958). Movie Quote. Retrieved November 6, 2022, from https://www.moviequotedb.com/movies/blob-the-1958.html.
The Guardian Staff. (2019, October 17). The ‘blob’: Zoo showcases slime mold with 720 sexes that can heal itself in minutes. The Guardian. Retrieved November 6, 2022, from https://www.theguardian.com/world/2019/oct/17/the-blob-zoo-unveils-baffling-new-organism-with-720 sexes#:~:text=The%20slime%20mold%2C%20Physarum%20polycephalum,minutes%20if%20cut%20in%20half.&text=%E2%80%9CThe%20blob%20is%20a%20living,the%20Zoological%20Park%20is%20part.
Mirna Kramar, Karen Alim. Encoding memory in tube diameter hierarchy of living flow network. Proceedings of the National Academy of Sciences, 2021; 118 (10): e2007815118 DOI: 10.1073/pnas.2007815118
National Cancer Institute. (2018). Angiogenesis inhibitors. National Cancer Institute. Retrieved November 6, 2022, from https://www.cancer.gov/about-cancer/treatment/types/immunotherapy/angiogenesis-inhibitors-fact-sheet#:~:text=have%20side%20effects%3F-,What%20is%20angiogenesis%3F,chemical%20signals%20in%20the%20body.
Technical University of Munich (TUM). “A memory without a brain: How a single cell slime mold makes smart decisions without a central nervous system.” ScienceDaily. ScienceDaily, 23 February 2021. <www.sciencedaily.com/releases/2021/02/210223121643.htm>.
Wogan , T. (2012). A slimy insight into treating cancer. Science. Retrieved November 6, 2022, from https://www.science.org/content/article/slimy-insight-treating-cancer.