A tiny, transparent worm may not seem like the most exciting scientific test subject, but this humble organism has helped scientists shed light on intricate scientific ideas and provided invaluable researching techniques. Caenorhabditis elegans (C. elegans) are a type of microscopic roundworm that were largely invisible to the scientific community up until 1963, when Sydney Brenner introduced them as a potential model organism, or animal test subject (Brenner). In terms of practicality and flexibility, Brenner hit a scientific goldmine–C.elegans possess a plethora of useful properties. For one, they are very easy to breed, only requiring an agar plate seeded with the appropriate food to flourish (Wormbook). These plates are compact and can easily be tucked away in a laboratory corner. Additionally, C. elegans are semi-transparent, allowing for the observation of their internal organs and metabolic processes (Harvard). Since Brenner’s discovery, scientists have completely mapped out the genome of C. elegans, allowing for genetic mutations to be easily administered. This property is especially significant because it provides a platform for studying complex cellular automata on a simpler, smaller scale. The collection of these C. elegan properties have allowed scientists to make groundbreaking discoveries in programmed cell death and green fluorescent proteins.
Thanks to its easy breeding and mutability properties, C. elegans have allowed scientists such as Robert Horvtiz to make strides in cancer research. The mechanisms behind cancer are notoriously difficult to understand, partly because cancer cells are ordinary cells gone haywire. In the 1970’s, scientists knew that programmed cell death, also known as apoptosis, was a natural defense mechanism aginst these rogue cells, but an in-depth genetic analysis had yet to be done. Robert Horvitz utilized mutated C. elegans strains to study this phenomenon (Howard Hughes Medical InstituteNobel Prize). Through a series of isolating certain genes, Horvitz was able to deduce four main genes that are necessary for apoptosis: ced-3, ced-4, ced-9, and egl-1. To find the respective roles of each gene, Horvitz knocked out each of the genes from the C. elegans and observed how it affected cell division. The ced-3 gene was responsible for encoding an enzyme that cleaves proteins, basically doing the heavy work in destroying the cell (Horvitz). Ced-4 plays a role in activating ced-3, acting as a messenger for apoptosis. The proteins coded by egl-1 and ced-9 act as the apoptosis signals. The ced-9 protein inhibits apoptosis while egl-1 promotes it. Horvitz figured that the balance between ced-9 proteins and egl-1 proteins determined whether a cell undergoes apoptosis (Horvitz). These four main genes are vital for C. elegans cell programmed death, and their discoveries paved the way for future cancer research for other multicellular organisms, ultimately winning Horvitz a Nobel Prize. The genes that Horvitz identified have counterparts in mammals such as humans and mice, allowing for scientists to narrow down their research focus. The mutability property of C.elegans made it possible for Horvitz to find this information. Similarly, the next discovery relies on the worms’ transparent property.
Green fluorescent proteins (GFPs), are biotechnological tools that are able to emit a greenish hue when exposed to certain wavelengths of light. They are naturally found in some jellyfish species, however they can be introduced to other organisms for scientific research. One of the first scientists to try this out was Martin Chalfie. In order to demonstrate the feasibility of his project, he started his investigation by trying to express the GFP gene in E. coli bacteria. After this initial success, Chalfie moved on to C. elegans, where his lab was able to fuse the GFP gene to other known genes. This process is now known as GFP tagging, and it allows for researchers to observe the location and movement of tagged proteins in real time (Chalfie). The transparent property of C. elegans helped Chalfie’s lab to identify the proteins and develop a specialized microscope that allowed for GFPs to be observed in other organisms. The discovery and usage of green fluorescent proteins has revolutionized the biotechnology field by allowing scientists to observe the behavior and movement of specific proteins in real-time.
The humble organism Caenorhabditis elegans, with its properties of genetic mutability and semi-transparency, have played a pivotal role in the biotechnology field. It all started with Brenner’s introduction of C. Elegans as a model organism, a sort of call to other researchers on the flexibility and ease of use of C. elegans. Through its genetic mutability, Horvtiz was able to isolate genes that are necessary for apoptosis, while Chalfie was able to make use of its transparency to invent the green fluorescent protein tagging process. The contributions of C. elegans to the research community can’t be overstated, and it will remain a crucial model organism for continued scientific advancements.
References:
Brenner, Sydney. “The genetics of Caenorhabditis elegans.” Genetics, vol. 77, no. 1, 1974, pp. 71-94. PubMed Central, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1213120/.
Chalfie, Martin. “Green Fluorescent Protein as a Marker for Gene Expression.” Science, vol. 263, no. 5148, 1994, pp. 802-805. Science, https://www.science.org/doi/abs/10.1126/science.8303295?casa_token=nSLf9osJuVQAAAAA:5B53P-WolvbSus0a2tOTcFxzgNIUmzKiNY-oozVs3NN3vdNbvgJFYMyrJ-L4xAk9HZ4U5_FoAqGlzciS.
“C. elegans.” Mair Lab, Harvard T.H. Chan School of Public Health, https://www.hsph.harvard.edu/mair-lab/c-elegans/.
Nobel Prize: “Horvitz Wins 2002 Nobel Prize in Physiology or Medicine.” Howard Hughes Medical Institute, 2002, https://www.hhmi.org/news/horvitz-wins-2002-nobel-prize-physiology-or-medicine.
Horvitz, H. Robert. “Genetic Control of Cell Death in the Nematode C. elegans.” Cancer Res, vol. 4, Issue 4, 1994, pp. 581s-586s. Google Scholar, https://scholar.google.com/scholar?hl=en&as_sdt=0%2C11&q=programmed+cell+death+c.+elegans&btnG=&oq=.
“Maintaining and culturing Caenorhabditis elegans.” WormBook, edited by Andrew Singson, WormBook, 2006, pp. 1-11. http://www.wormbook.org/chapters/www_strainmaintain/strainmaintain.html.
