C. elegans: A Versatile Model Organism in Genetics - Research Paper

Introduction

Caenorhabditis elegans (C. elegans) is a non-pathogenic, non-hazardous, non-infectious, and non-parasitic nematode ("What is C. elegans? | College of Biological Sciences", 2015). It survives in the soil by consuming microbes, such as bacteria. This organism has been used in various genetic investigations, especially in studying neurobiology, cell biology, and developmental biology. Free-living species can be cultured without a host, and this characteristic has made C. elegans to the main model species used in genetic analysis (Nigon & Felix, 2018). This essay will discuss the history of C. elegans in biological research, the characteristics that make it a suitable model species, disadvantages associated with it, and some human conditions that have successfully modeled through it.

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The history of C. elegans in biological research occurred in phases (Nigon & Felix, 2018). The first phase involved the collection and morphological observation of the free-living nematodes and which started in the 17th century during the advent of microscopy. The second phase began when the 19th century came to an end to study overall biological mechanisms with nematodes as the model species. At this phase, observations were replaced by essential experimentation. The third historical phase started in the 1940s headed by Ellsworth C. Dougherty and Victor M. Nigon, who were the first team to use free-living nematodes. They focused on the analysis of nutrition and reproduction of nematodes, resulting in redefining experimental methods and culture conditions. The fourth phase started in1974 when Sydney Brenner and his colleagues made the initial publications. He overcame the challenges faced by Nigon and Dougherty, and he opened up to innovation and new perspectives. Therefore, the study of free-living nematodes has evolved from each of these phases.

C. elegans has several characteristics that make it a suitable model species. First, it can be cultured without a host throughout the lifecycle, hence crucial in genetic analysis (Nigon & Felix, 2018). Secondly, it can be cultured continuously because it produces sperms and eggs. Thirdly, it is a single cell that undergoes an intricate development process, beginning with embryonic cleavage, then morphogenesis, and lastly, growth to adult. Fourthly, C. elegans is one millimeter long and can be handled as a microorganism and be grown on Petri plates containing bacteria.

Additionally, C. elegans have a specific development feature, where cells divide and specialize in a certain way, making it possible to track each cell back to the embryo. It is also transparent throughout its life, following its development all through. C. elegans have also been used successfully as model organisms due to their simplicity character. Numerous signals that control its development are also evident in complex organisms such as a human. It is a small organism convenient to keep in the lab and an examination of its development and anatomy under a microscope. The mutants of C. elegans are extremely useful models for human diseases and disorders, including congenital heart disease, neurological disorders, kidney disease, and so on (Marsh & May, 2012).

Despite the numerous advantages of working with C. elegans, various disadvantages prevent it from being used as model organisms (Tissenbaum, 2015). This species has simple anatomy that lacks several defined organs and tissues such as blood, brain, internal organs. Therefore, making it evolutionarily distant from humans, and it cannot be used for blood or liver research as it does not have them. They are also small in size, making it hard to see them, and they are also only 1 mm in length, thus make biochemistry more challenging. C. elegans do not have cell lines that used in cell culture analysis. Besides, its embryo is challenging to get at, conducting of biochemistry, immunoprecipitation, and microarray on whole worm extracts. Henceforth using C. elegans may cause a limited understanding of gene expression in the intestine, hypodermis, etc. (Tissenbaum, 2015).

Alzheimer's disease (AD) and polycystic kidney disease (PKD) are examples of human conditions that have been modeled successfully using C. elegans. Mutations of genes associated with AD have equivalents in C. elegans. According to (Alexander, Marfil, & Li, 2014), the connectivity of neurons found in C. elegans is beneficial in memory impairments seen during AD. Barr experimented with C. elegans to show that worm proteins have a relationship with human polycystins that mediate signals in sensory neurons (Adams, 2008). In his experiment, a gene mutation in the PKD1 homolog influenced a specific behavioral step of mating in male worms. His results showed that there is a similar interaction between the two proteins.

Conclusion

This essay discussed the history, characteristics, and disadvantages of C. elegans as well as modeling the human conditions in C. elegans. There are four phases of the historical research of C. elegans in different periods. Some of the characteristics of C. elegans include continuous culture, can be cultured without a host, etc. The disadvantages of using it as a model organism include; it is small-sized, has simple anatomy, and so on. Some human conditions modeled in C. elegans include AD and PKD.

References

Adams, J. (2008). C. elegans: Model organism in the discovery of pkd. Nature Education, 1(1).

Alexander, A. G., Marfil, V., & Li, C. (2014). Use of Caenorhabditis elegans as a model to study Alzheimer's disease and other neurodegenerative diseases. Frontiers in genetics, 5, 279.

Marsh, E. K., & May, R. C. (2012). Caenorhabditis elegans, a model organism for investigating immunity. Appl. Environ. Microbiol., 78(7), 2075-2081.

Nigon, V. M., & Felix, M. A. (2018). History of research on C. elegans and other free-living nematodes as model organisms. In WormBook: The Online Review of C. elegans Biology [Internet]. WormBook.

Tissenbaum, H. A. (2015). Using C. elegans for aging research. Invertebrate reproduction & development, 59(sup1), 59-63.

What is C. elegans? | College of Biological Sciences. (2015). Retrieved 27 February 2020, from https://cbs.umn.edu/cgc/what-c-elegans