Model Organisms

2025-09-09 69

Model organisms are species used to study and reveal biological phenomena that follow universal patterns in living systems. In simple terms, due to ethical and practical constraints, life science research often cannot be conducted directly on humans or within complex ecosystems. To uncover fundamental principles of life or physiological mechanisms, scientists rely on organisms that are highly representative and experimentally tractable—these are model organisms.

Common model organisms include Escherichia coli, yeast, Arabidopsis thaliana, Caenorhabditis elegans, Drosophila melanogaster, Danio rerio, and Mus musculus. From microorganisms to mammals, these model organisms, these model organisms play unique and irreplaceable roles across different scales of biological research.

Fig 1. An illustration of some common animal and plant model organisms（Frontiers for Young Minds. 2025;13）

Generally, model organisms should meet the following criteria: represent a major group in the biological kingdom, be harmless to humans and the environment, be readily available and easy to rear and propagate in the laboratory, have short generation times and high fecundity, possess a well-defined genetic background, and be amenable to experimental manipulation—particularly through genetic tools and phenotypic analysis methods.

Fig 2. Important characteristics of model organisms used in scientific research.（Frontiers for Young Minds. 2025;13）

1. Escherichia coli

Escherichia coli is a bacterium that inhabits the intestines of humans and other mammals. It belongs to the family Enterobacteriaceae, is Gram-negative, and is either aerobic or facultatively anaerobic. It does not form spores or capsules and produces smooth, white, circular colonies on agar plates. Due to its well-understood genetics, simple culture conditions, and ease of manipulation, E. coli is the most widely used and successful system for foreign gene expression. Due to its broad availability, rapid division, short life cycle, and structural simplicity, it has become a key model organism in modern life science research, particularly in molecular genetics and bioengineering.

Fig 3. Escherichia coli

2. Yeast

Saccharomyces cerevisiae, a eukaryotic model microorganism, exhibits highly conserved cell cycle regulation mechanisms with higher organisms. Through the screening of temperature-sensitive mutants, scientists identified key cell cycle regulators such as CDK and cyclins—work that was awarded the Nobel Prize and provided a critical foundation for cancer research. Yeast has continued to yield breakthroughs in autophagy, chromatin remodeling, and protein quality control. It also serves as an ideal chassis in synthetic biology, offering a key platform for metabolic engineering and disease mechanism studies.

Fig 4. Yeast

3. Caenorhabditis elegans

Caenorhabditis elegans is a non-parasitic nematode, approximately 1 mm in length, and transparent throughout its body. It holds a unique position among model organisms due to its fully mapped cell lineage and complete neural connectome. Using this model, scientists first revealed the genetic regulation of programmed cell death in a multicellular organism—a discovery that also earned the Nobel Prize. Its transparency provides great advantages for developmental biology and in vivo neural imaging. Today, it is a core model system for studying aging, behavioral neurogenetics, and host-microbe interactions.

Fig 5. Caenorhabditis elegans（Annu Rev Food Sci Technol. 2018 Mar 25:9:1-22.）

4. Drosophila melanogaster

Drosophila melanogaster offers unique advantages in biological research due to its small size, rapid reproduction, short life cycle, low maintenance cost, easily distinguishable sexes, small genome with only four pairs of morphologically distinct chromosomes, and suitability for genetic manipulation. Approximately half of the proteins encoded by the Drosophila genome show high homology with those of mammals, and about 75% of known human disease genes have homologs in Drosophila, making it a valuable model for studying human diseases. Recent high-throughput genetic screens in Drosophila have provided new insights into neurodegenerative diseases and immune mechanisms.

Fig 6. Drosophila melanogaster（The Berg Lab, washington.edu）

5. Arabidopsis thaliana

Arabidopsis thaliana serves as a model organism in plant science due to its small genome, short life cycle, and high efficiency of genetic transformation, which have greatly advanced plant molecular biology research. Studies using Arabidopsis have successfully elucidated the molecular mechanisms of photomorphogenesis, identified the epigenetic regulatory network of the FLC gene controlling flowering time, and revealed plant hormone signaling pathways. Nobel Laureate George P. Redei referred to it as the "reference model for plant biology." This model has led to groundbreaking progress in plant hormone signaling, epigenetic regulation, and abiotic stress response, providing a theoretical basis for crop genetic improvement and sustainable agriculture.

Fig 7. Life cycle of Arabidopsis thaliana（Elife 2015 Mar 25:4:e06100）

6.  Danio rerio (Zebrafish)

Zebrafish are ideal models for vertebrate developmental biology and genetics due to their transparent embryos, external development, and high fecundity. Their remarkable regenerative capacity provides a unique window into heart and fin repair mechanisms, with discovered genetic regulatory pathways offering new directions for regenerative medicine. Additionally, zebrafish models show significant advantages in high-throughput drug screening, toxicology assessment, and human disease modeling. Their highly conserved genes and physiological structures make them a vital bridge in translational research.

Fig 8. Danio rerio

7. Mouse (Mus musculus)

Mice, derived from the house mouse, are distributed worldwide and have been bred into over 1000 inbred strains and distinct outbred populations through long-term artificial selection. As the undisputed king of mammalian model organisms, mice are central to biomedical research due to their high genomic, physiological, and metabolic similarity to humans. Nearly all areas of basic life science research and drug development involve mouse models. Recent applications of CRISPR-Cas9 technology have greatly accelerated the construction of disease models, and humanized mouse models play an irreplaceable role in preclinical drug testing and precision medicine, continuously advancing translational research.

Fig 9. Mus musculus

8. Rabbit

The domestic rabbit holds a foundational position in the history of biomedical research. Its relatively large size, ease of handling, and physiological similarity to humans make it an irreplaceable classic model. Its contributions to immunology are particularly notable—New Zealand Rabbits was first used in antiserum production and studies of antibody generation, directly advancing immunological theory. Additionally, rabbits are ideal models for studying cardiovascular diseases (e.g., atherosclerosis), ocular diseases, reproductive physiology, and allergic reactions. In recent years, their use in bioengineering and virology (e.g., rabbit hemorrhagic disease virus models) has reaffirmed their unique value as a medium-sized mammalian model in translational medicine.

Fig 10. New Zealand Rabbits

Model organisms are the unsung heroes of the life sciences. From micro to macro, prokaryotic to eukaryotic, they form the core research system through which humans explore the mysteries of life. They are not only reliable models for studying gene function but also bridges connecting basic discoveries to clinical applications. These remarkable organisms, with their reproducible operability, clear genetic backgrounds, and highly conserved biological principles, enable us to decode the fundamental mechanisms of life, uncover disease pathogenesis, and drive innovation in biotechnology. It is through the contributions of these model organisms that our understanding of life continues to deepen, ultimately laying a solid scientific foundation for medical progress and human health.

References

1. Yadav A, Maneesh Lingwan, Choudhury SD. What Are Model Organisms and Why Do We Use Them in Biology Research. Frontiers for Young Minds. 2025;13.

2. Gerv￩ MP, S￡nchez JA, Ingaramo MC, Dekanty A. Myc-regulated miRNAs modulate p53 expression and impact animal survival under nutrient deprivation. PLoS genetics. 2023;19(8):e1010721.

3. Shen P, Yue Y, Zheng J, Park Y. Caenorhabditis elegans: A Convenient In Vivo Model for Assessing the Impact of Food Bioactive Compounds on Obesity, Aging, and Alzheimer’s Disease. Annual Review of Food Science and Technology. 2018;9(1):1-22.

4. KRÄMER U. Planting molecular functions in an ecological context with Arabidopsis thaliana. eLife. 2015;4(1):e06100.

AntibodySystem provides Model Organisms-related products, delivering more tools and solutions for Mechanism research.

Recombinant Proteins

Antibodies