Drosophila as a Model Organism
Why are Drosophila melanogaster used as a model organism?
Drosophila have been used for genetic studies due to the fact it is more similar to humans that what you would think. About 60% of the genes that have been mutated are mutated in various human diseases. There are many benefits to using Drosophila which include:
- A short life cycle
- Easy maintenance
- Low number of chromosomes
- Small genome size
Due to their small size and short life span, many experiments can be ran on several individuals without a need for a massive storage space. They are very inexpensive, considering you can get 30 organisms online for less than $10 here. In addition, since they live in the same environment as humans, flies do not need to be incubated at a specific temperature for growth. Due to their small size and ease to maintain, these organisms can also be used in Biochemical assays in addition to several genetic studies and developmental studies.
Genetic studies are very simple to do considering most mutant strains can be purchased easily online, which makes it so that it is not necessary to create different mutants each time when doing an experiment. This also allows for consistency throughout the research area in addition to ease for the scientist.
Only having four chromosomes, in comparison to the human count (23 chromosomes), is much easier to work with. Classic genetics was very attracted to this since the basis was to mutate then look for the location of the mutation in the organism.
History of the Use of Drosophila
Drosophila have been a model organism for over a century for both basic science and medical research. Thomas Hunt, in 1911, published a paper in Science that consisted of genetic experiments that led to the conclusion that there are some traits that are sex linked. This discovery was made with the white eyed mutations that he noted that only occurred in males.
This experiment contributed significantly to the genetics field. While Drosophila have been of great use for determining function of genes that are orthologs in humans. Genetics have excelled due to the use of this organism, there are also a lot of tools that have been developed in this organism that have helped with the understanding of genetics and development.
Since this experiment, the entire genome of the fly has been sequenced and defined, which further supports the usefulness and ease of using Drosophila as a model organism.
Tools Frequently Used in Drosophila
Some tools that have been useful in genetic and development studies in Drosophila:
- FLP/FRT: A method to mutate the genome in which an FRT domain is inserted into the gene of interest, then FLP recombinase is used to cause insertion, excision, inversion or translocation of the DNA ultimately causing the mutation of the gene. The insertion can be used to not only disrupt a gene, but establish a reporter such as GFP. This can be used in conjugation with the Cre-lox system to create double mutants.
Insertion using FLP/FRT system
- Cre/Lox: Also used to carry out insertion, excision, inversion or translocation of the DNA ultimately causing the mutation of the gene. This system also uses recombination to cause mutations in the genome.
- Balancer Chromosomes: Balancer chromosomes are used to create heterozygous mutations to look at what happens when mutations occur in homozygous mutant lethal genes. This mutation also occurs using recombination. The balancer chromosome is a blank chromosome so that if the fly ends up with both copies it is lethal. Only if a fly has heterozygous will it survive this breeding.
- CRISPR/Cas9: The CRISPR/Cas9 system has taken over the science field because of its ease in creating a mutation in genomes of any organism. This tool requires gRNA to be designed to target the area, and the CRISPR/Cas9 system will create random cuts that cause mutations within the genome.
To read more about Drosophila as a model organism, you can browse the literature used to create this site here.