- Reverse genetics
- Forward genetics
- Diagnostic strategy

Genetic tools for Drosophila

 The chemotaxis assay is used to study C. elegans olfactory behavior. The odorant or chemical of study is applied to one side of the agar plate, with a control chemical applied to the opposite side. Sodium azide is added to both sides to immobilize the worms upon reaching their chosen odorant. Worms are placed equidistant from either chemical and allowed to chemotax, or roam freely, for a set period of time (roughly an hour to ensure the sodium azide immobilizes all worms). A chemotaxis index is calculated by subtracting the number of worms on the control zone from the number of worms on the odorant zone, divided by the total number of worms. Therefore, a chemotaxis close to 1 indicates a strong preference for the odorant, while a value close to -1 indicates either a strong repulsion to the odorant, or a lack of preference in general. This assay is also applicable to Drosophila larvae, and can be adapted to study more complex behaviors such as associative learning.

Chemotaxis Assay

- Electroretinogram (ERG)
- Neuromuscular junction electrophysiology
- Giant-fiber-system recordings
- Wing injury assay


Nervous system assays in Drosophila

 Drosophila melanogaster (fruit flies) are valuable model organisms for studying mechanisms underlying development and human disease. Like C. elegans, Drosophila are favored models due to their short generation time, high rate of reproduction, and convenient maintenance within the laboratory. Around 65% of genes that cause disease in humans have functional homologs in flies, and 38 of 59 human neurological genes have orthologs in flies. Additionally, the Drosophila genome has been fully sequenced, allowing for more precision when manipulating genes.

Pomona College

- Caenorhabditis elegans (roundworm)
- Drosophila melanogaster (fruit fly)
- Astatotilapia burtoni (cichlid fish)
- Danio rerio (zebrafish)
- Xenopus laevis (frog)
- Rodentia (mouse, rat)

Common model organisms

Kaur, K., Simon, A. F., Chauhan, V., & Chauhan, A. (2015). Effect of bisphenol A on Drosophila melanogaster behavior – A new model for the studies on neurodevelopmental disorders. Behavioural Brain Research, 284, 77–84. https://doi.org/10.1016/j.bbr.2015.02.001

Effect of bisphenol A on Drosophila melanogaster behavior – A new model for the studies on neurodevelopmental disorders (2015)

Ugur, B., Chen, K., & Bellen, H. J. (2016). Drosophila tools and assays for the study of human diseases. Disease Models & Mechanisms, 9(3), 235–244. https://doi.org/10.1242/dmm.023762

Drosophila tools and assays for the study of human diseases (2016)

Hales, K., Korey, C., Larracuente, A., & Roberts, D. (2015). Genetics on the Fly: A Primer on the Drosophila Model System. Genetics, 201, 815–842. https://doi.org/10.1534/genetics.115.183392

Genetics on the fly: a primer on the Drosophila model system (2015)

Caenorhabditis elegans (C. elegans) is a 1-1.5mm-long nematode that lives in soil and feeds on bacteria such as Escherichia coli (E. coli). Most C. elegans are hermaphrodites, or self-fertilizing. C. elegans is a popular model organism in a variety of biological research due to its short lifespan, its ability to self-reproduce, and its small size. Additionally, its translucent body enables easy visualization of cells tagged with fluorescent proteins. For neuroscience research in particular, C. elegans is a favored model because it is the first animal to have its entire genome sequenced. The adult hermaphrodite C. elegans has 302 neurons, and the connectome of the C. elegans nervous system has been extensively documented and is widely available in databases such as Wormbook and OpenWorm.

Caenorhabditis elegans (C. elegans)

Rodents are the most widely used model organism in neuroscience and biomedical research. Rats and mice differ significantly in gene expression, social behaviors, and physiology, giving them unique advantages and disadvantages as the favorable model in any particular research. For example, mice were more commonly used due to their larger “genetic toolbox,” which includes transgenic and “knockout”/”knock-in” mice. However, adult rats typically weigh up to ten times more than adult mice. Their larger size makes surgery and other invasive procedures such as catheter insertion easier to perform, while mice are chosen for optogenetics experiments because light passes more easily through their smaller brains and can therefore reach deeper regions of the brain.

Rodentia (mouse, rat)

Drosophila melanogaster (fruit fly)

Astatotilapia burtoni (A. burtoni) is a cichlid fish native to East Africa. Male A. burtoni are separated by a defined social hierarchy, in which dominant males defend territory and court females, while subordinate males shoal with other subordinate males. A. burtoni are a desirable model system for studying social behaviors (e.g. aggression) and social plasticity.

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