Zebra fish utilization in drug discovery

1. Zebra Fish model to screen Pharmaceutical compounds
Presented by: Aditya Singh
PC/2019/212
Pharmacology & Toxicology
Subject code: PC-611
Subject teacher: Dr. Dharmendra
Kumar Khatri

2. General Introduction
• It is a tropical fresh water fish
• It is abundant in the Ganges and Brahmaputra river
• Biological name: Danio rerio
• Size is usually small i.e- 1-1.5 inches hence easy to breed
and captivate
1-1.5 inch

3. History of its usage
1972
• At the
University of
Oregon, USA
• Dr. Scitsinger
First to develop
zebrafish as an
animal model to
screen drugs
1975
• Zebrafish was
sent into space
1987
• First transgenic
variant of
zebrafish model
developed
1990-
95
• First cortisol
assay done
• Mutagenesis done
• Cancer studies
• Anxiety, learning,
sleep and
cognitive
experiments
performed
2005
• EEG of
brain
• c-fos assays
performed
2013
• Sanger
institute
sequenced
full genome
and created
a gene
library
Tavares B, Santos Lopes S. The importance of Zebrafish in biomedical research. Acta Med Port. 2013 Sep-Oct;26(5):583-92.

4. Life cycle of Zebrafish
Ribas, Laia, and Francesc Piferrer. "The zebrafish (D anio rerio) as a model organism, with emphasis on applications for finfish aquaculture research." Reviews in
Aquaculture 6.4 (2014): 209-240.
Zygote
Blastula
Gastrula
Hatching
Larvae
Juvenile
Adult

5. Zebrafish: Eureka!
• Zebra fish is named after its five
blue striped horizontal sections on
its body
• These stripes resembles the stripes
of zebra and extend up to the
caudal fin
• It is laterally compressed with
mouth directed upwards
Anatomy of zebrafish larva
Anatomy of a male adult zebrafish
Engeszer, Raymond E., et al. "Zebrafish in the wild: a review of natural history and new
notes from the field." Zebrafish 4.1 (2007): 21-40.

6. Advantages of the model
When using animals in research, it is important to minimise animal, scientific reasons
why ‘lower’ organisms, such as zebrafish, can create a better model system.
• Small size and speedy growth:
Adult zebrafish are small in size, they grow quickly, and they breed readily. They can
reach sexual maturity in three months in the lab, and each adult female can produce
hundreds of eggs a week. Conducting larger studies with higher numbers in your
exposure groups is much easier with zebrafish than with mice.
• Easier to house and care than rodents
Due to their small size and the relatively simple nature of their natural environment, it is
easier to keep zebrafish in more natural conditions than it is possible to simulate for
mammals. minimises housing stress, it also minimises the number of animals that need
to be used because it reduces the subject variation that can be caused by stress.
• External fertilization and development:
The eggs are fertilized and undergo development outside the mother’s body, rather than
the internal development of mammals or even the internal fertilization of birds,
amphibians and reptiles. This allows researchers to examine and manipulate the
embryos from the moment they are fertilized
• Lots of offspring
Zebrafish have a much larger number of offspring in each generation than rodents.
Rodents have 5-10 offspring per pairing, in comparison to the 200-300 obtained from
fish. Zebrafish offspring also grow and develop very quickly.
Zebrafish storage tanks
Siccardi III, Anthony J., et al. "Growth and survival of zebrafish (Danio rerio) fed different commercial and laboratory diets." Zebrafish 6.3 (2009): 275-280.

7. Advantages of the model
• Impact of any genetic mutation or drug treatment is easy to see
Zebrafish embryos and larvae are completely transparent, meaning that it is possible to follow
the impact of a genetic manipulation or pharmacological treatment using non-invasive
imaging techniques
• Easier to introduce genetic changes
Zebrafish embryos are able to absorb chemicals that have been added to their water, meaning
it is easy to introduce changes to their genes using nothing more than chemical mutagens.
• See-through embryos:
The optical clarity of zebrafish embryos and the chorions that surround them offers an
amazing view of morphological development, organ development and function.
• Homology to humans:
Zebrafish have many of the same genes, tissues, and organ systems as humans. Because
zebrafish are more similar to humans than invertebrate models (such as the
worm Caenorhabditis elegans and the fly Drosophila melanogaster), discoveries made in
zebrafish are more likely to be directly applicable to humans than those made in invertebrate
systems.
Howe, K., Clark, M., Torroja, C. et al. The zebrafish reference genome sequence and its relationship to the human genome. Nature 496, 498–503 (2013).

8. Zebrafish model in cancer
Mutagenesis or transplant
Dexamethasone
Immunosuppression
Chemical
treatment
Tumour cells
injected
Tumour cells excised from humans
Mutagenesis Transgenesis Transplant
Treatment and further
studies
Adult fish Embryo stage
Astone, M., Dankert, E.N., Alam, S.K. et al. Fishing for cures: The alLURE
of using zebrafish to develop precision oncology therapies. npj Precision
Onc 1, 39 (2017).

9. Zebrafish model in Alzheimer's
Acoustic stimuli
Startle response
Aβ1-42
amyloid plagues and tau tangles study can be
performed
Trimethlytin chloride
(TMT)
neurobehavioral toxicity,
specifically, apoptosis in the
tail, modulations in
photomotor response and
frequency of tail flexion
Okadaic acid
Deficits in cognition , learning and locomotor
activity
Saleem, S., Kannan, R.R. Zebrafish: an emerging real-time model system to study Alzheimer’s disease and neurospecific drug discovery. Cell Death Discov. 4, 45 (2018).
Hind brain ventricle or
intraventricular

10. Zebrafish model in Depression studies

11. Zebrafish model for toxicity studies
1. Ecotoxicology: OECD TG- 236 : Fish
embryo toxicity for LC-50
2. Monitoring endocrine disruptors
3. Teratogenicity
4. Neurobehavioral toxicity
5. Cardiotoxicity
6. Ototoxicity
Toxicity endpoints
Kathryn Bambino, Jaime Chu, Chapter Nine - Zebrafish in Toxicology and Environmental Health, Current Topics in Developmental Biology, Academic Press, Volume 124,2017,
Pages 331-367.

12. Disadvantages of the model
1. Zebrafish as a model lacks some clinical applicability
2. Zebrafishes are extensively used to study developmental biology but lacks direct co-relation to humans as they can
regenerate their organs
3. Mostly chemical treatment and inducers are added in water, but the quantity entering actually into the bodies are
highly variable
4. Zebrafish model has been used extensively for neurological studies, but neurons in them divide abruptly which is
very impractical to co- relate to humans

13. References
1. Tavares B, Santos Lopes S. The importance of Zebrafish in biomedical research. Acta Med Port. 2013 Sep-
Oct;26(5):583-92.
2. Ribas, Laia, and Francesc Piferrer. "The zebrafish (D anio rerio) as a model organism, with emphasis on
applications for finfish aquaculture research." Reviews in Aquaculture 6.4 (2014): 209-240.
3. Engeszer, Raymond E., et al. "Zebrafish in the wild: a review of natural history and new notes from the
field." Zebrafish 4.1 (2007): 21-40.
4. Siccardi III, Anthony J., et al. "Growth and survival of zebrafish (Danio rerio) fed different commercial and
laboratory diets." Zebrafish 6.3 (2009): 275-280.
5. Howe, K., Clark, M., Torroja, C. et al. The zebrafish reference genome sequence and its relationship to the human
genome. Nature 496, 498–503 (2013).
6. Astone, M., Dankert, E.N., Alam, S.K. et al. Fishing for cures: The alLURE of using zebrafish to develop
precision oncology therapies. npj Precision Onc 1, 39 (2017).
7. Saleem, S., Kannan, R.R. Zebrafish: an emerging real-time model system to study Alzheimer’s disease and
neurospecific drug discovery. Cell Death Discov. 4, 45 (2018).
8. Kathryn Bambino, Jaime Chu, Chapter Nine - Zebrafish in Toxicology and Environmental Health, Current Topics
in Developmental Biology, Academic Press,Volume 124,2017, Pages 331-367.