The Characteristics of Zebrafish

This tiny, easy-to-breed fish has become one of the most popular models used for scientific research and Drug discovery. An alternative to animal models, such as rats and mice, the zebrafish is a major contributor to Drug development and the cure and prevention of human diseases.

Why are zebrafish an ideal alternative model?

A large number of eggs a female zebrafish can produce (over 200 eggs every 2-3 days) and rapid embryo development (this fish develops and has functional most of its organs) make it ideal for medical research. This compares to in vitro models, which are non-live and can be combined with in vivo studies, making them a very suitable model.

Being small makes husbandry more economical and having a large number of spawns every few days also makes it a cost-effective model. It is particularly suitable for high-capacity assays that require multiple testing.

Zebrafish are also transparent, making it easy to view the internal organs and monitor how processes, such as tumour development in cancer, occur.

As an ethical solution, zebrafish are compliant with the 3Rs (Replacement, Reduction, and Refinement of animals), a policy that provides a set of regulations for an alternative to testing in animals. This applies to zebrafish as testing can be carried out in embryos, before they reach the 5-day in vivo stage and they start feeding independently out of the chorion In addition, their transparency can avoid invasive procedures.

Zebrafish and pharmacogenomics

The zebrafish also has a very similar genome to the human one, with vital organs such as the heart, eyes, and brain having a comparable structure and functionality. Almost 82% of genes that can cause diseases in humans are present in the zebrafish, making it a suitable model to test for Drug toxicity and disease development.

However, not everyone reacts in the same way to a drug, which can depend on their specific genes. This is why some drugs have adverse reactions in some people. Having a similar genetic makeup to humans means zebrafish are especially suited to the study of pharmacogenomics – how a person’s genes cause a certain reaction to a drug. Zebrafish are responsive to genetic engineering, so scientists can study how gene changes react to certain candidates.

This allows for research into and the development of drugs that can be tailored to treat different human diseases, rather than a generic solution. Therefore, people who may not be able to take a particular drug could be given an alternative that they will not react to.

Modern technology and the zebrafish

As technology develops rapidly so has its use in medical research. The use of Artificial Intelligence (AI) is bringing us closer to finding a cure for terminal conditions such as cancer and cardiovascular diseases as it speeds up the Drug discovery process. Deep learning is also a significant analysis method that is gaining more and more attention in the field of research using zebrafish. This technique teaches computers how to behave like humans, based on neurological patterns, which can be also applied to zebrafish studies.

Scientists can develop algorithms to identify different drug types given to zebrafish to observe their behaviour and movement patterns. Whilst a fairly basic example, this demonstrates how data can be trained for use in scientific research.

Image analysis screening tools are a useful choice for zebrafish screening as they can gather images for phenotypic screening and analyze them and the data extracted from them automatically, for example, by studying the progress of a disease and the effects certain compounds have on it.

Zebrafish development

Another characteristic of the zebrafish is that it can be used to detect changes in cells as the embryo develops, particularly concerning embryogenesis and cell sizes. During the evolution of an embryo, the cells migrate only once, creating the body and organs of the zebrafish. This creation of cells can be altered artificially to monitor how they develop and react to disease. This gives results of a high statistical value as data monitoring the cause of the changes can be collected and analyzed.

The characteristics of the zebrafish make it an ideal model for the study of the toxicity but also the efficacy of drugs in many medical fields. Its use is constantly growing as scientists find more ways to study common (and rare) human diseases.

Sources

https://www.sciencedirect.com/science/article/abs/pii/S0278584621001640

https://www.sciencedirect.com/science/article/pii/S2472630321000273

https://uh-ir.tdl.org/handle/10657/1147