Zebrafish

Zebrafish research continues at a fast pace. New rounds of mutation identification are in progress. To supplement chemical mutagenesis, retroviral vectors were developed as mutagenic agents and applied on a large scale. Tools to study the functions of individual genes, such as transgenics, were developed in parallel to mutant screening approaches. A technique that complements mutagenesis screens in zebrafish very well is known as gene knockdown. This approach uses modified antisense oligonucleotides to block the function of specific genes. These oligonuculeotides contain a substitution of the sugar ring in the nucleic acid backbone that makes them resistant to degradation by enzymes in living tissues. Gene knockdown is widely used to study mutant phenotypes of genes for which chemically induced mutations are not available.

The usefulness of the zebrafish as a model organism originates in its unique combination of genetic and embryological characteristics. Genetic approaches, such as mutagenesis screens, can be combined in zebrafish with other techniques, enabling researchers to study cell movements, cell birth dates, or interactions between cells in the living embryo. Although most of the zebrafish genetic research focuses on embryonic development, other problems, such as the genetic basis of circadian rhythms, cancer formation, neurodegenerative disorders, and drug addiction, are also being addressed.