The zebrafish has become an important model for studying early vertebrate development. This is largely because of the pioneering work of George Streisinger and the later work of his colleagues in establishing much of the methodology in rearing and studying the animal (1). The large numbers of progeny and the ease of performing genetic crosses have also allowed large-scale screens for mutations in genes affecting early development (2-6). The development of the genetic linkage map (7,8) means that the genes identified by these mutation screens can now be cloned.
The number of zebrafish genes cloned by different methods is growing rapidly, and there is a need to exploit transgenic methods to study gene regulation and interactions in the zebrafish. There are three ways in which transgenic zebrafish can be used to answer important biological questions.
1. Transgenes are expressed transiently in living embryos to study gene regulation and interactions.
2. Stable transgenic lines are generated to study cis-acting regulatory elements, perform rescue of mutant phenotypes, and study genetic regulatory pathways.
3. Integration of foreign DNA provides a means of generating new mutations. Insertional mutations allow cloning of the DNA sequences at the point of insertion by transgene tagging or plasmid rescue.
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