This phenomenon allows the Tc1 insertion to be used as a substratte for the isolation of deletion mutants where a significant portion of flanking DNA has been deleted. If the Tc1 ids in a gene of interest this will result in the deletion of coding sequences and thus in the formation of a null or loss of function mutation in the gene. This forward or directed mutagenesis protocol is a powerful method of isolating mutants. This allows uptake by multiple nuclei of any substance injected into this syncytial gonad. This gene causes the nematodes to develop a helically twisted cuticle and to roll longditudinally when they move forward.
Homologous recombination is very, very rare.
By hooking the presumed promoter region of a gene up to a reporter system, an idea ofd the developmental regulation and tissue specific expression of a gene can be derived. The chromogenic stain is stable, and the enzyme is still active after mild fixation. GFP is a naturally fluorescent protein which can be used to mark the cells in which a promoter is active. It has the benefit that the animals can be observed live. It is also possible to add short tags of amino acids to the native genes, and then detect expression patterns by using an antibody which is specific to the epitope tag.