However, information on the longevity of DNA expression
and/or diffusion of injected DNA, which might lead to the creation of transgenic fish,
is limited. These matters must be clarified before commercialisation of DNA vaccines
for fish becomes a reality. To analyse the duration of expression and the diffusion of
expression through the body over a prolonged period of time, we developed an in vivo
assay for luciferase detection in live glass catfish that had been injected with DNA
encoding the luciferase gene. An advantage of this system over the analysis of isolated
tissues is that fish survive the analysis and thus we were able to monitor luciferase
expression in individual fish for an extended time period.