Expression of firefly luciferase gene in Xenopus laevis oocyte

Fusion plasmid pSV-Luc20 and pSV-Luc19 were constructed by using the larger BamHI restricted fragments of plasmid pDO432 containing the firefly luciferase (luc) gene and HindIII-BamHI restricted fragment of plasmid pSVK100 containing the SV-40 promoter as insert and vector, respectively. The fusion plasmid had different ligation orientations between the encoding sequence of luc gene and the SV-40 promoter, i.e., they were sense and antisense plasmid. When they were introduced into Xenopus oocyte by micro-injection, only pSV-Luc20 could be transcribed and translated into the enzymatic protein of luciferase with high biological activity. Therefore, firefly luciferase gene and Xenopus oocyte can be used as an excellent system for monitoring the activity of various promoters.