Enhancer-controlled expression of the simian virus 40 T-antigen in the green alga Acetabularia.

Nuclei from Acetabularia mediterranea were isolated, microinjected with simian virus 40 (SV40) DNA and fused with cytoplasts from the same species. Various times after fusion of the injected nuclei the fusion products were screened for expression of the T-antigen by indirect immunofluorescence. One and two days after injection a bright fluorescence could be observed in the nuclei of Acetabularia. On the basis of this immunofluorescence we conclude that in Acetabularia cells the T-antigen is expressed and accumulated in the nucleus. Moreover, evidence is presented that the Acetabularia cell recognizes the SV40 enhancer sequence. The expression product of the SV40 DNA appears significantly earlier than the expression products of other foreign genes in Acetabularia. The results suggest that the well characterized SV40 can be used as a vector system for the introduction and expression of foreign genes in Acetabularia.