In this project we have analysed the use of an intron-containing neomycin phosphotransferase II - nptII - gene. The advantage of this construct is that only eukaryotic organisms will be able to process this gene. Accordingly, the theoretical risk of horizontal gene flow of antibiotic resistance genes from transgenic plants to enteric bacteria is eliminated. The ST-LS1 intron IV2 from potato was inserted into the coding region of nptII. Transformation of Solanum tuberosum (potato) and Nicotiana tabacum (tobacco) with constructs containing the intron nptII showed similar transformation frequencies to transformation with constructs containing the normal nptII. Analysis of total DNA and RNA confirmed that the intron-containing nptII gene was present in the plants and that the mRNA was processed correctly.