Introns of Plasmodium falciparum var genes act as transcriptional silencing elements that help control antigenic variations. In transfected episomes, intron silencing of a drug-selectable marker under var promoter control is reversed by the spontaneous deletion of key intron regions. The resulting promoter activation does not affect the transcription of chromosomal var genes.

Bacterial Artificial Chromosomes (BACs) have been used to complement a metabolic defect and to transfer a drug resistance marker into mammalian cells by electroporation. The selectable markers are stable and the recipient cells have BAC DNA integrated into the chromosomes as shown by fluorescent in situ hybridization, PCR and Southern hybridization.

Presence of antibiotic resistance markers has always been considered as one of the main safety concerns in transgenic plants and their derived products. Elimination of antibiotic selectable markers from transgenics is a major hurdle for finding efficient and safe candidates. Herbicide tolerance genes might be attractive alternatives. In this study, a variant form of the 5-enoylpyruvyl shikimate...

The ribosomal protein L41 gene of Phaffia rhodozyma was cloned and used as a dominant selectable marker for cycloheximide resistance in the transformation of P. rhodozyma. Electrotransformation with a plasmid containing a ribosomal DNA fragment as a targeting signal typically yielded 800 to 1,200 transformants/microgram of DNA with an integrated copy number of about seven per haploid genome.

Here we report the characterization of the Chlamydomonas reinhardtii gene ARG9, encoding the plastid resident N-acetyl ornithine aminotransferase, which is involved in arginine synthesis. Integration of an engineered ARG9 cassette in the plastid chromosome of the nuclear arg9 mutant restores arginine prototrophy. This suggests that ARG9 could be used as a new selectable marker for plastid trans...

Two methods were developed for the generation of cisgenic apples. Both have been successfully applied producing trees. The first method avoids the use of any foreign selectable marker genes; only the gene-of-interest is integrated between the T-DNA border sequences. The second method makes use of recombinase-based marker excision. For the first method we used the MdMYB10 gene from a red-fleshed...