Green fluorescent protein as a marker in Plasmodium berghei transformation

We present a new marker that confers both resistance to pyrimethamine and g reen fluorescent protein-based fluorescence on the malarial parasite Plasmo dium berghei. A single copy of the cassette integrated into the genome is s ufficient to direct fluorescence in parasites throughout the life cycle, in both its mosquito and vertebrate hosts. Erythrocyte stages of the parasite that express the marker ran be sorted from control parasites by flow cytom etry. Pyrimethamine pressure is not necessary for maintaining the cassette in transformed parasites during their sporogonic cycle in mosquitoes, inclu ding when it is borne by a plasmid. This tool should thus prove useful in m olecular studies of P. berghei, both for generating parasite variants and m onitoring their behavior.