Re-examination of earlier work on repetitive DNA and mosquito infectivity in rodent malaria.

Previous results, relating mosquito infectivity to percentage of repetitive DNA in the genome of Plasmodia, are re-examined in the light of the finding that a parasite line used in the previous studies and classified as Plasmodium berghei NK65, was a mixed infection, where the major component appeared to be Plasmodium yoelii. This conclusion was reached through cloning and isoenzyme typing of different clones. Isoenzyme typing alone is not sufficiently sensitive to reveal contamination amounting to less than 20% in a mixture. Attention is drawn to the risk inherent in work with uncloned lines, where the proportions of species or sub-species present may vary according to line history and gametocyte viability.