An examination of the mitomycin C induction of chromosome polymorphisms in cultures of Plasmodium falciparum.
Cloned parasites of the FCR3 strain of Plasmodium falciparum that survived treatment with either mitomycin C or ethidium bromide were grown and subcloned. The chromosomes of 10 cloned isolates from each population were analysed by contour-clamped homogenous electric field gel electrophoresis. Eight of 10 isolates from the mitomycin C-treated population contained a detectable polymorphic chromosome change while none of the isolates from the ethidium bromide-treated population did. One of the polymorphic changes involved chromosome #4. A pyrimethamine resistant derivative of FCR3, FCR3-D5, that had previously been shown to contain a single nucleotide change in the dihydrofolate reductase-thymidylate synthase (DHFR-TS) gene but no detectable chromosome polymorphisms, was sequentially treated with mitomycin C and a higher concentration of pyrimethamine than the strain had previously been shown to be resistant to in order to determine if there was a correlation between the selection of chromosome #4 polymorphisms and the applied selective pressure. Most of the cloned survivors of this treatment were found to contain chromosome polymorphisms that involved chromosome #4, the chromosome on which the DHFR-TS gene is located. The polymorphic changes were usually different in the different isolates. The selection of mitomycin C-treated, pyrimethamine resistant strains with chromosome #4 polymorphisms will be discussed.
Inselburg
J
J
Department of Microbiology, Dartmouth Medical School, Hanover, NH 03756.
Lee
S
S
D000818:Animals; D015139:Blotting, Southern; D002875:Chromosomes / Q000187:drug effects / Q000648:ultrastructure; D004351:Drug Resistance; D004587:Electrophoresis, Agar Gel; D004996:Ethidium / Q000494:pharmacology; D016685:Mitomycin / Q000494:pharmacology*; D010963:Plasmodium falciparum / Q000187:drug effects* / Q000235:genetics; D011110:Polymorphism, Genetic; D011739:Pyrimethamine / Q000494:pharmacology
D016685:Mitomycin; D004996:Ethidium; D011739:Pyrimethamine