Unstable DNA amplifications in methotrexate resistant Leishmania consist of extrachromosomal circles which relocalize during stabilization

Stephen M. Beverley, Jeffrey A. Coderre, Daniel V. Santi, Robert T. Schimke

Research output: Contribution to journalReview article

146 Scopus citations

Abstract

Methotrexate-resistant Leishmania tropical contain two separate regions of DNA amplification, one encoding the bifunctional thymidylate synthetase-dihydrofolate reductase (TS-DHFR) characteristic of protozoans and the other of yet unknown function. The amplified DNAs are initially found as extrachromosomal closed circular forms, which are unstable in the absence of selection. After prolonged culture in methotrexate the amplified DNAs are found as repetitive arrays associated with the chromosomal DNA fraction after CsCl-ethidium bromide density gradient centrifugation, and are stable once selection is removed. The molecular description of gene amplification in Leishmania thus closely parallels the cytological features of gene amplification in cultured mammalian cells.

Original languageEnglish
Pages (from-to)431-439
Number of pages9
JournalCell
Volume38
Issue number2
DOIs
StatePublished - Sep 1984
Externally publishedYes

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