Unstable amplification of two extrachromosomal elements in alpha-difluoromethylornithine-resistant Leishmania donovani.
AUTOR(ES)
Hanson, S
RESUMO
We describe the first example of unstable gene amplification consisting of linear extrachromosomal DNAs in drug-resistant eukaryotic cells. alpha-Difluoromethylornithine (DFMO)-resistant Leishmania donovani with an amplified ornithine decarboxylase (ODC) gene copy number contained two new extrachromosomal DNAs, both present in 10 to 20 copies. One of these was a 140-kb linear DNA (ODC140-L) on which all of the amplified copies of the odc gene were located. The second was a 70-kb circular DNA (ODC70-C) containing an inverted repeat but lacking the odc gene. Both ODC140-L and ODC70-C were derived from a preexisting wild-type chromosome, probably by a conservative amplification mechanism. Both elements were unstable in the absence of DFMO, and their disappearance coincided with a decrease in ODC activity and an increase in DFMO growth sensitivity. These results suggest the possibility that ODC70-C may play a role in DFMO resistance. These data expand the diversity of known amplification mechanisms in eukaryotes to include the simultaneous unstable amplification of both linear and circular DNAs. Further characterization of these molecules will provide insights into the molecular mechanisms underlying gene amplification, including the ability of linear amplified DNAs to acquire telomeres and the determinants of chromosomal stability.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=360487Documentos Relacionados
- Genetic analysis of nucleoside transport in Leishmania donovani.
- Stage-specific variations in lectin binding to Leishmania donovani.
- Susceptibilities of macrophage populations to infection in vitro by Leishmania donovani.
- Activity and mode of action of acridine compounds against Leishmania donovani.
- Functional expression of a myo-inositol/H+ symporter from Leishmania donovani.