Biomaterial Database

Stable amplification of a linear extrachromosomal DNA in mycophenolic acid-resistant Leishmania donovani. 1992

K Wilson, and S M Beverley, and B Ullman

Department of Biochemistry and Molecular Biology, Oregon Health Sciences University, Portland 97201-3098.

Pulsed field gel electrophoretic analysis of chromosomes of MPA100 cells, a strain of Leishmania donovani that possesses an approx. 15-fold amplified IMP dehydrogenase (IMPDH) gene copy number, revealed a new 280-kb extrachromosomal DNA, IMPDH-280, that was not present in wild type parental cells. Southern blots of these pulsed field gels revealed that the vast majority of the amplified impdh genes were localized on IMPDH-280. In addition to the 700-kb wild type chromosome, the impdh probe also recognized a 740-kb chromosome in the MPA100 genome. The pulse time-dependent relative mobility of IMPDH-280 in pulsed field gels, the failure of limited gamma-irradiation to generate a new discrete DNA fragment, and the susceptibility of IMPDH-280 to lambda-exonuclease digestion, demonstrated that IMPDH-280 was a linear molecule. IMPDH-280 was also recognized by a telomere probe but not by fragments derived from amplified DNAs found in other drug-resistant Leishmania. IMPDH-280 and the drug resistance phenotype remained stable when MPA100 cells were propagated in the absence of drug for 2 years. The appearance of IMPDH-280 in MPA100 cells represents one of the first examples of an amplification of a linear extrachromosomal DNA element mediating drug resistance in Leishmania and the first instance of a linear DNA amplification that is stable in the absence of selective pressure.

UI	MeSH Term	Description	Entries
D007168	IMP Dehydrogenase	An enzyme that catalyzes the dehydrogenation of inosine 5'-phosphate to xanthosine 5'-phosphate in the presence of NAD. EC 1.1.1.205.	Inosinic Acid Dehydrogenase,Inosine-5-Monophosphate Dehydrogenase,Acid Dehydrogenase, Inosinic,Dehydrogenase, IMP,Dehydrogenase, Inosine-5-Monophosphate,Dehydrogenase, Inosinic Acid,Inosine 5 Monophosphate Dehydrogenase
D007893	Leishmania donovani	A parasitic hemoflagellate of the subgenus Leishmania leishmania that infects man and animals and causes visceral leishmaniasis (LEISHMANIASIS, VISCERAL). The sandfly genera Phlebotomus and Lutzomyia are the vectors.	Leishmania (Leishmania) donovani,Leishmania leishmania donovani,Leishmania donovanus,Leishmania leishmania donovanus,donovani, Leishmania leishmania,donovanus, Leishmania,donovanus, Leishmania leishmania,leishmania donovanus, Leishmania
D009173	Mycophenolic Acid	Compound derived from Penicillium stoloniferum and related species. It blocks de novo biosynthesis of purine nucleotides by inhibition of the enzyme inosine monophosphate dehydrogenase (IMP DEHYDROGENASE). Mycophenolic acid exerts selective effects on the immune system in which it prevents the proliferation of T-CELLS, LYMPHOCYTES, and the formation of antibodies from B-CELLS. It may also inhibit recruitment of LEUKOCYTES to sites of INFLAMMATION.	Cellcept,Mycophenolate Mofetil,Mycophenolate Mofetil Hydrochloride,Mycophenolate Sodium,Mycophenolic Acid Morpholinoethyl Ester,Myfortic,RS 61443,RS-61443,Sodium Mycophenolate,Mofetil Hydrochloride, Mycophenolate,Mofetil, Mycophenolate,Mycophenolate, Sodium,RS61443
D010957	Plasmids	Extrachromosomal, usually CIRCULAR DNA molecules that are self-replicating and transferable from one organism to another. They are found in a variety of bacterial, archaeal, fungal, algal, and plant species. They are used in GENETIC ENGINEERING as CLONING VECTORS.	Episomes,Episome,Plasmid
D002460	Cell Line	Established cell cultures that have the potential to propagate indefinitely.	Cell Lines,Line, Cell,Lines, Cell
D004270	DNA, Circular	Any of the covalently closed DNA molecules found in bacteria, many viruses, mitochondria, plastids, and plasmids. Small, polydisperse circular DNA's have also been observed in a number of eukaryotic organisms and are suggested to have homology with chromosomal DNA and the capacity to be inserted into, and excised from, chromosomal DNA. It is a fragment of DNA formed by a process of looping out and deletion, containing a constant region of the mu heavy chain and the 3'-part of the mu switch region. Circular DNA is a normal product of rearrangement among gene segments encoding the variable regions of immunoglobulin light and heavy chains, as well as the T-cell receptor. (Riger et al., Glossary of Genetics, 5th ed & Segen, Dictionary of Modern Medicine, 1992)	Circular DNA,Circular DNAs,DNAs, Circular
D004351	Drug Resistance	Diminished or failed response of an organism, disease or tissue to the intended effectiveness of a chemical or drug. It should be differentiated from DRUG TOLERANCE which is the progressive diminution of the susceptibility of a human or animal to the effects of a drug, as a result of continued administration.	Resistance, Drug
D005784	Gene Amplification	A selective increase in the number of copies of a gene coding for a specific protein without a proportional increase in other genes. It occurs naturally via the excision of a copy of the repeating sequence from the chromosome and its extrachromosomal replication in a plasmid, or via the production of an RNA transcript of the entire repeating sequence of ribosomal RNA followed by the reverse transcription of the molecule to produce an additional copy of the original DNA sequence. Laboratory techniques have been introduced for inducing disproportional replication by unequal crossing over, uptake of DNA from lysed cells, or generation of extrachromosomal sequences from rolling circle replication.	Amplification, Gene
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D015139	Blotting, Southern	A method (first developed by E.M. Southern) for detection of DNA that has been electrophoretically separated and immobilized by blotting on nitrocellulose or other type of paper or nylon membrane followed by hybridization with labeled NUCLEIC ACID PROBES.	Southern Blotting,Blot, Southern,Southern Blot