The cellular transformation of the Leishmania protozoan parasite from the promastigote to the amastigote stages takes place in the phagolysosomal compartment of vertebrate host macrophage cells. This cytodifferentiation is a prerequisite for parasite survival and for the establishment of the infection in the mammalian host. The differential screening of a L. donovani amastigote cDNA library using stage-specific cDNA probes allowed the identification of the A2 genes, which are only expressed by the parasite as an amastigote. A2 specific transcripts are developmentally expressed in Leishmania in response to a combination of pH and temperature shifts, conditions associated with the transfer from the insect vector to the phagolysosomal compartment in macrophages. The coding genes are clustered on a 850 kb chromosome and arranged in tandem arrays with copies of another gene, the A2rel gene. The developmental expression is mediated post-transcriptionally and involves elements located in the 3$ prime$ untranslated region; accurate processing by trans splicing is essential for the A2 mRNAs developmental accumulation in cells transferred into phagolysosomal conditions. The A2 protein product is composed mostly of highly repeated domains, carries a functional signal peptide at its amino-terminal end, and shares sequence homology with other developmentally expressed proteins in unrelated parasites of humans. Using A2 locus sequences, vectors and transfection systems were designed and developed to differentially express reporter or selectable markets specifically in the amastigote stage.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.28706 |
| Date | January 1995 |
| Creators | Charest, Hugues |
| Contributors | Matlashewski, Gregory (advisor) |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Doctor of Philosophy (Institute of Parasitology.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 001464770, proquestno: NN05685, Theses scanned by UMI/ProQuest. |
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