title: Single-molecule analysis of DNA replication reveals novel features in the divergent eukaryotes Leishmania and Trypanosoma brucei versus mammalian cells.
abstract: Leishmania and Trypanosoma are unicellular parasites that possess markedly original biological features as compared to other eukaryotes. The Leishmania genome displays a constitutive 'mosaic aneuploidy', whereas in Trypanosoma brucei, the megabase-sized chromosomes are diploid. We accurately analysed DNA replication parameters in three Leishmania species and Trypanosoma brucei as well as mouse embryonic fibroblasts (MEF). Active replication origins were visualized at the single molecule level using DNA molecular combing. More than one active origin was found on most DNA fibres, showing that the chromosomes are replicated from multiple origins. Inter-origin distances (IODs) were measured and found very large in trypanosomatids: the mean IOD was 160 kb in T. brucei and 226 kb in L. mexicana. Moreover, the progression of replication forks was faster than in any other eukaryote analyzed so far (mean velocity 1.9 kb/min in T. brucei and 2.4-2.6 kb/min in Leishmania). The estimated total number of active DNA replication origins in trypanosomatids is ~170. Finally, 14.4% of unidirectional replication forks were observed in T. brucei, in contrast to 1.5-1.7% in Leishmania and 4% in MEF cells. The biological significance of these original features is discussed.
authors.affiliation: University of Montpellier, Faculty of Medicine, Laboratory of Parasitology-Mycology, Montpellier, F34090, France.
authors.forename: Slavica
authors.initials: S
authors.lastname: Stanojcic
authors.affiliation: University of Montpellier, Faculty of Medicine, Laboratory of Parasitology-Mycology, Montpellier, F34090, France.
authors.forename: Lauriane
authors.initials: L
authors.lastname: Sollelis
authors.affiliation: University of Montpellier, Faculty of Medicine, Laboratory of Parasitology-Mycology, Montpellier, F34090, France.
authors.forename: Nada
authors.initials: N
authors.lastname: Kuk
authors.affiliation: CNRS 5290 - IRD 224 - University of Montpellier (UMR "MiVEGEC"), Montpellier, F34090, France.
authors.forename: Lucien
authors.initials: L
authors.lastname: Crobu
authors.affiliation: University of Montpellier, Faculty of Medicine, Laboratory of Parasitology-Mycology, Montpellier, F34090, France.
authors.forename: Yves
authors.initials: Y
authors.lastname: Balard
authors.affiliation: Institute of Molecular Genetics, CNRS UMR5535 &University of Montpellier, Montpellier, F34293, France.
authors.forename: Etienne
authors.initials: E
authors.lastname: Schwob
authors.affiliation: University of Montpellier, Faculty of Medicine, Laboratory of Parasitology-Mycology, Montpellier, F34090, France.|CNRS 5290 - IRD 224 - University of Montpellier (UMR "MiVEGEC"), Montpellier, F34090, France.|University Hospital Centre (CHU), Department of Parasitology-Mycology, Montpellier, F34090, France.
authors.forename: Patrick
authors.initials: P
authors.lastname: Bastien
authors.affiliation: CNRS 5290 - IRD 224 - University of Montpellier (UMR "MiVEGEC"), Montpellier, F34090, France.
authors.forename: Michel
authors.initials: M
authors.lastname: Pagès
authors.affiliation: University of Montpellier, Faculty of Medicine, Laboratory of Parasitology-Mycology, Montpellier, F34090, France.|CNRS 5290 - IRD 224 - University of Montpellier (UMR "MiVEGEC"), Montpellier, F34090, France.|University Hospital Centre (CHU), Department of Parasitology-Mycology, Montpellier, F34090, France.
authors.forename: Yvon
authors.initials: Y
authors.lastname: Sterkers
mesh_terms: D000818:Animals; D002460:Cell Line; D004261:DNA Replication; D016054:DNA, Protozoan / Q000235:genetics*; D004622:Embryo, Mammalian / Q000166:cytology; D005347:Fibroblasts / Q000378:metabolism*; D007891:Leishmania / Q000235:genetics*; D051379:Mice; D018741:Replication Origin; D014346:Trypanosoma brucei brucei / Q000235:genetics*
chemical_list: D016054:DNA, Protozoan