title: Comparative gene expression analysis throughout the life cycle of Leishmania braziliensis: diversity of expression profiles among clinical isolates.
abstract: BACKGROUND
  Most of the Leishmania genome is reported to be constitutively expressed during the life cycle of the parasite, with a few regulated genes. Inter-species comparative transcriptomics evidenced a low number of species-specific differences related to differentially distributed genes or the differential regulation of conserved genes. It is of uppermost importance to ensure that the observed differences are indeed species-specific and not simply specific of the strains selected for representing the species. The relevance of this concern is illustrated by current study.
  
  
  RESULTS
  We selected 5 clinical isolates of L. braziliensis characterized by their diversity of clinical and in vitro phenotypes. Real-time quantitative PCR was performed on promastigote and amastigote life stages to assess gene expression profiles at seven time points covering the whole life cycle. We tested 12 genes encoding proteins with roles in transport, thiol-based redox metabolism, cellular reduction, RNA poly(A)-tail metabolism, cytoskeleton function and ribosomal function. The general trend of expression profiles showed that regulation of gene expression essentially occurs around the stationary phase of promastigotes. However, the genes involved in this phenomenon appeared to vary significantly among the isolates considered.
  
  
  CONCLUSIONS
  Our results clearly illustrate the unique character of each isolate in terms of gene expression dynamics. Results obtained on an individual strain are not necessarily representative of a given species. Therefore, extreme care should be taken when comparing the profiles of different species and extrapolating functional differences between them.
authors.affiliation: Instituto de Medicina Tropical Alexander von Humboldt, Universidad Peruana Cayetano Heredia, Lima, Peru.
authors.forename: Vanessa
authors.initials: V
authors.lastname: Adaui
authors.forename: Denis
authors.initials: D
authors.lastname: Castillo
authors.forename: Mirko
authors.initials: M
authors.lastname: Zimic
authors.forename: Andres
authors.initials: A
authors.lastname: Gutierrez
authors.forename: Saskia
authors.initials: S
authors.lastname: Decuypere
authors.forename: Manu
authors.initials: M
authors.lastname: Vanaerschot
authors.forename: Simonne
authors.initials: S
authors.lastname: De Doncker
authors.forename: Kathy
authors.initials: K
authors.lastname: Schnorbusch
authors.forename: Ilse
authors.initials: I
authors.lastname: Maes
authors.forename: Gert
authors.initials: G
authors.lastname: Van der Auwera
authors.forename: Louis
authors.initials: L
authors.lastname: Maes
authors.forename: Alejandro
authors.initials: A
authors.lastname: Llanos-Cuentas
authors.forename: Jorge
authors.initials: J
authors.lastname: Arevalo
authors.forename: Jean-Claude
authors.initials: JC
authors.lastname: Dujardin
mesh_terms: D016054:DNA, Protozoan / Q000737:chemistry / Q000235:genetics; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation; D007892:Leishmania braziliensis / Q000235:genetics* / Q000254:growth & development*; D008969:Molecular Sequence Data; D015800:Protozoan Proteins / Q000096:biosynthesis / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017422:Sequence Analysis, DNA
chemical_list: D016054:DNA, Protozoan; D015800:Protozoan Proteins