title: Coordinated Changes in Gene Expression Throughout Encystation of Giardia intestinalis.
abstract: Differentiation into infectious cysts through the process of encystation is crucial for transmission and survival of the intestinal protozoan parasite Giardia intestinalis. Hitherto the majority of studies have focused on the early events, leaving late encystation poorly defined. In order to further study encystation, focusing on the later events, we developed a new encystation protocol that generates a higher yield of mature cysts compared to standard methods. Transcriptome changes during the entire differentiation from trophozoites to cysts were thereafter studied using RNA sequencing (RNA-seq). A high level of periodicity was observed for up- and down-regulated genes, both at the level of the entire transcriptome and putative regulators. This suggests the trajectory of differentiation to be coordinated through developmentally linked gene regulatory activities. Our study identifies a core of 13 genes that are consistently up-regulated during initial encystation. Of these, two constitute previously uncharacterized proteins that we were able to localize to a new type of encystation-specific vesicles. Interestingly, the largest transcriptional changes were seen in the late phase of encystation with the majority of the highly up-regulated genes encoding hypothetical proteins. Several of these were epitope-tagged and localized to further characterize these previously unknown genetic components of encystation and possibly excystation. Finally, we also detected a switch of variant specific surface proteins (VSPs) in the late phase of encystation. This occurred at the same time as nuclear division and DNA replication, suggesting a potential link between the processes.
authors.affiliation: Department of Cell and Molecular Biology, BMC, Uppsala University, Uppsala, Sweden.
authors.forename: Elin
authors.initials: E
authors.lastname: Einarsson
authors.affiliation: Department of Cell and Molecular Biology, BMC, Uppsala University, Uppsala, Sweden.|Department of Microbiology, National Veterinary Institute, Uppsala, Sweden.
authors.forename: Karin
authors.initials: K
authors.lastname: Troell
authors.affiliation: Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden.|Christian-Albrechts-University of Kiel, Institute of Clinical Molecular Biology, Kiel, Germany.
authors.forename: Marc P
authors.initials: MP
authors.lastname: Hoeppner
authors.affiliation: Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden.
authors.forename: Manfred
authors.initials: M
authors.lastname: Grabherr
authors.affiliation: Department of Cell and Molecular Biology, BMC, Uppsala University, Uppsala, Sweden.
authors.forename: Ulf
authors.initials: U
authors.lastname: Ribacke
authors.affiliation: Department of Cell and Molecular Biology, BMC, Uppsala University, Uppsala, Sweden.
authors.forename: Staffan G
authors.initials: SG
authors.lastname: Svärd
mesh_terms: D005786:Gene Expression Regulation; D016829:Giardia lamblia / Q000502:physiology*; D011506:Proteins / Q000235:genetics / Q000378:metabolism*; D012313:RNA / Q000235:genetics / Q000378:metabolism; D059467:Transcriptome; D015854:Up-Regulation
chemical_list: D011506:Proteins; D012313:RNA