title: Structural changes of the paraflagellar rod during flagellar beating in Trypanosoma cruzi.
abstract: BACKGROUND
  Trypanosoma cruzi, the agent of Chagas disease, is a protozoan member of the Kinetoplastidae family characterized for the presence of specific and unique structures that are involved in different cell activities. One of them is the paraflagellar rod (PFR), a complex array of filaments connected to the flagellar axoneme. Although the function played by the PFR is not well established, it has been shown that silencing of the synthesis of its major proteins by either knockout of RNAi impairs and/or modifies the flagellar motility.
  
  
  RESULTS
  Here, we present results obtained by atomic force microscopy (AFM) and transmission electron microscopy (TEM) of replicas of quick-frozen, freeze-fractured, deep-etched and rotary-replicated cells to obtain detailed information of the PFR structures in regions of the flagellum in straight and in bent state. The images obtained show that the PFR is not a fixed and static structure. The pattern of organization of the PFR filament network differs between regions of the flagellum in a straight state and those in a bent state. Measurements of the distances between the PFR filaments and the filaments that connect the PFR to the axoneme as well as of the angles between the intercrossed filaments supported this idea.
  
  
  CONCLUSIONS
  Graphic computation based on the information obtained allowed the proposal of an animated model for the PFR structure during flagellar beating and provided a new way of observing PFR filaments during flagellar beating.
authors.affiliation: Laboratório de Ultraestrutura Celular Hertha Meyer, Universidade Federal do Rio de Janeiro, Cidade Universitária, Ilha do Fundão, Rio de Janeiro, Brazil.
authors.forename: Gustavo Miranda
authors.initials: GM
authors.lastname: Rocha
authors.forename: Dirceu Esdras
authors.initials: DE
authors.lastname: Teixeira
authors.forename: Kildare
authors.initials: K
authors.lastname: Miranda
authors.forename: Gilberto
authors.initials: G
authors.lastname: Weissmüller
authors.forename: Paulo Mascarello
authors.initials: PM
authors.lastname: Bisch
authors.forename: Wanderley
authors.initials: W
authors.lastname: de Souza
mesh_terms: D000818:Animals; D005407:Flagella / Q000648:ultrastructure*; D005614:Freeze Fracturing; D018625:Microscopy, Atomic Force; D046529:Microscopy, Electron, Transmission; D014349:Trypanosoma cruzi / Q000502:physiology*