title: Malaria parasites form filamentous cell-to-cell connections during reproduction in the mosquito midgut.
abstract: Physical contact is important for the interaction between animal cells, but it can represent a major challenge for protists like malaria parasites. Recently, novel filamentous cell-cell contacts have been identified in different types of eukaryotic cells and termed nanotubes due to their morphological appearance. Nanotubes represent small dynamic membranous extensions that consist of F-actin and are considered an ancient feature evolved by eukaryotic cells to establish contact for communication. We here describe similar tubular structures in the malaria pathogen Plasmodium falciparum, which emerge from the surfaces of the forming gametes upon gametocyte activation in the mosquito midgut. The filaments can exhibit a length of > 100 μm and contain the F-actin isoform actin 2. They actively form within a few minutes after gametocyte activation and persist until the zygote transforms into the ookinete. The filaments originate from the parasite plasma membrane, are close ended and express adhesion proteins on their surfaces that are typically found in gametes, like Pfs230, Pfs48/45 or Pfs25, but not the zygote surface protein Pfs28. We show that these tubular structures represent long-distance cell-to-cell connections between sexual stage parasites and demonstrate that they meet the characteristics of nanotubes. We propose that malaria parasites utilize these adhesive "nanotubes" in order to facilitate intercellular contact between gametes during reproduction in the mosquito midgut.
authors.affiliation: Research Center for Infectious Diseases, University of Würzburg, Germany.
authors.forename: Ingrid
authors.initials: I
authors.lastname: Rupp
authors.forename: Ludmilla
authors.initials: L
authors.lastname: Sologub
authors.forename: Kim C
authors.initials: KC
authors.lastname: Williamson
authors.forename: Matthias
authors.initials: M
authors.lastname: Scheuermayer
authors.forename: Luc
authors.initials: L
authors.lastname: Reininger
authors.forename: Christian
authors.initials: C
authors.lastname: Doerig
authors.forename: Saliha
authors.initials: S
authors.lastname: Eksi
authors.forename: Davy U
authors.initials: DU
authors.lastname: Kombila
authors.forename: Matthias
authors.initials: M
authors.lastname: Frank
authors.forename: Gabriele
authors.initials: G
authors.lastname: Pradel
mesh_terms: D000199:Actins; D000818:Animals; D002448:Cell Adhesion; D015815:Cell Adhesion Molecules; D002450:Cell Communication; D009033:Culicidae / Q000469:parasitology*; D004064:Digestive System / Q000378:metabolism / Q000469:parasitology; D019084:Fluorescent Antibody Technique, Indirect; D005854:Germ Cells / Q000378:metabolism*; D006790:Host-Parasite Interactions; D008288:Malaria / Q000469:parasitology; D008854:Microscopy, Electron; D043942:Nanotubes / Q000469:parasitology*; D010963:Plasmodium falciparum / Q000378:metabolism / Q000502:physiology*; D020033:Protein Isoforms; D015800:Protozoan Proteins / Q000378:metabolism / Q000502:physiology; D012098:Reproduction
chemical_list: D000199:Actins; D015815:Cell Adhesion Molecules; D020033:Protein Isoforms; D015800:Protozoan Proteins