title: Cell surface nanoanatomy of Leishmania major as revealed by fracture-flip. A surface meshwork of 44 nm fusiform filaments identifies infective developmental stage promastigotes.
abstract: Fracture-flip (Anderson-Forsman and Pinto da Silva, J. Cell Sci. 90, 531-541; 1988) was used to reveal the nanoanatomy of the surface of Leishmania major promastigotes. Over the cell surface of infective metacyclic promastigotes we identify a meshwork of 44 nm long, fusiform filaments. These filaments are not seen in noninfective stages of the parasite. Replica-staining immunocytochemistry with monoclonal antibody against infective metacyclic lipophosphoglycan shows a uniform distribution of protein A-colloidal gold complexes over the cell surface. Thin sections show that acquisition of the high molecular weight lipophosphoglycan is reflected in a thicker glycocalyx. Conventional freeze-fracture shows that in infective metacyclic promastigotes there is a reversal of the partition of intramembrane particles--an additional morphological marker for the infective developmental stage. We hypothesize that the fusiform filaments represent metacyclic developmental lipophosphoglycan.
authors.affiliation: Membrane Biology Section, National Cancer Institute-Frederick Cancer Research Facility, MD 21701.
authors.forename: P F
authors.initials: PF
authors.lastname: Pimenta
authors.forename: R P
authors.initials: RP
authors.lastname: da Silva
authors.forename: D L
authors.initials: DL
authors.lastname: Sacks
authors.forename: P P
authors.initials: PP
authors.lastname: da Silva
mesh_terms: D000818:Animals; D002462:Cell Membrane / Q000648:ultrastructure; D005614:Freeze Fracturing / Q000379:methods*; D006017:Glycolipids / Q000378:metabolism; D007895:Leishmania tropica / Q000254:growth & development / Q000648:ultrastructure*; D008854:Microscopy, Electron
chemical_list: D006017:Glycolipids