title: Autocrine/paracrine activator of cell proliferation: purification of a 4-6 kD compound with growth-factor-like effects in Tetrahymena thermophila.
abstract: Extracellular medium from cultures of Tetrahymena thermophila was collected, concentrated and fractionated by ultrafiltration and low-pressure column chromatography. The effect on proliferation of various fractions was tested on cultures of T. thermophila in synthetic medium at low initial cell densities (< 250 cells/ml). In unsupplemented cultures, cells failed to thrive and died before proliferation. Addition of the fraction isolated from the extracellular medium in the molecular weight range of 1-10 kD activated the cells to proliferate. The size of the main compound in this fraction, herein referred to as TPAF, was in the range of 4-6 kD as estimated by SDS-PAGE. Evidence of a dialysable factor produced by cells in the stationary phase inhibiting cell proliferation has also been found.
authors.affiliation: Department of Cell Biology, University of Odense, Denmark. p.schousboe@winsloew.ou.dk
authors.forename: P
authors.initials: P
authors.lastname: Schousboe
authors.forename: D N
authors.initials: DN
authors.lastname: Wheatley
authors.forename: L
authors.initials: L
authors.lastname: Rasmussen
mesh_terms: D000818:Animals; D000837:Anion Exchange Resins; D002021:Buffers; D002455:Cell Division / Q000187:drug effects*; D002725:Chloroform / Q000737:chemistry; D004591:Electrophoresis, Polyacrylamide Gel; D006133:Growth Substances / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology; D008970:Molecular Weight; D016808:Tetrahymena thermophila / Q000737:chemistry*; D014462:Ultrafiltration
chemical_list: D000837:Anion Exchange Resins; D002021:Buffers; D006133:Growth Substances; D002725:Chloroform