title: Ageing-related changes in Mycoplasma canadense membranes.
abstract: Fluidity and composition of cell membranes during progression of Mycoplasma canadense cultures grown in a serum-free medium was assessed. The fluorescence anisotropy of 1,6-diphenyl-1,3,5-hexatriene at 25 degrees C of intact cells and liposomes in the exponential and stationary phases of growth was compared. A decrease in fluidity and an increase in the ratio of saturated to unsaturated fatty acids was detected in cell membranes on aging. Nevertheless, membrane density remained unaltered although the molar ratio of cholesterol to phospholipids decreased. It is proposed that the increase in lipid order is primarily due to the increase in the ratio of saturated to unsaturated membrane fatty acids, being the diminished molar ratio of cholesterol to phospholipids involved in the reduced unsaturated fatty acid uptake.
authors.affiliation: Laboratorio de Genética Molecular, Facultad de Ciencias Básicas y Matemáticas, Universidad Católica de Valparaiso, Chile.
authors.forename: G E
authors.initials: GE
authors.lastname: Muñoz
authors.forename: C P
authors.initials: CP
authors.lastname: Sotomayor
mesh_terms: D001425:Bacterial Outer Membrane Proteins / Q000032:analysis; D002462:Cell Membrane / Q000737:chemistry / Q000502:physiology; D002500:Centrifugation, Isopycnic; D003470:Culture Media; D004161:Diphenylhexatriene / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D005227:Fatty Acids / Q000032:analysis; D005454:Fluorescence Polarization; D007038:Hypotonic Solutions; D008560:Membrane Fluidity; D009174:Mycoplasma / Q000737:chemistry / Q000254:growth & development* / Q000502:physiology; D009996:Osmotic Fragility; D013997:Time Factors
chemical_list: D001425:Bacterial Outer Membrane Proteins; D003470:Culture Media; D005227:Fatty Acids; D007038:Hypotonic Solutions; D004161:Diphenylhexatriene