title: Influence of phospholipid species on membrane fluidity: a meta-analysis for a novel phospholipid fluidity index.
abstract: Generalized membrane lipid composition determinants of fluidity have been widely investigated, including phospholipid/cholesterol ratio and unsaturation index. Individual phospholipids differ in their physical characteristics, including their interaction with cholesterol and level of unsaturation, emphasizing the importance of examining their individual influence on membrane fluidity. Thus, the purpose of this study was to examine the dominant phospholipids of biological membranes (phosphatidylcholine, PC; phosphatidylethanolamine, PE; sphingomyelin, SM) through a meta-analysis to assess the validity of an inclusive phospholipid fluidity index (PFI = PC/(PE + SM)) as a determinant for membrane fluidity (expressed as polarization of fluorescent probe 1,6 diphenyl-1,3,5-hexatriene) in comparison to previous phospholipid ratios (PC/PE and PC/SM). The results demonstrate that all indices significantly predicted membrane fluidity at 25°C (based on 10-13 data points). In contrast, only PFI approached significance when predicting membrane fluidity at 37°C (P = 0.10 based on five points). As a result, PFI appears to be the only phospholipid index close to significantly predicting membrane fluidity at mammalian physiological temperature. Because this meta-analysis only assessed studies using mammalian membranes, future work should experimentally assess the validity of the PFI utilizing membranes from mammals and a variety of other species and tissues at their respective physiological temperatures.
authors: Centre for Muscle Metabolism and Biophysics, Department of Community Health Sciences, Brock University, St. Catharines, ON, Canada.
authors: Val Andrew
authors: VA
authors: Fajardo
authors: Lauren
authors: L
authors: McMeekin
authors: Paul J
authors: PJ
authors: LeBlanc
mesh_terms: D000818:Animals; D002462:Cell Membrane / Q000737:chemistry / Q000378:metabolism*; D002784:Cholesterol / Q000737:chemistry / Q000378:metabolism; D004161:Diphenylhexatriene / Q000032:analysis* / Q000378:metabolism; D005456:Fluorescent Dyes / Q000032:analysis / Q000378:metabolism; D006801:Humans; D008322:Mammals; D008560:Membrane Fluidity / Q000502:physiology*; D008563:Membrane Lipids / Q000737:chemistry / Q000378:metabolism*; D010713:Phosphatidylcholines / Q000737:chemistry / Q000378:metabolism; D010714:Phosphatidylethanolamines / Q000737:chemistry / Q000378:metabolism; D012044:Regression Analysis; D015203:Reproducibility of Results; D013109:Sphingomyelins / Q000737:chemistry / Q000378:metabolism; D013696:Temperature
chemical_list: D005456:Fluorescent Dyes; D008563:Membrane Lipids; D010713:Phosphatidylcholines; D010714:Phosphatidylethanolamines; D013109:Sphingomyelins; D004161:Diphenylhexatriene; D002784:Cholesterol