title: Homeostasis of plasma membrane viscosity in fluctuating temperatures.
abstract: Temperature has a direct effect at the cellular level on an organism. For instance, in the case of biomembranes, cooling causes lipids to lose entropy and pack closely together. Reducing temperature should, in the absence of other factors, increase the viscosity of a lipid membrane. We have investigated the effect of temperature variation on plasma membrane (PM) viscosity. We used dispersion tracking of photoactivated green fluorescent protein (GFP) and fluorescence recovery after photobleaching in wild-type and desaturase mutant Arabidopsis thaliana plants along with membrane lipid saturation analysis to monitor the effect of temperature and membrane lipid composition on PM viscosity. Plasma membrane viscosity in A. thaliana is negatively correlated with ambient temperature only under constant-temperature conditions. In the more natural environment of temperature cycles, plants actively manage PM viscosity to counteract the direct effects of temperature. Plasma membrane viscosity is regulated by altering the proportion of desaturated fatty acids. In cold conditions, cell membranes accumulate desaturated fatty acids, which decreases membrane viscosity and vice versa. Moreover, we show that control of fatty acid desaturase 2 (FAD2)-dependent lipid desaturation is essential for this homeostasis of membrane viscosity. Finally, a lack of FAD2 function results in aberrant temperature responses.
authors.affiliation: School of Life Sciences, Oxford Brookes University, Headington, Oxford OX3 0BP, UK.
authors.forename: Alexandre
authors.initials: A
authors.lastname: Martinière
authors.forename: Maria
authors.initials: M
authors.lastname: Shvedunova
authors.forename: Adrian J W
authors.initials: AJ
authors.lastname: Thomson
authors.forename: Nicola H
authors.initials: NH
authors.lastname: Evans
authors.forename: Steven
authors.initials: S
authors.lastname: Penfield
authors.forename: John
authors.initials: J
authors.lastname: Runions
authors.forename: Harriet G
authors.initials: HG
authors.lastname: McWatters
mesh_terms: D017360:Arabidopsis / Q000737:chemistry / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D002462:Cell Membrane / Q000737:chemistry / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D002940:Circadian Rhythm; D005227:Fatty Acids / Q000378:metabolism; D014644:Genetic Variation; D006706:Homeostasis; D030821:Plants, Genetically Modified; D013696:Temperature; D014783:Viscosity
chemical_list: D005227:Fatty Acids