Journal: bioRxiv
Article Title: Solvatochromic reporter to image plasma membrane order leaflet by leaflet reveals a highly asymmetric bilayer locally modulated by transbilayer interactions
doi: 10.1101/2024.07.23.604763
Figure Lengend Snippet: (a) Confocal images of equatorial plane of cells labelled with 1uM Laurdan, NR12S or C3L showing the sub-cellular distribution of the respective probes. (b) Schematic showing the BSA back extraction assay used for extracting the outer leaflet population of probe in adherent cells. (c-f) Confocal images (c, e) collected from the bottom membrane plane of untreated cells (left panels) or cells treated with 2mM NEM to inhibit flippase activity (c) or 10uM Ionomycin to activate scramblase activity (e), before (top) and after (bottom) back extraction by BSA. Graphs (d, f) show the extent of incorporation (-) and remainder (+) of C3L after extraction with BSA. Each dataset is normalized to the mean intensity of untreated cells labelled with C3L. Data were obtained from from at least 40 cells. (g) Graph shows the time course of fluorescence intensity of C3L remaining at cell surface as a function of exposure to BSA added at t=0 mins (obtained using a CSU22 spinning disk confocal) in untreated cells (-), NEM treated cells (--) and NEM+Ionomycin treated cells (-.-). Each dataset is normalized to its mean starting intensity at t=0mins. Lines indicate fits to single exponential decay where k is the rate constant for the decay in fraction of C3L at the membrane after adding BSA, C i is the BSA resistant fraction after back-extraction. Data were obtained from atleast 20 cells in each condition. (h) Table shows rate constant (k) and BSA resistant fraction (C i ) obtained from the fit to a single exponential decay shown in panel g. All data is plotted as mean±s.d. p values determined from unpaired t test where ** indicates significance indicated by p<0.005. Scale=10µm.
Article Snippet: Live confocal imaging was done on a CSU W1 SORA (or where indicated a CSU22 mounted on Nikon TiE microscope with Andor iXon 897 cameras) spinning disk mounted on a Nikon Eclipse Ti2 microscope equipped with two Andor iXon 888 cameras.
Techniques: Extraction, Membrane, Activity Assay, Fluorescence