Fig. 1: Layers of Collembola cuticular lipids and their bioadhesion properties.
From: Entropic repulsion of cholesterol-containing layers counteracts bioadhesion
a, Image of Tetrodontophora bielanensis, an exemplary Collembola sp. Scale bar, 1 mm. b, Scanning electron microscopy image of a T. bielanensis cuticula. Scale bar, 500 nm. c, Cross-sectional schematic of the cuticula, showing a layered structure consisting of a chitin-rich inner skeleton covered by a protein-rich layer. A thin, lipid-rich envelope covers the protein-rich layer. Scale bar, 200 nm. d, Summary of lipids detected in the outer cuticula layer of T. bielanensis7. e, Layers of Collembola cuticular lipids; SCLs containing cholesterol facilitate orientational adaptation of the topmost lipids to the polarity of the environment. ATR–FTIR (Supplementary Fig. 2) and dynamic contact angle measurements (Fig. 2c and Extended Data Fig. 4a) indicate highly ordered cholesterol molecules, with the hydrocarbon tail of the outer cholesterol layer initially oriented towards the interface and the hydroxyl groups oriented inward. SAMs chemisorbed to gold via thiol groups, with either the polar or non-polar side of cholesterol oriented to the interface, served as references in selected experiments. f–i, Adsorbed amount of protein (f,i) and normalized adherent cells (g,h). Adsorbed amount of protein (lysozyme or fetal bovine serum) on monocomponent layers of Collembola cuticular lipids (f) and multicomponent SCLs of stearyl palmitate and cholesterol (i), as determined by quartz crystal microbalance measurements. Normalized adherent cells of S. epidermidis on monocomponent layers of Collembola cuticular lipids (g) and multicomponent SCLs of stearyl palmitate and cholesterol (h). Data normalized to average adherent cell density on a silica (SiO2) substrate. h,i, Pure stearyl palmitate SCLs (100/0) and pure cholesterol SCLs (0/100) served as negative and positive controls, respectively. f–i, Mean + s.d. The number of observations (n) is indicated. P values (comparison with cholesterol SCL condition in f,g and with the 0/100 condition in h,i) were determined using one-way analysis of variance. AU, arbitrary units.
