Molino Paul J, Hodson Oliver M, Quinn John F, Wetherbee Richard
School of Botany, The University of Melbourne, Parkville, Victoria 3010, Australia.
Langmuir. 2008 Jun 1;24(13):6730-7. doi: 10.1021/la800672h. Epub 2008 May 29.
Diatoms are a major component of the biofoul layer found on modern low-surface-energy, 'foul release' coatings. While diatoms adhere more strongly to hydrophobic, as opposed to hydrophilic, surfaces, surprisingly little is known of the chemical composition of their adhesives. Even less is known about the underlying processes that characterize the interaction between the adhesive and a given surface, including those of differing wettability. Using the quartz crystal microbalance with dissipation monitoring (QCM-D), we examined differences in the viscoelastic properties of the extracellular adhesives produced by the marine diatoms Amphora coffeaeformis Cleve and Craspedostauros australis Cox interacting with surfaces of differing wettability; 11-mercaptoundecanoic acid (MUA) that is hydrophilic and 1-undecanethiol (UDT) that is hydrophobic. While the overall delta f/delta D ratios were slightly different, the trends were the same for both diatom species, with the layer secreted upon UDT to be more viscoelastic and far more consistent over several experiments, compared to that on MUA which was less viscoelastic and demonstrated far more variability between experiments. While the nature of the parameter shifts for C. australis were the same for both surfaces, A. coffeaeformis cells settling upon UDT illustrated significant positive f and D shifts during the initial stages of cell settlement and adhesion to the surface. Further experiments revealed the parameter shifts to occur only during the initial adhesion of cells upon the pristine virgin UDT surface. The mechanism behind these parameter responses was isolated to the actin-myosin/adhesion complex (AC), using the myosin inhibitor 2,3-butanedione 2-monoxime (BDM) to remove the cells ability to 'pull' on adhesive strands emanating from the cell raphe. The observations made herein have revealed that adhesives secreted by fouling diatoms differ significantly in their interaction with surfaces depending on their wettability, as well as illustrating the unique mechanics behind the adhesion of A. coffeaeformis upon hydrophobic surfaces, a mechanism that may contribute significantly to the cells success in colonizing hydrophobic surfaces.
硅藻是现代低表面能“防污释放”涂层上生物污垢层的主要组成部分。虽然硅藻与疏水表面（而非亲水表面）的附着力更强，但令人惊讶的是，人们对其粘合剂的化学成分知之甚少。对于粘合剂与给定表面之间相互作用的潜在过程，包括那些具有不同润湿性的表面，了解得更少。我们使用具有耗散监测功能的石英晶体微天平（QCM-D），研究了海洋硅藻咖啡双眉藻（Amphora coffeaeformis Cleve）和澳大利亚皱盘藻（Craspedostauros australis Cox）产生的细胞外粘合剂与不同润湿性表面相互作用时的粘弹性差异；亲水的11-巯基十一烷酸（MUA）和疏水的1-十一硫醇（UDT）。虽然总的δf/δD比值略有不同，但两种硅藻的趋势相同，与MUA相比，UDT上分泌的层粘弹性更强，并且在多次实验中更一致，而MUA上的层粘弹性较小，实验间的变异性更大。虽然澳大利亚皱盘藻在两个表面上参数变化的性质相同，但咖啡双眉藻细胞在UDT上沉降时，在细胞沉降和粘附到表面的初始阶段显示出显著的正向f和D变化。进一步的实验表明，参数变化仅发生在细胞最初粘附到原始的UDT表面时。使用肌球蛋白抑制剂2,3-丁二酮单肟（BDM）去除细胞“拉动”从细胞中缝发出的粘附链的能力后，这些参数响应背后的机制被分离到肌动蛋白-肌球蛋白/粘附复合物（AC）。本文的观察结果表明，污损硅藻分泌的粘合剂与表面的相互作用因其润湿性而有显著差异，同时也说明了咖啡双眉藻在疏水表面上粘附的独特机制，这一机制可能对细胞在疏水表面上的定殖成功有很大贡献。
