title: THE ROLE OF NITRIC OXIDE IN DIATOM ADHESION IN RELATION TO SUBSTRATUM PROPERTIES(1).
abstract: Adhesion of raphid diatoms to surfaces, mediated by the secretion of extracellular polymeric substances (EPS), is an important strategy for growth and survival. Diatom biofilms are also important in the context of biofouling. Diatoms exhibit selectivity in adhering to surfaces, but little is understood about how they perceive the properties of a substratum and translate that perception into altered adhesion properties. In this study, we demonstrate that Seminavis robusta Danielidis et D. G. Mann, like many other pennate diatoms, adheres more strongly to hydrophobic surfaces (such as silicone elastomer foul-release coatings) than to hydrophilic surfaces. To explore the cellular mechanisms that may underlie this selectivity, we tested the hypothesis that diatoms may perceive a hydrophilic surface as unconducive to adhesion through a form of stress response involving nitric oxide (NO) production. Single-cell imaging with the fluorescent indicator DAF-FM DA (4-amino-5-methylamino-2',7'-difluorofluorescein diacetate), revealed NO levels that were 4-fold higher in cells adhered to a hydrophilic surface (acid-washed glass) compared with a hydrophobic surface (polydimethylsiloxane elastomer, PDMSE). Elevated levels of NO caused by the addition of the NO donor S-nitroso-N-acetylpenicillamine (SNAP) did not affect growth, but cells showed reduced adhesion strength to both glass and PDMSE. Addition of the nitric oxide synthase inhibitor NG-monomethyl-l-arginine (NMMA) caused a small but significant increase in adhesion strength. Overall, the results suggest that NO acts as a signal of the wettability properties of substrata for Seminavis.
authors.affiliation: School of Biosciences, The University of Birmingham, Birmingham B15 2TT, UK Marine Biological Association, The Laboratory, Citadel Hill, Plymouth PL1 2PB, UKMarine Biological Association, The Laboratory, Citadel Hill, Plymouth PL1 2PB, UKSchool of Biosciences, The University of Birmingham, Birmingham B15 2TT, UK.
authors.forename: Stephanie E M
authors.initials: SE
authors.lastname: Thompson
authors.affiliation: School of Biosciences, The University of Birmingham, Birmingham B15 2TT, UK Marine Biological Association, The Laboratory, Citadel Hill, Plymouth PL1 2PB, UKMarine Biological Association, The Laboratory, Citadel Hill, Plymouth PL1 2PB, UKSchool of Biosciences, The University of Birmingham, Birmingham B15 2TT, UK.
authors.forename: Alison R
authors.initials: AR
authors.lastname: Taylor
authors.affiliation: School of Biosciences, The University of Birmingham, Birmingham B15 2TT, UK Marine Biological Association, The Laboratory, Citadel Hill, Plymouth PL1 2PB, UKMarine Biological Association, The Laboratory, Citadel Hill, Plymouth PL1 2PB, UKSchool of Biosciences, The University of Birmingham, Birmingham B15 2TT, UK.
authors.forename: Colin
authors.initials: C
authors.lastname: Brownlee
authors.affiliation: School of Biosciences, The University of Birmingham, Birmingham B15 2TT, UK Marine Biological Association, The Laboratory, Citadel Hill, Plymouth PL1 2PB, UKMarine Biological Association, The Laboratory, Citadel Hill, Plymouth PL1 2PB, UKSchool of Biosciences, The University of Birmingham, Birmingham B15 2TT, UK.
authors.forename: Maureen E
authors.initials: ME
authors.lastname: Callow
authors.affiliation: School of Biosciences, The University of Birmingham, Birmingham B15 2TT, UK Marine Biological Association, The Laboratory, Citadel Hill, Plymouth PL1 2PB, UKMarine Biological Association, The Laboratory, Citadel Hill, Plymouth PL1 2PB, UKSchool of Biosciences, The University of Birmingham, Birmingham B15 2TT, UK.
authors.forename: James A
authors.initials: JA
authors.lastname: Callow
keywords: DAF-FM; diatom adhesion; nitric oxide (NO); silicone elastomer