Microscopic and infrared spectroscopic comparison of the underwater adhesives produced by germlings of the brown seaweed species Durvillaea antarctica and Hormosira banksii.
Adhesives from marine organisms are often the source of inspiration for the development of glues able to create durable bonds in wet environments. In this work, we investigated the adhesive secretions produced by germlings of two large seaweed species from the South Pacific, Durvillaea antarctica, also named 'the strongest kelp in the word', and its close relative Hormosira banksii The comparative analysis was based on optical and scanning electron microscopy imaging as well as Fourier transform infrared (FTIR) spectroscopy and principal component analysis (PCA). For both species, the egg surface presents peripheral vesicles which are released soon after fertilization to discharge a primary adhesive. This is characterized by peaks representative of carbohydrate molecules. A secondary protein-based adhesive is then secreted in the early developmental stages of the germlings. Energy dispersive X-ray, FTIR and PCA indicate that D. antarctica secretions also contain sulfated moieties, and become cross-linked with time, both conferring strong adhesive and cohesive properties. On the other hand, H. banksii secretions are complemented by the putative adhesive phlorotannins, and are characterized by a simple mechanism in which all constituents are released with the same rate and with no apparent cross-linking. It is also noted that the release of adhesive materials appears to be faster and more copious in D. antarctica than in H. banksii Overall, this study highlights that both quantity and quality of the adhesives matter in explaining the superior attachment ability of D. antarctica.
Department of Chemical and Process Engineering, University of Canterbury, Private Bag 4800, Christchurch 8140, New Zealand Biomolecular Interaction Centre, University of Canterbury, Private Bag 4800, Christchurch 8140, New Zealand Simone.Dimartino@ed.ac.uk.
Simone
http://orcid.org/0000-0002-9695-1278
S
Dimartino
Department of Chemistry, University of Otago, PO Box 56, Dunedin 9054, New Zealand.
David M
DM
Savory
Department of Chemistry, University of Otago, PO Box 56, Dunedin 9054, New Zealand The Dodd-Walls Centre, University of Otago, Dunedin 9054, New Zealand.
Sara J
http://orcid.org/0000-0003-1061-2441
SJ
Fraser-Miller
Department of Chemistry, University of Otago, PO Box 56, Dunedin 9054, New Zealand The Dodd-Walls Centre, University of Otago, Dunedin 9054, New Zealand.
Keith C
http://orcid.org/0000-0003-2833-6166
KC
Gordon
Department of Chemistry, University of Otago, PO Box 56, Dunedin 9054, New Zealand.
A James
AJ
McQuillan
D000269:Adhesives / Q000378:metabolism*; D008855:Microscopy, Electron, Scanning; D000459:Phaeophyceae / Q000378:metabolism* / Q000648:ultrastructure*; D017550:Spectroscopy, Fourier Transform Infrared
D000269:Adhesives
ATR-FTIR; adhesive; brown algae; microscopy; principal component analysis