Biology Reference
In-Depth Information
a
b
c
Figure 8.3
Images of algal adhesives. (a and b) Scanning electron
microscope images of single microalgal cells attached to
glass coverslips. A layer of extracellular polymeric substance
(EPS) covers the surface of each cell, and differentiated region
forming the adhesive pad can be seen beneath the cells. Scale
bar = 1 µm. (c) Atomic force microscope image of the adhesive
beneath a single microalgal cell after the cell was removed
from the coverslip surface. Scan size = 5 µm. (a and b) from A.
S. Mostaert, C. Giordani, R. Crockett, U. Karsten, R. Schumann,
and S. P. Jarvis, Characterisation of amyloid nanostructures
in the natural adhesive of unicellular subaerial algae,
Journal
of Adhesion
, 465 (2009), reprinted by permission of the
publisher (Taylor & Francis Ltd, http://www.tandf.co.uk/
journals).
16
See also Colour Insert.
,
85
AFM was initially found to be particularly useful for exploring
the mechanical properties of natural adhesives from marine
organisms, as it allowed measurements to be made on materials
in their hydrated, native state under aqueous conditions, without
isolation or fixation. Examples include those of Dammer
et al
.
27
for
28
cell-adhesion proteoglycans of a marine sponge, Smith
et al
.
for
29
the lustrin A adhesive binding abalone nacre, and Callow
et al
.
for the green alga,
), a common
marine fouling organism. Wetherbee and co-workers later worked
on the nanomechanical properties of adhesives from motile and
sessile diatoms
Ulva linza
(syn.
Enteromorpha linza
30-34
and Jarvis and co-workers focused on adhesives
from sub-aerial algae (Fig. 8.3)
14-16
17
In the
latter group, the unusually repetitive mechanical response of the
adhesive led the researchers into the new area of characterizing
mechanically functional amyloid in natural adhesives.
Using AFM the elastic and inelastic response of amyloid fibrils
may be measured and related to the response of monomers within
the amyloid core. The quantitative variation in mechanical response
at the molecular level has been measured to characterize amyloid
and a marine parasite.
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