Thesis-PDF - IAP/TU Wien

on the glass slide. In order to achieve sufficient attachment of the material onto
the glass surface the material was given time to adsorb to the surface (incubation
time). Depending on preparation type and liquid, this time varied from seconds
to over an hour.
Poly-l-lysine coated slides were sometimes used in this setup to improve adhesion
of the algae to the slides (see Fig. 5.9).
5.3.4 Experimental Preparations
For experimental purposes other types of preparations were tried out. It turned
out that the most effective sample preparation method is the one given in 5.3.2.
Experimental preparations include prior calcium treatment of cells for ejection
of the reservoir system and the flagellar apparatus. Through calcium diffusion
internal cell pressure was raised until ejection. With the ejection of the flagellar
apparatus the paraflagellar body (crystalline photoreceptor) attached to the longer
flagellum becomes accessible. This procedure proved viable for good results with
the optical microscope. Unfortunately, investigation with fluorescence microscopy
showed that the fluorescence characteristics of the photoreceptor had deteriorated.
The three-dimensional integrity of the photoreceptor was no longer guaranteed and
therefore no additional investigation of these samples under the AFM was carried
out.
Another experimental procedure tried was the chitosan matrix procedure. Fixated,
demembranated cells were included in a chitosan matrix (its main component
is chitin). Subsequent washing with alcohol, and freeze fracturing gave surfaces
that were possible to scan with scanning probe techniques. Although this approach
yielded some images on cell surface features, it is a time consuming process and
the data obtained by ambient AFM investigation of dried specimen was clearly of
better quality.
74