Scales
are unique components of the ECM of many primitive green algae.
They may be elaborately designed, exist in large numbers and
found in multiple layers on the cell surface (Moestrup 1979).
Scales are also produced on cells of specific life cycle phases
of some CGA and on sperm cells of some land plants. In the
most primitive group of CGA, the Mesostigmales, spectacular
basket scales cover the plasma membrane. The scales consist
primarily of polysaccharide comprised of unique 2-keto-sugars
(Domozych et al. 1992, 1991, Becker et al. 2001) along with
small amounts of protein. The scales are processed (i.e. synthesized)
in the Golgi Apparatus and are packaged in secretory vesicles.
The vesicles carry the scales to the cell surface where they
are released to the cell surface. Scales are also produced
on the plasma membrane and flagellar membrane surfaces of
the zoospores or sperm of other CGA (e.g. Chara sperm,
Chlorokybus zoospores). Virtually, nothing is known
about the biochemistry of these scales. Inclusive references
above may be accessed in the CGA
References section.
