Page 90 - Algae Anatomy, Biochemistry, and Biotechnology

Anatomy 73

FIGURE 2.47 Schematic drawing of cruciate arrangements of basal bodies and roots of Chlorophyta.
11 o’clock–5 o’clock type (a), 12 o’clock–6 o’clock type (b), 1 o’clock–7 o’clock type (c).

The 11 o’clock–5 o’clock configuration is present in Ulvophyceae, Cladophorophyceae,
Bryopsidophyceae, Trentepohliophyceae, and Dasycladophyceae, while both the 12 o’clock–
6 o’clock and 1 o’clock–7 o’clock configurations are present in the Chlorophyceae.
In the case of many basal bodies, the increase in their number and the corresponding increase in
the number of flagella can result from:

. A replica of each basal body of the pair, as in the stephanokont zoospore of Oedogonium
(Chlorophyceae, Chlorophyta)
. Replica of the primordial pair, indicated by the formula X 2A, as in the dinoflagellate
Phaeopolykrikos sp. (Dinophyta) where the primordial pair has undergone four replicas
(4 2A)
. Addition of new basal bodies in the surroundings of the primordial pair without a replica-
tion of it, indicated by the formula 2A þ N; algae with four flagella, as Tetraselmis suecica
or Pyramimonas lunata (Prasinophyceae, Chlorophyta), have a formula 2A þ 2N, while
algae with eight flagella as Pyramimonas octopus (Prasinophyceae, Chlorophyta), are indi-
cated by the formula 2A þ 6N

Root System
All algal flagella appear to possess flagellar roots, that is, microtubular or fibrillar, often cross-
banded structures, which extend from the basal bodies into the cytoplasm either underlying the
plasma membrane or projecting into the cell and making contact with other organelles such as
the nucleus, the mitochondria, the Golgi apparatus, or the chloroplasts. Diverse functions have
been assigned to the flagellar roots: anchoring devices or stress absorbers, sensory transducers,
and skeletal and organizational structures for morphogenetic processes.
The great diversity of morphology and arrangement of the flagellar root systems among the
different algae make it necessary to describe them separately in each division. As described
earlier, Cyanophyta, Prochlorophyta, and Rhodophyta lack any flagellar apparatus, hence they
will not be considered in the following.