The aim of this paper is to review the present knowledge of
the main aspects of differentiation of Acetabularia, a
unicellular, eukaryotic organism, and to underline the multiple
control pathways modulated by circadian rhythmicity. Growth and
morphogenesis are sequentially programmed. Timing of cap
differentiation is highly dependent on external conditions. The
importance of the sequence of processes is shown by experimental
disregulation.
The alga is a highly polarized cell, both in morphology and in the
relative concentrations of a number of the molecules it contains.
Apical cap differentiation is regulated at the post-transcriptional
level and could also depend in part on polyamines and on proteolytic
activity.