Polymerization and Oligomerization Phenomena in Protozoan Evolution

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Abstract
Polymerization and oligomerization of nuclei and organelles during macroevolution of Protozoa are considered in the light of Dogiel''s theory about the leading role of oligomerization of homologous organs in progressive evolution of the Metazoa and about a similar role of polymerization of organelles in that of the Protozoa. Polymerization in Protozoa primarily involves the locomotor organelles (flagella, cilia). Nuclear polymerization proceeds in homokaryotic protozoa at 2 levels, that of whole nuclei, which process predominates and leads to multinuclearity, and that of genomes inside polyploid nuclei. Nuclear dualism in ciliates opens wide possibilities of re-formation of the genic apparatus of the macronucleus. Polymerization of whole nuclei (especially of diploid type macronuclei), of genomes inside a polyploid macronucleus, or of separate genes (amplification) inside macronuclei with a fragmented genome, are all possible. In the last 2 cases, the macronuclei themselves show a tendency to oligomerization. There is a complex interaction of polymerization and oligomerization of structures in evolution of the ciliary apparatus in ciliates, the 2 opposite phenomena usually acting at different structural levels. Oligomerization of complex organelles is frequently based on polymerization of their unit organelles (e.g., of cilia inside cirri). The tendency of unit organelles to polymerization depends on the rigidity of their macromolecular structure.