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Flagellar apparatus structure of choanoflagellates
1Zoological Institute RAS, Universitetskaya emb. 1., St. Petersburg, 199034 Russia ; St. Petersburg State University, Universitetskaya emb. 7/9., St. Petersburg, 199034 Russia.
Cilia
|May 6, 2016
Summary
Choanoflagellates, the closest unicellular relatives of animals, possess a unique flagellar apparatus. This structure, including distinct basal bodies and a central filament, is crucial for their cell division and provides insights into early animal evolution.
Area of Science:
- * Cell Biology
- * Evolutionary Biology
- * Protistology
Background:
- * Choanoflagellates are unicellular eukaryotes and the closest living relatives to multicellular animals (metazoa).
- * They exhibit a characteristic flagellar collar structure, essential for filter feeding.
- * Their flagellar apparatus, including basal bodies and associated structures, is complex and conserved.
Purpose of the Study:
- * To detail the intricate structure of the choanoflagellate flagellar apparatus.
- * To elucidate the function of basal bodies during cell division in choanoflagellates.
- * To provide insights into the evolutionary origins of animal cell structures.
Main Methods:
- * Comparative analysis of flagellar apparatus ultrastructure across choanoflagellate species.
- * Transmission Electron Microscopy (TEM) for detailed structural visualization.
- * Examination of basal body replication and segregation during mitosis.
Main Results:
- * Described the unique flagellar basal body (FB) and non-flagellar basal body (NFB), their orthogonal arrangement, and interconnection.
- * Identified the central filament in the flagellar transition zone, a unique eukaryotic feature.
- * Detailed the microtubule organizing center (MTOC) and microtubular root systems associated with basal bodies.
- * Observed basal body replication and function as MTOCs during semiopen orthomitosis.
Conclusions:
- * The choanoflagellate flagellar apparatus exhibits unique structures, including the central filament, critical for cell function.
- * Basal bodies play a conserved role as microtubule organizing centers during nuclear division, similar to early animal cells.
- * Understanding choanoflagellate cell biology offers crucial insights into the transition from unicellular to multicellular life.
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