Free-living dinoflagellates are major causatic agents of redtides and regular algal blooms. Symbiotic relationship between coral and dinoflagellates, compromised during coral beaching, is the main contribution to primary production in coral reef.
Calcareous dinoflagellates, which have carbonate deposited on cell wall, represented a major sink of atmospheric carbon dioxide from the world oceans(1).
However, very little is known about their molecular mechanism of action, understanding of which will lead to better prediction to climatic changes, as ocean acidification could potentially limit carbonate deposition. Cellulose is the most abundant biomacromolecules and their biosynthesis from photosynthetically-fixed carbon is carbon-negative. Dinoflagellate cell walls are cellulosic and thecate species have cellulosic thecal plates (CTPs). We recently demonstrated cellulose synthase is required the biogenesis of CTPs. CTPs have the mechanical properties of wood but are apparently transmissible to light for photosynthesis(2). Cellulose synthesis is highly orchestrated with cell cycle progression(3, 4).
In many oceanic calcareous dinoflagellates, it is not sure as to where carbonate crystals were deposited . Carbonote deposition in alveoli sac is likely linked to glucan-binding and carbonate-binding domains, their identifications with proteomic-genomic approach from alveoli proteome would be instrumental to identification of key components in this novel pathway. Cellulose was found to be an in vitro substrate favoring the deposition of calcite crystals from stable supersaturated solutions at pH 8.50 and at 25 degrees C(5).
1. Elbrchter Mel. 2008. Establishing an Agenda for Calcareous Dinoflagellate Research (Thoracosphaeraceae, Dinophyceae) including a nomenclatural synopsis of generic names. Taxon 57:1289-130
2. Lau RK, Kwok A, Chan W, Zhang T, Wong JT. 2007. Mechanical characterization of cellulosic thecal plates in dinoflagellates by nanoindentation. Journal of nanoscience and nanotechnology 7:452-457
3. Kwok AC, Wong JT. 2010. The activity of a wall-bound cellulase is required for and is coupled to cell cycle progression in the dinoflagellate Crypthecodinium cohnii. The Plant Cell Online 22:1281-1298
4. Kwok AC, Wong JT. 2003. Cellulose synthesis is coupled to cell cycle progression at G1 in the dinoflagellate Crypthecodinium cohnii. Plant physiology 131:1681-1691
5. Dalas E, Klepetsanis PG, Koutsoukos PG. 2000. Calcium Carbonate Deposition on Cellulose. Journal of Colloid and Interface Science 224:56-62 https://doi.org/10.1006/jcis.1999.6670.