Effect of nutrient concentration and salinity on immotile-motile transformation of Chromera velia.

Chromera velia (Chromerida: Alveolata) is a photosynthetic, unicellular organism closely related to parasitic apicomplexa. Diurnal rhythmicity of an immotile-motile transformation has been observed but its role in the life cycle remains largely unknown. Using a multiwell system, we show that salinity and f-medium concentration significantly affect the percentage of motile C. velia cells. An inverse relationship between salinity and motility in C. velia occurred, and flagellation was also suppressed at high nutrient levels. These results suggest a low salinity environment with relatively low nutrient levels enables flagellate transformation during the diurnal cycle of C. velia.