Dunaliella (done-al-ee-ella), a solitary volvocid (flagellated green algal cell). Cell surrounded by a cellulosic wall, with two similar flagella emerging from near the apex. The photosynthetic pigments are located within a cup-shaped chloroplast which has a large pyrenoid with associated polysaccharide materials located posteriorly. The nucleus is located within the cup. From marine and usually hypersaline habitats, grown commercially because of the tendency to produce large quantities of beta carotene when intensely illuminated. Differential interference contrast. This picture was taken by David Patterson, Linda Amaral Zettler, Mike Peglar and Tom Nerad from cultures and other materials maintained at the American Type Culture Collection during 2001. Image copyright: D. J. Patterson, L Amaral-Zettler, M. Peglar and T. Nerad, image used under license to MBL (micro*scope).
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From the collection
American Type Culture Collection
|Description of Dunaliella: Cells mostly radially symmetrical, sometimes bilaterally symmetrical, flattened, dorsoventrally curved or slightly asymmetrical; cell shape ellipsoidal, ovoid, cylindrical, pyriform, or fusiform to almost spherical; cell size and shape may vary within a given species depending on different environmental conditions; cell surface smooth with distinctive mucilaginous cell coat; flagella 2, of equal length; chloroplast single, cup-, dish-, or bell-shaped; pyrenoid basal with continuous starch shell; eyespot anterior; nucleus anterior; Golgi bodies (2-4) parabasal; contractile vacuoles absent (freshwater species of doubtful affiliation); asexual reproduction by longitudinal division of vegetative flagellate cells; asexual cysts subspherical, thick-walled with bumpy surface; sexual reproduction isogamous, gametic fusion involves flagellar agglutination and activation of mating structures; several species are homothallic, the type species is reported to be heterothallic; zygote with a thick, smooth wall; after a resting stage, the zygote forms 32 progeny cells, which are liberated through a rupture in the zygote cell wall; meiosis takes place during germination of the zygote; habitat euryhaline or hypersaline. |