Portrait (lateral view) of the cryptomonad flagellate, Rhodomonas (Karsten,1898). The cells are laterally flattened. The anterior end is obliquely truncate and the posterior rounded. Two subequal flagella insert into a ventral furrow-gullet complex. A single contractile vacuole is seen adjacent to the anterior opening of the ventral furrow. The inner layer of the periplast is composed of overlapping rounded or square proteinaceous organic plates about 0.4 um in diameter. There is a single large boat-shaped chloroplast with a small pyrenoid. Although not always this color, this species is red due to a chloroplast containing Cr-phycoerythrin 545. Like other cryptomonads, ultrastructural studies of Rhodomonas reveal a nucleomorph associated with the plastid. The nucleomorph is thought to represent a nuclear remnant of an ancestral endosymbiotic red alga. The function, if any, of the nucleomorph is unknown. Large ejectosomes are seen here lining the ventral furrow-gullet. Rhodomonas is phototrophic. This genus is found in both freshwater and marine habitats. This specimen was collected from a commercial saltwater aquarium in Boise, Idaho, September 2004. DIC.
Image by Bill Bourland, he uses a Zeiss Axioskop 2 with a Spot Insight CCD camera (Diagnostic Instruments). Image copyright: William Bourland, image used under license to MBL (micro*scope).
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From the collection
Marine microbes from Idaho
|Description of Rhodomonas: Cryptomonad flagellates, cells with a variable furrow and a short tubular gullet. Periplast consisting of inner, more or less, square plates which taper slightly toward the anterior and a surface component of intertwining fibrils. The periplastidial compartment usually has a single, bilobed chloroplast with a pyrenoid situated between the two lobes of the chloroplast. Thylakoids do not traverse the pyrenoid. Nucleomorph located in an evagination of the periplastidal cytoplasm into the pyrenoid. Cells not necessarily coloured red; chloroplasts contain Cr-phyco-erythrin 545. Marine and freshwater |