Synurids

Synura (sigh-new-ra) is a synurophyte alga, traditionally regarded as a chrysophyte or related to the chrysophytes, but distinguished by the presence of extracellular siliceous scales. This genus is one in which many cells are joined together to form a swimming spherical colony. Each cell has two large chlorophyll a and c containing plastids, two emergent flagella, and a coating of flattened scales. This image is a detail of the of several cells showing the plastids and the periplast around the individual cells. Differential interference contrast.

Synura (sigh-new-ra) is a synurophyte alga, traditionally regarded as a chrysophyte or related to the chrysophytes, but distinguished by the presence of extracellular siliceous scales. This genus is one in which many cells are joined together to form a swimming spherical colony. Each cell has two large chlorophyll a and c containing plastids, two emergent flagella, and a coating of flattened scales. Differential interference contrast.

Synura (sigh-new-ra) is a synurophyte alga, traditionally regarded as a chrysophyte or related to the chrysophytes, but distinguished by the presence of extracellular siliceous scales. This genus is one in which many cells are joined together to form a swimming spherical colony. Each cell has two large chlorophyll a and c containing plastids, two emergent flagella, and a coating of flattened scales. Differential interference contrast.

Synura (sigh-new-ra) colonial chrysophyte alga, each cell with two flagella beating with a sine wave pattern. Differential interference contrast.

Individual cell detail of colonial chrysophyte, Synura. Species identification is based on ultrastructure of silica scales on the cell surface. Scales (seen in this image) originate in cytoplasmic vesicles and are extruded to the cell exterior. Several different types of scales occur on an individual cell. Cells have two subequal flagella, one hairy and the other smooth on electron microscopy (only one is seen in this image). Two yellow-brown chloroplasts flank a central nucleus. A posterior contractile vacuole is seen in the cell at the lower left of this image. From a freshwater pond near Boise, Idaho. Oblique illumination.

Portrait Synura uvella (Ehrenberg,1835), a colonial chrysophyte flagellate. Colonies are spherical or cylindrical, composed of pyriform cells attached by their posterior ends.The cells of this colony have loosened slightly from one another. Species identification is based on ultrastructure of silica scales on the cell surface (giving the surface of these cells a serrated appearance). Scales originate in cytoplasmic vesicles and are extruded to the cell exterior. Several different types of scales occur on an individual cell. Cells have two subequal flagella, one hairy and the other smooth on electron microscopy. Two yellow-brown chloroplasts flank a central nucleus. A contractile vacuole is seen posterior to the large chrysolaminarian vacuole in these cells. Although a stigma is absent, colonies are phototrophic, a basal flagellar swelling acting as photoreceptor. Red droplets in the anterior end of cells, not associated with chloroplasts may be mistaken for stigmata. Multiple contractile vacuoles may be present, usually located posteriorly. From freshwater pond near Boise, Idaho. DIC.

A scale of the stalk (long) anda scale of the cell body (short) of Synura petersenii wholemount by transmission electron microscopy.

Scanning EM showing the colony of cells covered with scales

Inset upper left are colonies viewed by light microscopy, main picture is of the cells of the colony by whole-mount transmission electron microscopy

Synura sphagnicola, a colonial chrysophyte. Synonymous with Skadovskiella. Cells are joined at their posterior ends in the center of the colony. Cells are ovoid with two golden chloroplasts. There are two equal flagella less than 1 cell length. Siliceous scales with a unique ring form from which there is a rod-like projection cover the cell. A detached scale is seen in the center of this image. The scale structure is diagnostic for the species. A stigma is absent. Large vacuoles containing the glucopyranoside storage polymer, chrysolaminarin (leucosin) accumulate in the cytoplasm . The colonies swim with a slow rolling motion.From a polysaprobic temporary freshwater farm pond near Boise, Idaho. Differential interference contrast.Differential interference contrast optics.

Synura sphagnicola, a colonial chrysophyte. Synonymous with Skadovskiella. Cells are joined at their posterior ends in the center of the colony. Cells are ovoid with two golden chloroplasts. There are two equal flagella less than 1 cell length. The cell is covered by siliceous scales the morphology of which is diagnostic for the species (see accompanying image). A stigma is absent. Large vacuoles containing the glucopyranoside storage polymer, chrysolaminarin (leucosin) accumulate in the cytoplasm. The colonies swim with a slow rolling motion.From a polysaprobic temporary freshwater farm pond near Boise, Idaho. Differential interference contrast.