Synurids

Mallomonas, a flagellate included in the Synurophyceae. Mallomonas is a very large genus with over 120 recognized species. Cells are solitary and biflagellate although the short flagellum is usually not visible by light microscopy. Chloroplasts are either double or single and bilobed. The chloroplasts of Mallomonas differ from those of chrysophytes in that they contain chlorophyll a and c1 but not chlorophyll c2. A red stigma is absent. There is a posterior contractile vacuole. Cells are covered by siliceous scales and bristles. Both are formed intracellularly then extruded to the cell surface where the bristles then articulate with or adhere to the scales. Taxonomy is based on scale and bristle ultrastructure. There are some species which form siliceous cysts known as stomatocysts. These have a terminal opening or porus which is sealed with a plug. From a freshwater pond near Boise, Idaho. Phase contrast.

Mallomonas, a very large genus with over 120 recognized species. Cells are solitary and biflagellate although the short flagellum is usually not visible by light microscopy. Chloroplasts are either double or single and bilobed. The chloroplasts of Mallomonas differ from those of chrysophytes in that they contain chlorophyll a and c1 but not chlorophyll c2. A red stigma is absent. There is a posterior contractile vacuole. Cells are covered by siliceous scales and bristles. Both are formed intracellularly then extruded to the cell surface where the bristles then articulate with or adhere to the scales. Taxonomy is based on scale and bristle ultrastructure. There are some species which form siliceous cysts known as stomatocysts. These have a terminal opening or "porus" which is sealed with a plug. From a freshwater pond near Boise, Idaho. Brightfield illumination

Portrait of an encysted individual of the synurophyte flagellate Mallomonas akrokomos (Ruttner in Pascher,1913). Mallomonas is a very large genus with over 120 recognized species. Cells are solitary and biflagellate although the short flagellum is usually not visible by light microscopy (no flagellum is seen in this encysted cell). Chloroplasts are either double or single and bilobed. The chloroplasts of Mallomonas differ from those of chrysophytes in that they contain chlorophyll a and c1 but not chlorophyll c2. A red stigma is absent. Siliceous scales and bristles cover cells. Both are formed intracellularly then extruded to the cell surface where the bristles then articulate with or adhere to the scales. Taxonomy is based on scale and bristle ultrastructure. In M. akrokomos, only a few anterior apical siliceous scales bear long serrated bristles almost the length of the cell. Small flat scales cover the body (not seen in this image). From a freshwater pond near Boise, Idaho. DIC optics.

Portrait of the synurophyte flagellate Mallomonas akrokomos (Ruttner in Pascher,1913). Mallomonas is a very large genus with over 120 recognized species. Cells are solitary and biflagellate although the short flagellum is usually not visible by light microscopy. Chloroplasts are either double or single and bilobed. The chloroplasts of Mallomonas differ from those of chrysophytes in that they contain chlorophyll a and c1 but not chlorophyll c2. A red stigma is absent. Siliceous scales and bristles cover cells. Both are formed intracellularly then extruded to the cell surface where the bristles then articulate with or adhere to the scales. Taxonomy is based on scale and bristle ultrastructure. In M. akrokomos, only a few anterior apical siliceous scales bear long serrated bristles almost the length of the cell. Small flat scales cover the body. From a freshwater pond near Boise, Idaho. Phase contrast.

Mallomonas insignis (Penard, 1919). M. insignis has ovoid siliceous scales. Scales arranged around the flagellar opening bear short, sharp spines. Scales at the posterior end of the tail bear long fine spines. M. insignis is similar to M. mesolepis (Skuja) which lacks terminal spinous projections and has diamond-shaped scales. Collected from a temporary slow-flowing freshwater stream near Boise, Idaho. May 2005. DIC.

Portrait of Chrysodidymus synuroideus, a colonial synurophyte chrysophyte. Chrysodidymus is a monospecific genus. Two cells united at their bases form the colonies. The cells are conical. Each is covered by siliceous scales. The scales are formed in the chloroplast endoplasmic reticulum and transported to the cell surface. There are two flagella, one long (bearing tripartite hairs typical of stramenopiles on electron microscopy) and one short. There are two golden-colored parietal chloroplasts without pyrenoids. A posterior storage vacuole may contain chrysolaminarin. Red pigment granules can be seen at the apices of these cells. Swimming movement is a distinctive back and forth motion. From a freshwater irrigation ditch near McCall, Idaho. Differential interference contrast.

Portrait of Chrysodidymus synuroideus, a colonial synurophyte chrysophyte. Chrysodidymus is a monospecific genus. Two cells united at their bases form the colonies. The cells are conical. Each is covered by siliceous scales, some bearing spines (seen well in this image). The scales are formed in the chloroplast endoplasmic reticulum and transported to the cell surface. There are two flagella, one long (bearing tripartite hairs typical of stramenopiles on electron microscopy) and one short. There are two golden-colored parietal chloroplasts without pyrenoids. A posterior storage vacuole may contain chrysolaminarin. Red pigment granules can be seen at the apices of these cells. Swimming movement is a distinctive back and forth motion. From a freshwater irrigation ditch near McCall, Idaho. Differential interference contrast

Portrait of Chrysodidymus synuroideus, a colonial synurophyte chrysophyte. Chrysodidymus is a monospecific genus. Two cells united at their bases form the colonies. The cells are conical. Each is covered by siliceous scales. The scales are formed in the chloroplast endoplasmic reticulum and transported to the cell surface. There are two flagella, one long (bearing tripartite hairs typical of stramenopiles on electron microscopy) and one short. There are two golden-colored parietal chloroplasts without pyrenoids. A posterior storage vacuole may contain chrysolaminarin. Red pigment granules can be seen at the apices of these cells. Swimming movement is a distinctive back and forth motion. From a freshwater irrigation ditch near McCall, Idaho. 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. Phase 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. This image is a detail showing the scales of the periplast . 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. 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.