Euglenoides

Peranema (pear-o-knee-ma) is one of the better known gliding heterotrophic euglenids. The body is referred to as sac-shaped but this applies best to P. trichophorum, the most common species and the one illustrated here. At first glance, it would seem that there is just one flagellum, but careful observations reveal a second flagellum tightly adpressed to the body or lying in a groove in the body surface. At magnifications such as this, this species usually cannot be distinguished from Jenningsia, which has a single flagellum. The recurrent structure looks a little wider than the normal ridges of the body. The body is metabolic - meaning it squirms, and members of this genus have an ingestion organelle with which to manipulate food into the body. Phase contrast.

Peranema (pair-a-knee-ma) trichophorum (Ehrenberg, 1830) Stein, 1878. Cells are metabolic and 35 to 50 microns long, have longitudinal pellicular striations around the cell. The anterior end of the cell is slightly pointed and the posterior end is truncated, rounded, or indented. This body is slightly curved and the flagellar pocket is also to the right. The flagellar pocket including the flagellar canal is up to 40 % the length of the cell. The anterior flagellum is as long as the cell, is thick and is directed forward when the cell is moving. The posterior flagellum may be hard to observe, is thin, and tightly adpressed to the cell surface, lying in a narrow longitudinal groove. The ingestion organelle has two rods and is weakly developed. The nucleus is posterior to the centre of the cell. The cells glide in contact with the substratum. Relatively common.

Peranema trichophorum (Ehrenberg, 1830) Stein, 1878. Cells are metabolic and 35 to 50 microns long, have longitudinal pellicular striations around the cell. The anterior end of the cell is slightly pointed and the posterior end is truncated, rounded, or indented. This body is slightly curved and the flagellar pocket is also to the right. The flagellar pocket including the flagellar canal is up to 40 % the length of the cell. The anterior flagellum is as long as the cell, is thick and is directed forward when the cell is moving. The posterior flagellum may be hard to observe, is thin, and tightly adpressed to the cell surface, lying in a narrow longitudinal groove. The ingestion organelle has two rods and is weakly developed. The nucleus is posterior to the centre of the cell. The cells glide in contact with the substratum.

Peranema trichophorum. Cell observed in freshwater habitats in the vicinity of Broome, Western Australia in September 2003. This image was taken using phase contrast optics.   This work was supported by the Australian Biological Resources Study.

Peranema trichophorum. Surface of a cell observed in freshwater habitats in the vicinity of Broome, Western Australia in September 2003. This image was taken using differential interference contrast optics.   This work was supported by the Australian Biological Resources Study.

Gliding Peranema cell. One thick flagellum pprojects from the front of the cell. There is a second flagellum - but it lies close to the cell surface and can only be seen with careful observation. It is not visible in these two cells. The cell on the surface of the air bubble is seen from side view. Phase contrast microscopy

The two rods of the phagotrophic apparatus revealed by immunofluorescence microscopy (from A. Belhadri & G. Brugerolle).

Nomarski image of living gliding cells. There are two flagella, but only one is visible, the other adheres to the surface of the cell. The rods of the ingestion apparatus are visible just behind the anterior end of the cell. Animations by Rosemary Arbur of flagellar beat patterns are available here.

Peranema cuneatum Playfair, 1921. Cells are metabolic, 25-70 microns long and 5-15 microns wide. When free-swimming, it is cuneate, sharp-pointed in front and abruptly truncate behind, one corner is sometimes produced as a pointed tail directed backwards, or a blunt wart-like prominence often bifid and placed to one side. A minute stigma has been reported as occurring occasionally. Cytoplasm homogeneous and transparent. Fig 7 of Plate 9 in Playfair (1921) appears to be Jenningsia fusiforme and Fig 9 of Plate 8 appears to be Peranema trichophorum.

Entosiphon (ent-owe-siphon) heterotrophic euglenid, with a strongly developed ingestion organelle that is easy to see with the light microscope. With two flagella, the anterior one beats with a sweeping motion, the posterior or recurrent one trails under moving cells (and seems to be more important in the process of moving the cells around). Ingests bacteria and detritus. Not capable of metaboly, but the mouth (siphon) can make slight pumping movements. Common and widespread in freshwater habitats. Phase Contrast.

Entosiphon (ent-owe-siphon) heterotrophic euglenid, with a strongly developed ingestion organelle that is easy to see with the light microscope. With two flagella, the anterior one beats with a sweeping motion, the posterior or recurrent one usually trails under moving cells (and seems to be more important in the process of moving the cells around). Ingests bacteria and detritus. Not capable of metaboly, but the mouth (-siphon+) - to the right - can make slight pumping movements. Common and widespread in freshwater habitats. Differential interference contrast.

This is a transmission electron micrograph of the siphon (or mouth, or ingestion organelle) of Entosiphon sulcatum. There are three stout rods comprised of microtubules, and four lamellae which seem to assist in pushing food into the body. Each of the microtubules is about 25 nm in diameter. This species eats filamentous bacteria and other moderately large particles, and this presumably requires a stiff ingestion structure.

Entosiphon sulcatum. Cell observed in freshwater habitats in the vicinity of Broome, Western Australia in September 2003. This image was taken using differential interference contrast optics.   This work was supported by the Australian Biological Resources Study.

The ingestion apparatus is revealed by immunofluorescence microscopy.

Electron micrograph of a grazing thin section along the length of the recurrent flagellum, showing axoneme to the upper left, the crystalline paraxial rod, membrane, and thin hairs over the flagellar surface.

Transmission electron micrograph of a thin section across the anterior part of the cell. The two flagella lie in the flagellar pocket / reservoir (the recurrent flagellum is the one with the more crystalline paraxial rod). This species uses this flagellum to adhere to the substrate as it glides. The ingestion apparatus, with three microtubular rods and four lamella, lies in the lower right part of the cell. The cell surface has folds.

Bright field light micrograph of a cell dried in a suspension of Nigrosin. The stain dries around the cell and in surface irregularities. It therefore shows up the surface folds. The recurrent (trailing) flagellum is the thicker one.

Transmission electron micrograph of a thin section across a fold in the cell surface. Several cytoskeletal elements are associated with the fold. The proteinaceous epiplasm underlies the whole fold, and this is subtended by microtubules. Darker material is associated with the crest of the fold and with the bottom of the fold. the circular structures upper right are sections through extrusomes.

Entosiphon ovatus Stokes,1885. Body ovate, somewhat depressed, a little less than twice as long as wide, rounded posteriorly, narrowed anteriorly, and slightly curved toward the ventral aspect, the frontal border somewhat emarginated on the left side, the cuticular surface traversed by ten or twelve longitudinal sulci, the two flagella inserted near together on the left side of the ingestion organelle, the posterior or trailing appendage about twice as long as the body, the anterior or vibratile not exceeding the body in length, ingestion organelle protrusible, extending backwards for fully four-fifths of the entire length of the body, contractile vacuole single, near the left border of the frontal margin, nucleus spherical, near the centre of the left border. Reproduction by longitudinal fission. Length of body 25-28 microns Probably the same as E. sulcatum.

Ploeotia (plee-owe-sha) a gliding heterotrophic euglenid. One flagellum projects anteriorly and beats with an undulating motion, the posterior flagellum is thickened and trails. The cells are rigid, usually flattened and have a well-developed ingestion apparatus as can be seen here. Cyst. Differential interference contrast.

Ploeotia (plee-owe-sha) a gliding heterotrophic euglenid. One flagellum projects anteriorly and beats with an undulating motion, the posterior flagellum is thickened and trails. The cells are rigid, usually flattened and have a well-developed ingestion apparatus as can be seen here. Dividing cell with duplicated flagella, and ingestion devices. Differential interference contrast.