An oblique section of the cell shows the anterior flagellar insertion and the positions of major organelles. Food vacuoles contain ingested bacteria. Extrusomes are small organelles on the cell periphery that have ejectable contents; when viewed at just the right angle, the extrusomes of Jakoba seem to have vase-shaped contents. A single Golgi body/dictyosome lies next to the flagellar bases (not visible in this image).

The single mitochondrion is located next to, and mostly posterior to, the nucleus. The cristae are irregular in shape, sometimes appearing tubular as in the image above, or flattened as in the image at left. The nucleoid is the region of the mitochondrion that contains the DNA. It is not always visible in mitochondria sectioned for the transmission microscope; they can be viewed more reliably in the epifluorescence microscope with suitable dyes.
The cytoskeleton is an asymmetrical system of two flagellar bases, two (or three) ventral microtubular roots, and a dorsal fan of secondary microtubules. The "dorsal fan" microtubule arrangement is also found in Reclinomonas and Histiona. In Malawimonas, the dorsal fan microtubules are subtended by a two-stranded microtubular root arising from the anterior basal body. The left ventral root is associated with a multilayered structure, as in Reclinomonas and Histiona but not Malawimonas. Most of the microtubules that form the floor of the ventral groove come from the left ventral root, again as in Reclinomonas and Histiona but not Malawimonas, in which most of the ventral groove microtubules comes from the right root.
The posterior flagellum possesses a conspicuous and characteristic flagellar vane. This vane arises on the dorsal surface of the flagellum as in Reclinomonas (from which this figure is taken) and Histiona; in Malawimonas, the vane arises on the ventral surface.

Return to summary information