Take a virtual tour of the African Trypanosome Cytoskeleton.

Each image in the tour has links that will take you to another image that further describes the cytoskeleton. Clicking on the numbers in each image will take you a textual description of that structure. Have a nice tour.  

A unique feature of the trypanosome cytoskeleton is that upon membrane extraction with non-ionic detergents (e.g. Nonidet P40, Triton X100), the entire cytoskeleton of the cell remains in-tact. The extracted cytoskeletons can be separated from the detergent insoluble material by centrifugation. Pictured above is an idealized drawing of how a detergent extracted cytoskeleton appears under the microscope. 

The Trypanosome cytoskeleton consists primarily of microtubule-based structures, which can be both physically and conceptually divided into two fractions, "the subpellicular fraction" and "the flagellar fraction".  (1) The subpellicular fraction consists of the interlinked microtubule corset that subtends the plasma membrane along the entire body of the cell . All of the microtubules in the subpellicular corset are oriented with their fast (+) ends at the posterior tip of the cell and their slow (-) ends at the anterior tip of the cell.  There are no microtubules that traverse the cytoplasm of the cell.  Thus, it is the cage of subpellicular microtubules that give the trypanosome its characteristic shape. 

The density of the corset that subtends the plasma membrane is thought to limit all membrane scission and fusion events to a specialized organelle called the flagellar pocket. (3) The flagellar pocket is formed by an invagination of the plasma membrane where the flagellum emerges from the cell body. The flagellar pocket is free of obstructing subpellicular microtubules and has many specialized cytoskeleton-associated features that allows it to serve as a  port of entry and exit to the cell.  Although the flagellar pocket is a critical organelle in the biology of a trypanosome, very little is currently known about how molecules get to and from the flagellar pocket to the rest of the cell. To learn more about the cytoskeletal structures in the flagellar pocket region click here or on the image above.

 The flagellum (2), which is responsible for cellular motility, emerges from the cell body at the flagellar pocket. The flagellar axoneme originates from the basal body complex and is oriented with the fast (+) end of the axoneme microtubules at the anterior end of the cell (opposite orientation to the subpellicular microtubules). The flagellum is anchored to the cell body by a series of the complex structures, the paraflagellar rod (PFR), the flagellum attachment zone (FAZ) filament, and uncharacterized inter-membrane cross links. To learn more about the flagellum click here or on the image above.

(1)  The Subpellicular Microtubule Corset: The interlinked microtubules that subtend the plasma membrane. All microtubules in the corset are oriented in the same direction with their plus ends at the posterior end of the cell. The subpellicular microtubules are attached to each other and to the plasma membrane by cross links. These microtubules are resistant to detergent extraction but depolymerize in the presence of calcium ions or high salt.

(2)  The Flagellum: The membrane enclosed structure that provides the force to make the cell motile. The flagellum emerges from the cell body at the posterior end of the cell and is attached to the cell body via specialized structures called the paraflagellar rod and flagellum attachment zone. The movement of the flagellum is provided by the sliding motion of specialized microtubule doublets that comprize the flagellar axoneme. To learn more about these structures, click HERE.

(3) The Flagellar Pocket: The flagellar pocket is formed by an invagination in the plasma membrane where the flagellum emerges from the cell body. To learn more about the flagellar pocket, click HERE.