Polar filament

Polar filament is a unique structure found in the spores of Microsporidia, a group of parasitic fungi. The filament is coiled within the spore and can be rapidly ejected to pierce the membrane of a host cell, allowing the spore to inject its contents into the host.

Structure and Function

The polar filament is a long, tubular structure that is tightly coiled within the spore. It is composed of a series of concentric layers of protein, with the innermost layer forming a hollow tube. The filament is attached at one end to the spore wall, and at the other end to a structure called the anchoring disc, which is located at the tip of the spore.

When the spore comes into contact with a suitable host, the polar filament is rapidly ejected from the spore. This process, known as polar filament extrusion, is triggered by changes in the environment, such as changes in temperature or pH. The filament pierces the membrane of the host cell, creating a conduit through which the contents of the spore, including the infectious sporoplasm, can be injected into the host.

Role in Disease

Microsporidia are responsible for a range of diseases in humans and animals, including microsporidiosis. The polar filament plays a crucial role in the infection process, as it allows the spore to inject its infectious contents into the host cell. This makes the polar filament a potential target for antimicrobial drugs.

See Also

• Microsporidia
• Microsporidiosis
• Parasitic fungi