Gliding Velocity of Euglena mutabilis Can Fluctuate over Tenfold

Abstract

Euglena are unicellular, photosynthetic flagellates that can move toward and away from light. While many Euglena swim, Euglena mutabilis lacks an external flagellum and relies on metaboly, or contractile movements, and gliding for cell locomotion. Although the exact mechanism of the gliding phenomenon is unknown, some studies have proposed that E. mutabilis utilize metaboly to glide; in our laboratory, however, gliding has been observed independent of metaboly. To provide a more detailed description of this motility, nonstop gliding at constant velocity was observed using an inverted microscope. From our preliminary observations of a strain isolated from a pristine North Idaho lake, the slowest velocities observed were close to 1 mm/s whereas some cells moved considerably faster in a range of 5 to 7 mm/s; a small number of cells moved even faster at speeds up to 12 mm/s. In addition, cells were observed to change their gliding velocities to move faster or slower, suggesting that each cell has the ability to regulate its gliding machinery. We are now prepared to do similar analyses of gliding in extremophilic E. mutabilis strains that have been isolated from toxic environments like acid mine drainage