Chapter 13
Measurement of the Cell-Body Rotation of Leptospira
Shuichi Nakamura
Abstract
Leptospira spp. swim in liquid and crawl on surfaces with two periplasmic flagella. The periplasmic flagella
attach to the protoplasmic cylinder via basal rotary motors (flagellar motors) and transform the ends of the
cell body into spiral or hook shape. The rotations of the periplasmic flagella are thought to gyrate the cell
body and rotate the protoplasmic cylinder for propelling the cell; however, the motility mechanism has not
been fully elucidated. Since the motility is a critical virulence factor for pathogenic leptospires, the kinematic
insight is valuable to understand the mechanism of infection. This chapter describes microscopic methodologies to measure the motility of Leptospira, focusing on rotation of the helical cell body.
Key words Leptospira, Motility, Cell-body rotation, Rotation speed, Image analysis, Bead assay
1 Introduction
1.1 Background
Leptospira spp. have a thin (~0.14 μm in diameter), long (~10 μm in
length), helical cell body with the helix pitch of ~0.7 μm and the
helix diameter of ~0.2 μm. Two short flagella (~3 μm in length)
reside within the periplasmic space, so-called periplasmic flagella
(PFs), one PF per each cell end (Fig. 1). The PFs isolated from cells
show coiled shape, and the existence of the curved and quasi-rigid
PF within the periplasmic space results in bending of both ends of
the cell body into spiral or hook shape. Leptospira spp. not only
swim in liquids but also crawl on surfaces [1, 2]. Swimming
involves gyrations of the spiral-shaped anterior (spiral-end) and
hook-shaped posterior end (hook-end) and rolling of the shortpitch cell body (protoplasmic cylinder, PC) [3, 4]. When Leptospira
spp. crawl, the PC rolling propels the spirochete attached to a solid
surface, to which gyrations of spiral-end and hook-end hardly
contribute [2]. The shapes of the cell end frequently change
between spiral shape and hook shape (Fig. 2). When both ends
show the same morphology (“spiral-spiral” and “hook-hook” in
Fig. 2), the cell rotates but does not migrate.
Nobuo Koizumi and Mathieu Picardeau (eds.), Leptospira spp.: Methods and Protocols, Methods in Molecular Biology, vol. 2134,
https://doi.org/10.1007/978-1-0716-0459-5_13, © Springer Science+Business Media, LLC, part of Springer Nature 2020
139
Measurement of the Cell-Body Rotation of Leptospira
Shuichi Nakamura
Abstract
Leptospira spp. swim in liquid and crawl on surfaces with two periplasmic flagella. The periplasmic flagella
attach to the protoplasmic cylinder via basal rotary motors (flagellar motors) and transform the ends of the
cell body into spiral or hook shape. The rotations of the periplasmic flagella are thought to gyrate the cell
body and rotate the protoplasmic cylinder for propelling the cell; however, the motility mechanism has not
been fully elucidated. Since the motility is a critical virulence factor for pathogenic leptospires, the kinematic
insight is valuable to understand the mechanism of infection. This chapter describes microscopic methodologies to measure the motility of Leptospira, focusing on rotation of the helical cell body.
Key words Leptospira, Motility, Cell-body rotation, Rotation speed, Image analysis, Bead assay
1 Introduction
1.1 Background
Leptospira spp. have a thin (~0.14 μm in diameter), long (~10 μm in
length), helical cell body with the helix pitch of ~0.7 μm and the
helix diameter of ~0.2 μm. Two short flagella (~3 μm in length)
reside within the periplasmic space, so-called periplasmic flagella
(PFs), one PF per each cell end (Fig. 1). The PFs isolated from cells
show coiled shape, and the existence of the curved and quasi-rigid
PF within the periplasmic space results in bending of both ends of
the cell body into spiral or hook shape. Leptospira spp. not only
swim in liquids but also crawl on surfaces [1, 2]. Swimming
involves gyrations of the spiral-shaped anterior (spiral-end) and
hook-shaped posterior end (hook-end) and rolling of the shortpitch cell body (protoplasmic cylinder, PC) [3, 4]. When Leptospira
spp. crawl, the PC rolling propels the spirochete attached to a solid
surface, to which gyrations of spiral-end and hook-end hardly
contribute [2]. The shapes of the cell end frequently change
between spiral shape and hook shape (Fig. 2). When both ends
show the same morphology (“spiral-spiral” and “hook-hook” in
Fig. 2), the cell rotates but does not migrate.
Nobuo Koizumi and Mathieu Picardeau (eds.), Leptospira spp.: Methods and Protocols, Methods in Molecular Biology, vol. 2134,
https://doi.org/10.1007/978-1-0716-0459-5_13, © Springer Science+Business Media, LLC, part of Springer Nature 2020
139