Movement of antibody-coated latex beads attached to the spirochete Leptospira interrogans.

Abstract

Antibody-coated latex beads (Ab-beads) were attached to Leptospira interrogans serovars iMini 3055 and icterohaemorrhagiae SC1157. The movement of the Ab-beads relative to the motion of the cells was observed by direct darkfield microscopy or was recorded on videotape. When the Ab-beads were attached to the front end of motile cells, the Ab-beads were displaced towards the back end of the cells. When the cells reversed direction, the Ab-beads also reversed direction. A number of hypotheses were proposed and tested to account for this Ab-bead displacement. The one best supported by the evidence states that the Ab-beads are attached to antigens of the outer membrane sheath. These antigens are dragged laterally through the sheath due to the forward motion of the cells and the retarding forces of the medium acting on the beads. The results obtained provide information on the nature of the outer membrane sheath of L. interrogans, the basis for certain movements of spirochetes, and insight on how spirochetes attach to eukaryotic cells and tissues. In addition, the results indicate that antigens can move laterally through membranes as rapidly as 11 ,tm/sec. Leptospira interrogans is a spirochete with a well-characterized ultrastructure and a unique mode of motility. Outermost is an outer membrane sheath (OS), and within this sheath is the righthanded helical cell cylinder and two axial filaments (AF) (1-4). Each AF is subterminally attached to the cell cylinder, and genetic evidence suggests that the AFs are directly involved in motility (5). On the basis of this and other evidence, a motility model was proposed which states that rotational motors at the base of the AFs propel the organisms in a manner analogous to the flagella of rod-shaped bacteria (6).In the course of testing this motility model, we coated latex beads with antibodies directed to whole cells (Ab-beads) and attached these Ab-beads to swimming cells. Our goal was to track the rotational movement ofthe Ab-beads as the cells swam in a given direction. However, we were surprised to find that when Ab-beads were attached to the front end ofthe cells they were rapidly displaced along the length ofthe cells until the Abbeads reached the back end. The Ab-beads reversed direction as the cells reversed direction. These and related motions of cells and the attached Ab-beads were recorded on videotape, and tracings from these tapes are presented in this communication. The results suggest that the Ab-beads are attached to antigens ofthe OS. These antigens are dragged laterally through the OS to the back end of the cells due to the forward motion of the cells and the retarding forces of the medium acting on the beads. EXPERIMENTAL PROCEDURES Bacteria. L. interrogans serovar illini 3055 (referred to as serovar illini), and the linear motility mutants DB115, DB218, DB290, and DB340 derived from serovar illini have been described (5). These linear mutants lack the hook-and spiralshaped ends typical of wild-type serovar illini; they are also deficient in both t...

Morphology and dynamics of protruding spirochete periplasmic flagella

“…4). These motions are reminiscent of the movement of antibody-coated latex beads attached to members of the Leptospiraceae (14,16,22) and indicate that protrusions have a fluid surface. They are also consistent with the notion that PFs are surrounded by an outer membrane sheath.…”

“…To estimate the frequency of cell protrusions, we examined 30 cells by dark-field microscopy at several time points during a growth curve and determined the fraction of cells with protrusions at one or both ends. In certain instances, methylcellulose was added to the medium (4,16,24).…”

A model for transcellular transport of calcium based on membrane fluidity and movement of calcium carriers within the more fluid microdomains of the plasma membrane

“…A relatively recent observation shows that lateral "qntramembrane" movement occurs at remarkably rapid rates. Charon et al [25] have shown that the movement of a molecule within the plasma membrane can occur within the substance of the membrane at the rate of 10-14 microns per second. The degree of fluidity demonstrated by the experiments of these authors needs to be regarded as a general property of biological membranes, provided that they possess the appropriate kinds of phospholipids.…”

Multiple-exposure photographic analysis of a motile spirochete.

“…Cell motions were slow enough not to be confused with stroboscopic effects. Because these cells are immobilized by strong blue light (18,27,28), observations were made at low-light intensities, usually using a yellow-green filter.…”