Giardia lamblia attachment force is insensitive to surface treatments

Abstract

Giardia lamblia cell populations show 90% detachment from glass under normal forces of 2.43+/-0.33 nN applied by centrifugation. Detachment forces were not significantly different for cells attached to positively charged, hydrophobic, or inert surfaces than for cells attached to plain glass. The insensitivity of attachment force to surface treatment is consistent with a suction-based mechanism of attachment.

FIG. 1.

(A) Attachment of cells to chemically modified glass in comparison to plain glass. Data points are calculated as the fraction of detached cells after centrifugation at a given speed (up to 12,800 × g, or 2.7 nN normal force) compared to the fraction for unspun samples (1 × g). Data from coated surfaces are normalized by plain-glass-surface data from the same day. Error bars indicate standard deviations of mean cell counts over multiple images. No significant difference in cell detachment was observed with positively charged poly-l-lysine-coated (triangles), hydrophobic Teflon-like silane-coated (circles), or inert polyethylene glycol (PEG)-coated (diamonds) glass surfaces in comparison to plain glass (squares). Cell populations showed 50% detachment at forces of 1.81 nN for poly-l-lysine, 1.92 nN for PEG, and 1.92 nN for Teflon-like surfaces. All data fit were fit well by sigmoidal curves, with R² values of 0.96 for plain glass (black line), 0.96 for poly-l-lysine (green line), 0.99 for Teflon (blue line), and 0.94 for PEG (magenta line). (B) Phase-contrast image showing typical cell density of unspun samples. (C) Phase-contrast image showing typical cell density after centrifugation at 12,000 × g. Bar, 100 μm.