Table 2.
Comparison of the effects of extracellular CaCl2, KCl and a spatial gradient of cAMP on behavior, cell morphology and myosin II localization.
| Parametersa | 0 mM CaCl2 (no cAMP) |
0 mM CaCl2 (cAMP grad.)b |
10 mM CaCl2 (no cAMP) |
10 mM CaCl2 (cAMP grad.)b |
40 mM K+Cl2 (no cAMP) |
|---|---|---|---|---|---|
| Inst. Velocity | 6μm/min | 7μm/min | 14μm/min | 14μm/min | 9μm/min |
| Proportion ≥ 9μm/min | 10% | 15% | 65% | 92% | 45% |
| Persistence | 0.25 | 0.45 | 0.40 | 0.80 | 0.60 |
| Dir. change | 45 deg/4sec | 35 deg/4sec | 30 deg/4 sec | 20 deg/4 sec | 30 deg/4 sec |
| Uropod | no | no | yes | yes | yes |
| Rel. cort. myo II. ant. | 70 | 165 | 100 | 120 | 160 |
| Rel. cort. myo II. post. | 70 | 175 | 150 | 200 | 190 |
| Ratio cort. myo II (post/ant) | 1.0 | 1.1 | 1.6 | 1.7 | 1.3 |
| Ant. ps. form. | 4/10 min | 1/10 min | 4/10 min | 0.2/10 min | n.p. |
| Post. ps. form. | 4/10 min | 3/10 min | 1/10 min | 0.2/10 min | n.p. |
| Chem. index | n.a. | +0.3 | n.a. | +0.8 | +0.7 |
| % pos chem. | n.a. | 80% | n.a. | 95% | 90% |
a
Inst. velocity, instantaneous velocity; Dir. change, directional change; Rel. cort. myo II. ant. or post., relative cortical myosin II anterior or posterior, respectively; Ant. ps. form., anterior pseudopod formation; Post. ps. form., posterior pseudopod formation; Chem. index, chemotactic index; % pos. chem.., percent positive chemotaxis. Average values of parameters have been rounded off.
b
cAMP grad., cAMP gradient.
c
n.a., not available.
d
n.p., not performed.