Adhesion of Dictyostelium amoebae to deposited langmuir‐blodgett monolayers and derivatized solid surfaces. A study of the conditions which trigger a contact‐mediated cytoplasmic contractile response

The motile behaviour of Dictyostelium amoebae on a variety of solid surfaces has been studied. These included deposited long chain alcohol, acid and glycoside monolayers, as well as glass derivatized with (a) covalent hydrophobic methyl groups (octadecyl glass) and amine groups (amine glass) and (b) an adsorbed polyamino acid. Amoebae spread on all these surfaces, but responded by strong centripetal cytoplasmic retraction, forming an ultrathin lamella on hydrophobic glass and amino glass. An extensive study of the cytoplasmic response on derivatized glass, relating the streaming (zeta) potential of the substratum to bulk pH and ionic strength, showed no simple correlation with the electrostatic properties of the interface. This response may be triggered when the strength of adhesion exceeds a certain threshold value. A tentative model for the transductive events linking cell adhesion to the cytoskeletal response is presented after a consideration of the motile machinery of Dictyostelium amoebae and its activation by external signals.

Key words:

• transducer
• adhesion
• motility
• cytoskeleton
• deposited monolayer
• Dictyostelium amoebae