UCL Discovery

Abstract

Observations of surface microlayer material collected from freshwaters demonstrate its ability to assemble rapidly at the water-air interface following experimental disruption. This property is exploited to provide a means for studying and manipulating the in situ locomotory behaviour of some surface microlayer amoebae (Acanthamoeba, Naegleria, Vannella) under laboratory conditions. Amoeboid movement is substratum-dependent and so it is important to know the means by which these organisms attach to a water-air interface. Reflection interference microscopy (RIM) demonstrates that during locomotion Vannella adheres to a glass coverslip by means of an unstable platform, of associated contact (parallel to, but similar to100-nm off it) within which stable, focal contacts form attaching to the substratum. These two key features of cell-substratum interactions occur also in Acanthamoeba and Naegleria. Direct examination of cell-substratum interactions during amoeboid movement at the water-air interface by RIM proves that the associated contact is also established here.