Contractile fibers in the ciliated protozoan Vorticella convallaria

The ciliated protozoan Vorticella convallaria possesses a highly contractile cytoskeleton and is a good model system to study mechanochemical motility. Since calcium triggers this contraction, we have undertaken the molecular characterization of the calcium-binding proteins (CBP) associated with these organelles. We have identified a multi-gene family of CBP and have isolated and identified seven unique centrin-like cDNAs from V. convallaria. Each encodes an acidic protein of approximately 20-kDa, containing a unique N-terminus and four potential calcium-binding domains. We predict each centrin has a distinct function within the cell. To define these functions, we have initiated immunofluorescence and immunolocalization studies at the ultrastructural level utilizing various anti-centrin antibodies. This image shows labeling with anti Vc Centrin 4 antibody. This polyclonal antibody localizes to the longitudinal myonemes in the cell body. The labeling of the oblique myonemes surrounding the oral apparatus is especially pronounced. Scale bar = 10 micrometers. The image was taken using Zeiss Axiovision Scope.