Identification of actin filaments in the rhabdomeral microvilli of Drosophila photoreceptors

• Published in: The Journal of cell biology 1990-06, Vol.110 (6), p.1993-1998
• Main Authors: Arikawa, K. (Indiana University, Bloomington, IN), Hicks, J.L, Williams, D.S
• Format: Article
• Language: English
• Subjects: actin; Actin Cytoskeleton - metabolism; Actin Cytoskeleton - ultrastructure; Actins; Actins - immunology; Actins - metabolism; Analytical, structural and metabolic biochemistry; Animals; Antibodies - immunology; Astacoidea; Biological and medical sciences; Cell membranes; CELL STRUCTURE; Cells; Contractile proteins; Cytoplasm; CYTOSKELETON; Cytoskeleton - metabolism; Cytoskeleton - ultrastructure; Diptera; DROSOPHILA; Drosophila melanogaster - anatomy & histology; Drosophila melanogaster - cytology; Drosophilidae; Epithelial cells; ESTRUCTURA CELULAR; Fundamental and applied biological sciences. Psychology; Holoproteins; Immunohistochemistry - methods; Intestinal Mucosa - metabolism; Intestines - cytology; Intestines - ultrastructure; Microfilaments; Microscopy, Electron - methods; Microvilli; Microvilli - metabolism; Microvilli - ultrastructure; Myosin Subfragments - metabolism; ORGANE DES SENS; ORGANOS SENSORIALES; Phalloidine; Photoreceptor Cells - metabolism; Photoreceptor Cells - ultrastructure; Photoreceptors; PROTEINAS; PROTEINE; PROTEINS; rhabdomeres; Rhodamines; SENSE ORGANS; STRUCTURE CELLULAIRE
• ISSN: 0021-9525; 1540-8140
• DOI: 10.1083/jcb.110.6.1993

The phototransductive microvilli of arthropod photoreceptors each contain an axial cytoskeleton. The present study shows that actin filaments are a component of this cytoskeleton in Drosophila. Firstly, actin was detected in the rhabdomeral microvilli and in the subrhabdomeral cytoplasm by immunogold labeling with antiactin. Secondly, the rhabdomeres were labeled with phalloidin, indicating the presence of filamentous actin. Finally, the actin filaments were decorated with myosin subfragment-1. The characteristic arrowhead complex formed by subfragment-1 decoration points towards the base of the microvilli, so that the fast growing end of each filament is at the distal end of the microvillus, where it is embedded in a detergent-resistant cap. Each microvillus contains more than one actin filament. Decorated filaments extend the entire length of each microvillus and project into the subrhabdomeral cytoplasm. This organization is comparable to that of the actin filaments in intestinal brush border microvilli. Similar observations were made with the photoreceptor microvilli of the crayfish, Procambarus. Our results provide an indication as to how any myosin that is associated with the rhabdomeres might function.