Lepidosomes acquire fluorescence after encystation: Including additional notes of morphological events during encystation and reconsideration of the morphological features in the ciliate Colpoda cucullus

摘要

The resting cyst formation (encystment) is a survival strategy against environmental stressors, and is found in many species of single-celled eukaryotic organisms. The process incorporates cell differentiation accompanied by drastic morphological changes. This study presents observation via fluorescence microscopy on the encystation process of Colpoda cucullus. We confirmed that C. cucullus, which was identified by 18S rRNA analysis, contains lepidosomes, which are cyst-specific cell structures. Theexistence of these structures in Colpoda species is controversial at present, so we present background information concerning the controversy. Moreover, we reveal that lepidosomes acquire autofluorescence after formation, that is，encysting cells containlepidosomes lacking autofluorescence while mature cysts contain lepidosomes exhibiting autofluorescence. In addition, we describe the process of formation of nuclear surrounding particles (NSPs), which are cyst-specific cell structures.