Proteomic identification and expression of oral apparatus constituents in cell regeneration of giant ciliate Stentor coeruleus (strain WHEL)

Abstract Background The giant ciliate Stentor coeruleus is a suitable model organism for studying morphogenesis and regeneration at the single-cell level. The anterior end of the cell is dominated by thousands of cilia organized into a ciliated band of membranelles, known as the oral apparatus (OA). This feeding organelle can be induced to shed by urea treatment. The OA then regenerates via a series of defined morphological events and the cell resumes normal feeding activity. These defined events provide an ideal opportunity to identify the protein constituents of OA and their expression patterns in OA regeneration. Results We identified OA constituents in S. coeruleus by mass spectrometry. A total of 882 OA-associated proteins were identified; the homologs of 181 of these are known OA constituents in other organisms. The expression pattern of OA-associated genes during regeneration was investigated using single-cell transcriptome sequencing. The expression of most OA-associated genes was high during regeneration, indicating their stable expression after OA shedding. We also identified OA-associated differentially expressed genes that may be involved in regulating OA reconstruction. This information enabled us to hypothesize the architecture of OA of S. coeruleus WHEL. Conclusions We have identified protein components of the OA and determined the temporal changes in their expression during OA regeneration in S. coeruleus WHEL. Although our results are preliminary, they form the basis of further studies into the molecular mechanisms of OA development in S. coeruleus. In addition, as S. coeruleus is an important model organism for studying morphogenesis, our findings may help to improve the understanding of OA formation in ciliates.