The ciliate Stentor coeruleus is a remarkable cell–individuals can reach up to 1 mm in length and exhibit great subcellular complexity, including its beautiful wineglass shape. Stentor additionally has incredible regenerative abilities: almost any portion of the cell, when removed through excision, will give rise to a normally proportioned cell with intact subcellular organization. Pioneering studies of Stentor elucidated morphological principles of its regeneration (Morgan, 1901; Tartar, 1961), but we know little about the molecular basis of Stentor’s regenerative and healing abilities. In general, little is known about regeneration and healing at the level of an individual cell. Because of its large size and its subcellular coordinate system where the anterior and posterior are clearly marked by the oral apparatus and holdfast, respectively, Stentor is a very useful system for understanding single cell regeneration and wound repair.
We have recently sequenced and annotated the genome of Stentor coeruleus, which will serve as a foundation for future molecular studies. I am currently using RNA-seq to study the transcriptional dynamics underlying the regeneration of the oral apparatus (OA), one of the most prominent features of the cell and a complex organelle composed of thousands of cilia. Upon subjecting cells to sucrose shock, the OA is induced to shed, and 8 hours later a new one forms. We show that genes are organized into five groups of gene expression with distinct temporal signatures, corresponding to the known morphological changes taking place during OA regeneration. During the earliest waves of gene expression, conserved genes involved in centriole production and ciliogenesis are expressed, necessary to replace the OA. Also during these earliest stages, genes involved in RNA metabolism are expressed, including Pumilio, suggesting the requirement for large scale transcriptome alteration through regeneration. The detailed transcriptional time course, in combination with RNAi manipulations, will further reveal the genetic networks that regulate OA regeneration, and will help elucidate the fundamental principles of cell regeneration and healing at the scale of a single cell.