Abstract
Author SummaryCells have the ability to develop complex morphologies, but the mechanisms that determine these varied shapes are not well understood. Cell shape determination can be challenging to study in multicellular organisms because it can be difficult to know whether shape changes are determined internally within an individual cell or externally, driven by input from neighboring cells or by both. The giant unicellular ciliate, Stentor coeruleus, provides an ideal single-cell model in which to study morphogenesis due to its large size and reproducible, complex patterning. Although Stentor was a popular experimental organism around 100 years ago, molecular tools were not subsequently developed to sustain its use as a model system today. Here we demonstrate that RNA interference (RNAi) “by feeding” is effective in Stentor and demonstrate its utility for studying morphogenesis and cell polarity patterning in this organism. We show that the conserved Mob1 kinase regulator protein is asymmetrically localized to the posterior end of Stentor and is positioned at the newly forming posterior pole during cell division, suggesting that it may have a role in morphogenesis. Using RNAi, we show that depletion of Mob1 results in Stentor cells with marked defects in morphogenesis. Our findings suggest that Stentor coeruleus can be a powerful model system studying morphogenesis and regeneration at the single-cell level and that Mob1 is a patterning protein required for its normal development and regeneration.
Highlights
The ability to develop and regenerate complex morphologies from a simpler starting point is among the properties that set living organisms apart from inanimate matter
Cell shape determination can be challenging to study in multicellular organisms because it can be difficult to know whether shape changes are determined internally within an individual cell or externally, driven by input from neighboring cells or by both
We demonstrate that RNA interference (RNAi) ‘‘by feeding’’ is effective in Stentor and demonstrate its utility for studying morphogenesis and cell polarity patterning in this organism
Summary
The ability to develop and regenerate complex morphologies from a simpler starting point is among the properties that set living organisms apart from inanimate matter. These processes are most often considered in the context of embryos and multicellular organisms, even individual cells need to develop and regenerate after injury. Metazoan development is conceptually straightforward, in that organisms rely on the existence of numerous individual cells that differentiate into various cell types with specialized functions, thereby creating the complex architecture of the larger organism. The process of regeneration mimics that of morphogenesis, so a single-cell model for regeneration could be a very powerful tool For this reason, we turned to the large ciliate Stentor coeruleus (,1 mm long). Perhaps the most striking property of Stentor is that it has the ability to regenerate an entire normal organism from only a fraction of the original cell
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