Sood, P. | bioRxiv Science

bioRxiv2017

The Transcriptional Program of Regeneration in the Giant Single Cell, Stentor coeruleus

The giant ciliate Stentor coeruleus is a classical model system for studying regeneration and morphogenesis at the level of a single cell. Stentor are polarized cells with a complex subcellular architecture. The anterior of the cell is marked by an array of cilia, known as the oral apparatus. This feeding organelle can be induced to shed and regenerate in a series of reproducible morphological steps, previously shown to require transcription. We used RNAseq to assay the dynamic changes in Stentos transcriptome during regeneration with high temporal resolution, allowing us to identify five distinct waves of gene expression. We show that the oral apparatus is a model for organelle regeneration, as well as for centriole assembly and ciliogenesis as many conserved genes involved in those processes are induced. Additionally, we find genes involved in signaling, cell cycle regulation, transcription, and RNA binding to be expressed at distinct stages of organelle regeneration, suggesting that the morphological steps of regeneration are driven by a complex regulatory system.

cell biology↗

bioRxiv2017

Cargo crowding at actin-rich regions along axons causes local traffic jams in neurons

Steady axonal cargo flow is central to the functioning of healthy neurons. However, a substantial fraction of cargo in axons remains stationary across a broad distribution of times. We examine the transport of pre-synaptic vesicles (pre-SVs), endosomes and mitochondria in C. elegans touch receptor neurons (TRNs), showing that stalled cargo are predominantly present at actin-rich regions along the neuronal process. Cargo stalled at actin-rich regions increase the propensity of moving cargo to stall at the same location, resulting in traffic jams. Such local traffic jams at actin-rich regions are likely to be a general feature of axonal transport since they occur in Drosophila neurons as well. These traffic jams can act as both sources and sinks of vesicles. We propose that they act as functional reservoirs that contribute to maintaining robust cargo flow in the neuron.

cell biology↗