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 a complex polarized 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 Stentor's 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 many conserved genes involved in centriole assembly and ciliogenesis 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. Materials and Methods Inducing Regeneration and Staging StentorCells were obtained from Carolina Biological Supply and cultured as previously described [20]. Briefly, cells were maintained in Pasteurized Spring Water (Carolina Biological Supply) and fed with Chlamydomonas and wheat seeds. Cells were collected from the same culture for each RNAseq experimental replicate. To induce regeneration, cells were shocked with a 15% sucrose solution for 2 minutes [11], and then washed in Carolina Spring Water thoroughly. Samples of ~20 cells were collected before shock, then at 30 minutes post shock, 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours and 8 hours. At each time point, a sample of cells was lysed into RNA-stabilizing buffers specified by the extraction kit, and then stored on ice until the end of the experiment when the RNA purification was performed in parallel on all samples (see below). 4 replicates were analyzed for each time-point. Total RNA extractionRNA was extracted at each time point using the Nucleospin RNA XS kit from Clontech (cat. num. 740902.250). RNA quality was assessed using a NanoDrop and then Bioanalyzer was used to quantify RNA amount. ERCC spike ins (ThermoFisher cat. num. 4456739) were added to each sample in a dilution ranging from 1:1000 to 1:10000 depending on the initial amount of RNA extracted. RNA-Seq library preparation and sequencingRNA-seq libraries were prepared with Ovation RNA-seq system v2 kit (NuGEN). In this method, the total RNA (50 ng or less) is reverse transcribed to synthesize the first-strand cDNA using a combination of random hexamers and a poly-T chimeric primer. The RNA template is then partially degraded by heating and the second strand cDNA is synthesized using DNA polymerase. The double-stranded DNA is then amplified using single primer isothermal amplification (SPIA). SPIA is a linear cDNA amplification process in which RNase H degrades RNA in DNA/RNA heteroduplex at the 5′-end of the double-st...

Background Stentor coeruleus is a large ciliated protist, about 1mm in length, with the extraordinary ability to fully regenerate each fragment after being cut into pieces, perfectly restoring cell polarity and morphology. Single-cell regeneration in Stentor remains one of the greatest long-standing mysteries of biology, but the recently published Stentor genome now enables studies on this organism at the molecular and genetic levels. Here we characterize the complete complement of kinases, or kinome, of Stentor, in order to begin to understand the signaling capacities that underlie Stentor 's unique biology.

Summary:Nocardia infarction is rare in bone marrow transplant recipients; only 10 cases have been reported. We describe a case of disseminated nocardiosis after allogeneic BMT with positive blood cultures and multiple cerebral and hepatosplenic abscesses.