UCSF

Over the last few decades scientists have often turned to one of a handful of well-established model systems in order to address a number of questions about how all of biology functions. This is absolutely useful and at the time that many of these systems were adopted the state of the art technologies were much more limited, which made it much more efficient to focus on just a few organisms to set the scientific standards. However, recently there have been many advances in technology that have allowed for the relatively quick development of new and interesting model organisms. This should allow scientists to tailor what we are working on with the types of questions we want to address without being limited to the handful of established models. The questions I seek to address are those related to morphogenesis and pattern formation, which are vital processes in any organism whether unicellular or multicellular. But in contrast to the developmental biology of plants and animals, the principles of morphogenesis and pattern formation in single cells remain largely unknown. Although all cells develop patterns, they are most obvious in ciliates; hence I have turned to a classical unicellular model system, the giant Heterotrich ciliate Stentor coeruleus. Here I show that the RNA interference (RNAi) machinery is conserved in Stentor. Using RNAi, I identified the kinase co-activator Mob1 - with conserved functions in cell division and morphogenesis from plants to humans - as an asymmetrically localized patterning protein required for global patterning during development and regeneration in Stentor. During this process I worked in collaboration to sequence and assemble Stentor's macronuclear genome. There is almost no information on Heterotrich genomes and no estimates for gene copy number in Stentor. Using digital droplet PCR, I was able to determine the average contig copy number in Stentor for a handful of loci including the small subunit rDNA gene. Finally, the Stentor genus is amazingly diverse. Different species can vary in size, shape, color, and some even contain algal endosymbionts. I identified sources of five species of wild Stentor near Woods Hole Marine Biological Laboratory and have also included methods and descriptions of these species. I think there is great potential for tapping natural diversity within the Stentor genus to discover new and interesting biology. My work reopens the door for Stentor as a model regeneration system with potential for many other areas of study.