Presenter(s): Alexander Miller − Biology
Faculty Mentor(s): Bruce Bowerman, Molly Jud
Oral Session 3M
Research Area: Natural/Physical Sciences
Funding: NIH funding, Oregon Undergraduate Researchers in SPUR (OURS) summer scholarship
Our research in the Bowerman laboratory focuses on embryonic morphogenesis in the soil nematode, Caenorhabditis elegans. Morphogenesis is the coordinated movement and shape changes of cells that occur during development in all animals. Defects in this process can cause a variety of human disorders, including neural tube closure, vascular, and
limb developmental defects. My research involves a forward genetic screen for genes required in C. elegans embryonic morphogenesis, utilizing a collection of roughly 1,000 temperature-sensitive embryonic lethal (TS-EL) mutants previously created in the Bowerman laboratory. TS-EL mutants are first terminally phenotyped to identify mutants with penetrant morphogenetic defects, which are then genetically characterized to isolate recessive, loss-of-function, single-mutant alleles. We identify the mutant genes through a combination of SNP-mapping and whole-genome sequencing to find candidate genes, followed by complementation testing with null alleles when available. Mutant strains are sent to our collaborators, the Zhirong Bao laboratory at the Sloan Kettering Cancer Center, for single cell-fate lineaging. This allows us to more accurately distinguish between morphogenesis and cell fate patterning defective mutants. I have terminally-phenotyped nineteen mutants, fourteen of which have penetrant phenotypes (where 70% of embryos display a single phenotype), and genetically characterized six recessive, single mutants. Alleles or388ts and or1113ts have been genetically identified to be mutations in the gene let-19, which is a transcriptional coactivation subunit containing Mediator domains. Allele or542ts is a mutation in the gene chaf-1, a chromatin assembly factor likely regulating gene transcription. Allele or614ts is a mutation in the zwl-1, which codes for a kinetochore protein. While let-19 and chaf-1 fall within the scope of this project, our allele of zwl-1 is probably a weak cell division-defective instead of a morphogenesis-defective mutant, and thus is no longer being studied. Most of the genes we have identified are involved in gene expression regulation, suggesting there is a preexisting gene regulatory program for morphogenesis. Future work is to be done to expand our and the Bao laboratory’s roster of genes known to be required for morphogenesis. This research will help to create a deeper understanding of the basic genetic pathways and cell biological changes required for embryonic morphogenesis in C. elegans, thus improving our comprehension of human development.