Environmental stressors trigger physiological adaptations in organisms that allow them to dynamically remodel tissues. As many of these processes in the gastrointestinal tract of Drosophila melanogaster are studied in the context of stem cell proliferation, we instead chose the novel approach of investigating visceral muscle adaptations in response to stressors to the gut. The three stress conditions we employed were starvation, damage, and aging. For starvation, we treated adult flies with only water following nutrient-enriched recovery. For epithelial damage, we fed them with the chemical damaging agent, bleomycin. Finally, for aging, the flies were subjected to different prolonged time periods on normal media. The flies were then dissected and processed for confocal imaging and phenotypic analysis, allowing us to categorically define and quantify the phenotypes in order to measure the degree to which the visceral muscle has changed. We discovered that various responses of the visceral muscle are induced by the types of stressors, and will further look into whether it is adaptive remodeling, muscle repair, or other undescribed mechanisms. We will investigate the molecular mechanisms that contribute to the remodeling of the visceral muscle using RNAi approach. This research would provide valuable resources as a model system for studying complex tissue responding to environmental challenges and understanding of its mechanisms utilizing the vast genetic tools of Drosophila.

Osteoporosis is an orthopedic disease in which old bone begins to dissolve, but is not replaced by new bone. This reduces overall bone density and increases a patient’s risk for fractures. Our lab studies genes that contribute risk to osteoporosis. One human gene associated with osteoporosis is WNT16, which is also expressed in zebrafish. Previously, we mutated the wnt16 gene at four different sites to produce a range of skeletal phenotypes. These studies show that wnt16 mutant fish have skeletal defects. The aim of my project was to find how wnt16 influenced spine segmentation in mutant zebrafish. Through GNOMAD, a Genome Aggregation Database, I collected data on the types of mutations that naturally occur in human Wnt genes. Across all human Wnts, there was no strong bias for stop-gained mutations in the terminal coding exon; however, in WNT16, stop-gained mutations were underrepresented in the terminal coding exon, which was of interest. Using CRISPR-based gene editing, we used a guide RNA to mutate the terminal coding exon in zebrafish wnt16 and found a range of severe skeletal abnormalities along the spine. Segmentation of the wnt16 mutant zebrafish was disrupted compared to the controls. I determined how wnt16 influenced segmentation of the spine by quantifying centrum fusions and other morphological abnormalities in these mutant zebrafish. Our results implicate the wnt16 gene as essential for spine morphology and contributes to understanding human phenotypes of osteoporosis.