Thermal Stress Induced Gene Expression During the Maternal-to-Zygotic Transition of the Purple Sea Urchin (Strongylocentrotus purpuratus)

Student: Aiyana Singh

Faculty Mentor: Mackenzie Zippay

Biology

College of Science, Technology, and Business

Marine heatwaves along California's coast have increased in frequency over the last 10 years, causing disturbances to benthic invertebrates that have pelagic embryonic larvae, such as purple sea urchins (Strongylocentrotus purpuratus). During stressful events, molecular chaperones generate a heat shock response (HSR) to combat cellular degradation when an organism is thermally stressed. Heat shock protein 90 (Hsp90) is used to regulate protein folding from stress-induced cell damage caused by thermal and developmental complications. During early development, all embryos pass through the maternal-to-zygotic transition (MZT), where development is driven by the maternal genome until zygotic transcription is activated. In an earlier study, urchin embryos were reared to four different developmental stages at an ambient (13 °C) and elevated (18 °C) temperature, subjected to a 1-hour heat shock, then analyzed for Hsp90 protein abundance. Preliminary data suggest that two-celled embryos reared at 13 °C had significantly lower protein abundance compared to those at early blastula and early gastrula stages, and had higher Hsp90 protein abundance when subjected to a 1-hour heat shock at 22 °C. In contrast, urchins reared at 18 °C were unaffected by any of the heat shock treatments. To capture a complete picture of HSR in developing urchin embryos, I will measure Hsp90 gene expression to identify if the same pattern holds true under thermal stress during the MZT, as gene expression tends to occur at a faster rate, signifying stress earlier. Understanding the impact of warming temperatures on developing larvae may provide information about how marine heatwaves will impact intertidal organisms' survival.