Stayin' Alive (Even Without Oxygen): Retinal Development in <i>Austrofundulus limnaeus</i>

The vertebrate eye is one of the most metabolically active organs in the body and is particularly sensitive to environmental stressors such as oxygen deprivation. Understanding how eye development proceeds under such conditions can provide critical insights into mechanisms of cellular resilience, tissue organization, and developmental plasticity. The annual killifish Austrofundulus limnaeus represents a unique model for investigating these processes due to its remarkable tolerance to anoxia during embryogenesis. However, the wild-type form is heavily pigmented, limiting the effectiveness of traditional imaging techniques for studying eye development. This thesis characterizes eye development and anoxia resilience in both wild-type and melanin-deficient (tyrKO) A. limnaeus embryos. Using a combination of morphological analysis, survival assays, and whole-mount immunohistochemistry, this work demonstrates that the tyrKO line offers enhanced optical access to the developing eye without compromising the species' hallmark stress tolerance. Results show that tyrKO embryos exit diapause earlier than their wild-type counterparts and exhibit significantly increased anoxia survival at intermediate developmental stages. High-resolution imaging reveals improved nuclear and cytoskeletal visualization in tyrKO embryos, although discrete retinal lamination remains unresolved under current conditions. Together, these findings establish the tyrKO line as a powerful new tool for studying vertebrate eye development under extreme physiological stress. This model may also provide a foundation for future studies on retinal diseases linked to hypoxia, including diabetic retinopathy, retinopathy of prematurity, and age-related macular degeneration. This work lays the foundation for future studies on molecular mechanisms of stress adaptation, retinal organization, and developmental resilience in an anoxia-tolerant system.