Hypoxia

The distribution and intensity of hypoxia (low dissolved oxygen, DO) is increasing due to eutrophication and algal blooms in estuaries like those in the Gulf of Mexico and the Indian River Lagoon. The objective of this study is to determine how low DO affects the development and lipid utilization of the Florida Pompano (Trachinotus carolinus) and Red Drum (Sciaenops ocellatus). Fertilized eggs were incubated in two DO hypoxia treatments: severe (20% DO saturation, 1.6 mg/L), moderate (50% DO saturation, 3.9 mg/L), and normoxia (100% DO saturation, 7.6 mg/L). Eggs and larvae were sampled at 24-hours post-fertilization to assess hatch survival, larval development, and fatty acid (FA) lipids utilization. Results suggest hypoxia significantly impacts Florida Pompano development, with polar FAs most affected, while Red Drum shows greater tolerance to low DO. These findings provide insight into early fish larval stages to improve conservation and management strategies for their recruitment.

The ocular lens is comprised of an epithelial cell population that undergoes a continuous process of cellular remodeling and differentiation to form elongated transparent fiber cells. This lens differentiation process is hallmarked by the complete elimination of organelles at the center of the lens, elongation of lens fiber cells, and production of lens fiber-cell specific crystallin proteins to form the mature functional structure of the transparent ocular lens. To date, our understanding of the mechanisms that drive the lens differentiation process is incomplete. This dissertation sought to elucidate the potential roles of both hypoxia and epigenetic chromatin remodeling processes as novel regulators of lens differentiation.
The lens lacks a direct blood supply and thus resides in a hypoxic microenvironment. Previous studies revealed the presence of a decreasing oxygen gradient in the region of the lens where cellular remodeling and organelle elimination occur to form mature transparent lens fiber cells. Thus we hypothesized that the hypoxic environment of the lens itself, was required to induce gene expression changes to drive the lens differentiation process. We utilized a multimoics analysis combining CUT&RUN and RNAseq high-throughput sequencing technologies to identify a role for the hypoxia-inducible transcription factor HIF1a as a novel regulator of lens gene expression during lens differentiation.