Recent technological breakthroughs have allowed important advances in the description of deep reefs (below 30 m). However most research has been restricted to the upper section of deep reefs (down to 80 m) and has primarily focused on fish and coral communities. By contrast, the composition of the lower portion of deep reefs, and of non-coral habitat-forming communities remains limited. This work focuses on how the composition and structure of habitat-forming communities change across the entire depth range of a tropical reef-dominated ecosystem, from 5 to 300 m. Using a combination of SCUBA and manned submersible diving, benthic transects were performed in  Curaçao , an island in the Southern Caribbean Sea. Using a combination of morphology, taxonomy, and trait ecology, I will evaluate the faunal breaks of habitat-forming communities with depth. In addition to providing one of the first descriptions of the diversity and community structure of habitat-forming communities across the entire range of a reef’s slope, this work will contextualize over a decade of deep-reef fish observations conducted at this study site. This study will also provide insights into the vertical reef connectivity and resilience, informing future management efforts of deep Caribbean reefs. 

Understanding the structure and habitat preferences of deep-reef fishes is crucial for effective conservation management. Mesophotic ecosystems, occurring between 40 and 150 m, are understudied ecosystems with limited biodiversity assessments, although their importance in supporting species of commercial interest is established.  In particular, very few studies have described mesophotic fish assemblages in the Mediterranean, where essential fish ecosystems face increasing pressures from human activities. This study investigates fish species composition, abundance, and depth distribution at two sites in the Aegean Sea (Eastern Mediterranean).  Fish observations were collected by technical rebreather divers from the surface to 90 meters depth, along with information on habitat and fishing pressure. I will complement this dataset with information collected from the IUCN to identify patterns in species distribution, vulnerability, and habitat associations. This study will provide valuable insights into the community structure and habitat associations of mesophotic fish assemblages, ultimately contributing to conservation strategies that protect vulnerable marine ecosystems in the Mediterranean.

Age-related macular degeneration arises from irreversible photoreceptor loss. Photoreceptors, rods and cones, are specialized cells in the retina that allow light and color detection. My project investigates the role of retinoic acid (RA) on cone and cone-opsin development to understand the timeline of cone specification and development. RA, an endogenously synthesized vitamin A derivative present in the retina during development, drives rod photoreceptor differentiation, but its effect on cone development is still unknown. To understand RA’s role in opsin development, I use a retinosphere (RS) model, an in vitro system to culture human fetal retina. More specifically, I used RS from 70 to 90 days old (D70-D90) and cultured the RS until D100, when the cone-opsin onset occurs. I then fixed, cryosectioned, and immunostained the two conditions for S-opsin, M/L opsin, and NR2E3 (rod marker) and investigated changes in the density of cone opsin-positive cells between the two conditions using confocal microscopy. My findings showed that the condition containing exogenous RA had a decreased density of opsin-positive cells. To confirm that the observed effect is due to RA, I mimic the experiment by instead using WIN18446, an RA inhibitor. I then determined if RA's effects are dose-dependent. My results showed that increasing the concentration of exogenous RA amplified my previous findings. The next step is to understand the timeline of cone specification and development by using RS of a younger age, before cone-opsin onset. These results will allow my mentors and me to use our knowledge about RA to determine if inhibiting endogenous RA synthesis in the retina will play a role in developing therapeutics involving cone regeneration to aid in cone-related macular diseases and injuries.

Retinal cell degeneration is one of the leading causes of blindness and vision loss caused by retinal diseases and is irreversible in humans. However, regeneration of retinal cells occurs after injury in some non-mammalian vertebrates and mimicking these strategies in humans could evolve treatment options for the visually impaired. Previous research in the Reh lab discovered a way to generate new neurons by reprogramming Müller glia (MG), a support cell of the retina, through overexpression of the proneural Ascl1 transcription factor in the mouse retina. To stimulate reprogramming, we used a lentiviral construct with a glial specific promoter (HES1) to drive the expression of ASCL1. However, HES1 represses its own expression by binding specific DNA sequences called N boxes which regulate gene transcription and expression, thus creating a negative feedback loop. In order to limit the negative feedback loop, we designed two new constructs using the HES1 promoter with modifications to the N box sequences. While the current construct has a reprogramming efficiency of approximately 25 percent, the aim of my project is to use constructs with modified N boxes to increase the ratio of MG reprogramming into neurons and verify specificity of the new constructs to MG cells. My research with mouse MG has shown that constructs with N box modifications significantly increase Ascl1 expression as compared to the construct with no modifications. These results seem promising and if reproducible, I will proceed with applying this strategy to human MG by using an in vitro culture system of retinal organoids.