# Structural and molecular determinants of duplex functionality in a pure-rod retina

> **NIH NIH SC2** · SAN FRANCISCO STATE UNIVERSITY · 2021 · $146,750

## Abstract

PROJECT SUMMARY/ABSTRACT:
 Proper function in the duplex retina depends on the utilization of rods and cones in the processing of
visual information across the scotopic and photopic ranges of illumination. Importantly, when either type of
photoreceptor is lost during retinal degeneration, the remaining photoreceptors, be they rods or cones, cannot
perform the function of the opposite cell type. Most vertebrate retinae have this “duality” barrier and many
current vision restoration efforts are targeted towards replacing the lost photoreceptor population. However, the
elasmobranch L. erinacea (Little skate) has a pure-rod simplex retina, which can function under scotopic and
photopic illumination. We have a poor understanding of what factors govern this remarkable plasticity in the
skate retina, but a detailed knowledge of how this is achieved could hold the key to expanding the functional
repertoire of surviving rods or cones in diseased duplex retinae. We propose that the skate retina exhibits a
number of hybrid features on the molecular and ultrastructural levels that mediate its functional plasticity.
Furthermore, our preliminary data leads us to two main hypotheses: 1) Skate rods function under scotopic and
photopic conditions through a combination of morphological adaptations at the level of the synaptic terminal,
and genetic adaptations at the level of opsin expression; and: 2) The skate retina exhibits multiple adaptions in
the cell circuitry downstream of rods in order to accommodate for their functional plasticity. We have based
these predictions on several pieces of preliminary data. First, a long-wavelength sensitive opsin (LWS) can be
detected in the global genome of the skate. Second, multiple hybrid features are present at the ultrastructural
level in the synaptic terminals of the skate rods. Third, there is a 3-fold increase in the number of postsynaptic
processes that invaginate into a skate rod terminal, compared to rods from duplex retinae. Therefore, we will
test our hypotheses in the following specific aims: Aim 1: To analyze differences in gene expression in light-
and dark-adapted pure-rod retinae and uncover molecular mechanisms of functional plasticity. The objective of
Aim 1 is to determine what molecular factors mediate this unusual functional plasticity. Aim 2: To determine
the contribution of cell- and circuit-level structural and physiological characteristics mediating functional
plasticity in a pure-rod retina. The objectives of Aim 2 are to determine if skate rods posses ultrastructural
elements that mediate their functional plasticity, and if the retinal circuitry downstream of rods has evolved
specific structural and physiological attributes in order to accommodate for a wider range of inputs. The
proposed research is innovative because the simplex skate retina has evolved naturally to the present state
and allows us the unique opportunity to study and describe the properties of rod circuitry within the context of
...

## Key facts

- **NIH application ID:** 10334306
- **Project number:** 1SC2GM144198-01
- **Recipient organization:** SAN FRANCISCO STATE UNIVERSITY
- **Principal Investigator:** Ivan Anastassov
- **Activity code:** SC2 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2021
- **Award amount:** $146,750
- **Award type:** 1
- **Project period:** 2021-09-21 → 2024-06-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10334306

## Citation

> US National Institutes of Health, RePORTER application 10334306, Structural and molecular determinants of duplex functionality in a pure-rod retina (1SC2GM144198-01). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/10334306. Licensed CC0.

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