# Mechanisms of Visual Transduction

> **NIH NIH R01** · UNIVERSITY OF CALIFORNIA AT DAVIS · 2021 · $424,976

## Abstract

Project Summary
 Human vision operates over a billion-fold range of light intensities ranging from starlight
to bright daylight, with night vision subserved by retinal rod photoreceptor cells, and day vision
by cone photoreceptor cells. Rods and cones mediate the first steps in vision by capturing light
in their G-protein coupled receptors Rhodopsin, and L/M and S-cone opsins, respectively,
whose activation then generates electrical responses through homologous G-protein-coupled
receptor signaling cascades. While the molecular mechanisms that underlie the rod's ability to
signal in dim light are now well understood, the mechanisms that enable some cones (but not
rods) to function in bright daylight are relatively poorly understood. Using non-invasive optical
and electroretinographic methodology applicable to humans, the proposed work proposed will
investigate cone and rod function in vivo under daylight conditions, testing hypotheses about the
mechanisms that allow cones expressing only M-opsin to operate in bright light, while cones
expressing only S-opsin, and rods do not, and to understand how the very abundant, non-
signaling rods cope with the enormous stress that daylight makes on their molecular machinery.
Among key resources for the project are cone-monochromat mice created by the author and his
collaborators, which only express one cone opsin, and adaptive-optics (AO) optical coherence
tomography (OCT) and scanning laser ophthalmoscopy (SLO) customized and calibrated for
precisely controlling the quantity of light captured by each of the mouse opsins. The work in this
project addresses a fundamental need for in vivo studies of cone and rod function in daylight
conditions, to establish cellular and molecular mechanistic foundations that support and
interpret the signal advances in AO imaging of human cones and rods.

## Key facts

- **NIH application ID:** 10104498
- **Project number:** 5R01EY002660-41
- **Recipient organization:** UNIVERSITY OF CALIFORNIA AT DAVIS
- **Principal Investigator:** Edward N Pugh
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2021
- **Award amount:** $424,976
- **Award type:** 5
- **Project period:** 1978-08-01 → 2023-02-28

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10104498

## Citation

> US National Institutes of Health, RePORTER application 10104498, Mechanisms of Visual Transduction (5R01EY002660-41). Retrieved via AI Analytics 2026-05-22 from https://api.ai-analytics.org/grant/nih/10104498. Licensed CC0.

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