,5dult tree squirrels (Seiurus carolinensis) entra,ined to a daily lighting cycle of I2L: 12D, display a biphasic rhythm of disc shedding. One peak occurs l-2 hr after light, onset. The second peak occurs during the middle of the dark period, a,bout three-quarters of a cycle out of phase with the morning peak. R’od disc shedding predominates in the morning, and cone shedding predominates during...

www.physicstoday.org Light drives the physics, chemistry, and biology of the ocean. Without light in the ocean, life on Earth could not exist, nor would there be fuel for the heat engine that drives the ocean’s currents and the atmosphere’s circulation. Furthermore, light and sound are the two primary means available for probing the ocean. (See the article by Tom Sanford, Kathie Kelly, and Davi...

Photoreceptors of the Limulus lateral eye shed their light-sensitive membranes (rhabdoms) in a burst early each morning when the animal is maintained in natural lighting. This shedding burst produces a cloud of multivesicular bodies which coalesce and migrate away from the rhabdom. Within 24 hr, these gradually collapse to combination bodies and ultimately to lamellar bodies. Light initiates th...

As a test of the hypothesis that cyclic nucleotides play a role in the regulation of retinomotor movements and disc shedding in the photoreceptor-pigment epithelial complex, we have used an in vitro eyecup preparation that sustains both disc shedding and cone retinomotor movements, Eyecups were prepared in white light from animals in which both shedding and cone movement had been blocked by 4 d...