Sleep is regulated by two mechanisms: the homeostatic process and the circadian clock. Light affects sleep and alertness by entraining the circadian clock, and acutely inducing sleep/alertness, in a manner mediated by intrinsically photosensitive retinal ganglion cells. Because intrinsically photosensitive retinal ganglion cells are believed to be minimally sensitive to red light, which is wide...

In previous experiments, migratory birds had been disoriented under 635 nm red light, apparently unable to use their magnetic compass. The present study with European robins, Erithacus rubecula, confirms these findings for red light at the levels of 6 x 10(15) quanta s(-1) m(-2) and 43 x 10(15) quanta s(-1) m(-2), suggesting that the disorientation under red light was not caused by the test lig...

Photoreceptors are biologically important for sensing changes in the color and intensity of ambient light and, for photosynthetic organisms, processing this light information to optimize food production through photosynthesis. Cyanobacteria are an evolutionarily and ecologically important prokaryotic group of oxygenic photosynthesizers that contain cyanobacteriochrome (CBCR) photoreceptors, who...

Background. Light exposure to the eye can influence different physiological functions, for example, the suprachiasmatic nucleus (SCN). By affecting the autonomic nervous system, the SCN may influence the heart rate variability (HRV). Standardized colored light exposure alters HRV but the results are inconsistent. In this study we investigated the effects of nonstandardized red light (approx. 64...

Chloroplasts change their positions in the cell depending on the light conditions. In the dark, chloroplasts in fern prothallia locate along the anticlinal wall (dark position). However, chloroplasts become relocated to the periclinal wall (light position) when the light shines perpendicularly to the prothallia. Red light is effective in inducing this relocation in Adiantum capillus-veneris, an...

The high frequency of red-light running and complex driving behaviors at the yellow onset at intersections cannot be explained solely by the dilemma zone and vehicle kinematics. In this paper, the author presented a red-light running prevention system which was based on artificial neural networks (ANNs) to approximate the complex driver behaviors during yellow and all-red clearance and serve as...

Unilateral blue light administered to corn coleoptile segments produces no alteration of transmembrane potential on the light side, and only a small and slow hyperpolarization on the dark side. Red light causes a 5-15 millivolt depolarization in cells on the light side causes and somewhat smaller effects on the dark side. Blue given after red causes a rapid hyperpolarization on both sides of th...

Brief exposure of etiolated maize seedlings to light induces large increases in adenylate kinase and inorganic pyrophosphatase activity of the leaf in the following 48 hr in the dark. Red light is more effective than white or far red light, and far red reverses the effect of red light, indicating phytochrome control. Out of several tested, only these 2 enzymes appear to be coordinately induced,...

Apical segments of etiolated oat (Avena sativa L. cv. Victory) coleoptiles showed enhanced uptake of [(86)Rb(+)] when tested 30 minutes after a 5-minute red irradiation. The response was partly reversible by far red light. Uptake was sensitive to carbonyl cyanide m-chlorophenyl hydrazone, but not to isotonic mannitol. Indoleacetic acid (10(-7) molar) caused a very pronounced and rapid stimulati...

Cryptochromes are flavoproteins that act as sensory blue light receptors in insects, plants, fungi, and bacteria. We have investigated a cryptochrome from the green alga Chlamydomonas reinhardtii with sequence homology to animal cryptochromes and (6-4) photolyases. In response to blue and red light exposure, this animal-like cryptochrome (aCRY) alters the light-dependent expression of various g...