Continuous light exposure can suppress circadian rhythms. In this issue of Neuron, Murad et al. demonstrate that, under certain genetic conditions, a novel cluster of pacemaker neurons can drive rhythmic behavior in constant light. Surprisingly, these neurons are distinct from those thought to drive rhythms in constant darkness.

Daily injection of microgram amounts of melatonin in rats decreased the incidence of estrus and reduced ovarian weight. Circulating melatonin was selectively taken up and retained by the ovary and pineal gland; this effect was reduced by exposure of rats to constant light. A single injection of melatonin lowered the incidence of estrus among rats exposed to constant light.

The matrix element which determines the B meson decay constant can be measured on the lattice using an effective field theory for heavy quarks. Various discretizations of the heavy-light bilinears which appear in this and other B decay matrix elements are possible. The heavy-light bilinear currently used for the determination of the B meson decay constant on the lattice suffers a substantial on...

A rabbit antiserum to somatostatin was used to develop radioimmunoassay methods for measuring somatostatin in monkey cerebrospinal fluid (CSF). By gel permeation chromatography, at least five molecular weight forms of immunoreactive somatostatin (IRS) were identified in monkey CSF; two of these species co-migrated with either synthetic somatostatin-14 or somatostatin-28. The 24-hr profile of CS...

Constant intense light causes apoptosis of photoreceptors in the retina of albino fish. However, very few studies have been performed on pigmented species. Tench (Tinca tinca) is a teleost inhabiting dimly lit environments that has a predominance of rods within the photoreceptor layer. To test the hypothesis that constant high intensity light can result in retinal damage in such pigmented epibe...

Holt, Stanley C. (University of California, Davis), and Allen G. Marr. Effect of light intensity on the formation of intracytoplasmic membrane in Rhodospirillum rubrum. J. Bacteriol. 89:1421-1429. 1965.-Cells of Rhodospirillum rubrum grown at low light intensity were found to contain much more internal membrane than cells grown at high light intensity. Highly purified membranes (chromatophores)...

There is increasing evidence that different light intensities strongly modulate the effects of ocean acidification (OA) on marine phytoplankton. The aim of the present study was to investigate interactive effects of OA and dynamic light, mimicking natural mixing regimes. The Antarctic diatom Chaetoceros debilis was grown under two pCO2 (390 and 1000 μatm) and light conditions (constant and dyna...

PURPOSE To evaluate the protective effects of midkine (MK), the product of a retinoic acid-responsive gene, on constant light-induced retinal degeneration in albino Sprague-Dawley rats. METHODS Midkine, basic fibroblast growth factor (bFGF), MK plus heparin, or buffer controls were injected intravitreally 2 days before constant light exposure. After 7 days of continuous light exposure, the ey...