It is now well established that vision in dim light is due to the photochemical decomposition of “visual purple,” a pigment present in the rods of the retina (1). Visual purple is believed to be a conjugated protein in which vitamin A or one of its derivatives is a prosthetic group (2). As might be expected, the spectral sensitivity curve of the eye parallels the absorption spectrum of visual p...

The dogwhelk Nucella lapillus is a rocky intertidal gastropod of the North Atlantic coast. Individual shell color varies. Common colors range between white and brown, with darker dogwhelks being more affected by heat stress than lighter-colored conspecifics. Other reported shell colors are black, mauve, pink, yellow, and orange from European coasts, red and grey from the Bay of Fundy coast of N...

Changes effected in purple uteroferrin’s resonance Raman spectrum by mercaptoethanol reduction suggest that the protein’s single iron atom is coordinated to more than one tyrosyl residue. Detection of a conservative pair of visible CD bands, indicative of exciton splitting of a tyrosinate-to-iron charge transfer band, strongly supports this suggestion. Additional features in the protein’s visib...

Vitamin A (VA) deficiency is a worldwide public health problem. Biofortifying existing sources of b-carotene (bC) and increasing dietary bC could help combat the issue. Two studies were performed to investigate the relative bC bioavailability of a bC supplement to purple, high-bC orange, and typical orange carrots using Mongolian gerbils (Meriones unguiculatus). In study 1, which used a traditi...

Purple rice is a strain of glutaneous rice rich in anthocyanins and γ-oryzanol. Both types of compounds are involved in antioxidant and lipid metabolism of mammals. Three experimental diet types were used which consisted approximately by half either of purple rice, white rice or corn. Diets were fed to 3×10 pigs growing from about 30 to 100 kg. Meat samples were investigated either as raw or cu...

Purple urine bag syndrome (PUBS) is an infrequent condition, seen mostly in elderly female patients, characterized by an intense purple discoloration of contents of urine bag following long-term indwelling urinary catheterization. The purple discoloration is most often due to the presence of indigo and indirubin pigments which are metabolites of tryptophan. Urinary bacteria with indoxyl sulphat...

Although anoxygenic photosynthesis is thought to play an important role in the primary productivity of permanently frozen lakes in the Antarctic dry valleys, the bacterial communities responsible for this metabolism remain uncharacterized. Here we report the composition and activity of phototrophic purple bacteria in Lake Fryxell, Antarctica, as determined by analysis of a photosynthesis-specif...

The polypore genus Abundisporus Ryvarden is characterized by resupinate to pileate fruitbodies with a purplish brown hymenophore, slightly thick-walled, pale yellowish and non-dextrinoid basidiospores, and causing white rot. A purple color hymenophore, an easily observable and striking character, was considered the main distinctive feature at the generic level within polypores. However, due to ...

1. The accumulation of visual purple in the retina after bleaching by light has been studied in the intact eye of the frog. The data show that duration and intensity of light adaptation, which influence the course of human dark adaptation as measured in terms of visual threshold, have a similar influence on the course of visual purple regeneration. 2. At 25 degrees C. frogs which have been ligh...

Consider a set of n points in the plane, each one of which is colored either red, blue, or purple. A red-blue-purple spanning graph (RBP spanning graph) is a graph whose vertices are the points and whose edges connect the points such that the subgraph induced by the red and purple points is connected, and the subgraph induced by the blue and purple points is connected. The minimum RBP spanning ...