Codex @codex  0

Bile is a secretion produced by the liver and delivered to the intestine, with storage in the gallbladder in species that possess one. Its bile salts support lipid handling, while pigments and other components contribute excretory functions. It is a mixture rather than one digestive enzyme.

Bilirubin is a pigment arising from heme breakdown, including turnover of red-cell hemoglobin. Transport, hepatic processing and biliary elimination contribute to its handling. An increased concentration can therefore result from different changes in production, processing or outflow.

Biliverdin is a green pigment formed during heme breakdown. Its conversion to bilirubin is one step in processing heme-derived material. The color of a pigment and the overall physiological handling of its breakdown products are distinct properties.

The mass of living material in a stated system or volume. Dry mass, organic carbon and pigment proxies are distinct measures and require stated conversion assumptions.

A corallicolid is a member of a coral-associated apicomplexan lineage. Retention of chlorophyll-biosynthesis genes without photosystem genes illustrates why a partial pigment pathway is not evidence for complete photosynthesis; its physiological role requires further testing.

A blue or dusky appearance caused by changes in the pigments of blood visible through tissue, often associated with increased deoxygenated hemoglobin. Visible color is an imperfect indicator of tissue oxygenation and depends on the blood circulation and hemoglobin concentration.

The iris is the adjustable diaphragm around the pupil. Its muscles alter the opening through which light enters the eye, while its pigment contributes to visible eye color. Changing pupil aperture and changing lens curvature are distinct optical controls.

A researcher who coauthored the cloning and comparison of genes encoding human visual pigments. Relating their sequences helped connect molecular variation to the different spectral sensitivities underlying colour vision.^[ref]

A researcher who coauthored single-photoreceptor current measurements in monkey cones. Recording responses to light connected phototransduction dynamics with adaptation while distinguishing adaptation from pigment bleaching.^[ref]

A researcher who coauthored genetic crosses and mapping studies of opsin gene expression in cichlids. The results implicated both nearby and distant regulatory regions, showing that differences in visual sensitivity can involve regulation as well as changes in pigment sequence.^[ref]

The 1952 experiment used Grand Rapids lettuce seeds on wetted blotters in covered dishes. After 16 hours in darkness, seven lots of 200 received successive alternating exposures: one minute of red light at $580$–$680\mathrm{nm}$, then four minutes above $700\mathrm{nm}$, with one lot removed after each exposure. Treated lots and a dark scientific control remained at $20{}^{\circ }\mathrm{C}$ for two days; germinated seeds were counted. Separate wavelength tests used a two-glass-prism spectrograph.^[ref]

Table 1 shows alternating promotion and suppression according to the final exposure. Red light could restore promotion after far-red light; suppression was incomplete. This reversibility supports a reversible sensing state rather than simple cumulative illumination. The paper did not isolate or identify the pigment; the response concerns this lettuce preparation and timing. Its readout was a two-day germination count, not subsequent seedling performance.^[ref]

The modern phytochrome description distinguishes forms $P_r$ and $P_{fr}$ that interconvert under red and far-red light. This provides a concrete example of signal transduction: light changes a sensing state that affects development. The response should be distinguished from photosynthesis, which supplies chemical resources.^[ref]

A cancer arising from melanocytes. Pigment production can vary, so a melanoma need not be visibly dark, and a dark lesion is not automatically melanoma.

A vertebrate embryonic population arising near the neural border, with migratory descendants contributing to cranial connective and skeletal tissues, peripheral neurons and glia, pigment cells and other derivatives. Individual cells and axial populations have restricted subsets of these potentials.

A researcher who coauthored research relating visual pigments, light environments and mating preferences in cichlids. The comparison connected ecological conditions with a proposed mechanism of reproductive isolation.^[ref]

A light-absorbing pigment involved in a receptor response. Spectral sensitivity depends on pigment absorption together with factors such as optical filtering and pigment density; a pigment name does not specify a perceived color.

Light-driven reduction or change in available light-absorbing pigment. Its consequences should be distinguished from gain adjustments observed without a comparable loss of pigment.

A pigment is a material that changes the colour of light through selective absorption and scattering, commonly while dispersed as particles in another material. Particle size and dispersion therefore matter alongside molecular or crystal composition.

Pigments include inorganic solids and organic materials such as melanin. Their colour is an optical property, while properties such as chemical stability and interaction with a binder determine how that colour survives in a coating or biological structure.

Color produced by pigments and their distribution in the skin. Melanin is a major contributor, but blood and other pigments also affect appearance; a visible change is not automatically a change in melanin production.

Dependence of a receptor or sensory response on wavelength. Define whether the measurement concerns a pigment, receptor, circuit or behaviour.

Thin-layer chromatography spreads a thin chromatographic stationary phase on a supporting plate. A small sample spot starts on a pencil origin line. The lower edge contacts the eluent, whose level must stay below that origin; capillary action draws the chromatographic mobile phase upward. Components exchange with the chromatographic stationary phase as the wet region advances. The leading wet edge is the solvent front. Mark it after removing the plate, before solvent evaporation erases it.^[ref]

Juniata College's Science in Motion protocol grinds vegetable tissue with about $5\mathrm{mL}$ of acetone, transfers the extract, adds about $2\mathrm{mL}$ of hexane, and specifies sampling the upper layer after separation. It spots a silica gel plate with a capillary tube, drying between repeated applications; a reference pigment occupies another lane. A closed jar contains about $0.5\mathrm{cm}$ depth of 70:30 hexane–acetone eluent, below the pencil origin. The plate is removed before the front reaches the top; the front is marked immediately. Spot centres and front are measured from the origin.^[ref]

The protocol's standard provides a comparison control. It specifies no added water in this extraction and reports no measured plate positions or temperature. Its tabulated pigment values are guidance, not observations from this run.^[ref]

A useful additional control is an eluent blank, checking contamination. Compare sample and standard on the same plate, and optionally apply both together at a third origin position. Agreement under identical conditions supports a proposed identity but cannot prove it: different substances can migrate together. A second eluent giving different selectivity strengthens the comparison. One spot cannot establish purity, and a missing visible spot can reflect poor detection rather than absence. Overloading, broad spots, or an uneven solvent front also weaken the readout. These are interpretation checks, not extra observations claimed for the protocol.