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PubMed1983

The dark brown integumentary pigment of a barnacle (Balanus eburneus). A comparative study.

A histochemical analysis involving tinctorial and solubility tests was pursued in conjunction with electron microscopy for the purpose of identifying the dark brown epidermal pigment of a barnacle (Balanus eburneus) as melanin and/or ommochrome. Histochemically, comparisons were made with other brown pigments located in the subcarapal epidermis of another crustacean, the fiddler crab (Uca pugilator), the dorsal skin of the red-backed salamander (Plethodon cinereus), the liver and testis of a slider turtle (Chrysemys sp.) and the substantia nigra of human brain. The solubility properties of the pigment of the two crustacean invertebrates were in general similar to one another and markedly different from the pigment of the three vertebrates. Insolubility in appropriate solvents classified the vertebrate pigment as melanin. The invertebrate pigment, however, which was soluble in the ommochrome solvents, concentrated sulfuric and formic acids and 2-chloroethanol, remained insoluble in the ommochrome solvents, dilute aqueous and methanolic hydrochloric acid and dilute sulfuric acid. On the basis of these solubilities, an unequivocal classification of the invertebrate pigment as either melanin or ommochrome did not appear possible. The tinctorial and electron microscopic properties of the barnacle pigment were also equally ambiguous in regard to its specific classification.

Animals↗
PubMed1985

The fine structure of pigment epithelium of the iris in capsular glaucoma.

An electron microscopic study was performed on the pigment epithelium of the iris in 13 patients with capsular glaucoma. Pseudoexfoliative material (PE) was often observed in small depressions or indentations of the cell membrane of the posterior pigment epithelium. PE was also found in the region where the cell membrane was indistinct and took a course perpendicular to the surface of the cell membrane. Serial sections revealed no PE in the cytoplasm of the posterior pigment epithelium. Furthermore, the PE found extracellularly was continuous with the cell membrane. Three stages were distinguished in the pigment epithelium as capsular glaucoma progressed. At an early stage (stage 1), the number of infoldings in the posterior pigment epithelium increased, and PE was found at that site. In a more advanced stage (stage 2), the cytoplasmic processes increased in number and the basement membrane became discontinuous. In a further advanced stage (stage 3), a large amount of PE was found in the posterior chamber. The intercellular space between two adjacent pigment epithelial cells increased and the cytoplasmic processes gradually disintegrated. Only one significant correlation was found between the glaucoma stage and the stage of changes in the pigment epithelium. No associations were found between the stage of changes in the pigment epithelium and patient age or gonioscopic findings.

Aged↗
PubMed1996

[Macular combined malformation (hamartoma) of the retina and retinal pigment epithelium].

BACKGROUND: Combined malformations (hamartomas) of the retina and the retinal pigment epithelium are extremely rare. Confusion of these pigmented lesions with choroidal melanomas or other malignancies is possible. MATERIALS AND METHODS: We present the cases of a 7-year-old girl who developed accommodative convergent strabism and the case of an 8-year-old boy with deterioration of visual acuity in the left eye. On examination the anterior segments were normal in both cases. Funduscopically both eyes showed a centrally located large, partly pigmented and slightly prominent tumor, which extended fanlike into the normal-appearing retina. Both lesions were partly obscured by grayish-white, semitranslucent and thickened retina with retinal folds and overlying tortuous vessels. On follow-up examination one lesion seemed to be slightly more pigmented whereas the other lesion remained unchanged. RESULTS AND DISCUSSION: Combined malformations of the retina and the retinal pigment epithelium were originally described as clinical entities (hamartomas) by Gass in 1973. A few additional cases were subsequently published by McLean in 1976, by Laqua and Wessing in 1979 and some other authors. Laqua and Wessing were the first to give a report of a histologic study in one case with a macular lesion that showed two distinguishable components. The outer pigmented portion consisted of hypertrophied retinal pigment epithelium; the inner unpigmented portion consisted of a malformed and thickened retina which, however, showed normal layering. The clinical characteristics are usually diagnostic. Fluorescein angiography is helpful in establishing the diagnosis and ruling out differential diagnoses. CONCLUSION: Although long-term follow-up did not show evidence of growth patients with combined malformation of the retina and retinal pigment epithelium should be followed up regularly.

Child↗
PubMed2004

Temporal shifts in visual pigment absorbance in the retina of Pacific salmon.

The visual pigments and photoreceptor types in the retinas of three species of Pacific salmon (coho, chum, and chinook) were examined using microspectrophotometry and histological sections for light microscopy. All three species had four cone visual pigments with maximum absorbance in the UV (lambda(max): 357-382 nm), blue (lambda(max): 431-446 nm), green (lambda(max): 490-553 nm) and red (lambda(max): 548-607 nm) parts of the spectrum, and a rod visual pigment with lambda(max): 504-531 nm. The youngest fish (yolk-sac alevins) did not have blue visual pigment, but only UV pigment in the single cones. Older juveniles (smolts) had predominantly single cones with blue visual pigment. Coho and chinook smolts (>1 year old) switched from a vitamin A1- to a vitamin A2-dominated retina during the spring, while the retina of chum smolts and that of the younger alevin-to-parr coho did not. Adult spawners caught during the Fall had vitamin A2-dominated retinas. The central retina of all species had three types of double cones (large, medium and small). The small double cones were situated toward the ventral retina and had lower red visual pigment lambda(max) than that of medium and large double cones, which were found more dorsally. Temperature affected visual pigment lambda(max) during smoltification.

Aging↗
PubMed1982

beta-haemolysis and pigment production by the oral bacterium Streptococcus mutans.

The prevalence of beta-haemolysis and yellow pigmentation among 89 isolates of Streptococcus mutans from human dental plaque and 59 Strep. mutans isolates from positive cultures of human dental root canals were investigated. beta-Haemolytic strains were more frequent among the root-canal isolates (25.4 per cent) than among the dental plaque isolates (12.4 per cent). The distribution of pigment production among beta-haemolytic strains (22 pigmented strains out of 26 strains) and among non-haemolytic strains (5 pigmented strains out of 122 strains) showed a relationship between haemolysin and pigment production. beta-Haemolytic, pigmented strains (biotype c and e and 35-39 per cent guanine plus cytosine) were common in plaque and were the dominant type of Strep. mutans in some plaques. As beta-haemolysis by Strep. mutans was only demonstrated after strict anaerobic growth, whereas pigment production was demonstrated after growth under less anaerobic conditions (candle jar) on sucrose-containing agar plates, the observation of pigment may facilitate a presumptive identification of beta-haemolytic strains of Strep. mutans.

Dental Plaque↗
PubMed1985

In vitro pigment formation from tryptamine. Role of indole-3-acetaldehyde.

The metabolic significance of indole-3-acetaldehyde in the process of in vitro pigment formation from tryptamine in the presence of guinea-pig liver mitochondria was investigated. Among the four type selective MAO inhibitors used, pargyline and deprenyl appear to be more effective in inhibiting pigment formation from tryptamine than serotonin, while in the presence of clorgyline and Lilly 51641, pigment formation from serotonin was preferentially inhibited. Reducing agents like ascorbic acid, cysteine and glutathione were found to block pigment formation significantly. Also, a reduction of pigment formation was noted in the presence of NADH and ethanol but not in the presence of NAD. It was observed that the amount of indole-3-acetaldehyde produced enzymatically from tryptamine under the present experimental conditions is not sufficient to account for the total amount of pigment formed in the standard incubation mixture and the generation of nascent aldehyde has greater contribution in pigment formation than that supplemented to the system exogenously. It appears that indole-3-acetaldehyde, tryptamine and MAO are associated with the process of pigment formation.

Animals↗
PubMed1991

Pigment patterns in neural crest chimeras constructed from quail and guinea fowl embryos.

The pattern of pigmentation in bird embryos is determined by the spatial organization of melanocyte differentiation. Some of the results from recent, neural crest transplantation experiments support a model based on a prepattern in the feathers; others could be interpreted in terms of a nonspecific pattern resulting from a failure of the crest cells to read the positional values in another species. To distinguish between these possibilities, the crucial test is to construct chimeras from two species with different pigment patterns. We have examined the wing plumage of quail and guinea fowl embryos. The quail has a characteristic pattern of pigmented and unpigmented feather papillae, whereas the guinea fowl shows uniform pigmentation. Chimeras were constructed by grafting wing buds isotopically between embryos. The wing buds were transplanted before they had become invaded by neural crest cells. Quail wing buds grafted to the guinea fowl developed, in most cases, a pigment pattern resembling that of the quail and not that of the guinea fowl. A few cases became uniformly pigmented and appeared to represent nonspecific patterns. The reciprocal grafts (guinea fowl wing buds grafted to the quail) became pigmented all over. We found evidence that the timing of melanocyte differentiation is controlled by cues in the feather papillae. Some cases developed a severe inflammatory response. The model which best accounts for these findings--and which can account for inconsistencies in previous reports--is the following. A prepattern is present in the feathers and this can control the differentiation of melanoblasts, even if they come from a different species. The local cues which constitute the prepattern are not positional values. In some chimeras melanoblasts fail to respond to the prepattern and so a nonspecific pattern of uniform pigmentation is produced.

Animals↗
PubMed1980

The human materno-foetal relationship in malaria: I. Identification of pigment and parasites in the placenta.

To facilitate investigations of the consequences of malarial infection during human pregnancy, several methods for the recognition of pigment and parasites in the placenta were evaluated. Pigment was visualized in infected blood smears and placental tissue using both white light and modified fluorescence microscopy. However, the characteristic pigment dots observed with fluorescent light were also apparent in unstained cryostat and deparaffinized placental sections, and following reaction with immunohistological reagents. Intact parasites were recognized immunohistologically in placental sections and blood smears using rabbit antisera to Plasmodium falciparum and P. berghei. Using these procedures, numerous erythrocytes containing parasites associated with small pigment dots were seen in intervillous spaces in heavily infected placentae. In these organs, larger irregular pigment aggregates were present within maternal cells which were shown to be monocytes by esterase staining. Pigment was also observed in the cytoplasm of the trophoblast and not infrequently in the mesenchymal stroma, but no intact parasites were observed within chorionic villi. These simple and sensitive methods thus confirm placental localization of parasites and pigment. Furthermore, the finding of pigment in all Gambian placentae examined, of which seven were thought initially to be uninfected, indicates that malaria may complicate pregnancy more frequently than hiterto anticipated.

Esterases↗
PubMed1994

Spectral characteristics of visual pigments in rainbow trout (Oncorhynchus mykiss).

We investigated retina preparations of young rainbow trout (Oncorhynchus mykiss) with body wt 5-40 g. Rods, single and double cones were measured in side-on orientation by microspectrophotometry, identifying five spectrally distinct visual pigments (or photoreceptors containing mixtures of visual pigments). The mean wavelength of peak absorbance (lambda max) of the alpha-bands were 365 and 434 nm in single cones, 531 and 576 nm in double cones, and 521 nm in the rods. The half-band width (HBW) of the main absorption bands were broader than expected of retinal- (vitamin A1-) based visual pigments, and thus, they were indicative of a mixed chromophore pool derived from both the vitamin A1 and A2 forms. One consequence of the utilization of mixed chromophores is the broadening of the alpha-band absorption in each pigment type. And yet, we obtained exceptionally narrow HBW for the UV-type pigment, when compared with HBW values expected on the basis of the linear trend seen in visual pigments absorbing in the visible spectrum. We conclude that the UV pigment in rainbow trout has an unusually narrow HBW. Nevertheless, this species is not exceptional in this regard, for the UV-absorbing visual pigments in other vertebrate species also have narrow HBW.

Animals↗
PubMed1995

Distribution of lipochrome pigment in the prostate gland: biological and diagnostic implications.

Lipochrome pigment is characteristically found in Wolffian duct-derived structures including seminal vesicles and ejaculatory ducts. The presence of lipochrome pigment is helpful in identifying atypical histological patterns of seminal vesicle or ejaculatory duct that mimic prostatic adenocarcinoma. The authors studied the distribution of lipochrome pigment in 28 radical prostatectomy specimens using a modified Ziehl-Neelson stain and fluorescence microscopy. In all cases secretory epithelium of the central zone contained lipochrome pigment often in significant amounts (2 to 3+). Secretory epithelium from peripheral and transition zones in each of four specimens (14.3%) contained lipochrome pigment. In addition, occasional examples of nodular hyperplasia, prostatic intraepithelial neoplasia, and prostatic adenocarcinoma contained lipochrome pigment. The preferential distribution of lipochrome pigment in central zone epithelium adds further support to the hypothesis that central zone glands are derived embryologically from Wolffian duct (mesoderm) rather than urogenital sinus (endoderm), which gives rise to transition and peripheral zone glands. Furthermore, lipochrome pigment should not be used as the sole diagnostic criterion for separating atypical histological patterns of seminal vesicle and ejaculatory duct from those of prostatic origin.

Adenocarcinoma↗
PubMed1991

Generation of developmental patterns in the neuroepithelium of the developing mammalian eye: the pigment epithelium of the eye.

Culture experiments with eye anlages of mouse embryos were performed to study developmental traits of the neuroepithelial cells of the prospective pigment epithelium in the eye anlage of pigmented mice. Between the neural plate stage on embryonic day 8 (ED 8, developmental stage 12) and the neural tube stage on embryonic day 9 1/2 (stage 15), the cultured neuroepithelium of the eye generated neurons and glia, identified by morphological and immunocytochemical evidence, but no pigmented cells. In contrast, eye anlages did produce pigment epithelium when cultured in their natural position in a head tissue fragment. A minority of developing neurons displayed tyrosine hydroxylase immunoreactivity, whereas GABAergic, serotoninergic and substance P-ergic neurons, which are common in the mature neuroretina, were not observed. When neuroepithelial cells from embryonic eyes older than stage 15 (ED 9 1/2) were cultured, they differentiated into pigment cells but not into nerve cells or glia. This developmental sequence indicates that the pigment cells derive from the neural lineage. Pigment cell fate dominates over the neural fate beginning at about stage 15 (ED 9 1/2-10). That is at least 2 days before the pigment cell phenotype becomes apparent in vivo (ED 11 1/2-12).

Animals↗
PubMed2005

Tertiary structure and spectral tuning of UV and violet pigments in vertebrates.

Many vertebrate species use ultraviolet (UV) vision for such behaviors as mating, foraging, and communication. UV vision is mediated by UV-sensitive visual pigments, which have the wavelengths of maximal absorption (lambda max) at approximately 360 nm, whereas violet (or blue) vision is mediated by orthologous pigments with lambda max values of 390-440 nm. It is widely believed that amino acids in transmembrane (TM) I-III are solely responsible for the spectral tuning of these SWS1 pigments. Recent molecular analyses of SWS1 pigments, however, show that amino acids in TM IV-VII are also involved in the spectral tuning of these pigments through synergistic interactions with those in TM I-III. Comparisons of the tertiary structures of UV and violet pigments reveal that the distance between the counterion E113 in TM III and amino acid sites 87-93 in TM II is narrower for UV pigments than for violet pigments, which may restrict the access of water molecules to the Schiff base pocket and deprotonate the Schiff base nitrogen. Both mutagenesis analyses of E113Q and quantum chemical calculations strongly suggest that unprotonated Schiff base-linked chromophore is responsible for detecting UV light.

Amino Acid Sequence↗
PubMed2001

Effect of Ca(2+)-free and Mg(2+)-free BSS Plus solution on the retinal pigment epithelium and retina in rabbits.

PURPOSE: To determine whether intravitreal irrigation with Ca(2+)-free and Mg(2+)-free BSS Plus (Alcon Laboratory, Fort Worth, Texas) solution alters the adhesiveness between the retinal pigment epithelium and the retina of rabbits. METHODS: Thirty-four eyes of 34 Dutch pigmented rabbits underwent lensectomy and vitrectomy. Subsequently, the vitreous cavity of 24 eyes was irrigated with Ca(2+)-free and Mg(2+)-free BSS Plus solution for 10 or 20 minutes. The other 10 eyes were irrigated with BSS Plus solution for 20 minutes as controls. To determine the adhesiveness between the retinal pigment epithelium and retina, a retinal detachment was produced in 12 of the 34 eyes. The apical surface of the retinal pigment epithelium and the photoreceptor outer segments were examined by scanning electron microscopy. Retinal physiology was assessed by electroretinography and retinal morphology by light microscopy. RESULTS: After retinal detachment was produced, the number of cone sheaths on the apical surface of the retinal pigment epithelium after irrigation with Ca(2+)-free and Mg(2+)-free BSS Plus solution for 20 minutes (33 +/- 15, mean +/- SD) was significantly less than the number of cone sheaths on the apical surface of the retinal pigment epithelium of eyes after irrigation with BSS Plus solution for 20 minutes (120 +/- 50) or the number of cone sheaths on the apical surface of the retinal pigment epithelium of eyes after 10 minutes of irrigation with Ca(2+)-free and Mg(2+)-free BSS Plus solution (115 +/- 49; P =.02). The b-wave amplitudes in the eyes irrigated with Ca(2+)-free and Mg(2+)-free BSS Plus solution for 20 minutes were depressed compared with the b-waves in eyes irrigated with BSS Plus solution for 20 minutes on the first postoperative day (P =.03). After the third postoperative day, there was no significant difference in the b-waves (P >.06). Light microscopy demonstrated no morphologic abnormalities after the use of both solutions. CONCLUSIONS: Intravitreal irrigation with Ca(2+)-free and Mg(2+)-free BSS Plus solution for 20 minutes altered the adhesion between the retinal pigment epithelium microvilli and retinal outer segments and made the creation of retinal detachment less traumatic. These results suggest that Ca(2+)-free and Mg(2+)-free BSS Plus solution may be of clinical value for the creation of an intentional retinal detachment for foveal translocation surgery.

Animals↗
PubMed1987

Raman microscope and quantum yield studies on the primary photochemistry of A2-visual pigments.

The 77-K resonance Raman vibrational spectrum of intact goldfish rod photoreceptors containing 3,4-dehydro (A2) retinal is dominated by scattering from the 9-cis component of the steady state at all excitation wavelengths. Intact goldfish photoreceptors were regenerated with an A1-retinal chromophore to determine whether this behavior is caused by the protein or the chromophore. The resulting Raman spectrum was typical of an A1-pigment exhibiting significant scattering from all three components of the steady state: rhodopsin, bathorhodopsin, and isorhodopsin. Furthermore, regeneration of bovine opsin with A2-retinal produces a characteristic "A2-Raman spectrum" that is dominated by scattering from the 9-cis pigment. We conclude that the differences between the Raman spectra of the A1-and A2-pigments are caused by some intrinsic difference in the photochemical properties of the retinal chromophores. To quantitate these observations, the 77-K adsorption spectra and the photochemical quantum yields (phi) of the native A2-goldfish and the regenerated A2-bovine pigments were measured. In the goldfish A2-pigment, the value of phi 4 (9-cis----trans) is 0.05; phi 3 (trans----9-cis) is 0.10; and phi 2 (trans----11-cis) is 0.35. By contrast, in the bovine A1-pigment, these quantum yields are 0.10, 0.053, and 0.50, respectively. The reduced value of phi 4 and the increased value of phi 3 in the goldfish pigment confirms that the 9-cis isomer is photochemically more stable in A2-pigments.

Animals↗
PubMed1989

Clonal origins of cells in the pigmented retina of the zebrafish eye.

Mosaic analysis has been used to study the clonal basis of the development of the pigmented retina of the zebrafish, Brachydanio rerio. Zebrafish embryos heterozygous for a recessive mutation at the gol-1 locus were exposed to gamma-irradiation at various developmental stages to create mosaic individuals consisting of wild-type pigmented cells and a clone of pigmentless (golden) cells in the eye. The contribution of individual embryonic cells to the pigmented retina was measured and the total number of cells in the embryo that contributed descendants to this tissue was determined. Until the 32-cell stage, almost every blastomere has some descendants that participate in the formation of the pigmented retina of the zebrafish. During subsequent cell divisions, up to the several thousand-cell stage, the number of ancestral cells is constant: approximately 40 cells are present that will give rise to progeny in the pigmented retina. Analysis of the size of clones in the pigmented retina indicates that the cells of this tissue do not arise through a rigid series of cell divisions originating in the early embryo. The findings that each cleavage stage cell contributes to the pigmented retina and yet the contribution of such cells is highly variable are consistent with the interpretation that clonal descendants of different blastomeres normally intermix extensively prior to formation of the pigmented retina.

Animals↗
PubMed2003

Stealth virus culture pigments: a potential source of cellular energy.

The cytopathic effect (CPE) induced in human MRC-5 fibroblasts by blood mononuclear cells of patients infected with stealth-adapted viruses is characterized by the formation of clusters of foamy vacuolated cells that commonly become heavily pigmented. The pigmented material coalesces into discrete structures of varying shapes and sizes, including solid particles, flat ribbons, and long, thin threads. Pigmented material can also be observed in long-term culture supernatants, sometimes accompanied by solid and needle-shaped lipid-like crystals. Accumulation of the pigmented material correlates with lessening of the CPE and outgrowth of normal appearing cells from cell clusters. The CPE can be rapidly reactivated by replacing the culture supernatant with fresh culture medium. Conversely, reactivation can be partially prevented by the addition of particulate pigmented material to fresh culture medium. The pigmented material displays striking luminescence and autofluorescence. Occasional particles are ferromagnetic. Varying percentages of different minerals are identifiable in the particles using energy dispersive X-ray (EDX) analysis. Metabolic studies indicate the particles can have reducing (electron donating) capacity and can liberate gas. These findings, along with the extended survival of viable cells in unfed virus-infected cultures, suggest that the pigments are a potential source of cellular energy. The presence of light and magnetic-sensitive alternative cellular energy (ACE) pigments has opened new approaches for the potential therapy of stealth virus-infected patients.

Cells, Cultured↗
PubMed1999

Isomerization of urocanic acid after ultraviolet radiation is influenced by skin pigmentation.

Exposure to ultraviolet (UV) radiation may induce erythema, DNA damage and suppression of immune responses. Melanin pigmentation offers protection against the first two of these effects, but immunosuppression seems to occur irrespective of the subject's pigmentation. Cis-urocanic acid (cis-UCA), produced by isomerization of trans-UCA in the stratum corneum on UV exposure, initiates some of the immunomodulatory effects of UV radiation. In the present study the relationship between skin pigmentation and UCA isomerization has been examined in 28 healthy individuals of skin types I-IV. Pigmentation is measured in five areas of not recently exposed back skin before irradiation with 0, 0.45, 0.9, 1.8 and 3.6 standard erythema dose (SED) of filtered broadband UV-B (1 SED = 10 mJ cm-2 at 298 nm). The concentration of UCA isomers is measured immediately after the irradiation. With 3.6 SED, the relative production of cis-UCA is close to the maximum obtainable, irrespective of skin type. A significant negative correlation is found between pigmentation and relative production of cis-UCA at 0.45 and 1.8 SED, and between pigmentation and absolute production of cis-UCA at 0.45 SED. At doses of 0.45 and 0.9 SED the relative and absolute production of cis-UCA are higher in the group with skin types I and II when compared with the group with skin types III and IV. The higher isomerization in the lightly pigmented subjects than in the more pigmented ones may indicate that people with fair skin are at a relatively higher risk of immunosuppression when exposed to low doses of UV radiation.

Adolescent↗
PubMedDate not supplied

Evidence for the prolonged photoactivated lifetime of an analogue visual pigment containing 11-cis 9-desmethylretinal.

Following bright flashes, rod photoreceptors exhibit a period of photocurrent saturation that increases linearly with the logarithm of flash intensity. In a recent report, Pepperberg et al. (1992) presented evidence that the slope of the function relating the saturation period (T) to the natural logarithm of flash intensity (ln If) represents the exponential lifetime (tau) of photoactivated visual pigment: tau = delta T/delta [ln If]. In salamander rods, 11-cis 9-desmethylretinal combines with opsin to form 9-desmethyl rhodopsin. Dim flash responses mediated by this analogue visual pigment exhibited slow recovery kinetics relative to those of native pigment (Corson et al., 1991). This observation raises the hypothesis that the physiological lifetime of photoactivated 9-desmethyl rhodopsin is substantially longer than that of native visual pigment. To test this hypothesis, we have examined the relation between the period of photocurrent saturation and flash intensity in salamander rods containing a mixture of the two pigments. Brief stimuli at two widely separated wavelengths (440 and 640 nm) elicited saturating photocurrent responses that were preferentially mediated by 9-desmethyl rhodopsin or residual native pigment, respectively. Plots of T vs. ln If revealed a linear increase in the period of response saturation over a large range of saturating intensities at both wavelengths. However, the slope of the relation between T and ln If with 440-nm flashes was more than twice as large (4.1 +/- 0.5 s, n = 5) as that measured with 640-nm flashes (1.7 +/- 0.4 s). For rods subjected only to bleaching of the native pigment, or to bleaching and resensitization with 11-cis retinal, the slope of the relation between T and ln If remained independent of wavelength and indistinguishable from that of native pigment in unbleached cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗