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At least 1,117 records · Page 62Linked to original sources
PubMed1986

Immunocytochemical discrimination of visual pigments in the retinal photoreceptors of the nocturnal gecko Teratoscincus scincus.

Using a monoclonal antibody (COS-1) against a chicken cone visual pigment and an anti-rhodopsin serum, two visual pigments were distinguished in the gecko retina. One pigment, recognized by the monoclonal antibody COS-1, was found in the outer segments of all photoreceptor cells except the thinner members of type C double cells and the middle members of the triplet cells. These COS-1-negative photoreceptors contained another pigment which could be demonstrated by the anti-rhodopsin serum. Based on an earlier microspectrophotometric study, the visual pigment recognized by COS-1 is a green-sensitive pigment, while the one demonstrated by anti-rhodopsin is a blue-sensitive photopigment.

Animals↗
PubMed1992

Observations on the pigmentation of the monogeneans, Anoplodiscus spp. (family Anoplodiscidae) in different microhabitats on their sparid teleost hosts.

The monogeneans Anoplodiscus australis and A. cirrusspiralis infect the fins of their respective hosts, the yellowfin bream, Acanthopagrus australis, and the snapper, Pagrus auratus. In these habitats the adult parasite contains melanin-like pigment deposits within the body. Very young parasites lack the pigment but deposits of pigment appear and coalesce into dense deposits within the parasite as it grows. The evidence suggests that the pigment is synthesized within the body of the parasite rather than acquired through feeding on the host epidermis. However, adults of Anoplodiscus cirrusspiralis from the nares of snapper lack this pigment, which suggests that environmental cues may promote the production of pigment as a possible aid to camouflage.

Animals↗
PubMed1975

Hepatic "intravenous fat pigment" in infants and children receiving lipid emulsion.

In 23 patients who received fat emulsion (Intralipid) intravenously and had subsequent necropsy, the deposition of pigment in the liver was evaluated quantitatively. Pigment was found in hepatic cells (HC) in 14 of 23 patients as well as reticuloendothelial cells (REC) in 22 of 23 patients. There was more pitment deposition in HC in younger children. HC pigment deposition occurred most frequently in patients with acute inflammatory processes within the abdomen. Patients infused with emulsion at rates less than 0.5 g/kg body wt/hr had less pigment deposition than patients infused at faster rates. Neonates infused at rates less than 0.2 g/kg body wt/hr for 24 hr had less HC pigment than neonates infused at higher rates. The quantity of REC pigment bore no apparent relationship to age, clinical diagnosis, rate or total dose of fat emulsion, but was increased in groups infused more than 14 days.

Adolescent↗
PubMed1985

The effect of pertussis toxin on alpha-2-adrenoceptor-mediated pigment migration in fish melanophores.

The aggregation of melanin-granules within fish pigment cells (melanophores) can be elicited either by electrical stimulation of intrinsic nerves or by the addition of adrenergic agonists. The pigment aggregation seems to be mediated by alpha-2-adrenoceptors. In this investigation we have used various agonists and antagonists (noradrenaline, (+)- and (-)-adrenaline, isoprenaline, yohimbine and prazosin) to further characterize the pigment-aggregating receptor of Labrus ossifagus. All the results obtained support the notion of alpha-2-adrenoceptor-mediated pigment aggregation. The pertussis toxin, islet-activating protein (IAP), is known to inhibit the alpha-2-adrenoceptor-mediated signal transduction in mammals. We have used IAP to investigated whether fish melanophore alpha-2-adrenoceptors are also inhibited by this toxin. We found that IAP inactivated the alpha-2-adrenoceptor-mediated pigment aggregation in a dose-dependent manner. The inhibitory IAP-effect had a remarkably short onset-time in the melanophores (maximal effect was obtained within 10 min of incubation). Interestingly, binding of an agonist (noradrenaline) to the receptors prevented IAP from exerting its inhibitory action, whereas binding of an antagonist (yohimbine) gave no protection against the IAP-inactivation. In conclusion, the pigment-aggregating receptors of melanophores of L. ossifagus are very similar to the mammalian alpha-2-adrenoceptors. It is possible to inactivate the melanophore receptor system with IAP and this inactivation has a remarkably short onset-time. Stimulation of the alpha-2-adrenoceptors prevents IAP from inactivating the receptor system.

Adrenergic alpha-Agonists↗
PubMed1984

Drugs and the frog retina. Effect of dopaminergic agents on the pigment screening of light- and dark-adapted frogs.

This is a study, using the light and electron microscope, of the action of a dopamine agonist (apomorphine) and of a dopamine antagonist (haloperidol) on the retinal pigment screening (PS) of light- and dark-adapted frogs. Pigment screening is a phenomenon which consists of the migration of melanin granules into processes of the pigment epithelium that extend between photoreceptors, in response to changes in the conditions of illumination. In the light the pigment migrates vitreally , in the dark it aggregates sclerally . A single intravenous injection of apomorphine (0.15 mg/kg) and of haloperidol (1 mg/kg) did not induce substantial modifications in the pattern of pigment screening which was similar to that of controls both in light- and dark-adapted frogs. This suggests that dopamine is probably not directly involved in the phenomenon of pigment screening in the retina of the frog.

Animals↗
PubMed1984

Physiologic pigmentation of the gingiva in Israeli Jews of different ethnic origin.

The prevalence of gingival physiologic pigmentation in three ethnic groups of a total of 2,465 Israeli Jews were determined. The distribution of this gingival pigmentation, according to anatomic parts and divisions, was examined. Results showed the presence of gingival pigmentation in 57.9% of the Eastern group, 49.3% of the Sephardic group, and 21.1% of the Ashkenazi group. No indication of sex predilection was found. The most common site of pigmentation was the labial part of the gingiva, and the attached gingiva was the most common pigmented anatomic division. The group of Eastern Jews showed the highest prevalence of physiologic pigmentation in each of the anatomic parts and divisions of the gingiva.

Adolescent↗
PubMed1985

Larval and adult visual pigments of the zebrafish, Brachydanio rerio.

Photoreceptors of adult and larval zebrafish were assayed by microspectrophotometry to characterize their visual pigments, and to determine when the visual pigments first appear during development. Short single cone outer segments contained a pigment with a lambdamax near 417 nm. Long single cones and long members of double cone outer segments contained a pigment with a lambdamax near 480 nm. Short members of double cone outer segments contained a pigment with a lambdamax near 556 nm. Rod outer segments contained a rhodopsin with a lambdamax near 501 nm. All four visual pigment types found in adult photoreceptors were present in the earliest measurable larval photoreceptors.

Aging↗
PubMed1986

Spectral sensitivity of blowfly photoreceptors: dependence on waveguide effects and pigment concentration.

Spectral and polarization sensitivities of blowfly R1-6 photoreceptor cells were measured by intracellular recordings in cells which differed in visual pigment content. The spectral sensitivity in the visible wavelength range can be quantitatively explained from the absorption spectrum of blowfly visual pigment when the waveguide properties of the rhabdomere are taken into account. The peak wavelengths of absorption and sensitivity spectrum are 490 and 487 nm respectively. At low visual pigment content a sensitizing pigment can enhance the relative U.V. sensitivity from 0.3 to 2.0. In flies with a high visual pigment content selfscreening substantially broadens the visible band of the spectral sensitivity and lowers the relative U.V. sensitivity. The gain of the electrical response appears to be independent of the visual pigment content.

Action Potentials↗
PubMed1988

Polymorphism of visual pigments in a callitrichid monkey.

Microspectrophotometric measurements of visual pigments have been obtained for a large sample of New World monkeys of the species Callithrix jacchus jacchus. These animals exhibit a polymorphism of visual pigments. The rods (Lmax 499 nm) and the short-wave receptors (Lmax 423 nm) appear to be common to all animals but individuals differ in the number and spectral position of pigments in the green-yellow spectral region. The latter pigments cluster near 545, 559 and 567 nm. Male monkeys draw one pigment from this set and female monkeys may draw one or two. The results are generally consistent with a genetic theory that postulates in Callithrix three possible alleles for a single locus in the X-chromosome. It appears that polymorphisms of cone pigments may be widespread among neotropical primates.

Animals↗
PubMed1991

The gecko visual pigment: the anion hypsochromic effect.

The 521-pigment in the retina of the Tokay gecko (Gekko gekko) readily responds to particular physical and chemical changes in its environment. When solubilized in chloride deficient state the addition of Class I anions (Cl-, Br-) induces a bathochromic shift of the absorption spectrum. Class II anions (NO3-, IO3-, N3-, OCN-, SCN-, SeCN-, N(CN)2-), which exhibit ambidental properties, cause an hypsochromic shift. Class III anions (F-, I-, NO2-, CN-, AsO3-, SO2(4-), S2O2(3-) have no spectral effect on the 521-pigment. Cations appear to have no influence on the pigment absorption and Class I anions prevent or reverse the hypsochromic shift caused by Class II anions. It is suggested that the spectral displacements reflect specific changes in the opsin conformation, which alter the immediate (dipolar) environment of the retinal chromophore. The protein conformation seems to promote excited-state processes most in the native 521-pigment state and least in the presence of Class II anions. This in turn suggests that the photosensitivity of the 521-pigment is controlled by the excited rather than by the ground-state properties of the pigment.

Animals↗
PubMed1992

The absorbance spectrum and photosensitivity of a new synthetic "visual pigment" based on 4-hydroxyretinal.

The firefly squid, Watasenia scintillans, is the only animal known to possess a visual pigment in which the chromophore is 4-hydroxyretinal. This paper describes the absorbance spectrum and some properties of a synthetic "A4" visual pigment generated from bovine opsin and 4-hydroxyretinal. The absorbance spectrum of this pigment is compared with (a) bovine rhodopsin and (b) a rhodopsin template with the same lambda max as the synthetic visual pigment. The A4 pigment is shown to have an absorbance spectrum that is almost identical to that of a rhodopsin template. It is also shown that the photosensitivity and thermal stability of the A4 pigment, dispersed in detergent micelles, is essentially similar to that of rhodopsin.

Animals↗
PubMed1994

Ultraviolet visual pigments in marine fishes of the family pomacentridae.

Near-UV visual pigments have been reported in single cones of several freshwater and euryhaline fishes. The presence of UV visual pigments in stenohaline marine fishes have, as yet, not been identified. In the pomacentridae near-UV visual pigments are present in single cones from the three species we examined--the tropical coral fishes Dascyllus trimaculatus and Pomacentrus coelestis, and the temperate Chromis punctipinnis. Maximum absorption of the UV pigments is centered around 360 nm. In juvenile Chromis, however, the UV visual pigment is not present. Instead there is a single cone containing a violet-sensitive pigment absorbing maximally around 420 nm. All three species are obligate diurnal planktivores. The UV sensitivity may function to enhance their ability to forage on zooplankton.

Animals↗
PubMed1987

The limits of bioaccumulation of organic pigments in fish: their relation to the partition coefficient and the solubility in water and octanol.

A reliable experimental determination of the partition coefficient Pow of organic pigments is met with serious difficulties due to the extremely low water solubilities of these compounds. Therefore, the Pow values and the water solubilities were calculated for 11 typical organic pigments and some disperse dyes as well. The calculated Pow values of the pigments were very high predicting bioaccumulation factors (BF) several orders of magnitude above 100. Based on recent studies confirming that n-octanol simulates lipids in their solubilizing effect on organic chemicals, the solubilities of these organic pigments in n-octanol were measured in order to estimate their potential for lipid storage. The very low solubility values indicate that in spite of the very high predicted BF such pigments cannot build up concentrations in lipids (hence in fish) which could be of concern considering their generally low toxicity and the extremely small amounts entering the environment. Therefore, there should be no need to perform a fish bioaccumulation test for assessing the bioaccumulation potential of such compounds, provided they show comparable solubility characteristics as the pigments investigated in this study.

Animals↗
PubMed1992

Effects of melatonin and light on porphyrin synthesis in the bovine retina, pigment epithelium and choroid.

The quantity of porphyrin synthesized in the presence of 10(-3) M delta-aminolevulinic acid (ALA) is several times higher in the bovine pigment epithelium than in the retina. Synthesis in the retina was found to be increased by illumination, whereas synthesis in the pigment epithelium was decreased if the whole anatomical unit (retina-pigment epithelium-choroid) was cultivated together. The quantity of porphyrin synthesized in the presence of 10(-3) M ALA or 10(-6) M melatonin was different when the pigment epithelium and retina were separated. The combination 10(-3) M ALA with 10(-6) M melatonin inhibited retinal porphyrin synthesis after green light adaptation, while in the pigment epithelium green light adaptation induced porphyrin synthesis. It is postulated that the light-sensitive porphyrin-haeme synthesis of the retina-pigment epithelium-choroid functional unit may serve and modulate the synthesis of guanylate cyclase for cGMP.

Adaptation, Physiological↗
PubMed1993

Use of the alexandrite laser (755 nm, 100 nsec) for tattoo pigment removal in an animal model.

BACKGROUND: All previous treatment modalities for the removal of tattoos, with the possible exception of the Q-switched ruby and YAG lasers, result in scarring. OBJECTIVE: The purpose of this study was to investigate the use of a new laser that may remove tattoo pigment without leaving a scar. METHODS: A Yucatan micropig was tattooed by a professional tattoo artist with black, blue, green, and red pigments. These tattoos were then treated with single overlapping pulses with the alexandrite laser (wavelength 755 nm, pulse 100 nsec) and evaluated clinically and histologically. Comparison treatment with an argon laser (wavelength 488 nm, 514 nm, continuous-wave) and flashlamp-pumped dye laser (wavelength 585 nm, pulse 450 microseconds) was performed as well for removal of red tattoo pigment. RESULTS: The alexandrite laser was found to be very effective in removal of professional and amateur black tattoo pigment, moderately effective in removal of blue and green pigment, and minimally effective in removal of red pigment. No scarring was seen clinically or histologically. CONCLUSION: The alexandrite laser shows promise as a treatment modality for tattoo removal without scarring.

Aluminum Oxide↗
PubMed1988

Lipid pigment (lipofuscin) in human perioral muscles with aging.

In a study of 80 perioral muscle specimens, lipid pigment (Lipofuscin) granules were present in 68.5% of the cases. The pigmented granules, which were stored at the nuclear poles, were PAS positive, stained black or brown with the Masson-Fontana procedure, black with Sudan black and strong purple-pink with Ziehl-Neelsen staining; yellow autofluorescence was emitted in ultraviolet light. The morphology, histochemical reactions and autofluorescence of the pigmented granules were characteristics of the endogenous lipid pigment--lipofuscin. Statistical analyses indicated a direct correlation between increase in quantity and distribution of the pigment and increase in age (p less than 0.0001), in both males and females. Accumulation of the pigment in the perioral muscles with aging was found to be similar to that in the myocardium and tongue muscles.

Aging↗
PubMed1984

A mechanism of action for the inhibition of black pigment dispersion in the fiddler crab, Uca pugilator, by naphthalene.

The polycyclic aromatic hydrocarbon, naphthalene, inhibits the circadian dispersion of epidermal black pigment in the fiddler crab, Uca pugilator, by inhibiting the release of black pigment dispersing hormone. Naphthalene caused no permanent neural damage in Uca pugilator. Naphthalene did not cause a chemically-induced phase shift in the circadian rhythm of black pigment dispersion but reduced the daytime peak of that dispersion. Black pigment concentration, which occurs at night, was not affected by exposure to naphthalene. Black pigment dispersing hormone in naphthalene-exposed crabs can be released by an injection of norepinephrine. Given the points above, and previously published data, it is concluded that naphthalene inhibits circadian black pigment dispersion in Uca pugilator by inhibiting the release of the neurotransmitter, norepinephrine.

Animals↗
PubMed1992

A locus control region adjacent to the human red and green visual pigment genes.

Deletion of sequences 5' of the human red and green pigment gene array results in blue cone monochromacy, a disorder in which both red and green cone function are absent. To test whether these sequences are required for transcription of the adjacent visual pigment genes in cone photoreceptors, we produced transgenic mice carrying sequences upstream of the red and green pigment genes fused to a beta-galactosidase reporter. The patterns of transgene expression indicate that the human sequences direct expression to both long and short wave-sensitive cones in the mouse retina and that a region between 3.1 kb and 3.7 kb 5' of the red pigment gene transcription initiation site is essential for expression. Sequences within this region are highly conserved among humans, mice, and cattle, even though the latter two species have only a single visual pigment gene at this locus. These experiments suggest a model in which an interaction between the conserved 5' region and either the red or the green pigment gene promoter determines which of the two genes a given cone expresses.

Animals↗