Fish Pigmentation Research Articles

Spectral sensitivity of cones in the goldfish, Carassius auratus.

The spectral sensitivities of retinal cones isolated from goldfish (Carassius auratus) retinas were measured in the range 277-737 nm by recording membrane photocurrents with suction pipette electrodes (SPE). Cones were identified with lambda max (+/- S.D.) at 623 +/- 6.9 nm, 537 +/- 4.7 nm, 447 +/- 7.7 nm, and about 356 nm (three cells). Two cells (lambda max 572 and 576 nm) possibly represent genetic polymorphism. A single A2 template fits the alpha-band of P447(2), P537(2), and P623(2). HPLC analysis showed 4% retinal:96% 3-dehydroretinal. Sensitivity at 280 nm is nearly half that at the lambda max in the visible. The lambda max of the beta-band (in nm) is a linear function of the lambda max of the alpha-band and follows the same relation as found for A1-based cone pigments of a cyprinid fish.

Photic Environment, Visual Pigments, and the Limits of the Visible Spectrum

The limits of the visible spectrum are set by the light available for vision, and by the visual pigment absorbance. The hundreds of visual pigments studied to the present day have absorbance maxima spread within the range from 350 to 620 nm. Yet this diversity is used for vision quite nonuniformly: rod and cone visual pigments are tightly clustered around a few preferred positions in the spectrum, eg near 500 nm in the rods of land animals. The so-called ‘sensitivity hypothesis’ assumes that the clustering is to maximise the number of absorbed photons available in the animals' light environment. In most cases, however, visual pigments are substantially more short-wave (blue-shifted) than is necessary for maximum quantal absorption. Examples of the ‘blue shift’ are the Purkinje shift during cone - rod transition in dark adaptation, the hypsochromic shift of rod visual pigments in deep-water fish, and a similar shift in the cone pigments of geckos and some snakes as a result of evolutionary adaptation to nocturnal habits. It is argued that an important limiting factor in vision is the dark noise produced by thermal isomerisation of the chromophore. Measurements of the dark noise in rods with different visual pigments show that the noise increases steeply when the absorbance maximum is shifted to longer wavelengths, thus precluding the use of long-wave pigments for vision at low intensities. The optimum spectral position of a pigment may be that which ensures a maximum light-to-noise ratio in a particular photic environment.

Mechanisms of wavelength tuning in the rod opsins of deep-sea fishes.

The main object of this study was to investigate the molecular basis for changes in the spectral sensitivity of the visual pigments of deep-sea fishes. The four teleost species studied, Hoplostethus mediterraneus, Cataetyx laticeps, Gonostoma elongatum and Histiobranchus bathybius, are phylogenetically distant from each other and live at depths ranging from 500 to almost 5000 m. A single fragment of the intronless rod opsin gene was PCR-amplified from each fish and sequenced. The wavelength of peak sensitivity for the rod visual pigments of the four deep-sea species varies from 483 nm in H. mediterraneus and G. elongatum to 468 nm in C. laticeps. Six amino acids at sites on the inner face of the chromophore-binding pocket formed by the seven transmembrane a-helices are identified as candidates for spectral tuning. Substitutions at these sites involve either a change of charge, or a gain or loss of a hydroxyl group. Two of these, at positions 83 and 292, are consistently substituted in the visual pigments of all four species and are likely to be responsible for the shortwave sensitivity of the pigments. Shifts to wavelengths shorter than 480 nm may involve substitution at one or more of the remaining four sites. None of the modifications found in the derived sequences of these opsins suggest functional adaptations, such as increased content of hydroxyl-bearing or proline residues, to resist denaturation by the elevated hydrostatic pressures of the deep sea. Phylogenetic evidence for the duplication of the rod opsin gene in the Anguilliform lineage is presented.

On the visual pigments of deep-sea fish

The retinal visual pigments of 52 species of deep-sea fish were measured by partial bleaching of detergent extracts. The retinae of 45 species contained only a single rhodopsin with maximum absorbance (λmax) at a wavelength between 474 and 490 nm, matching both the region of highest intensity downwelling sunlight and the maximum emission of most deep-sea bioluminescence. Seven species were shown to have more than one visual pigment within their retinae and these had λmax values that generally fell outside the usual range. One of these, Bonapartia pedaliota, was particularly interesting as, unlike most such multipigment species, it had one rhodopsin and one porphyropsin pigment, apparently based on different opsins. The relative proportions of the visual pigments in the seven multipigment species are presented.

The visual pigments of fish

The visual pigments of fish

Improvement of flat fish pigmentation through the use of DHA-enriched rotifers and Artemia

Improvement of flat fish pigmentation through the use of DHA-enriched rotifers and Artemia

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.

Optical biosensors based on fish pigment cells

Melanophores (black pigment cells) in isolated fish scales have the ability to either aggregate their intracellular pigment granules to the centre or disperse them throughout the cell. Noradrenaline stimulates aggregation within these cells. The sensitivity of noradrenaline is considerably increased after approximately one week of isolation of the scales in a tissue culture medium. In order to measure simultaneously pigment aggregation in several isolated scales, a multichannel fibre-optic system has been developed. The system enables the scales to be constantly perfused with tissue culture medium, which in turn allows measurements to be made over long periods of time. After nine days of isolation there is an approximately 12 000-fold increase in noradrenaline sensitivity. The fibre-optic system, combined with cultured melanophores and molecular biology techniques, should provide a number of interesting biosensing possibilities.

Destruction of Heme Pigment in Meat and Fish During Roasting

Destruction of Heme Pigment in Meat and Fish During Roasting

Single and multiple visual pigments in deep-sea fishes

The visual pigments in the retinal rods of 17 species of deep-sea fish were examined by microspectrophotometry or visual pigment extract spectrophotometry. In 15 species single visual pigments were found with peak sensitivities between 470 and 490 nm, typical of deep-sea fishes. However, in one species,Stylephorons cordatus, two visual pigments were found with λ values at 470 and 481 nm. In another species,Scopelarchus analis, three visual pigments were found with mean λ values of 444, 479 and 505 nm. The short-wave pigment of this species was found both in main and accessory retinae. It was present both in single rods and in outer segments which had the most long-wave sensitive pigment in their distal parts. It is argued that these two-pigment rods are in the process of changing their visual pigment from a ‘juvenile’ VP505 pigment to an ‘adult’ VP444 pigment. The VP479 was found only as a single pigment in rods in the accessory retina.

Bile pigments in fishes: a review.

Gallbladder (GB) bile of most cyclostomes, elasmobranchs, and teleosts contains appreciable amounts of biliverdin (BV) and bilirubin (BR) conjugates with lesser amounts of unconjugated BR in certain species. Certain elasmobranch and teleost species have been reported to have primarily BV or BR in bile. The appearance of the enzyme BV reductase, which converts BV to BR in mammals, evolved quite early in the evolution of vertebrate species; however, exceptions exist in certain fishes, amphibians, reptiles, and mammals whose bile contains primarily BV. Nearly all analytical studies on bile pigment composition in fishes to date have utilized only GB bile, which may or may not always be representative of the pigments excreted in freshly collected hepatic duct bile. The concentration of BV and BR in GB bile of fishes increases markedly during prolonged fasts. From the limited data currently available, there appears to be no systematic development from primitive to advanced forms in the appearance of certain bile pigments in fishes. While bile of most aquatic species contains appreciable amounts of both BV and BR, it is interesting that the bile of most terrestrial avian and reptilian forms contains primarily BV. The serum of fishes, except for certain bony species such as eels (Anguilleformes) and cottids (Scorpaeniformes), is a light yellow color due to the presence of BR and is similar to that observed in higher vertebrates. Serum from certain eels and cottids is bluish green in color due to the presence of a variety of chromoproteins that contain BV firmly bound as the prosthetic group.

The scotopic photoreceptors and their visual pigments of fishes: functions and adaptations

The scotopic photoreceptors and their visual pigments of fishes: functions and adaptations

Convergent evolution of the red- and green-like visual pigment genes in fish, Astyanax fasciatus, and human.

We have isolated and sequenced genes from the blind cave fish, Astyanax fasciatus, that are homologous to the human red and green visual pigment genes. The data strongly suggest that, like human, these fish have one red-like visual pigment gene and multiple green-like visual pigment genes. By comparing the DNA sequences of the human and fish visual pigment genes and knowing their phylogenetic relationship, one can infer the direction of amino acid substitutions in the red and green visual pigments. The results indicate that the red pigments in human and fish evolved from the green pigment independently by identical amino acid substitutions in only a few key positions.

Intestinal absorption of astaxanthin, plasma astaxanthin concentration, body weight, and metabolic rate as determinants of flesh pigmentation in salmonid fish

Experiments were conducted to determine whether poor intestinal absorption of astaxanthin or some other metabolic factor is primarily responsible for pigmentation failure in white chinook salmon and small juvenile fish of other salmonid species. None of the fish studied failed to absorb astaxanthin from a single oral dose of the pigment. Intensity of flesh pigmentation in coho ranging in weight from 30–400 g, and fed a diet supplemented with astaxanthin, was significantly correlated with body weight. There was no correlation, however, between flesh colour and plasma astaxanthin concentration or between body weight and plasma astaxanthin concentration. Dietary triiodothyronine reduced both flesh pigmentation and plasma astaxanthin. It is concluded that poor flesh pigmentation results from rapid metabolism of absorbed pigment to colourless derivatives rather than from failure of the fish to absorb pigment.

Adaptations for scotopic vision in the lemon shark (Negaprion brevirostris)

The visual pigments of teleost fishes are based upon either vitamin A1 or vitamin A2. The absorption spectra of these pigments provide a great enough range for fish to successfully inhabit a variety of photic environments. Elasmobranchs on the other hand, live in the same photic habitats as teleost fish, but have been found to possess visual pigments based only upon vitamin A1. The action spectrum for the dark adapted juvenile lemon shark has absorption maxima around 520 nm. This does not match the absorption spectra for the visual pigment extracted from the adult lemon shark, which is a rhodopsin, vitamin A1-based visual pigment with peak absorption at 501 nm. This mismatch has been resolved with the finding that the visual pigment of the juvenile lemon shark is a porphyropsin, vitamin A2-based visual pigment with maximum absorption at 522 nm. There thus seems to be a developmental change from a porphyropsin to a rhodopsin system with an accompanying change in the point of maximum absorption. This can be explained by the differences in the habitats of the juvenile vs. adult animals. This also suggests that other elasmobranchs may possess vitamin A2-based visual pigments.

Commentary how is microtubule-based organelle translocation regulated?

ABSTRACT It has long been appreciated from light-microscopical studies that components move in a directed fashion within cells, and this is particularly obvious in cells showing high degrees of asymmetry. The correlation between such movements and the presence of orientated aggregations of microtubules, first observed by electron microscopy and subsequently at the light-microscopic level using immunological techniques, pointed to the involvement of these linear organelles in this intracellular translocation (see Hyams and Stebbings, 1979). Many different cellular organelles, including endosomes, lysosomes, mitochondria and various types of secretory vesicles, show directed translocation along microtubules, and their movement is clearly crucial to normal cell physiological function. The most extensively studied example has been the axonal processes of neurones, but various protozoa, fish pigment cells and insect ovaries also show exaggerated forms of intracellular translocation, and have proved valuable in studying the phenomenon.

Earliest fossil evidence for protective pigmentation in an actinopterygian fish

The oldest known occurrence of an actinopterygian fish with preserved cryptic and disruptive pigmentation is a single specimen from a Permocarboniferous site in southeastern Kansas, U.S.A. It is a juvenile assignable to the Elonichthys species complex within the paraphyletic lower actinopterygian group “Palaeoniscoidea”;. The preserved pattern consists of dark dorsal mottlings and two lateral stripes that run the length of the body. These markings provide the earliest evidence in primitive fossil actinopterygians for (respectively) countershading and the use of disruptive markings to break up the body outline, two of the most common protective coloration strategies in Recent fishes. Anti‐predator protective markings therefore evolved in actinopterygians by at least the latter part of the Paleozoic (nearly 300 million years ago).

Dose response to astaxanthin and canthaxanthin pigmentation of rainbow trout fed various dietary carotenoid concentrations

Rainbow trout ( Salmo gairdneri Richardson) with a mean initial weight of 135 g were fed diets supplemented with astaxanthin or canthaxanthin in concentrations of 0.0, 12.5, 25.0, 50.0, 100.0 and 200.0 mg/kg for 6 weeks. Fish pigmentation increased with increasing dietary carotenoid concentration up to 3.7 mg/kg flesh in the best pigmented groups. The fish were pigmented faster with astaxanthin than with canthaxanthin. For both pigments, the retention coefficients de-creased as the pigment dose in the diet increased. The mean retention coefficient for astaxanthin was 1.3 times higher than for canthaxanthin.

Effects of Water Temperature on the Mortality of Field-Collected Fish Marked with Fluorescent Pigment

-The cumulative effects of collection, handling, and marking with fluorescent pigment on the mortality of adult minnows, young-of-the-year centrarchids, and large centrarchids and percids was determined at five water temperatures (10-20.6°C) in field trials. There have been few field trials of this type. The mortality of centrarchids and percids was directly related to temperature and decreased noticeably when the temperature was below 19.5°C. The mortality of minnows decreased somewhat as river temperatures cooled but was always at least 50%. Variation was high in the temperature-related patterns of mortality in different taxa and sizes of fish. This variation complicates the accuracy and usefulness of pigment in marking field-collected fish for mark-recapture studies in warmwater systems.

Bioaccumulation of dyestuffs and organic pigments in fish. Relationships to hydrophobicity and steric factors

For 23 disperse dyestuffs, 2 organic pigments and a fluorescent whitening agent, for which experimental bioaccumulation factors in fish are known, log P OW values (partition coefficient octanol/ water) were calculated and determined, if possible. For comparison, 16 halogenated aromatic hydrocarbons are included. Two parameters were chosen to parameterise the size of the molecules: the molecular weight and, following a suggestion by Opperhuizen et al., the second largest v.d.Waals diameter of the molecules, measured on conformations optimised by force field calculations. None of the disperse dyestuffs, even the highly lipophilic ones with log P OW > 3.0, accumulate in fish to a significant degree. It is argued that their large molecular size effectively prevents their permeation through biological membranes and thus their uptake during the time of exposure. For screening organic colorants for their bioaccumulation potential a decision scheme is roposed using as parameters the solubility in water and in octanol, the partition coefficient octanol/water, and the molecular weight and size. This scheme suggests in its last step that there should be no need to perform a fish bioaccumulation test provided the organic colorants have a molecular weight of more than 450 Daltons and a second largest cross section of over 1.05 nanometers.