Crustacean pigment

Sequence Similarities of Insect Pigment-Dispersing Factors and Crustacean Pigment-Dispersing Hormones... 

Various stereoisomers occur as fish and crustacean pigments. 

Hiller-Adams, P., Widder, E. A., and Case, J. F. (1988). The visual pigments of four deep-sea crustacean species. J. Comp. Physiol. 163A 63-72. 

Specific carotenoid-protein complexes have been reported in plants and invertebrates (cyanobacteria, crustaceans, silkworms, etc.), while data on the existence of carotenoproteins in vertebrates are more limited. As alternatives for their water solubilization, carotenoids could use small cytosolic carrier vesicles." Carotenoids can also be present in very fine physical dispersions (or crystalline aggregates) in aqueous media of oranges, tomatoes, and carrots. Thus these physicochemical characteristics of carotenoids as well as those of other pigments are important issues for the understanding of their bioavailability. 

Astaxanthin (3,3-dihydroxy-p,p-carotene-4,4-dione) is widely distributed in Nature and is the principal pigment in crustaceans and sahnonids. The carotenoid imparts distinctive orange-red coloration to the animals and contributes to consumer appeal in the market place. 

Many marine species also possess the tyrosinase-mediated pathway to synthesize the UV-absorbing pigment melanin. Melanin occurs in a wide range of taxa including bacteria, fungi, invertebrates, and chordates. While much is known about the role of melanin in the UV protection of mammalian skin, very little research has been conducted to examine the efficiency of melanin as a UV-protective mechanism in aquatic taxa.9 It is known that melanin levels in juvenile hammerhead sharks, Sphyrna lewini, are directly correlated to solar UV exposure in the freshwater crustacean Daphnia pulex, melanin concentrations are genetically determined within populations and are correlated to UV sensitivity.50-51 The few studies that have been undertaken suggest that melanin has an important role in UV protection in aquatic environments. 

Both of these peptides exhibited considerable sequence identity with the locust adipokinetic hormone (Lom-AKH-I) and the crustacean red pigment-concentrating hormone (RPCH), as had been suggested by chromatographic behavior, N-terminal analysis, and amino acid analysis (3,4). Indeed, both peptides were shown to be far more potent as stimulators of hyperglycaemia than as myotropins (3). 

Lom-AKH-I was found to be related to the red pigment-concentrating hormone (RPCH) that had been described previously from crustaceans (9). Subsequendy, two... 

Influence on Color Change In Insects and Chromatophoral Pigment Movements In Crustaceans... 

Leu-amide) isolated from cockroach heads (16). MRCH/PBAN peptides do not resemble any of the crustacean chromatophorotropins, and the former peptides may not be active on crustacean chromatophores and eye pigment cells. It remains unknown whether MRCH influences rapid color changes brought about by intracellular pigment migration in insects. 

The similarity of the crustacean blanching substance (Factor A) found in crustacean sinus glands and insect corpora cardiaca has been confirmed by the structural identification of a family of neuropeptides common to arthropods. The first identified member of this family is RPCH (red pigment concentrating hormone), an octapeptide (pGlu-Leu-Asn-Phe-Ser-Pro-Gly-Trp-amide) isolated from eyestalks of the shrimp Pandalus borealis (28). Shortly thereafter, a related peptide--designated as adipokinetic hormone (AKH)--was purified from locust... 

Pigment-Dispersing Actions of Insect Nervous Tissue Extracts on Crustacean Chromatophores... 

In tests for melanophore pigment dispersion in eyestalkless individuals of the fiddler crab Uca pugilator, head extracts from the cockroach Periplaneta americana and the honey bee Apis mellifera showed strong activity, as did the crustacean eyestalk extracts 36). Head extracts of the butterfly Danaus plexippus and the mealworm Tenebrio molitor fere, however, inactive in the chromatophoral dispersion assay. 

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