Incidence Of Melanosis Research Articles

Blood vessel melanosis: a physiological detoxification mechanism in Atlantic cod (Gadus morhua)

Melanin deposits in white muscle represent a potentially serious quality problem for farmed cod. Black lines of deposited melanin are associated with blood vessels and consist of layers of melanin-filled cells. Despite numerous anecdotal reports of melanosis in farmed cod no detailed investigations into the underlying mechanisms have been undertaken. In this study we have confirmed that melanosis is present in both farmed and wild cod. However, the incidence of melanosis in wild fish is much lower than that in farmed fish. In addition, we have demonstrated that tyrosinase, a copper-dependent metalloenzyme that is the primary enzyme of melanin synthesis, is present in cod tissues. Copper levels are significantly different in the white muscle of farmed (0.5 ± 0.03 mg/kg wet weight) and wild (0.34 ± 0.01 mg/kg wet weight) cod (P < 0.05) and in the blood vessels of farmed (2.23 ± 0.37 mg/kg wet weight) and wild (0.32 ± 0.02 mg/kg wet weight) cod (P < 0.05). Similarly, differences in the levels of tyrosinase activity were observed in both muscle and blood vessels. Melanised tissues contain higher copper concentrations than tissue containing little or no melanin. Furthermore, we have shown that the addition of copper to protein extracts from fish muscle causes an increase in tyrosinase activity in vitro. Our results suggest that overabundance of copper in commercial feeds leads to increased melanin synthesis via increased tyrosinase activity. We propose that melanin is deposited at sites of high copper exposure and subsequently sequesters copper as a means of reducing the overload stress on other homeostatic mechanisms.

Melanosis and squamous cell neoplasms of the upper aerodigestive tract in Japanese alcoholic men

Melanosis is frequently observed in the upper aerodigestive tract of Japanese alcoholic men, and the prevalences of squamous cell dysplasia and SCC in the upper aerodigestive tract of Japanese alcoholic men are high. This study evaluated associations between melanosis and both neoplasms of the upper aerodigestive tract and factors contributing to the development of melanosis in Japanese alcoholic men. Endoscopic screening of 643 Japanese alcoholic men (aged 50-79 years) was combined with oropharyngolaryngeal inspection and esophageal iodine staining, and ALDH2 genotyping was carried out in 425 of them. Melanosis was frequently (20.8%) observed in the upper aerodigestive tract. The palate was the most common site of melanosis (11.2%), followed by the pharynx (9.5%), and by the esophagus (7.0%). The incidence of melanosis was higher in those with esophageal dysplasia (31/126, 24.6%), esophageal SCC (19/42, 45.2%), and oropharyngolaryngeal SCC (8/14, 54.1%) than in cancer- and dysplasia-free controls (69/437, 15.8%). The presence of melanosis was associated with a higher risk of esophageal dysplasia, esophageal SCC, and oropharyngolaryngeal SCC (OR 1.69, 4.03, and 6.61, respectively). Multivariate analysis showed that older age, heavier smoking, and heterozygosity for inactive ALDH2 were positively associated with the presence of melanosis. The presence of melanosis indicates a high risk for neoplasms in the upper aerodigestive tract of Japanese alcoholic men. Melanosis and neoplasms have the same causes, including older age, heavy smoking, and high acetaldehyde exposure.

Utilization of chitosan for preservation of raw shrimp (Pandalus borealis)

Whole and headless shrimp (Pandalus borealis) were dipped in various concentrations of chitosan solution and stored for 20 days at 4–7°C. The effects of chitosan on microbial proliferation, total volatile bases, nucleotide breakdown, and blackspot formation were monitored over this period. Chitosan showed strong antimicrobial properties inhibiting several microorganisms at concentrations ranging between 0.0075 ‐ 0.01%. The Pseudomonads, however, were very resistant to chitosan requiring much higher concentrations (0.1%) for inactivation. Chitosan reduced the levels of total volatile bases but had no effect on nucleotide breakdown. On the incidence of melanosis, there were no significant differences (p > 0.05) between samples treated with chitosan and the non‐treated samples although blackspot formation was more extensive in whole than headless shrimp. Furthermore, treatment of shrimp with 2% chitosan showed consistently lower incidence of melanosis during storage. The results suggest that chitosan may prove useful as a tool for controlling microbial spoilage of shrimp, but may be limited by its ineffectiveness at controlling melanosis in the postmortem animal.

Black discoloration of spiny lobster of genus Panulirus WHITE - III. Incidence of melanosis in the integumentary tissue.

The incidence of black discoloration was verified in the integumentary tissues of tails of spiny lobster Panulirus laevicauda (LATREILLE), collected at a local plant and a retail shop. As already indicated in the previous work, the relationship beween the stages of molting cycle and melanosis is statistically confirmed, and furthemore, sex has also been found to be differentially affected, females being more prone to discoloration than males. All lobsters in these samples were found to be injured and to be in the stages C and D. Appearances of black discoloration in the integumentary tissue were observed histologically on the epidermis in stage C and on the epicuticle in stage D, respectively, and being identified as melanin.

The Production of Spontaneous Melanotic Neoplasms in Fishes by Selective Matings: II. Neoplasms with Macromelanophores Only. III. Neoplasms in Day Old Fishes

Introduction In previous work it has been shown that when a spotted platyfish ( Platy-poecilus maculatus ) is mated with a Mexican swordtail ( Xiphophorus hellerii ) melanosis develops in all those hybrids which inherit the spotting factor from their platyfish parent. When the platyfish parent is homozygous for the spotted factor ( SpSp ), melanosis develops in all the hybrids; whereas if the platyfish parent is heterozygous for the spotted factor ( Spsp ), one-half of the hybrids are melanotic and the other half are normal. The platyfish has two types of melanophores—one type, the smaller, called micromelanophores, is inherited as an autosomal dominant, whereas the large type, called macromelanophores, is inherited as a sex-linked dominant factor (Gordon 1927). Both types may be, and usually are, present in a single individual, though genetic strains have been developed in which only one or the other type of melanophore is present. A number of different hybrid combinations are possible between the platyfish and the swordtail with reference to their melanophore content. The combinations are listed below, together with the incidence of melanosis in the particular type of hybrid. It is evident from the above table and from Fig. 1 that, only when the platyfish parent transmits macromelanophores to the hybrid offspring, do these offspring develop melanosis. Platyfish may have micro- and macromelanophores, but macromelanophores alone combined with the hereditary factors of the swordtail are sufficient to bring melanosis to their hybrid young. In all the cases listed in the table and figure, the swordtail parent had micro-melanophores. The following experiments describe the results when sword-tails without melanophores are used as parents for hybrid offspring.