Melanins are negatively charged, hydrophobic pigments of high molecular weight (54, 88, 95, 139) that are composed of polymerized phenolic and/or indolic compounds (Fig. 1) (45, 128). Melanins are produced by organisms in all biological kingdoms, including a wide variety of pathogenic bacteria, fungi, and helminths (reviewed in reference 90). Remarkably little is known about the structures of m...

Melanin contained in pigment cells in a variety of tissues co-purifies with nucleic acids in standard RNA (or DNA) extraction procedures. The presence of melanin in RNA (or DNA) templates can inhibit reverse transcription polymerase chain reactions (RT-PCR) and/or PCR (5). In the past, to circumvent this problem, melanin has been separated from DNA by either columnchromatography (5) or acid-pre...

Dissimilatory metal-reducing bacteria (DMRB) utilize numerous compounds as terminal electron acceptors, including insoluble iron oxides. The mechanism(s) of insoluble-mineral reduction by DMRB is not well understood. Here we report that extracellular melanin is produced by Shewanella algae BrY. The extracted melanin served as the sole terminal electron acceptor. Upon reduction the reduced, solu...

BACKGROUND Melanin pigments are ubiquitous in nature. Melanized microorganisms are often the dominating species in certain extreme environments, such as soils contaminated with radionuclides, suggesting that the presence of melanin is beneficial in their life cycle. We hypothesized that ionizing radiation could change the electronic properties of melanin and might enhance the growth of melanize...

Background and objectives: Phytochemical studies have shown that the Phlomis species are rich in polyphenolics and iridoid glycosides and many of them have shown potential value in different biological and pharmacological activities. In this study, we evaluated the effect of Phlomis persica, P. brugieri, P. olivieri and P. anisodontea</em...

The relatively high co-occurrence of Parkinson's disease (PD) and melanoma has been established by a large number of epidemiological studies. However, a clear biological explanation for this finding is still lacking. Ultra-violet radiation (UVR)-induced skin melanin synthesis is a defense mechanism against UVR-induced damage relevant to the initiation of melanoma, whereas, increased neuromelani...

In birds, carotenoid-based plumage coloration is more dependent on physical condition and foraging abilities and less constrained developmentally than is melanin-based coloration. Thus, female mate choice for honest signals should result in more intense sexual selection on carotenoidthan on melanin-based plumage coloration. Using variation in sexual dimorphism as an indirect measure of the inte...

The presence of melanin in spleens of black C57BL/6 mice has been known for long. Although its origin and biological functions are still obscure, the relation of splenic melanin to the hair follicle and skin pigmentation was suggested. Here, we demonstrated using for the first time electron paramagnetic resonance spectroscopy that black-spotted C57BL/6 spleens contain eumelanin. Its presence he...

in this study, we investigate the potential of moricandia arvensis methanol leaf extract (meohl) on calpain activity, melanin biosynthesis and dna mutagenicity. cytotoxic effect and measurement of reactive oxygen species (ros) induced by lucigenin in colorectal cells (be) were also determined. in addition the chemical analysis of the extract was also studied and the chemical profile illustrates...