Genetic Factors and Genotype-Environment Interactions Contribute to Variation in Melanin Production in the Fungal Pathogen Cryptococcus neoformans.

Cryptococcosis is a common opportunistic fungal infection that often disseminates into the central nervous system, leading to meningitis. Production of melanin pigments during infections is one of the most important virulence factors of its causal agent, the human pathogenic yeast Cryptococcus neoformans species complex. However, almost nothing is known about the patterns of variation in melanin production among clinical and environmental strains and the potential effects of such variations on virulence. In this study, we assembled a global collection of C. neoformans var. neoformans strains and investigated their patterns of melanin variation and potential contributors to such variations. Our analyses revealed that genetic differences and genotype-environment interactions explained up to 59% and 43% of the population's melanin variance respectively, depending on the tested environments. In comparison, environmental factors alone contributed relatively little to melanin variance. We also identified specific changes within the LAC1 gene, whose protein product catalyzes melanin synthesis, to be associated with variable melanin levels. This study provides fresh insights into the origin and evolution of virulence traits in fungal pathogens while highlighting the complex interplay between genetic and environmental factors that lead to phenotypic variance.

Influence of different cosmetic vehicles in mechanical and physical properties of hair treated with oxidative hair dyes

ABSTRACT Hair care products play a significant role in the cosmetic market and aim at improving hair brightness, breakage resistance, and color change. In this study, we analyzed the possibility of the formulation of oxidative dyes in different vehicles impacting the hair's both mechanical and physical properties. Light brown and light blond dyes were prepared using eight different vehicles. Among these, four vehicles were emulsifying agents and four gelling agents. Each formulation was applied to two types of virgin Caucasian hair (light blond and dark brown). Physical, chemical, and organoleptic properties of each formulation were assessed, as well as changes in hair parameters after oxidative dyeing, such as staining intensity, brightness, and breaking strength. The parameters of color and brightness differed in some formulations, but the hair type also responded differently. Brightness parameter was increased in dark brown hair colored with both dyes, whereas light blond hair showed the opposite result. Regarding the breaking strength, there were no significant differences between the two kinds of tresses. Cosmetic formulations should adjust the consumer desired effects (e.g. color change) in order to present minimal drawbacks (e.g. decrease of hair brightness and strength). Thus, the study of different vehicles is important when establishing the best oxidative dye formulation.

[Melanin pigments of fungi under extreme environmental conditions (review)].

This review is dedicated to the research on the functions of melanin pigments in fungi. The participation of melanin pigments in protection from environmental factors is considered. Data on the biosynthetic pathways and types of melanin pigments in fungi are presented.

Determination of melanin types and relative concentrations: an observational study using a non-invasive inverse skin reflectance analysis.

OBJECTIVE: Melanin is a major skin colour pigment that is made up of eumelanin (the dark brown-black colour) and pheomelanin (the light red-yellow colour) pigments. Skin-whitening products typically contain depigmentation agents that reduce the level of pigmentation by changing the pheomelanin-eumelanin production. Similarly, in skin pigment treatment of skin disorders, the melanin production is managed accordingly. To assess and improve treatment efficacy, it is important to have a measurement tool that is capable of determining the melanin types objectively. So far, the efficacy assessment is subjective. In this study, an inverse skin reflectance pigmentation analysis system that determines eumelanin and pheomelanin content is developed and evaluated in an observational study involving 36 participants with skin photo type IV. METHODS: The reflectance spectra of the left forearms of participants were analysed by the pigmentation analysis system to determine their skin parameters--pheomelanin and eumelanin concentrations, melanosome volume fraction, and epidermal thickness. The determined skin parameters are then inputted into the realistic skin model (RSM) of the Advanced Systems Analyses Program (asap®) to generate the ground truth reflectance spectra for the given skin parameters to validate the system. RESULTS: The developed pigmentation analysis system is found to be accurate with a spectral error of 0.0163 ± 0.009 between measured reflectance and the reflectance output of the analysis system and RSM. The regression analysis shows a strong linear relationship (R(2) = 0.994) indicating good precision. The relative concentrations of pheomelanin (38.23 ± 15.04) and eumelanin (1.68 ± 0.91) analysed by the system gives a ratio of pheomelanin to eumelanin of 0.048 ± 0.029; this value is consistent with previously reported figure of 0.049. CONCLUSION: The proposed pigmentation analysis system is able to determine melanin types and their relative concentrations. It has the potential to assess the efficacy of the skin-whitening and pigmentation treatments objectively in a non-invasive manner.

Melanins and melanogenesis: methods, standards, protocols.

Despite considerable advances in the past decade, melanin research still suffers from the lack of universally accepted and shared nomenclature, methodologies, and structural models. This paper stems from the joint efforts of chemists, biochemists, physicists, biologists, and physicians with recognized and consolidated expertise in the field of melanins and melanogenesis, who critically reviewed and experimentally revisited methods, standards, and protocols to provide for the first time a consensus set of recommended procedures to be adopted and shared by researchers involved in pigment cell research. The aim of the paper was to define an unprecedented frame of reference built on cutting-edge knowledge and state-of-the-art methodology, to enable reliable comparison of results among laboratories and new progress in the field based on standardized methods and shared information.

Finding new enzymes from bacterial physiology: a successful approach illustrated by the detection of novel oxidases in Marinomonas mediterranea.

The identification and study of marine microorganisms with unique physiological traits can be a very powerful tool discovering novel enzymes of possible biotechnological interest. This approach can complement the enormous amount of data concerning gene diversity in marine environments offered by metagenomic analysis, and can help to place the activities associated with those sequences in the context of microbial cellular metabolism and physiology. Accordingly, the detection and isolation of microorganisms that may be a good source of enzymes is of great importance. Marinomonas mediterranea, for example, has proven to be one such useful microorganism. This Gram-negative marine bacterium was first selected because of the unusually high amounts of melanins synthesized in media containing the amino acid L-tyrosine. The study of its molecular biology has allowed the cloning of several genes encoding oxidases of biotechnological interest, particularly in white and red biotechnology. Characterization of the operon encoding the tyrosinase responsible for melanin synthesis revealed that a second gene in that operon encodes a protein, PpoB2, which is involved in copper transfer to tyrosinase. This finding made PpoB2 the first protein in the COG5486 group to which a physiological role has been assigned. Another enzyme of interest described in M. mediterranea is a multicopper oxidase encoding a membrane-associated enzyme that shows oxidative activity on a wide range of substrates typical of both laccases and tyrosinases. Finally, an enzyme very specific for L-lysine, which oxidises this amino acid in epsilon position and that has received a new EC number (1.4.3.20), has also been described for M. mediterranea. Overall, the studies carried out on this bacterium illustrate the power of exploring the physiology of selected microorganisms to discover novel enzymes of biotechnological relevance.

Tradition of pigment cell research at Charles University in Prague.

A short review on the history of pigment cell research at Charles University (Ch.U.) in Prague is presented. The famous Czech physiologist and professor J.E. Purkyne started the pigment cell research at Ch.U. already in 1837. He discovered melanin granules in the cells of substantia nigra of the brain. Later, in 1858, a Czech professor of medicine at Ch.U., B. Eiselt, as the first, described melanogenuria in 3 patients with generalized melanoma. Also some German professors at Ch.U. contributed to the research of melanins and melanogenuria in the past, especially H. Waelsch (1932). After the World War II, a Czech professor of medical chemistry at Ch.U., A.F. Richter with his young assistant J. Duchon continued in the chemical exploration of melanins (1954) and J.D. with Z. Pechan, B. Matous and S. Pavel devoted their attention to melanogenuria in melanoma patients (1962-1980). In 1967 they identified 2 new metabolites in melanoma urine: 5-hydroxy-6-methoxy and 6-hydroxy-5-methoxy-indole-2-carboxylic acids. J. Duchon with J. Borovanský and P. Hach also studied morphology and chemical composition of different melanosomes (1972-1979) and brought the first evidence that melanosomes consist of several proteins (1972). In 1980's 4 groups devoted to the pigment cell research and originated from Ch.U. were formed. The groups of J.B., of B.M. and of J. Vachtenheim in Prague and the group of S.P. who moved to the Netherlands (Leiden). As for the clinical aspects of the pigment cell research, the s.c. Hermanský-Pudlák syndrome published in 1959 and the histopathological classification of malignant melanomas estimated by J. Trapl (1957), should be mentioned. Therefore it is not surprising that, as a result of the tradition of pigment cell research at Ch.U., the 3rd European Workshop on Melanin Pigmentation was held in Prague already in 1981 and that, in 1998 again, Ch.U. was entrusted with the arrangement of the 8th Meeting of the European Society for Pigment Cell Research at the occasion of the Ch.U. 650th anniversary.

Melanins in IGR 1 melanoma cells.

Information on the composition of melanins is obtained by analysis both of 4-amino-3-hydroxyphenylalanine (AHP) after hydriodic acid degradation and of pyrrole-2,3,5-tricarboxylic acid (PTCA) after potassium permanganate oxidation. Analysis of thiazole-4,5-dicarboxylic acid (TDCA) and pyrrole-2,3-dicarboxylic acid (PDCA) after permanganate oxidation, provides additional information on the composition, TDCA on pheomelanin residues, and PDCA on indolic residues without carboxy groups. Using model melanins formed from dopa and cysteinyldopa in different proportions, we found the TDCA/(PTCA+PDCA) ratio to yield a reliable estimate of the relative proportions of pheomelanin and eumelanin. The PDCA/PTCA ratio reflects the relationship between indole residues with and without carboxy groups. We have analyzed degradation products from cultures of IGR 1, an extensively studied melanoma cell line. Cell cultures were harvested after 2, 4, and 7 days. Culture media were changed after 2 days in all series, and also after 4 days in one series harvested at 7 days. Cells without medium change had seven times the amount of melanin found in cultures with medium change. The PDCA/PTCA ratio decreased with increasing amounts of melanin. With increased melanization, eumelanin is increased relatively more than pheomelanin. The cell content of 5-S-cysteinyldopa (5-S-CD) was similar in all cultures, while 6-hydroxy-5-methoxyindole-2-carboxylic acid (6H5MICA), a eumelanin precursor metabolite, was found in increased amounts of media of heavily pigmented cultures.

Quantitative analysis of eumelanin and pheomelanin in hair and melanomas.

In this study, a method is provided for analyzing quantitatively the content and the class of melanin pigments in the tissues, e.g., hair and melanoma. The method is simple and rapid because it does not require the isolation of melanins from the tissues. The rationale was that permanganate oxidation of eumelanin yields pyrrole-2,3,5-tricarboxylic acid (PTCA) as its major pyrrolic product, which may serve as a quantitatively significant indicator of eumelanin, while hydriodic acid hydrolysis of pheomelanin yields amino-hydroxyphenylalanine (AHP) as a specific indicator of pheomelanin. The degradation products, PTCA and AHP, were determined by high-performance liquid chromatography. Sepia melanosome-melanin and synthetic 5-S-cysteinyldopa-melanin served as reference standards of eumelanin and pheomelanin, respectively. Our method provided data that corresponded well to the content and class of melanins in normal hair. Based on this control study, it was found that the melanins in the melanosomes of both B16 and Harding-Passey (HP) melanomas were eumelanic and that the melanin content in B16 melanosomes was more than 10 times higher than that in HP melanosomes, though these two melanosomes revealed distinct colors and ultrastructures, i.e., brown-black, eumelanosome-like granules in B16 and reddish- or light-brown, pheomelanosome-like granules in HP.

Some aspects of melanin biology: 1950-1975.

Recent advances in the biology of mammalian pigmentation are reviewed. The multicellular epidermal melanin unit (melanocyte and associated pool of keratinocytes) rather than the melanocyte alone forms the focal point for melanin metabolism within mammalian epidermis. Within an epidermal melanin unit, melanosomes are synthesized by melanocytes and transferred to keratinocytes where they are degraded as they ascend to the epidermal surface. During the past 25 years, technical advances in biology and biochemistry have frosted a multidisciplinary approach to research on mammalian pigmentation. Emphasizing this perspective, we have examined the current state of knowledge of the form and function of epidermal melanin units from the levels of biologic organization ranging from the molecules relevant to melanin synthesis through the skin as a totally intergrated system. To an unusual degree, advances in melanin pigmentation have resulted from the integration of clinical medicine and basic science.