scholarly journals Unravelling the Role of Melanin in Cd and Zn Tolerance and Accumulation of Three Dark Septate Endophytic Species

2020 ◽  
Vol 8 (4) ◽  
pp. 537
Author(s):  
Charlotte Berthelot ◽  
Asfaw Zegeye ◽  
Dalia A. Gaber ◽  
Michel Chalot ◽  
Philipp Franken ◽  
...  
Keyword(s):  
Trace Element ◽  
Cell Walls ◽  
Functional Trait ◽  
Dark Septate Endophytes ◽  
Melanin Synthesis ◽  
Melanin Production ◽  
Cd Accumulation ◽  
Series Of Experiments ◽  
Zn Tolerance

Dark septate endophytes (DSEs) are often trace element (TE)-tolerant fungi and are abundant in TE-polluted environments. The production of melanin, a black polymer found in cell walls, was hypothesized by several authors to play a role in the TE tolerance of DSEs. To test this hypothesis, we established a series of experiments using albino strains and melanin inhibitors and examined the responses to Cd and Zn. Six DSEs belonging to genera Cadophora sp., Leptodontidium sp. and Phialophora mustea, were evaluated. The strains mainly produced 1,8-dihydroxynaphthalene (DHN) melanin whereas 3,4-dihydroxyphenylalanin melanin was also synthetized. Cd and Zn decreased melanin synthesis in most of the strains. A reduction in melanin concentration in hyphae through the use of tricyclazole, an inhibitor of DHN-melanin synthesis, did not reduce the tolerance of the strains to Cd and Zn. Similarly, albino mutants of Leptodontidium sp. were not more sensitive to Cd and Zn than the WT strain. Moreover, tricyclazole-treated colonies accumulated less Cd but more Zn compared to untreated colonies. The Cd and Zn contents of Leptodontidium albino strains were variable and similar to that of the WT. The results suggest that melanin production is not an important functional trait that contributes to Cd and Zn tolerance, but might contribute to Cd accumulation.

Occurrence of high tyrosinase activity in the non-Peltigeralean lichenDermatocarponminiatum(L.) W. Mann

2012 ◽  
Vol 44 (6) ◽  
pp. 827-832 ◽  
Author(s):  
Richard P. BECKETT ◽  
Farida V. MINIBAYEVA ◽  
Christiane LIERS
Keyword(s):  
Cell Walls ◽  
Redox Cycling ◽  
Tyrosinase Activity ◽  
Melanin Synthesis ◽  
Multicopper Oxidases ◽  
Apparent Absence ◽  
Ph Optimum ◽  
Cellular Location

AbstractIn our earlier work, we demonstrated the presence of the multicopper oxidases tyrosinase and laccase in the cell walls of lichens from thePeltigerales, while these enzymes appeared to be absent in lichens from other orders. Likely roles for tyrosinase in lichens include melanin synthesis, the generation of quinones needed for laccase-mediated redox cycling, and the removal of harmful reactive molecules formed by this cycling. Non-Peltigeralean lichens will not need tyrosinase to detoxify laccase-generated radicals. However, many non-Peltigeralean lichens are often heavily melanized. Apparent absence of tyrosinase activity in these species prompted us to suggest that, in these lichens, melanins are probably synthesized by the polyketide pathway, which does not involve tyrosinase. Here, we surveyed intracellular tyrosinase activity in thallus homogenates from a range of lichens. Results showed that Peltigeralean species generally have much higher activities than species from other orders. However, the non-Peltigeralean lichenDermatocarpon miniatumdisplays significant tyrosinase activity. InD. miniatum, tyrosinase differs from the corresponding enzyme from Peltigeralean lichens with respect to cellular location, substratum specificity, stability and pH optimum. Furthermore, unlike Peltigeralean lichens, inD. miniatumtyrosinase activity increased strongly following the rehydration of dry thalli. These differences are possibly a consequence of the role of tyrosinase in melanin synthesis rather than laccase-mediated redox cycling.

scholarly journals Activation of Melanin Synthesis in Alternaria infectoria by Antifungal Drugs

2015 ◽  
Vol 60 (3) ◽  
pp. 1646-1655 ◽  
Author(s):  
Chantal Fernandes ◽  
Rafael Prados-Rosales ◽  
Branca M. A. Silva ◽  
Antonio Nakouzi-Naranjo ◽  
Mónica Zuzarte ◽  
...  
Keyword(s):  
Cell Walls ◽  
Therapeutic Potential ◽  
Morphological Changes ◽  
Antifungal Drugs ◽  
Protective Mechanism ◽  
Melanin Synthesis ◽  
Melanin Production ◽  
Minimum Effective Concentration ◽  
Content Type ◽  
Alternaria Infectoria

The importance ofAlternariaspecies fungi to human health ranges from their role as etiological agents of serious infections with poor prognoses in immunosuppressed individuals to their association with respiratory allergic diseases. The present work focuses onAlternaria infectoria, which was used as a model organism of the genus, and was designed to unravel melanin production in response to antifungals. After we characterized the pigment produced byA. infectoria, we studied the dynamics of 1,8-dihydroxynaphthalene (DHN)-melanin production during growth, the degree of melanization in response to antifungals, and how melanization affected susceptibility to several classes of therapeutic drugs. We demonstrate thatA. infectoriaincreased melanin deposition in cell walls in response to nikkomycin Z, caspofungin, and itraconazole but not in response to fluconazole or amphotericin B. These results indicate thatA. infectoriaactivates DHN-melanin synthesis in response to certain antifungal drugs, possibly as a protective mechanism against these drugs. Inhibition of DHN-melanin synthesis by pyroquilon resulted in a lower minimum effective concentration (MEC) of caspofungin and enhanced morphological changes (increased hyphal balloon size), characterized by thinner and less organizedA. infectoriacell walls. In summary,A. infectoriasynthesizes melanin in response to certain antifungal drugs, and its susceptibility is influenced by melanization, suggesting the therapeutic potential of drug combinations that affect melanin synthesis.

scholarly journals LATS1 Is a Mediator of Melanogenesis in Response to Oxidative Stress and Regulator of Melanoma Growth

2021 ◽  
Vol 22 (6) ◽  
pp. 3108
Author(s):  
Urszula Kazimierczak ◽  
Ewelina Dondajewska ◽  
Maria Zajaczkowska ◽  
Marianna Karwacka ◽  
Tomasz Kolenda ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Tumor Growth ◽  
Protective Role ◽  
Melanin Synthesis ◽  
Melanin Content ◽  
Melanin Production ◽  
And Oxidative Stress ◽  
Pigmentation Disorders ◽  
Melanoma Growth

The LATS1 kinase has been described as a tumor suppressor in various cancers. However, its role in melanoma has not been fully elucidated. There are several processes involved in tumorigenesis, including melanin production. Melanin content positively correlates with the level of reactive oxygen species (ROS) inside the cell. Accordingly, the purpose of the study was to assess the role of LATS1 in melanogenesis and oxidative stress and its influence on tumor growth. We have knocked down LATS1 in primary melanocytes and melanoma cells and found that its expression is crucial for melanin synthesis, ROS production, and oxidative stress response. We showed that LATS1 ablation significantly decreased the melanogenesis markers’ expression and melanin synthesis in melanocyte and melanoma cell lines. Moreover, silencing LATS1 resulted in enhanced oxidative stress. Reduced melanin content in LATS1 knocked down tumors was associated with increased tumor growth, pointing to melanin’s protective role in this process. The study demonstrated that LATS1 is highly engaged in melanogenesis and oxidative stress control and affects melanoma growth. Our results may find the implications in the diagnosis and treatment of pigmentation disorders, including melanoma.

Natural Tyrosinase Inhibitors: Role of Herbals in the Treatment of Hyperpigmentary Disorders

2019 ◽  
Vol 19 (10) ◽  
pp. 796-808 ◽  
Author(s):  
Kamal Uddin Zaidi ◽  
Sharique A. Ali ◽  
Ayesha Ali ◽  
Ishrat Naaz
Keyword(s):  
Critical Role ◽  
Enzymatic Browning ◽  
Melanin Production ◽  
Natural Sources ◽  
Pigmentary Disorders ◽  
Normal Manner ◽  
Abnormal Accumulation ◽  
Current Article ◽  
Tyrosinase Inhibitors

Cutaneous pigmentation plays critical role in determining the color of skin along with photo protection of skin from dreadful effects of ultraviolet radiations. Conversely, abnormal accumulation of melanin is responsible for hyper pigmentary disorders such as melasma, senile lentigines and freckles. Because of the visible nature of dermatologic diseases, they have a considerable psychosomatic effect on affected patients. Tyrosinase inhibitors are molecules that interrelate in some way with the enzyme to prevent it from working in the normal manner. Past many decades witnessed the quest for the development of natural tyrosinase inhibitors due to imperative role played by tyrosinase in the process of melanogenesis and fungi or fruit enzymatic browning. Mechanism of pigmentation is characterized by the intact process of the synthesis of specialized black pigment within melanosomes. Melanin is synthesized by a cascade of enzymatic and chemical reactions. For this reason, melanin production is mainly controlled by the expression and activation of tyrosinase. In the current article, we discussed tyrosinase inhibitors from the natural sources, which can be an essential constituent of cosmetics products and depigmenting agents for the treatment of hyperpigmentory disorders.

scholarly journals Inhibitory Effects of Cycloheterophyllin on Melanin Synthesis

Molecules ◽  
2021 ◽  
Vol 26 (9) ◽  
pp. 2526
Author(s):  
Joong-Hyun Shim
Keyword(s):  
Functional Materials ◽  
Tyrosinase Activity ◽  
Melanin Synthesis ◽  
Activity Assay ◽  
Inhibitory Effects ◽  
Melanin Production ◽  
Messenger Ribonucleic Acid ◽  
B16f10 Cells ◽  
Cell Line Cell ◽  
Tyrosinase Related Protein

This study was performed to clarify the inhibitory effects of cycloheterophyllin on melanin synthesis. In order to elucidate the inhibitory effects of cycloheterophyllin on the B16F10 cell line, cell viability, messenger ribonucleic acid (mRNA) expressions, tyrosinase activity assay, and melanin production assay were measured. The effects of cycloheterophyllin on tyrosinase-related protein 1 (TYRP1)/TYRP2/tyrosinase (TYR)/microphthalmia-associated transcription factor (MITF) mRNA expressions and melanin content were determined. Quantitative real-time RT-PCR showed that cycloheterophyllin decreased the mRNA expression level of TYRP1/TYRP2/TYR/MITF genes and melanin production contents than α-MSH-treated B16F10 cells. The tyrosinase activity assay revealed that cycloheterophyllin decreased the melanin production in the B16F10 cells. These data show that cycloheterophyllin increases the whitening effects in the B16F10 cells; thus, cycloheterophyllin is a potent ingredient for skin whitening. Thus, further research on the mechanism of action of cycloheterophyllin for the development of functional materials should be investigated.

scholarly journals The role of sulphur on the melting of Ca-poor sediment and on trace element transfer in subduction zones: an experimental investigation

2021 ◽  
Author(s):  
Anne-Aziliz Pelleter ◽  
Gaëlle Prouteau ◽  
Bruno Scaillet
Keyword(s):  
Trace Element ◽  
Partial Melting ◽  
Subduction Zones ◽  
Sediment Flux ◽  
Arc Magmas ◽  
Trace Element Contents ◽  
The Stability ◽  
Element Transfer ◽  
High Sediment

Abstract We performed phase equilibrium experiments on a natural Ca-poor pelite at 3 GPa, 750-1000 °C, under moderately oxidizing conditions, simulating the partial melting of such lithologies in subduction zones. Experiments investigated the effect of sulphur addition on phase equilibria and compositions, with S contents of up to ∼ 2.2 wt. %. Run products were characterized for their major and trace element contents, in order to shed light on the role of sulphur on the trace element patterns of melts produced by partial melting of oceanic Ca-poor sediments. Results show that sulphur addition leads to the replacement of phengite by biotite along with the progressive consumption of garnet, which is replaced by an orthopyroxene-kyanite assemblage at the highest sulphur content investigated. All Fe-Mg silicate phases produced with sulphur, including melt, have higher MgO/(MgO+FeO) ratios (relative to S-free/poor conditions), owing to Fe being primarily locked up by sulphide in the investigated redox range. Secular infiltration of the mantle wedge by such MgO and K2O-rich melts may have contributed to the Mg and K-rich character of the modern continental crust. Addition of sulphur does not affect significantly the stability of the main accessory phases controlling the behaviour of trace elements (monazite, rutile and zircon), although our results suggest that monazite solubility is sensitive to S content at the conditions investigated. The low temperature (∼ 800 °C) S-bearing and Ca-poor sediment sourced slab melts show Th and La abundances, Th/La systematics and HFSE signatures in agreement with the characteristics of sediment-rich arc magmas. Because high S contents diminish phengite and garnet stabilities, S-rich and Ca-poor sediment sourced slab melts have higher contents of Rb, B, Li (to a lesser extent), and HREE. The highest ratios of La/Yb are observed in sulphur-poor runs (with a high proportion of garnet, which retains HREE) and beyond the monazite out curve (which retains LREE). Sulphides appear to be relatively Pb-poor and impart high Pb/Ce ratio to coexisting melts, even at high S content. Overall, our results show that Phanerozoic arc magmas from high sediment flux margins owe their geochemical signature to the subduction of terrigenous, sometimes S-rich, sediments. In contrast, subduction of such lithologies during Archean appears unlikely or unrecorded.

scholarly journals Melanin production in coelomycetous agents of black grain eumycetoma

2021 ◽  
Author(s):  
Wilson Lim ◽  
Florianne Parel ◽  
Sybren de Hoog ◽  
Annelies Verbon ◽  
Wendy W J van de Sande
Keyword(s):  
Fungal Infection ◽  
Therapeutic Targets ◽  
Biosynthetic Pathways ◽  
Melanin Synthesis ◽  
Melanin Production ◽  
Causative Agents ◽  
New Therapeutic Targets

Abstract Background Eumycetoma is a fungal infection characterised by the formation of black grains by causative agents. The melanin biosynthetic pathways used by the most common causative agents of black-grain mycetoma are unknown and unravelling them could identify potential new therapeutic targets. Method Melanin biosynthetic pathways in the causative fungi were identified by the use of specific melanin inhibitors. Results In Trematosphaeria grisea and Falciformispora tompkinsii, 1,8-dihydroxynaphthalene (DHN)-melanin synthesis was inhibited, while DHN-, 3,4-dihydroxyphenylalanine (DOPA)- and pyo-melanin were inhibited in Medicopsis romeroi and Falciformispora senegalensis. Conclusion Our data suggest that Me. romeroi and F. senegalensis synthesise DHN-, DOPA- and pyo-melanin, while T. grisea and F. tompkinsii only synthesise DHN-melanin.

scholarly journals Molecular and Biochemical Basis of Minocycline-Induced Hyperpigmentation—The Study on Normal Human Melanocytes Exposed to UVA and UVB Radiation

2021 ◽  
Vol 22 (7) ◽  
pp. 3755
Author(s):  
Jakub Rok ◽  
Zuzanna Rzepka ◽  
Justyna Kowalska ◽  
Klaudia Banach ◽  
Artur Beberok ◽  
...  
Keyword(s):  
Uv Radiation ◽  
Therapeutic Potential ◽  
Melanin Synthesis ◽  
Uvb Radiation ◽  
Biochemical Basis ◽  
Skin Hyperpigmentation ◽  
Human Melanocytes ◽  
Anti Cancer ◽  
Normal Human

Minocycline is a drug which induces skin hyperpigmentation. Its frequency reaches up to 50% of treated patients. The adverse effect diminishes the great therapeutic potential of minocycline, including antibacterial, neuroprotective, anti-inflammatory and anti-cancer actions. It is supposed that an elevated melanin level and drug accumulation in melanin-containing cells are related to skin hyperpigmentation. This study aimed to evaluate molecular and biochemical mechanism of minocycline-induced hyperpigmentation in human normal melanocytes, as well as the contribution of UV radiation to this side effect. The experiments involved the evaluation of cyto- and phototoxic potential of the drug using cell imaging with light and confocal microscopes as well as biochemical and molecular analysis of melanogenesis. We showed that minocycline induced melanin synthesis in epidermal melanocytes. The action was intensified by UV irradiation, especially with the UVB spectrum. Minocycline stimulated the expression of microphthalmia-associated transcription factor (MITF) and tyrosinase (TYR) gene. Higher levels of melanin and increased activity of tyrosinase were also observed in treated cells. Moreover, minocycline triggered the supranuclear accumulation of tyrosinase, similar to UV radiation. The decreased level of premelanosome protein PMEL17 observed in all minocycline-treated cultures suggests disorder of the formation, maturation or distribution of melanosomes. The study revealed that minocycline itself was able to enhance melanin synthesis. The action was intensified by irradiation, especially with the UVB spectrum. Demonstrated results confirmed the potential role of melanin and UV radiation minocycline-induced skin hyperpigmentation.

Nitric oxide decreases lung liquid production via guanosine 3′,5′-cyclic monophosphate

2001 ◽  
Vol 280 (5) ◽  
pp. L923-L929 ◽  
Author(s):  
James J. Cummings ◽  
Huamei Wang
Keyword(s):  
Nitric Oxide ◽  
Pulmonary Epithelium ◽  
Fetal Sheep ◽  
Cgmp Analog ◽  
Pulmonary Arterial ◽  
Series Of Experiments ◽  
Lung Liquid ◽  
Tracer Dilution ◽  
Induced Changes

We studied the role of cGMP in nitric oxide (NO)-induced changes in lung liquid production ( J v ) in chronically instrumented fetal sheep. Forty-five studies were done in which J v was measured by a tracer dilution technique. Left pulmonary arterial flow (Qlpa) was measured by a Doppler flow probe. There were two series of experiments. In the first, we gave 8-bromo-cGMP, a cGMP analog, by either the pulmonary vascular or intraluminal route; in the second, we used agents to inhibit or enhance endogenous cGMP activity. When infused directly into the pulmonary circulation, 8-bromo-cGMP significantly increased Qlpa but had no effect on J v. Conversely, when instilled into the lung liquid, 8-bromo-cGMP had no effect on Qlpa but significantly reduced J v. Inhibition of guanylate cyclase activity with methylene blue totally blocked, whereas phosphodiesterase inhibition with Zaprinast significantly enhanced, the effect of instilled NO on J v. Thus the reduction in lung liquid caused by NO appears to be mediated by cGMP, perhaps through a direct effect on the pulmonary epithelium.

Role of (1,3)(1,4)-β-Glucan in Cell Walls: Interaction with Cellulose

2014 ◽  
Vol 15 (5) ◽  
pp. 1727-1736 ◽  
Author(s):  
Sarah N. Kiemle ◽  
Xiao Zhang ◽  
Alan R. Esker ◽  
Guillermo Toriz ◽  
Paul Gatenholm ◽  
...  
Keyword(s):  
Cell Walls
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