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Characterization of Spontaneous Melanization by Fluorescence Spectroscopy: A Basis for Analytical Application to Biological Substrates. BIOLOGY 2023; 12:biology12030433. [PMID: 36979125 PMCID: PMC10044826 DOI: 10.3390/biology12030433] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/21/2023] [Revised: 03/07/2023] [Accepted: 03/10/2023] [Indexed: 03/16/2023]
Abstract
Melanin is present in various biological substrates where it may participate in several processes, from innate immunity to the still-unsolved opposite roles in antioxidant protection, including photoprotection and the related ability to interact with light. Melanin–light interaction has also been an important source of inspiration for the development of innovative bioengineering applications. These are based on melanin’s light-energy-absorption ability of its chemically and structurally complex components and precursors, and on the improvement in analytical and diagnostic procedures in biomedicine. In this regard, here, we characterized the fluorescence spectral properties of melanin and of its precursor L-tyrosine in an aqueous solution during spontaneous melanization. Besides the confirmation of the typical fluorescence-emission signature of melanin and L-tyrosine, we provide additional insights on both emission and excitation spectra recorded during melanization. On these bases, we performed a subsequent characterization on the aqueous extracts from two different melanin-containing biological substrates, namely hairs from a domestic black cat and eggs from the Asian tiger mosquito. The results from the mild extraction procedure, purposely applied to obtain only the soluble components, combined with fluorescence spectral analysis are expected to promote further investigation of the melanization processes, particularly in insects.
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Smith DFQ, Mudrak NJ, Zamith-Miranda D, Honorato L, Nimrichter L, Chrissian C, Smith B, Gerfen G, Stark RE, Nosanchuk JD, Casadevall A. Melanization of Candida auris Is Associated with Alteration of Extracellular pH. J Fungi (Basel) 2022; 8:1068. [PMID: 36294632 PMCID: PMC9604884 DOI: 10.3390/jof8101068] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2022] [Revised: 10/05/2022] [Accepted: 10/07/2022] [Indexed: 11/29/2022] Open
Abstract
Candida auris is a recently emerged global fungal pathogen, which causes life-threatening infections, often in healthcare settings. C. auris infections are worrisome because the fungus is often resistant to multiple antifungal drug classes. Furthermore, C. auris forms durable and difficult to remove biofilms. Due to the relatively recent, resilient, and resistant nature of C. auris, we investigated whether it produces the common fungal virulence factor melanin. Melanin is a black-brown pigment typically produced following enzymatic oxidation of aromatic precursors, which promotes fungal virulence through oxidative stress resistance, mammalian immune response evasion, and antifungal peptide and pharmaceutical inactivation. We found that certain strains of C. auris oxidized L-DOPA and catecholamines into melanin. Melanization occurred extracellularly in a process mediated by alkalinization of the extracellular environment, resulting in granule-like structures that adhere to the fungus' external surface. C. auris had relatively high cell surface hydrophobicity, but there was no correlation between hydrophobicity and melanization. Melanin protected the fungus from oxidative damage, but we did not observe a protective role during infection of macrophages or Galleria mellonella larvae. In summary, C. auris alkalinizes the extracellular medium, which promotes the non-enzymatic oxidation of L-DOPA to melanin that attaches to its surface, thus illustrating a novel mechanism for fungal melanization.
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Affiliation(s)
- Daniel F. Q. Smith
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, The Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21205, USA
| | - Nathan J. Mudrak
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, The Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21205, USA
- Krieger School of Arts & Science, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Daniel Zamith-Miranda
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, New York, NY 10461, USA
- Division of Infectious Diseases, Department of Medicine, Albert Einstein College of Medicine, Bronx, New York, NY 10461, USA
| | - Leandro Honorato
- Laboratório de Glicobiologia de Eucariotos, Departamento de Microbiologia Geral, Instituto de Microbiologia, Universidade Federal do Rio de Janeiro, Rio de Janeiro 21941-901, Brazil
| | - Leonardo Nimrichter
- Laboratório de Glicobiologia de Eucariotos, Departamento de Microbiologia Geral, Instituto de Microbiologia, Universidade Federal do Rio de Janeiro, Rio de Janeiro 21941-901, Brazil
| | - Christine Chrissian
- Department of Chemistry and Biochemistry, City College of New York and CUNY Institute for Macromolecular Assemblies, The City University of New York, New York, NY 10031, USA
| | - Barbara Smith
- Institute for Basic Biomedical Sciences Microscope Facility, The Johns Hopkins School of Medicine, Baltimore, MD 21205, USA
| | - Gary Gerfen
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, New York, NY 10461, USA
| | - Ruth E. Stark
- Department of Chemistry and Biochemistry, City College of New York and CUNY Institute for Macromolecular Assemblies, The City University of New York, New York, NY 10031, USA
| | - Joshua D. Nosanchuk
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, New York, NY 10461, USA
- Division of Infectious Diseases, Department of Medicine, Albert Einstein College of Medicine, Bronx, New York, NY 10461, USA
| | - Arturo Casadevall
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, The Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21205, USA
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Song W, Xing R, Yang H, Liu S, Li P. Optimization of extractions of eumelanin from cuttlefish ink and the hypoglycemic effects: In vitro enzyme inhibitory activity and glucose consumption in HepG2 cells. J FOOD PROCESS PRES 2021. [DOI: 10.1111/jfpp.15868] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Wen Song
- AS and Shandong Province Key Laboratory of Experimental Marine Biology, Center for Ocean Mega‐Science, Institute of Oceanology Chinese Academy of Sciences Qingdao China
- Laboratory for Marine Drugs and Bioproducts Pilot National Laboratory for Marine Science and Technology (Qingdao) Qingdao China
- School of Earth and Planetary University of Chinese Academy of Sciences Beijing China
| | - Rong‐e Xing
- AS and Shandong Province Key Laboratory of Experimental Marine Biology, Center for Ocean Mega‐Science, Institute of Oceanology Chinese Academy of Sciences Qingdao China
- Laboratory for Marine Drugs and Bioproducts Pilot National Laboratory for Marine Science and Technology (Qingdao) Qingdao China
| | - Haoyue Yang
- AS and Shandong Province Key Laboratory of Experimental Marine Biology, Center for Ocean Mega‐Science, Institute of Oceanology Chinese Academy of Sciences Qingdao China
- Laboratory for Marine Drugs and Bioproducts Pilot National Laboratory for Marine Science and Technology (Qingdao) Qingdao China
| | - Song Liu
- AS and Shandong Province Key Laboratory of Experimental Marine Biology, Center for Ocean Mega‐Science, Institute of Oceanology Chinese Academy of Sciences Qingdao China
- Laboratory for Marine Drugs and Bioproducts Pilot National Laboratory for Marine Science and Technology (Qingdao) Qingdao China
| | - Pengcheng Li
- AS and Shandong Province Key Laboratory of Experimental Marine Biology, Center for Ocean Mega‐Science, Institute of Oceanology Chinese Academy of Sciences Qingdao China
- Laboratory for Marine Drugs and Bioproducts Pilot National Laboratory for Marine Science and Technology (Qingdao) Qingdao China
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