Exposure to ionizing radiation affects the growth of ectomycorrhizal fungi and induces increased melanin production and increased capacities of reactive oxygen species scavenging enzymes

Kothamasi, David; Wannijn, Jean; Hees, May Van; Nauts, Robin; Gompel, Axel Van; Vanhoudt, Nathalie; Vandenhove, Hildegarde

doi:10.1016/j.jenvrad.2018.11.005

Cited by 17 publications

(7 citation statements)

References 25 publications

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“…Moreover, compound 9a also effectively inhibited the production of melanin and urease in C. neoformans cells. Melanin has antioxidant properties and protects fungal cells against the oxidative stress responses, which is generally understood to be the first line of defense against reactive oxygen species (ROS) formation. , Several compounds (e.g., o -vanillin) with fungicidal activity were reported to cause mitochondrial dysfunction by triggering oxidative stress responses . Thus, it is suggested that compound 9a might induce the oxidative stress in fungal cells, leading to the inhibition of melanin production and fungicidal effect.…”

Section: Discussionmentioning

confidence: 99%

Discovery of Simplified Sampangine Derivatives with Potent Antifungal Activities against Cryptococcal Meningitis

Liu

et al. 2019

ACS Infect. Dis.

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Cryptococcal meningitis (CM) is associated with high morbidity and mortality. Current antifungal drug therapy for CM has the following challenges: limited efficacy, significant side effects, emerging drug resistance, and unavailability in highly needed countries. There is an urgent need to develop novel CM therapeutic agents with a new mode of action. On the basis of the antifungal natural product sampangine, herein, novel simplified isoxazole derivatives were identified to possess excellent inhibitory activity against Cryptococcus neoformans (C. neoformans). Particularly, compound 9a was highly active (the minimum inhibitory concentration of 80% inhibition, MIC80 = 0.031 μg/mL) and significantly inhibited biofilm formation, melanin, and urease production of C. neoformans. 9a had good blood–brain barrier (BBB) permeability and effectively reduced the brain fungal burden in a murine model of cryptococcosis. The antifungal mechanism of compound 9a was preliminarily investigated by transmission electron microscopy and flow cytometry. It was able to cause necrocytosis of C. neoformans cells and cell cycle arrest in the G1/S phase. Isoxazole compound 9a represents a promising lead compound for the development of novel CM therapeutic agents.

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Section: Discussionmentioning

confidence: 99%

Discovery of Simplified Sampangine Derivatives with Potent Antifungal Activities against Cryptococcal Meningitis

Liu

et al. 2019

ACS Infect. Dis.

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“…Dark melanin‐based pigmentation is known to offer protection against different forms of radiation, including ionizing radiation (Cordero & Casadevall, 2020; Pacelli et al, 2017; Robertson et al, 2012). Exposure of fungi to high levels of ionizing radiation under laboratory conditions generates an increase in melanism and in the production of reactive oxygen species scavenging antioxidant enzymes, suggesting a key protective mechanism of melanin (Kothamasi et al, 2019). Likewise, exposure to ionizing radiation enhances the growth of some melanised fungi (Dadachova et al, 2007), which may even transform ionizing radiation into an energy source through the use of melanin pigments (Dadachova & Casadevall, 2008).…”

Section: Discussionmentioning

confidence: 99%

Ionizing radiation and melanism in Chornobyl tree frogs

Burraco

Orizaola

2022

Evolutionary Applications

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Human actions are altering ecosystems worldwide. Among human‐released pollutants, ionizing radiation arises as a rare but potentially devastating threat to natural systems. The Chornobyl accident (1986) represents the largest release of radioactive material to the environment. Our aim was to examine how exposure to radiation from the Chornobyl accident influences dorsal skin coloration of Eastern tree frog (Hyla orientalis) males sampled across a wide gradient of radioactive contamination in northern Ukraine. We assessed the relationship between skin frog coloration (which can act as a protective mechanism against ionizing radiation), radiation conditions and oxidative stress levels. Skin coloration was darker in localities closest to areas with high radiation levels at the time of the accident, whereas current radiation levels seemed not to influence skin coloration in Chornobyl tree frogs. Tree frogs living within the Chornobyl Exclusion Zone had a remarkably darker dorsal skin coloration than frogs from outside the Zone. The maintenance of dark skin coloration was not linked to physiological costs in terms of frog body condition or oxidative status, and we did not detect short‐term changes in frog coloration. Dark coloration is known to protect against different sources of radiation by neutralizing free radicals and reducing DNA damage, and, particularly melanin pigmentation has been proposed as a buffering mechanism against ionizing radiation. Our results suggest that exposure to high levels of ionizing radiation, likely at the time of the accident, may have been selected for darker coloration in Chornobyl tree frogs. Further studies are needed to determine the underlying mechanisms and evolutionary consequences of the patterns found here.

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“…It can both generate and absorb radicals and is a so-called stable radical [30, 31]. It can also change other types of energy into electric energy [32], and is known to be able to convert gamma radiation into chemical energy for growth and metabolism, as observed in the radiotrophic fungi detected in Chernobyl [33, 34]. Melanin is superoxide(O2-) donator [35] and serves as a naturally occurring biological source of electrons to power biochemical reactions [36].…”

Section: Discussionmentioning

confidence: 99%

Melanosomes degrade lipofuscin and precursors that are derived from photoreceptor membrane turnover in the retinal pigment epithelium—an explanation for the origin of the melanolipofuscin granule

Lyu¹,

Tschulakow²,

Schraermeyer³

2022

Preprint

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The accumulation of the age pigment lipofuscin within the retinal pigment epithelium (RPE) is one the most remarkable changes observed in association with age-related macular degeneration (AMD) and Stargardt disease. Both aging and pathological processes lead to the accumulation of melanolipofuscin (MLF) granules, which have been reported to reflect the onset of AMD more accurately than lipofuscin. The underlying mechanism by which MLF forms is still not understood. We investigate the potential role that melanin plays in the degradation of lipofuscin and MLF in pigmented Abca4-/- mice following treatment with several NO generating drugs. Abca4-/- mice are generally used as models for lipofuscin-related eye diseases. We also induced melanogenesis in albino Abca4-/- mice via the over-expression of tyrosinase, the key enzyme involved in melanogenesis. We compared the ultrastructure of lipofuscinogensis in the RPE of pigmented and albino Abca4-/- mice. Fluorescence microscopy was employed for the quantification of lipofuscin. We found high amounts of unique thin (3-4 nm) lamellar membranes (TLMs) that were left over from the degradation of photoreceptor disc membranes by high-resolution electron microscopy. Accumulated TLMs were significantly more frequent in the RPE cells of the albinos than the pigmented mice, indicating that melanin plays a role in removing TLMs. The intravitreal injection of several NO generating drugs was found to reduce the amount of autofluorescent lipofuscin in the cytoplasm of RPE cells, particularly the MLF granules of pigmented Abca4-/- mice. No effect was observed in terms of lipofuscin removal in NO-exposed albino Abca4-/- mice. However, transfection with tyrosinase led to a reduction in the lipofuscin levels of artificially pigmented RPE cells in albino Abca4-/- mice following the formation of melanin. The results show for the first time that melanin plays an important, if not a key, role in the degradation of lipofuscin in RPE cells.

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Exposure to ionizing radiation affects the growth of ectomycorrhizal fungi and induces increased melanin production and increased capacities of reactive oxygen species scavenging enzymes

Cited by 17 publications

References 25 publications

Discovery of Simplified Sampangine Derivatives with Potent Antifungal Activities against Cryptococcal Meningitis

Discovery of Simplified Sampangine Derivatives with Potent Antifungal Activities against Cryptococcal Meningitis

Ionizing radiation and melanism in Chornobyl tree frogs

Melanosomes degrade lipofuscin and precursors that are derived from photoreceptor membrane turnover in the retinal pigment epithelium—an explanation for the origin of the melanolipofuscin granule

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