Melanin In Bloom: My Journal

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Infection of G. mellonella larvae was performed as previously described 30. In summary, washed C. neoformans were resuspended to 10 7 cells/ml, and 10 µl were injected in the right rear proleg of larvae ranging from 175 to 225 mg, for an infectious inoculum of ~10 5 cells/larva. C. albicans was washed and resuspended in 5 × 10 7 cells/ml, and larvae were injected with 10 µl of culture for an infectious inoculum of ~5 × 10 5 cells/larva. Infected larvae were then incubated at 30 °C. 24 h following infection, or 72 h in the case of noted time course experiments with C. neoformans, larvae were removed from incubator, and hemolymph was extracted by puncturing the right rear proleg and/or side of the larvae with an 18 G needle. Removed hemolymph from three larvae was collected directly into 1 ml anticoagulation buffer at room temperature (98 mM NaOH, 186 mM NaCl, 1.7 mM EDTA, and 41 mM citric acid, pH 4.5) 58. Hemolymph was centrifuged for 5 min at 4000 × g and resuspended in 200 µl insect physiological saline (IPS) (150 mM sodium chloride, 5 mM potassium chloride, 7.21 mM calcium chloride, 1 mM sodium bicarbonate, pH 6.90—adapted from refs. 59, 60, 61). Samples were placed on slides and nodules were imaged using Olympus AX70 microscope with a ×100 oil immersion objective. C. neoformans GFP viability assay Washed H99-GFP strains of C. neoformans were resuspended to 10 7 cells/ml, and 10 µl was injected in the right rear proleg of larvae ranging from 175 to 225 mg, for an infectious inoculum of ~10 5 cells/larva. Infected larvae were then incubated at room temperature 30 °C for 24–72 h as noted. Hemolymph was extracted by puncturing the larvae with an 18 G needle in their right rear proleg, and hemolymph was collected into anticoagulation buffer, centrifuged for 5 min at 4000 × g, and resuspended in 200 µl insect physiological saline. Melanized nodules were visualized using an Olympus AX70 microscope with 488 excitation/520 nm emission fluorescence microscopy to visualize the GFP signal. Images were taken at ×100 magnification at the same exposure, and manually marked as positive or negative for GFP fluorescence, and melanin-encapsulated or unencapsulated. For fluorescence and melanin intensity measurements, images were analyzed using the Measure tool in FIJI 62, and the 8-bit mean gray value of each cell was measured in both channels. The region selected for the melanin measurements extended the edge of the fungal capsule, and the GFP intensity measurements were from selections limited to the fluorescent cell’s body. This protocol is summarized in Supplementary Fig. 3a. Phenoloxidase inhibition and fungal survival assay in vitro

Melasma. People with melasma have brown or blue-gray patches on their faces or arms. This condition may be caused by hormones, exposure to the sun or birth control pills. Prescription creams, laser skin resurfacing or chemical peels can help lighten the dark patches. Nappi, A. J. & Christensen, B. M. Melanogenesis and associated cytotoxic reactions: applications to insect innate immunity. Insect Biochem. Mol. Biol. 35, 443–459 (2005).

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a b Dadachova, Ekaterina; Casadevall, Arturo (2011). Horikoshi, Kōki (ed.). Extremophiles handbook. Tokyo New York City: Springer. pp.xxix+1247. ISBN 978-4-431-53898-1. OCLC 700199222. ISBN 978-4-431-53897-4. OCLC 711778164. In humans, melanin is the primary determinant of skin color. It is also found in hair, the pigmented tissue underlying the iris of the eye, and the stria vascularis of the inner ear. In the brain, tissues with melanin include the medulla and pigment-bearing neurons within areas of the brainstem, such as the locus coeruleus. It also occurs in the zona reticularis of the adrenal gland. [5] Hegna, Robert H.; Nokelainen, Ossi; Hegna, Jonathan R.; Mappes, Johanna (2013). "To quiver or to shiver: increased melanization benefits thermoregulation, but reduces warning signal efficacy in the wood tiger moth". Proc. R. Soc. B. 280 (1755): 20122812. doi: 10.1098/rspb.2012.2812. PMC 3574392. PMID 23363631. In fish, melanin occurs not only in the skin but also in internal organs such as eyes. If eumelanin appears to be the most widespread in fish integuments, [21] [22] pheomelanine was found in two fish species. [23] [24]

Mandato, C. A., Diehl-Jones, W. L., Moore, S. J. & Downer, R. G. H. The effects of eicosanoid biosynthesis inhibitors on prophenoloxidase activation, phagocytosis and cell spreading in Galleria mellonella. J. Insect Physiol. 43, 1–8 (1997). Mason, H. S. (1948). "The chemistry of melanin. Mechanism of the oxidation of dihydroxyphenylalanine by tyrosinase". Journal of Biological Chemistry. 172 (1): 83–99. doi: 10.1016/S0021-9258(18)35614-X. PMID 18920770. In the human skin, melanogenesis is initiated by exposure to UV radiation, causing the skin to darken. Eumelanin is an effective absorbent of light; the pigment is able to dissipate over 99.9% of absorbed UV radiation. [3] Because of this property, eumelanin is thought to protect skin cells from UVA and UVB radiation damage, reducing the risk of folate depletion and dermal degradation. Exposure to UV radiation is associated with increased risk of malignant melanoma, a cancer of melanocytes (melanin cells). Studies have shown a lower incidence for skin cancer in individuals with more concentrated melanin, i.e. darker skin tone. [4] Humans [ edit ] Albinism occurs when melanocytes produce little melanin. This albino girl is from Papua New Guinea. As with peoples having migrated northward, those with light skin migrating toward the equator acclimatize to the much stronger solar radiation. Nature selects for less melanin when ultraviolet radiation is weak. Most people's skin darkens when exposed to UV light, giving them more protection when it is needed. This is the physiological purpose of sun tanning. Dark-skinned people, who produce more skin-protecting eumelanin, have a greater protection against sunburn and the development of melanoma, a potentially deadly form of skin cancer, as well as other health problems related to exposure to strong solar radiation, including the photodegradation of certain vitamins such as riboflavins, carotenoids, tocopherol, and folate. [68]C. neoformans cultures were grown in minimal media with 1 mM L-DOPA for 7 days at 30 °C. Cells were collected and mixed 1:1 with 12 N hydrochloric acid (HCl), for a final concentration of 6 N HCl. Cells were heated for 1 h at 85 C under constant shaking at 350 RPM. Control cells from the acapsular mutant grown for 5–7 days in minimal media at at 30 °C without L-DOPA were heat-killed for 1 h at 85 °C in PBS. Cells were washed twice in PBS and subsequently used in the time-lapse microscopy. Statistics and reproducibility Arachnids are one of the few groups in which melanin has not been easily detected, though researchers found data suggesting spiders do in fact produce melanin. [35] Pigment loss following skin damage. If your skin becomes infected, burned or blistered, your body may not be able to replace melanin in the damaged area. Brenner M, Hearing VJ (2008). "The protective role of melanin against UV damage in human skin". Photochemistry and Photobiology. 84 (3): 539–49. doi: 10.1111/j.1751-1097.2007.00226.x. PMC 2671032. PMID 18435612. Blooming artifact is a susceptibility artifact encountered on some MRI sequences in the presence of paramagnetic substances that affect the local magnetic milieux. Although it is an artifact, it may be deliberately exploited to improve detection of certain small lesions, much as the T1 shortening effects of low concentration g adolinium are used to detect contrast enhancement.