NUBIAN QUEEN, BLACK KING, MELANIN POPPIN'.
Melanin comes from the Greek word “melas” which means “black, dark”
Everyone screams melanin from the rooftops but how many of us actually know what it is ? . It is common knowledge that melanin is what makes people darker than “white”. I think it’s time we dig a little deeper into what melanin actually is and how our skins produce it. Today we explore the relationship between the sun, the skin and melanin.
THE SUN AND SKIN
The sun has been a strong influence to life on earth, living organisms have adapted characteristics in response to the sun. The skin being the largest organ, its function is quite important. The main roles of the skin involve providing a barrier against environmental stress and regulates the loss of water from the body through sweating. Sunlight once absorbed by the skin does not only cause the skin to darken but also influences the production of vitamin D and human sleep cycles.
Exposure of the skin to sunlight is a form of environmental stress. Humans adaptations to the sun is intertwined with the regulation of the melanin pigment. Radiation from the sun reaches the earth at different wavelengths and these wavelengths can have different effects on melanin production. The main two being UV-A(320-400nm ) and UV-B (280-320nm). UV-A can usually penetrate through normal glass but UV-B cannot. Both forms of UV exposure to the skin can cause a multitude of responses. The rate of response depends on the intensity and type of UV light . A response can occur in just a couple of hours which involves the oxidation and polymerisation of melanin already present on the skin surface that causes the skin to darken.
MELANIN EXPLAINED
Melanin pigments are produced from cells known as melanocytes. Melanocytes can be found in the basal epidermal layer of the skin. They produce melanin in organelles known as melanosomes.
The melanosomes are then transferred to neighbouring keratinocytes to carry out their protective function against the sun. Keratinocytes are other cells that are also a part of the skins epidermis.
Mel-an-o-genesis is the process by which melanin is made. Melanogenesis is initiated by the exposure of the skin to UV radiation from the sun. The exposure of the skin to UV light is the most triggering effect that causes the movement of melanosomes to the epidermis for skin protection. The expression of these melanosomes on the epidermis which is the outermost layer of the skin is what causes the darker appearance in the skin.
This is a short introduction to the basics of the tanning process, next weeks post will explain the actual process of tanning under the different wavelengths of UV radiation.
References
Costin, G. E. & Hearing, V. J., 2007. Human skin pigmentation: melanocytes modulation color in response to stress. The FASEB Journal, Volume 21, pp. 977-994.
Kaidbey, K. H., Poh Agin, P., Sayre, R. M. & Kligman, A. M., 1979. Photoprotection by melanin—a comparison of black and Caucasian skin. Journal of the American Academy of Dermatology , 1(3), pp. 249-260.
Natarajan, V. T. et al., 2014. Multifaceted pathways protect human skin from UV radiation. nature:chemical biology, 10(1552-4469), pp. 542-551.
Slominsky, A., Tobin, D. J., Shibahara, S. & Wortsman, J., 2004. Melanin Pigmentation in Mammalian Skin and Its Hormonal Regulation. American Physiological Society , 84(4), pp. 1155-1228.
Tadokoro, T. et al., 2003. UV-induced DNA damage and melanin content in human skin differing in racial/ethnic origin. FASEB journal, 17(9).