Traits produced by melanin may signal the bearer's capacity to combat free radicalsOctober 06, 2008Some animal species have developed conspicuous traits produced by melanin pigments (for instance, dark manes in lions, black stripes in some birds and fishes). These traits are used as signals during contests for resources and/or contribute to increase the mating opportunities. However, the efficiency of these traits as signals depends on the fact that they transmit honest information about the quality of the bearer. This would be only assured by the fact that producing or maintaining the signal inevitability implies a cost. Thus, only those individuals able to afford the cost would also be able to conveniently express the signal. Signals produced by melanin pigments have challenged our understanding because they are apparently cost-free and strongly controlled by the genotype. Melanin pigments are not as limited in production as carotenoids, yellow-red pigments common in vertebrates and only obtained from certain food items. In fact, melanin is constructed from amino acids present in proteins of the organism. However, recent experimental studies have become to disentangle the cost at the basis of melanin-based signals. A recent article by Ismael Galván at the Museo Nacional de Ciencias Naturales (CSIC) in Madrid and Carlos Alonso-Alvarez at IREC-CSIC, Spain, published in the online, open-access journal PLoS ONE proposes a novel hypothesis suggesting that these traits could indicate the ability of the bearer in fighting free radicals and oxidative damage. On the basis of medical bibliography, the researchers realized that tissue melanization is constrained in the presence of high enough levels of a key intracellular antioxidant named glutathione, which is considered one of the most powerful antioxidants present in virtually all animal cells. The scientists hypothesized that low levels of this substance are also required to express melanin-based signals present in many animals. This implies that individuals able to express these signals should be also able to fight off an oxidative challenge, as a consequence of the low levels of the cited antioxidant. Only those animals with alternative antioxidant resources would be able to afford the cost of signaling. By chemically inhibiting the production of glutathione at the red blood cells, authors were able to significantly increase the size of a black stripe present in the feathers of the breast of great tits (a common garden bird). This stripe is a conspicuous trait playing a significant role during combats for territory, food or mates. Furthermore, the reduction of glutathione levels also induced a mobilization of other antioxidant molecules to the blood plasma, supporting the cost, such as hypothesized by Alonso-Alvarez and colleagues. Public Library of Science |
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| Related Melanin Current Events and Melanin News Articles New findings on the formation of body pigment The skin's pigment cells can be formed from completely different cells than has hitherto been thought, a new study from the Swedish medical university Karolinska Institutet shows. The results, which are published in the journal Cell, also mean the discovery of a new kind of stem cell. Afib triggered by a cell that resembles a pigment-producing skin cell The source and mechanisms underlying the abnormal heart beats that initiate atrial fibrillation (Afib), the most common type of abnormal heart beat, have not been well determined. BUSM researchers identify better laser for treating facial spider veins Researchers from Boston University School of Medicine (BUSM) have concluded that the 940nm wavelength laser is superior for treating facial spider veins (telangiectasias) as compared to the 532nm wavelength laser. Iridescence found in 40-million-year-old fossil bird feather Known for their wide variety of vibrant plumage, birds have evolved various chemical and physical mechanisms to produce these beautiful colors over millions of years. Scientists find evidence of iridescence in 40 million-year-old feather fossil Known for their wide variety of vibrant plumage, birds have evolved various chemical and physical mechanisms to produce these beautiful colors over millions of years. Sensitizing tumor response to cancer therapy Two forms of skin and brain cancer respond very poorly to chemotherapy and radiation: melanoma and glioblastoma multiforme brain cancer. Study catches 2 bird populations as they split into seperate species A new study finds that a change in a single gene has sent two closely related bird populations on their way to becoming two distinct species. Skin color clue to nicotine dependence Higher concentrations of melanin -- the color pigment in skin and hair -- may be placing darker pigmented smokers at increased susceptibility to nicotine dependence and tobacco-related carcinogens than lighter skinned smokers, according to scientists. UCI researchers find new way to fight cocaine addiction UC Irvine pharmacological researchers have discovered that blocking a hormone related to hunger regulation can limit cocaine cravings. Not enough vitamin D in the diet could mean too much fat on adolescents Too little vitamin D could be bad for more than your bones; it may also lead to fatter adolescents, researchers say. More Melanin Current Events and Melanin News Articles |
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