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Influencia diferencial de la expresión de Slc7a11 y la condición corporal sobre la pigmentación producida por feomelanina en dos poblaciones de trepador azul Sitta europea con diferente riesgo de depredación

The expression of the gene Slc7a11 promotes the antioxidant capacity of cells by providing them with cysteine that can be used for the synthesis of glutathione (GSH), the most important intracellular antioxidant. In melanocytes, intracellular cysteine can also enter melanosomes and get incorporated in the pigment pheomelanin synthesis pathway, thus decreasing cysteine availability for GSH synthesis and potentially creating chronic oxidative stress. Therefore, this study hypothesized that a mechanism limiting the use of intramelanocytic cysteine for pheomelanin synthesis in environmental conditions generating oxidative stress may be physiologically advantageous and favored by natural selection. Evidence we searched of such a mechanism by comparing the influence of melanocytic Slc7a11 expression on pheomelanin?based pigmentation in developing Eurasian nuthatch Sitta europaea nestlings from two populations differing in predation risk, a natural source of oxidative stress. Pheomelanin synthesis and pigmentation tended to increase with Slc7a11 expression in the low?risk population as expected from the activity of this gene, but decreased with Slc7a11 expression in the high?risk population. The same was not observed in the expression of five other genes influencing pheomelanin synthesis without affecting cysteine availability in melanocytes. The influence of body condition on the intensity of pheomelanin?based pigmentation also differed between populations, being positive in the low?risk population and negative in the high?risk population. The resulting pigmentation of birds was more intense in the high?risk population. These findings suggest that birds perceiving high predation risk may limit the use of cysteine for pheomelanin synthesis, which becomes independent of Slc7a11 expression. Some birds may have thus evolved the ability to adjust their pigmentation phenotype to environmental stress. informacion[at]ebd.csic.es: Galván & Sanz (2020) Differential influence of Slc7a11 expression and body condition on pheomelanin-based pigmentation in two Eurasian nuthatch Sitta europaea populations with different predation risk. J Avian Biol DOI 10.1111/jav.02275


https://onlinelibrary.wiley.com/doi/10.1111/jav.02275
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A new species of bat was hiding in our forests

A new species of bat was hiding in our forests

While it is believed that European biodiversity no longer brings surprises, an unusual discovery has just been made: in Western Europe a new species of bat has been described. More exactly, it is distributed along the northern mountain forests of Iberia, south of France and Italy. How did it go unnoticed so far? Bats are represented by more than 50 species in Europe (according to www.Eurobats.org), but many of them look alike and it is mainly through molecular genetic comparisons that the identity is confirmed for these otherwise alike species. Indeed, the new species now described, called the cryptic myotis (Myotis crypticus), was until now confused in Iberia with the closely related species, the Escalera's bat (Myotis escalerai), from which it differs only by subtle external characters. The information of the DNA sequences, on the other hand, is indisputable: these two species do not mix despite sharing many areas in the mountain forests of the northern half of the Peninsula. This discovery has consequences for species conservation, since not only its identification in nature is very difficult, but its geographical distribution and the status of its populations are still largely unknown. As the new species lives in forested areas of Italy, Switzerland, France and Spain under increasing human pressure, it is urgent to study it in more detail to determine its protection status. In Northern Africa, where a second new species, the Zenati myotis (Myotis zenatius), is also described in the same publication, the conservation situation is even more critical. In fact, the species is extremely rare and vulnerable. Only a few caves are known to house it and human disturbances are frequent. Just after being discovered, it could therefore already be included in the too long list of endangered species. informacion[at]ebd.csic.es: Juste et al (2019) Two new cryptic bat species within the Myotis nattereri species complex (Vespertilionidae, Chiroptera) from the Western Palaearctic. Acta Chiropterol https://doi.org/10.3161/15081109ACC2018.20.2.001


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