Availability of nonpigmentary antioxidant affects red coloration in gulls

Pérez, C., Lores, M. & Velando, A. Availability of nonpigmentary antioxidant affects red coloration in gulls. Behavioral Ecology 19, 967–973 (2008).

Red, orange, and yellow carotenoid-based colorations displayed by fishes and birds may function as honest sexual signals of the bearer’s quality. However, the mechanisms underlying the expression of these traits and the information they convey are still controversial. Because carotenoids are antioxidants and carotenoid-based pigmentation is bleached as a consequence of oxidative processes, it has been suggested that the pigmentation may signal antioxidant status. We tested this hypothesis in the yellow-legged gull (Larus michahellis), a seabird that exhibits a carotenoid-based red spot on the lower mandible. The availability of a nonpigmentary antioxidant (i.e., vitamin E) to the gulls was modified before egg laying by means of a supplementary feeding experiment. During the incubation period, breeding pairs were captured to assess the intensity of the color and the size of the red bill spots. We measured the plasma level of lipid peroxidation, total antioxidant capacity, and carotenoids. We found that males that received vitamin E supplements had larger red spot than control birds but that color intensity was not affected by the supplements. Moreover, we found that only those plasma carotenoids involved in the red coloration were affected by the antioxidant supplementation, suggesting an active mechanism to increase red coloration. Overall, our results provide experimental evidence for the hypothesis that carotenoid-based coloration reflects the bearer’s antioxidant status in male gulls.

Pre-fledgling oxidative damage predicts recruitment in a long-lived bird

Noguera, J. C., Kim, S.-Y. & Velando, A. Pre-fledgling oxidative damage predicts recruitment in a long-lived bird. Biology letters rsbl20110756 (2011).

Empirical evidence has shown that stressful conditions experienced during development may exert long-term negative effects on life-history traits. Although it has been suggested that oxidative stress has long-term effects, little is known about delayed consequences of oxidative stress experienced early in life in fitness-related traits. Here, we tested whether oxidative stress during development has long-term effects on a life-history trait directly related to fitness in three colonies of European shags Phalacrocorax aristotelis. Our results revealed that recruitment probability decreased with oxidative damage during the nestling period; oxidative damage, in turn, was related to the level of antioxidant capacity. Our results suggest a link between oxidative stress during development and survival to adulthood, a key element of population dynamics.

Differential effects of specific carotenoids on oxidative damage and immune response of gull chicks

Lucas, A., Morales, J. & Velando, A. Differential effects of specific carotenoids on oxidative damage and immune response of gull chicks. Journal of Experimental Biology 217, 1253–1262 (2014).

Micronutrients are essential for normal metabolic processes during early development. Specifically, it has been suggested that diet-derived carotenoids can play a key role in physiological functions because of their antioxidant and immunostimulant properties. However, their role as antioxidants remains controversial. Additionally, it is also unclear whether oxidative stress mediates their immunostimulatory effects. In this field study, we separately supplemented yellow-legged gull (Larus michahellis) chicks with two carotenoids (lutein and β-carotene) with different molecular structures and different transformation pathways into other oxidative forms of carotenoids. We quantified their effect on the oxidative status and the immune response of chicks before and after an oxidative challenge with paraquat, a pro-oxidant molecule. Prior to oxidative challenge, none of the carotenoid treatments affected the oxidative status of chicks, but they enhanced the inflammatory response to an antigen compared with controls. The oxidative challenge enhanced plasma vitamin E levels (but not in β-carotene-supplemented chicks) and the antioxidant capacity in the short term. Interestingly, lutein-supplemented chicks showed lower oxidative damage to proteins than non-lutein-supplemented chicks. After the oxidative challenge, the positive effect of carotenoid supplementation on the immune response disappeared. Thus, these results suggest differential effects of two carotenoids with different molecular structures on the oxidative status. Lutein but not β-carotene helps to combat oxidative damage after a free-radical exposure. Additionally, the results indicate that the immunostimulatory effects of carotenoids are linked to oxidative status during early life.

Antioxidants safeguard telomeres in bold chicks

Kim, S.-Y. & Velando, A. Antioxidants safeguard telomeres in bold chicks. Biology letters 11, 20150211 (2015).

Telomeres are sensitive to damage induced by oxidative stress, and thus it is expected that dietary antioxidants may support the maintenance of telomere length in animals, particularly those with a fast rate of life (e.g. fast metabolism, activity and growth). We tested experimentally the effect of antioxidant supplements on telomere length during early development in wild gull chicks with natural individual variations in behaviour pattern and growth rate. Proactive chicks had shorter telomeres than reactive chicks, but the penalty for the bold behaviour pattern was reduced by antioxidant supplementation. Chicks growing faster had longer telomeres during early growth, suggesting that inherited quality supports a fast life history.