Carlos Alonso-Alvarez

Bio: Carlos Alonso-Alvarez is an academic researcher from Spanish National Research Council. The author has contributed to research in topics: Carotenoid & Oxidative stress. The author has an hindex of 35, co-authored 71 publications receiving 5100 citations. Previous affiliations of Carlos Alonso-Alvarez include University of Vigo & Pierre-and-Marie-Curie University.

THE ECOLOGY OF ANTIOXIDANTS & OXIDATIVE STRESS IN ANIMALS Oxidative stress as a life-history constraint: the role of reactive oxygen species in shaping phenotypes from conception to death

Abstract: Summary 1. Oxidative stress is usually defined as an imbalance arising when the rate of production of reactive oxygen species (ROS) exceeds the capacity of the antioxidant defence and repair mechanisms, leading to oxidative damage to biomolecules, but the concept can be expanded to include the disruption of reduction : oxidation (redox) reactions involved in cellular signalling. In this review, we consider how the need to circumvent oxidation may shape the phenotypes of organisms throughout their life and that of their offspring, underpinning a diverse range of life-history trade-offs. 2. A recent explosion of interest in this field has shown that both ROS production and the capacity of animals to deal with it change from early development through to adulthood, and vary with environmental conditions and lifestyle. Oxidative stress may both stimulate and be caused by reproduction, although direct evidence of either process is surprisingly weak. Many forms of secondary sexual traits may signal the individual’s oxidative balance to potential mates, but the underlying mechanisms are still debated. 3. Germline cells may be especially vulnerable to oxidative stress, leading to transgenerational effects on offspring viability and possible consequences for the evolution of mate choice. 4. Both antioxidant defences and the ability to repair oxidative damage tend to decline with old age, contributing to cellular and whole organism senescence. This increasing vulnerability to oxidative stress, although little studied, appears especially marked in sexually selected traits. 5. Challenges for the future include the incorporation of longitudinal approaches into experiments that analyse oxidative balance over an individual’s lifetime (preferably under near-natural conditions), the exploration of the genetic basis for trade-offs involving oxidative stress, the assimilation of current redox signalling knowledge, and the study of the consequences of heritable oxidative damage to germline DNA.

Oxidative stress as a life‐history constraint: the role of reactive oxygen species in shaping phenotypes from conception to death

Abstract: Summary 1. Oxidative stress is usually defined as an imbalance arising when the rate of production of reactive oxygen species (ROS) exceeds the capacity of the antioxidant defence and repair mechanisms, leading to oxidative damage to biomolecules, but the concept can be expanded to include the disruption of reduction : oxidation (redox) reactions involved in cellular signalling. In this review, we consider how the need to circumvent oxidation may shape the phenotypes of organisms throughout their life and that of their offspring, underpinning a diverse range of life-history trade-offs. 2. A recent explosion of interest in this field has shown that both ROS production and the capacity of animals to deal with it change from early development through to adulthood, and vary with environmental conditions and lifestyle. Oxidative stress may both stimulate and be caused by reproduction, although direct evidence of either process is surprisingly weak. Many forms of secondary sexual traits may signal the individual’s oxidative balance to potential mates, but the underlying mechanisms are still debated. 3. Germline cells may be especially vulnerable to oxidative stress, leading to transgenerational effects on offspring viability and possible consequences for the evolution of mate choice. 4. Both antioxidant defences and the ability to repair oxidative damage tend to decline with old age, contributing to cellular and whole organism senescence. This increasing vulnerability to oxidative stress, although little studied, appears especially marked in sexually selected traits. 5. Challenges for the future include the incorporation of longitudinal approaches into experiments that analyse oxidative balance over an individual’s lifetime (preferably under near-natural conditions), the exploration of the genetic basis for trade-offs involving oxidative stress, the assimilation of current redox signalling knowledge, and the study of the consequences of heritable oxidative damage to germline DNA.

Increased susceptibility to oxidative stress as a proximate cost of reproduction

Abstract: Carlos Alonso-Alvarez*, Sophie Bertrand, Godefroy Devevey, Josiane Prost, Bruno Faivre and Gabriele Sorci Laboratoire de Parasitologie Evolutive, CNRS UMR 7103, Université Pierre et Marie Curie, xquai St. Bernard, 75252 Paris cedex 05, France UMR CNRS 5561 BioGéo Sciences, Equipe Ecologie Evolutive, Université de Bourgogne, 6 Blvd Gabriel, 21000 Dijon, France UPRES Lipides Nutrition, Université de Bourgogne, EA 2422, 6 Blvd Gabriel, 21000 Dijon, France *Correspondence: E-mail: calonso@snv.jussieu.fr Abstract In iteroparous species high investment in current reproduction is usually paid in terms of reduced future reproduction and increased mortality. However, the proximal mechanisms of these costs remain poorly understood. Free radicals arising as by-products of normal metabolic activities have deleterious effects on cellular proteins, lipids and DNA, and this phenomenon is known as oxidative stress. Since reproduction is an energetically demanding activity, which increases both basal and field metabolic rates, one could expect that breeding effort generates an oxidative stress whose strength depends on the availability and efficiency of antioxidant defences. In agreement with this prediction, we show here for the first time that reproduction decreases antioxidant defences, illustrating that oxidative stress represents a cost of reproduction. We suggest that increased susceptibility to oxidative stress might be a general proximal connection between reproduction and survival underlying other mechanistic links previously acknowledged.

Testosterone and oxidative stress: the oxidation handicap hypothesis

Abstract: Secondary sexual traits (SST) are usually thought to have evolved as honest signals of individual quality during mate choice Honesty of SST is guaranteed by the cost of producing/maintaining them In males, the expression of many SST is testosterone-dependent The immunocompetence handicap hypothesis has been proposed as a possible mechanism ensuring honesty of SST on the basis that testosterone, in addition to its effect on sexual signals, also has an immunosuppressive effect The immunocompetence handicap hypothesis has received mixed support However, the cost of testosterone-based signalling is not limited to immunosuppression and might involve other physiological functions such as the antioxidant machinery Here, we tested the hypothesis that testosterone depresses resistance to oxidative stress in a species with a testosterone-dependent sexual signal, the zebra finch Male zebra finches received subcutaneous implants filled with flutamide (an anti-androgen) or testosterone, or kept empty (control) In agreement with the prediction, we found that red blood cell resistance to a free radical attack was the highest in males implanted with flutamide and the lowest in males implanted with testosterone We also found that cell-mediated immune response was depressed in testosterone-treated birds, supporting the immunocompetence handicap hypothesis The recent finding that red blood cell resistance to free radicals is negatively associated with mortality in this species suggests that benefits of sexual signalling might trade against the costs derived from oxidation

An Experimental Test of the Dose-Dependent Effect of Carotenoids and Immune Activation on Sexual Signals and Antioxidant Activity

Abstract: Carotenoid‐based sexual traits are thought to be reliable indicators of male quality because they might be scarce and therefore might indicate the ability of males to gather high‐quality food and because they are involved in important physiological functions (as immune enhancers and antioxidants). We performed an experiment where male and female zebra finches (Taeniopygia guttata) were provided with increasing carotenoid doses in the drinking water during 4 weeks (bill color of this species is a carotenoid‐based sexual signal). Simultaneously, birds were split into two groups: one receiving weekly injections of Escherichia coli lipopolysaccharide in order to activate the immune system, the other being injected with the same volume of phosphate buffered saline. We assessed how carotenoid availability and immune activation affected the amount of circulating plasma carotenoids, the beak color, and the antioxidant defenses (assessed as the resistance of red blood cells to a controlled free radical a...

Evolution and the Theory of Games

Abstract: In the Hamadryas baboon, males are substantially larger than females. A troop of baboons is subdivided into a number of ‘one-male groups’, consisting of one adult male and one or more females with their young. The male prevents any of ‘his’ females from moving too far from him. Kummer (1971) performed the following experiment. Two males, A and B, previously unknown to each other, were placed in a large enclosure. Male A was free to move about the enclosure, but male B was shut in a small cage, from which he could observe A but not interfere. A female, unknown to both males, was then placed in the enclosure. Within 20 minutes male A had persuaded the female to accept his ownership. Male B was then released into the open enclosure. Instead of challenging male A , B avoided any contact, accepting A’s ownership.

No evidence that carotenoid pigments boost either immune or antioxidant defenses in a songbird

Abstract: Dietary carotenoids have been proposed to boost immune system and antioxidant functions in vertebrate animals, but studies aimed at testing these physiological functions of carotenoids have often failed to find support. Here we subject yellow canaries (Serinus canaria), which possess high levels of carotenoids in their tissue, and white recessive canaries, which possess a knockdown mutation that results in very low levels of tissue carotenoids, to oxidative and pathogen challenges. Across diverse measures of physiological performance, we detect no differences between carotenoid-rich yellow and carotenoid-deficient white canaries. These results add further challenge to the assumption that carotenoids are directly involved in supporting physiological function in vertebrate animals. While some dietary carotenoids provide indirect benefits as retinoid precursors, our observations suggest that carotenoids themselves may play little to no direct role in key physiological processes in birds.