Carotenoid content in Anguilla anguilla (L.) individuals undertaking spawning migration

The authors investigated the carotenoid content in different parts of Anguilla anguilla (L.) undertaking spawning migration, in spring, summer and autumn. By means of column and thin-layer chromatography, the following carotenoids were found to be present: beta-carotene, epsilon-carotene, beta-cryptoxanthin, neothxanthin, lutein, tunaxanthin, zeaxanthin, lutein epoxide, 3'-hydroxyechincnone, canthaxanthin, idoxanthin, phoenicoxanthin, alpha-doradexanthin, beta-doradexanthin and astaxanthin. In the eel examined individuals a different carotenoid content was found in October. In winter when eels do not feed and therefore do not absorb carotenoids, carotenoid content decreases in the liver, the intestines, and particularly in the muscles. In spring when eels undertake active life carotenoid concentration increases rapidly in these organs within a month. In summer during intensive predation, carotenoid concentration in the muscles reaches a maximum.     

Carotenoid supplementation and GnRH challenges influence female endocrine physiology, immune function, and egg-yolk characteristics in Japanese quail (Coturnix japonica)

Androgens and carotenoids circulating in plasma affect the physiology and behavior of vertebrates. Much is known about control mechanisms and functions of each of these substances, yet their interactive effects are not well understood. Here we examine possible additive, multiplicative, and interactive effects of testosterone and carotenoids on female endocrine physiology, immunocompetence, and investment in eggs by simultaneously manipulating levels of testosterone [via gonadotropin releasing hormone (GnRH) challenges] and carotenoids (via diet supplementation) in captive female Japanese quail (Coturnix japonica). Females were randomly assigned to one of four treatments: carotenoid supplementation, GnRH challenge, GnRH challenge?+?carotenoid supplementation, or control. Carotenoid supplementation significantly increased circulating plasma carotenoid levels and acquired immune system performance, but not innate immunity. GnRH challenges elevated circulating testosterone and carotenoid levels, and induced immunosuppression in females. However, females in the GnRH challenge?+?carotenoid supplementation treatment had higher cell-mediated immune responses than control females and similar responses to those of carotenoid-supplemented females. Hence, availability of carotenoids in female quail seemed to counteract immunosuppressive effects of GnRH challenges. Our results provide further evidence for synergistic effects of carotenoids and testosterone on endocrine physiology and immune function in female birds. Elevated plasma testosterone or carotenoids levels resulted in increased deposition of those compounds to eggs, respectively. Furthermore, because we found that concentrations of testosterone and carotenoids in yolks were correlated within each treatment group, differential deposition of hormones and carotenoids in eggs may not only respond to surrounding social and environmental conditions, but also to other components of the egg.     

Phenotypic, genetic, and environmental causes of variation in yellow skin pigmentation and serum carotenoids in Eurasian kestrel nestlings

In the context of sexual selection and parent-offspring communication, carotenoid-based coloration operates as a dynamic condition-dependent signal, as pigments stored in the skin and in the bill can be reallocated to other tissues in accordance with physiological needs. We studied the proximate factors affecting the carotenoid-dependent coloration of the Eurasian kestrel (Falco tinnunculus). Kestrel nestlings show carotenoid-based coloration at the integument level. Adult males and females share similar characteristics, but to a different extent. By cross-fostering nestlings, we evaluated the importance of the “nest of rearing” and the “nest of origin” to determine variation in skin color and blood carotenoids. The nest of rearing accounted for most of the observed variance in skin color, as well as serum carotenoids, while the nest of origin was not causal to the variability of carotenoids in young kestrels. The study indirectly shows that carotenoid-based color expressed by young kestrels is not affected by pre-laying conditions. Furthermore, we found that carotenoid coloration and blood carotenoid concentration were correlated at phenotypic and environmental levels, while the hereditary component of the carotenoid traits was too low to estimate their correlation at the genetic level.     

Effect of food deprivation on transformation of carotenoids in the bivalve mollusc <Emphasis Type="Italic">Anadara kagoshimensis</Emphasis> (Tokunaga, 1906)

The composition and content of carotenoids in tissues of Anadara kagoshimensis (Tokunaga, 1906) were analyzed under food deprivation over 30 days. By the end of the experiment, a little and uneven decrease in the total carotenoid level was observed in the foot, hepatopancreas, gills, and tissue remainder. Initially, β-carotine, pectenolon, zeaxanthine, diatoxanthine, alloxanthine and the ethers of the latter four carotenoids were detected in tissue extracts. The qualitative carotenoid composition in the tissues under study was similar. During the experiment, changes common to all tissues were found both in the composition and content of carotenoids. β-carotene disappeared on days 3–4, the level of pectenolon, zeaxanthine, diatoxanthine and alloxanthine ethers decreased over 30 days, while the pectenolon and alloxanthine levels increased. Tissue specificity was revealed. Specifically, in the foot and hepatopancreas, a considerable increase was observed in the pectenolon and alloxanthine levels parallel to the decreasing total level of carotenoid esthers and increasing level of diatoxanthine and zeaxanthine; in the gills and lump of the remaining tissues, at the similar increase in the pectenolon and alloxanthine levels, those of diatoxanthine and zeaxanthine remained intact or even a little below the initial level. The diagram of carotenoid transformation in Anadara kagoshimensis is supplemented.     

Relationships between dietary carotenoids, body tissue carotenoids, parasite burden, and health state in wild mallard (Anas platyrhynchos) ducklings

While rodents and other mammals have traditionally served as models for studying carotenoid physiology, many wild animals from a variety of other taxa utilize carotenoids for self-maintenance and reproduction and accumulate far greater concentrations than those found in mammals. Though we have basic understandings of the control and value of carotenoids in some wild animal systems, many gaps remain. For example, parasites and pathogens impose severe survival constraints on free-ranging organisms, but little is known of how carotenoids work in concert with the immune system to combat natural infectious challenges. Furthermore, due to the high mortality rate from which many young animals suffer, health and carotenoid status during the early stages of development may be critical to survival. The relative importance of dietary versus physiological mechanisms for carotenoid uptake has also been understudied in the wild. To begin to shed light on these issues, we studied relationships between dietary and tissue carotenoids, hematological immune parameters, and endoparasitism of wild mallard (Anas platyrhynchos) ducklings at a variety of ages. Lutein, zeaxanthin, β-cryptoxanthin, β-carotene, and canthaxanthin were the most common carotenoids in liver, plasma, and gut contents. We found that, early in development (when food intake is limited), carotenoids were comparatively concentrated in internal tissue (e.g., liver), presumably a carry-over from maternal contributions in yolk, but as ducklings approached independence (and increasingly fed on their own) concentrations were greatest in gut contents. Canthaxanthin concentrations were lower in the plasma and liver of older individuals compared to younger ducklings, even though gut canthaxanthin concentration did not change with age. Additionally, β-carotene was nearly absent from circulation, despite moderate levels within the gut, suggesting a high rate of conversion to retinol. Using principal components analysis, we revealed a correlation between an increased ability to assimilate dietary carotenoids and lower levels of chronic stress (as assessed by lower heterophil-to-lymphocyte ratios) and a correlation between a reduced carotenoid status and increased investment in the immune system (as assessed by higher total leukocyte count). We also found that individuals without parasites had an overall reduced carotenoid status. Thus, we demonstrate age-specific differences in carotenoid allocation in growing animals from a precocial bird species and provide correlational evidence that parasitism and health in wild animals are related to carotenoid status and assimilation ability.     

A review of animal model studies of tomato carotenoids,lycopene, and cancer chemoprevention

There are relatively few reports on the cancer chemopreventive effects of lycopene or tomato carotenoids in animal models. The majority, but not all, of these studies indicate a protective effect. Inhibitory effects were reported in two studies using aberrant crypt foci, an intermediate lesion leading to colon cancer, as an end point and in two mammary tumor studies, one using the dimethylbenz(a)anthracene model, and the other the spontaneous mouse model. Inhibitory effects were also reported in mouse lung and rat hepatocarcinoma and bladder cancer models. However, a report from the author's laboratory found no effect in the N-nitrosomethylurea-induced mammary tumor model when crystalline lycopene or a lycopene-rich tomato carotenoid oleoresin was administered in the diet. Unfortunately, because of differences in routes of administration (gavage, intraperitoneal injection, intra-rectal instillation, drinking water, and diet supplementation), species and strain differences, form of lycopene (pure crystalline, beadlet, mixed carotenoid suspension), varying diets (grain-based, casein based) and dose ranges (0.5-500 ppm), no two studies are comparable. It is clear that the majority of ingested lycopene is excreted in the feces and that 1000-fold more lycopene is absorbed and stored in the liver than accumulates in other target organs. Nonetheless, physiologically significant (nanogram) levels of lycopene are assimilated by key organs such as breast, prostate, lung, and colon, and there is a rough dose-response relationship between lycopene intake and blood levels. Pure lycopene was absorbed less efficiently than the lycopene-rich tomato carotenoid oleoresin and blood levels of lycopene in rats fed a grain-based diet were consistently lower than those in rats fed lycopene in a casein-based diet. The latter suggests that the matrix in which lycopene is incorporated is an important determinant of lycopene uptake. A number of issues remain to be resolved before any definitive conclusions can be drawn concerning the anticancer effects of lycopene. These include the following: the optimal dose and form of lycopene, interactions among lycopene and other carotenoids and fat soluble vitamins such as vitamin E and D, the role of dietary fat in regulating lycopene uptake and disposition, organ and tissue specificity, and the problem of extrapolation from rodent models to human populations.     

The sub-cellular localisation of the potato (Solanum tuberosum L.) carotenoid biosynthetic enzymes, CrtRb2 and PSY2

Carotenoids are isoprenoids with important biological roles both for plants and animals. The yellow flesh colour of potato (Solanum tuberosum L.) tubers is a quality trait dependent on the types and levels of carotenoids that accumulate. The carotenoid biosynthetic pathway is well characterised, facilitating the successful engineering of carotenoid content in numerous crops including potato. However, a clear understanding concerning the factors regulating carotenoid accumulation and localisation in plant storage organs, such as tubers, is lacking. In the present study, the localisation of key carotenoid biosynthetic enzymes was investigated, as one of the unexplored factors that could influence the accumulation of carotenoids in potato tubers. Stable transgenic potato plants were generated by over-expressing β-CAROTENE HYDROXYLASE 2 (CrtRb2) and PHYTOENE SYNTHASE 2 (PSY2) genes, fused to red fluorescent protein (RFP). Gene expression and carotenoid levels were both significantly increased, confirming functionality of the fluorescently tagged proteins. Confocal microscopy studies revealed different sub-organellar localisations of CrtRb2-RFP and PSY2-RFP within amyloplasts. CrtRb2 was detected in small vesicular structures, inside amyloplasts, whereas PSY2 was localised in the stroma of amyloplasts. We conclude that it is important to consider the location of biosynthetic enzymes when engineering the carotenoid metabolic pathway in storage organs such as tubers.     

Yolk carotenoids and stable isotopes reveal links among environment, foraging behavior and seabird breeding success

Nutrients that are limited in availability, such as carotenoids, are potentially involved in trade-offs between homeostasis and reproduction. Despite their importance, factors that affect the capacity of female birds to meet their carotenoid requirements are poorly understood. We used δ¹⁵N stable isotope analysis to relate foraging behavior to yolk carotenoid deposition in two seabirds, Cassin’s auklet (Ptychoramphus aleuticus) and rhinoceros auklet (Cerorhinca monocerata), during each of five years. As expected from their narrower trophic range, Cassin’s auklets produced yolks with fewer carotenoid types than did rhinoceros auklets (one vs. three). Cassin’s auklets also fed on a lower trophic level diet richer in carotenoids, yet had lower total yolk carotenoid levels, which suggests a role for species-specific adaptations for carotenoid uptake and utilization. Within both species, lower trophic-level feeding was linked to higher yolk carotenoid levels, but through different mechanisms. In Cassin’s auklets, it was due to a population-wide response to environmental variation: in warm-water years, all females fed at a low trophic level and produced carotenoid-rich yolks. In rhinoceros auklets, it was due to individual differences similarly expressed in all years: females fed across a wide trophic range, and those that fed at a low trophic level produced carotenoid-rich yolks. Rhinoceros auklets bred more successfully in years when their yolks were rich in carotenoids, probably due to a correlated response to stronger marine primary production. Our results are novel because they link avian yolk carotenoid deposition to behavioral and environmental variations.     

Phenotypic correlates of yolk and plasma carotenoid concentration in yellow-legged gull chicks

Abstract Carotenoids perform important biological actions in animal tissues, including contributing antioxidant protection. However, the function of transmission of maternal carotenoids to bird eggs is still largely unknown. We made a yolk biopsy of yellow-legged gull (Larus michahellis) eggs and found that the concentration of lutein declined with laying date and across the laying order and increased with egg mass. The concentration of all the main carotenoids (lutein, zeaxanthin, and dehydrolutein) pooled also declined with date and increased with egg mass. We also performed a partial reciprocal cross-fostering of eggs between clutches and investigated the covariation between morphology, T cell-mediated immunity, and plasma carotenoid concentrations of the chicks and carotenoid concentrations in their original eggs. Absolute plasma carotenoid concentrations did not covary with those in the yolk, whereas a positive covariation was found for relative concentrations. Yolk and absolute plasma carotenoid concentrations positively predicted chick body mass and size but not the intensity of the cell-mediated immune response. Thus, yolk carotenoid concentrations may affect chick carotenoid profile and growth, possibly mediating early maternal effects. However, rearing conditions also contributed to determining relative concentrations of circulating carotenoids. Since yolk or plasma antioxidant capacity did not correlate with carotenoid concentrations, future studies of maternal effects mediated by antioxidants should integrate information on carotenoids with information on other components of the antioxidant systems.     

The effects of dietary carotenoid intake on carotenoid accumulation in the retina of a wild bird, the house finch (Carpodacus mexicanus)

Carotenoid pigments accumulate in the retinas of many animals, including humans, where they play an important role in visual health and performance. Recently, birds have emerged as a model system for studying the mechanisms and functions of carotenoid accumulation in the retina. However, these studies have been limited to a small number of domesticated species, and the effects of dietary carotenoid access on retinal carotenoid accumulation have not been investigated in any wild animal species. The purpose of our studies was to examine how variation in dietary carotenoid types and levels affect retinal accumulation in house finches (Carpodacus mexicanus), a common and colorful North American songbird. We carried out three 8-week studies with wild-caught captive birds: (1) we tracked the rate of retinal carotenoid depletion, compared to other body tissues, on a very low-carotenoid diet, (2) we supplemented birds with two common dietary carotenoids (lutein + zeaxanthin) and measured the effect on retinal accumulation, and (3) we separately supplemented birds with high levels of zeaxanthin - an important dietary precursor for retinal carotenoids - or astaxanthin - a dominant retinal carotenoid not commonly found in the diet (i.e. a metabolic derivative). We found that carotenoids depleted slowly from the retina compared to other tissues, with a significant (∼50%) decline observed only after 8 weeks on a very low-carotenoid diet. Supplementation with lutein + zeaxanthin or zeaxanthin alone significantly increased only retinal galloxanthin and ε-carotene levels, while other carotenoid types in the retina remained unaffected. Concentrations of retinal astaxanthin were unaffected by direct dietary supplementation with astaxanthin. These results suggest highly specific mechanisms of retinal carotenoid metabolism and accumulation, as well as differential rates of turnover among retinal carotenoid types, all of which have important implications for visual health maintenance and interventions.     

Carotenoid responses to environmental stimuli: integrating redox and carbon controls into a fruit model

Carotenoids play an important role in plant adaptation to fluctuating environments as well as in the human diet by contributing to the prevention of chronic diseases. Insights have been gained recently into the way individual factors, genetic, environmental or developmental, control the carotenoid biosynthetic pathway at the molecular level. The identification of the rate‐limiting steps of carotenogenesis has paved the way for programmes of breeding, and metabolic engineering, aimed at increasing the concentration of carotenoids in different crop species. However, the complexity that arises from the interactions between the different factors as well as from the coordination between organs remains poorly understood. This review focuses on recent advances in carotenoid responses to environmental stimuli and discusses how the interactions between the modulation factors and between organs affect carotenoid build‐up. We develop the idea that reactive oxygen species/redox status and sugars/carbon status can be considered as integrated factors that account for most effects of the major environmental factors influencing carotenoid biosynthesis. The discussion highlights the concept of carotenoids or carotenoid‐derivatives as stress signals that may be involved in feedback controls. We propose a conceptual model of the effects of environmental and developmental factors on carotenoid build‐up in fruits.     

Variations in the carotenoid content of Chlamydomonas reinhardii throughout the cell cycle.

Synchronous cultures of Chlamydomonas reinhardii have been examined for the total amounts of carotenoid and chlorophyll present throughout a 12 hrs light -- 4 hrs dark life cycle. Variations in the carotenoid distribution at different points within the cell cycle have been found. During the greater part of the light period all major carotenoids increased at a proportionally similar rate. However, the increases in lutein and violaxanthin preceded those in beta-carotene and neoxanthin by some 2 hrs and that in loroxanthin, and algal xanthophyll, by abour 3 hrs. A marked drop in total carotenoid accumulation, corresponding to similar temporary falling away in the accumulation of beta-carotene, lutein and violaxanthin occurred at 9 hrs. The correspondence of this with the established drop in RNA accumulation and the break-up of the nucleolus was pointed out. Considerable redistribution among the carotenoids occurred during the dark period, notably the amount of beta-carotene increased relative to the total xanthophylls. The full significance of these results can not be estimated in the absence of comparative data on related organisms.     

Variations in the carotenoid content of Chlamydomonas reinhardii throughout the cell cycle

Synchronous cultures of Chlamydomonas reinhardii have been examined for the total amounts of carotenoid and chlorophyll present throughout a 12 hrs light–4 hrs dark life cycle. Variations in the carotenoid distribution at different points within the cell cycle have been found. During the greater part of the light period all major carotenoids increased at a proportionally similar rate. However, the increases in lutein and violaxanthin preceded those in β-carotene and neoxanthin by some 2 hrs and that in loroxanthin, an algal xanthophyll, by about 3 hrs. A marked drop in total carotenoid accumulation, corresponding to similar temporary falling away in the accumulation of β-carotene, lutein and violaxanthin occurred at 9 hrs. The correspondence of this with the established drop in RNA accumulation and the break-up of the nucleolus was pointed out. Considerable redistribution among the carotenoids occurred during the dark period, notably the amount of β-carotene increased relative to the total xanthophylls. The full significance of these results can not be estimated in the absence of comparative data on related organisms.     

Sequestration of host plant carotenoids in the larval tissues of Helicoverpa zea

To determine the cause of the unique yellow coloration in mandibular glands of soybean-fed Helicoverpa zea larvae, the accumulation of carotenoids in various tissues of last instar larvae fed soybean, cotton and tomato foliage was quantified. Five carotenoids were detected in the foliage of all host plants but at significantly different concentrations. Xanthophylls rather than carotenes were most likely to accumulate in larval tissues. Carotenoids accumulated at different rates and some were significantly affected by larval diet. Highest levels of carotenoid accumulation, notably lutein, were detected in the testes, followed by midgut epithelium, fat body and integument. The midgut epithelium contained the greatest and the testes the least diversity of carotenoid types. Low levels of lutein were detected in both labial and mandibular glands. Tomato foliage had the highest carotenoid content and caterpillar tissues fed these leaves often had the highest amounts of carotenoid. However, the accumulation of carotenoids did not protect larvae from antibiotic effects of tomato foliage because these caterpillars had the highest mortality and slowest growth rates of all the three host plants. Transport and absorption of lipid and oxidative stress may be some reasons for differential carotenoid accumulation.     

Carotenoids,vitamin A,and vitamin E concentrations during egg development in panther chameleons (Furcifer pardalis)

Insects are known to be poor sources of preformed vitamin A, leading to the speculation that insectivorous species, including reptiles, may be able to convert carotenoid precursors to meet dietary requirements for this nutrient. This study was conducted to indirectly evaluate carotenoid and vitamin A metabolism in the panther chameleon (Furcifer pardalis). Eggs were obtained from females in Madagascar that were yolked either early or later in the breeding season, and carotenoid (α‐ and β‐carotene, cryptoxanthin, lutein/zeaxanthin, and lycopene), vitamin A, and vitamin E concentrations were measured in egg contents in early, middle, or late embryonic development. An overall trend of decreased nutrient concentration as eggs matured (from egg period 1 (yolks) to egg period 3 (embryos)) was seen within both clutch groups. The season of clutch deposition was a significant influence on egg weight, α‐carotene, and lutein/zeaxanthin concentrations, but on no other nutrients. Chameleon yolks contained considerably higher levels of carotenoids than levels previously reported from two viviparous lizard species, and β‐carotene concentrations were of the same magnitude as reported in grazing tortoises. β‐Carotene and β‐cryptoxanthin were the predominant carotenoids in yolk and embryos, comprising about 95% of total carotenoids detected. Measurable concentrations of retinol at all stages of egg development in the chameleons suggests effective conversion from carotenoid precursors, with concentrations similar to those measured in other lizard eggs. Information from eggs obtained in native habitats may provide baseline data on nutrient interactions to improve and optimize captive dietary management; preliminary data suggest that micronutrient environments may vary over the protracted breeding season, with possible implications for embryo health and survival. Zoo Biol 21:295–303, 2002. © 2002 Wiley‐Liss, Inc.     

Contributions of pterin and carotenoid pigments to dewlap coloration in two anole species

Animals can acquire bright coloration using a variety of pigmentary and microstructural mechanisms. Reptiles and amphibians are known to use two types of pigments - pterins and carotenoids - to generate their spectrum of colorful red, orange, and yellow hues. Because both pigment classes can confer all of these hues, the relative importance of pterins versus carotenoids in creating these different colors is not always apparent. We studied the carotenoid and pterin content of red and yellow dewlap regions in two neotropical anole species - the brown anole (Norops sagrei) and the ground anole (N. humilis). Pterins (likely drosopterins) and carotenoids (likely xanthophylls) were present in all tissues from all individuals. Pterins were more enriched in the lateral (red) region, and carotenoids more enriched in the midline (yellow) region in N. humilis, but pterins and carotenoids were found in similar concentrations among lateral and midline regions in N. sagrei. These patterns indicate that both carotenoid and pterin pigments are responsible for producing color in the dichromatic dewlaps of these two species, and that in these two species the two pigments interact differently to produce the observed colors.     

Carotenoid Crystal Formation in Arabidopsis and Carrot Roots Caused by Increased Phytoene Synthase Protein Levels

Background

As the first pathway-specific enzyme in carotenoid biosynthesis, phytoene synthase (PSY) is a prime regulatory target. This includes a number of biotechnological approaches that have successfully increased the carotenoid content in agronomically relevant non-green plant tissues through tissue-specific PSY overexpression. We investigated the differential effects of constitutive AtPSY overexpression in green and non-green cells of transgenic Arabidopsis lines. This revealed striking similarities to the situation found in orange carrot roots with respect to carotenoid amounts and sequestration mechanism.

Methology/Principal Findings

In Arabidopsis seedlings, carotenoid content remained unaffected by increased AtPSY levels although the protein was almost quantitatively imported into plastids, as shown by western blot analyses. In contrast, non-photosynthetic calli and roots overexpressing AtPSY accumulated carotenoids 10 and 100-fold above the corresponding wild-type tissues and contained 1800 and 500 µg carotenoids per g dry weight, respectively. This increase coincided with a change of the pattern of accumulated carotenoids, as xanthophylls decreased relative to β-carotene and carotene intermediates accumulated. As shown by polarization microscopy, carotenoids were found deposited in crystals, similar to crystalline-type chromoplasts of non-green tissues present in several other taxa. In fact, orange-colored carrots showed a similar situation with increased PSY protein as well as carotenoid levels and accumulation patterns whereas wild white-rooted carrots were similar to Arabidopsis wild type roots in this respect. Initiation of carotenoid crystal formation by increased PSY protein amounts was further confirmed by overexpressing crtB, a bacterial PSY gene, in white carrots, resulting in increased carotenoid amounts deposited in crystals.

Conclusions

The sequestration of carotenoids into crystals can be driven by the functional overexpression of one biosynthetic enzyme in non-green plastids not requiring a chromoplast developmental program as this does not exist in Arabidopsis. Thus, PSY expression plays a major, rate-limiting role in the transition from white to orange-colored carrots.     

Oxidation of carotenoids by heat and tobacco smoke

The stability to autoxidation of the polar carotenoids, lutein and zeaxanthin, was compared to that of the less polar carotenoids, beta-carotene and lycopene at physiologically or pathophysiologically relevant concentrations of 2 and 6 microM, after exposure to heat or cigarette smoke. Three methodological approaches were used: 1) Carotenoids dissolved in solvents with different polarities were incubated at 37 and 80 degrees C for different times. 2) Human plasma samples were subjected to the same temperature conditions. 3) Methanolic carotenoid solutions and plasma were also exposed to whole tobacco smoke from 1-5 unfiltered cigarettes. The concentrations of individual carotenoids in different solvents were determined spectrophotometrically. Carotenoids from plasma were extracted and analyzed using high performance liquid chromatography. Carotenoids were generally more stable at 37 than at 80 degrees C. In methanol and dichloromethane the thermal degradation of beta-carotene and lycopene was faster than that of lutein and zeaxanthin. However, in tetrahydrofuran beta-carotene and zeaxanthin degraded faster than lycopene and lutein. Plasma carotenoid levels at 37 degrees C did not change, but decreased at 80 degrees C. The decrease of beta-carotene and lycopene levels was higher than those for lutein and zeaxanthin. Also in the tobacco smoke experiments the highest autoxidation rates were found for beta-carotene and lycopene at 2 microM, but at 6 microM lutein and zeaxanthin depleted to the same extent as beta-carotene. These data support our previous studies suggesting that oxidative stress degrade beta-carotene and lycopene faster than lutein and zeaxanthin. The only exception was the thermal degradation of carotenoids solubilized in tetrahydrofuran, which favors faster breakdown of beta-carotene and zeaxanthin.     

Carotenoids bolster immunity during moult in a wild songbird with sexually selected plumage coloration

Carotenoid‐based colours in animals are valuable models for testing theories of sexual selection and life‐history trade‐offs because the pigments used in coloration are chemically tractable in the diet and in the body, where they serve multiple purposes (e.g. health enhancement, photoprotection). An important assumption underlying the hypothesized signalling value of carotenoid coloration is that there is a trade‐off in carotenoid pigment allocation, such that not all individuals can meet the physiological/morphological demands for carotenoids (i.e. carotenoids are limited) and that only those who have abundant supplies or fewer demands become the most colourful. Studies of carotenoid trade‐offs in colourful animals have been limited largely to domesticated species, which may have undergone artificial selection that changed the historical/natural immunomodulatory roles of carotenoids, to young animals lacking carotenoid‐based signals or to species displaying carotenoid‐based skin and bare parts. We studied the health benefits of carotenoids during moult in house finches (Carpodacus mexicanus), which display sexually selected, carotenoid‐based plumage coloration. We manipulated dietary carotenoid availability during both winter (nonmoult) and autumn (moult) in captive males and females and found that carotenoid‐supplemented birds mounted stronger immune responses (to phytohemagglutinin injection and to a bacterial inoculation in blood) than control birds only during moult. This study provides experimental, seasonal support for a fundamental tenet of Lozano's ‘carotenoid trade‐off’ hypothesis and adds to a growing list of animal species that benefit immunologically from ingesting higher dietary carotenoid levels. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 102 , 560–572.