Riccardo Stradi

Carotenoid concentration in barn swallow eggs is influenced by laying order, maternal infection and paternal ornamentation

Carotenoids are critical to embryonic development, immunity and protection from oxidative stress. Transmission of carotenoids to the eggs may affect development and maturation of immunity in offspring, but carotenoids may be available to females in limiting amounts. Females may thus transfer carotenoids to the eggs differentially in relation to the reproductive value of the offspring as affected by sexual ornamentation of their father. In this study of maternal allocation of carotenoids to the eggs in the barn swallow (Hirundo rustica), females whose immune system had been experimentally challenged with an antigen had smaller lutein concentrations in their eggs than controls. We manipulated the size of a secondary sexual character (tail length) of males, and analysed the effect of manipulation on allocation of lutein to eggs by their vaccinated mates. Contrary to our prediction based on parental allocation theory, mates of tail–shortened males had a larger lutein concentration in their eggs compared with those of control and tail–elongated males. According to previous studies, offspring of short–tailed males have larger exposure and/or susceptibility to parasites. A larger lutein concentration in the eggs of females mated to males with experimentally reduced ornaments may thus reflect adaptive maternal strategies to enhance offspring viability.

Carotenoid Plasma Concentration, Immune Profile, and Plumage Ornamentation of Male Barn Swallows (Hirundo rustica)

Carotenoids exert immunomodulating, immunostimulating, and antioxidant actions in mammals and are major determinants of coloration in animals. Honest advertisement models of sexual selection propose that male ornaments, including coloration, are reliable indicators of male quality. Because of their simultaneous effects on male coloration and immunity, carotenoids might mediate the hypothesized relationship between the expression of epigamic coloration and parasitism in vertebrates. We analyzed the relationship between immune profile and concentration of lutein, the most abundant carotenoid in the plasma of male barn swallows (Hirundo rustica). Consistent with our predictions, lutein plasma concentration was negatively correlated with gamma‐globulin plasma levels and concentration of selected leukocyte types in peripheral blood, suggesting that, to exert immune function, carotenoids are taken up from plasma, thus becoming unavailable for epigamic signaling. The coloration of red feathers of the throat of adult males was positively related to plasma concentration of lutein, but not with immunologic variables, consistent with the idea that more brightly colored males do not pay a larger immunological cost for their coloration compared with less brightly colored males. Length of male tail ornaments, which is currently under directional sexual selection, was positively correlated with lutein plasma levels. In species where carotenoids limit immune function, demands for pigments for sexual signaling might compete with those for immunity, thus generating a mechanism that enforces honesty on the signal.

The effect of dietary carotenoid access on sexual dichromatism and plumage pigment composition in the American goldfinch

We investigated potential dietary and biochemical bases for carotenoid-based sexual dichromatism in American goldfinches (Carduelis tristis). Captive male and female finches were given access to the same type and amount of carotenoid pigments in the diet during their nuptial molt to assess differences in the degree to which the two sexes incorporated ingested pigments into their plumage. When birds were fed a uniform, plain-seed diet, or one that was supplemented with the red carotenoid canthaxanthin, we found that males grew more colorful plumage than females. HPLC analyses of feather pigments revealed that male finches incorporated a higher concentration of carotenoids into their pigmented feathers than females. Compared to females, males also deposited significantly more canary xanthophyll B into feathers when fed a plain-seed diet and a greater concentration and proportion of canthaxanthin when fed a carotenoid-supplemented diet. These results indicate that sex-specific expression of carotenoid pigmentation in American goldfinches may be affected by the means by which males and females physiologically utilize (e.g. absorb, transport, metabolize, deposit) carotenoid pigments available to them in the diet.

Carotenoids in bird plumage—I. The carotenoid pattern in a series of palearctic carduelinae

Abstract The coloured feathers of Carduelis chloris, Carduelis sinica, Carduelis spinoides, Carduelis carduelis (European and Asiatic), Carduelis spinus, Carduelis citrinella, Serinus serinus and Serinus pusillus were extracted with a new procedure which permits the use of mild conditions (a few minutes at room temperature). After the separation of melanins and proteins, the extracts were analysed by liquid chromatography coupled with mass spectrometry and UV-vis spectroscopy. Two main pigments identified as all trans ϵ,ϵ-carotene-3,3′-dione and 3-hydroxy-ϵ,ϵ-carotene-3′-one were present in all species, accompanied by several cis isomers. In the plumage of C. chloris, C. sinica and C. spinoides significant amounts of lutein were also detected. In the head plumage of C. carduelis more oxidized ϵ,ϵ-carotenoids (C 40 H 52 O 3 and C 40 H 52 O 4 ) were present in all individuals examined.

The chemical structure of the pigments in Ara macao plumage.

Parrots (Psittaciformes) harbor unusually bright, non-carotenoid, feather pigments. We successfully extracted and purified a sufficient quantity of pigment from the red plumage of the Scarlet Macaw (Ara macao) for a partial chemical analysis. The extracts were analyzed by HPLC coupled with UV-VIS and mass spectroscopy before and after total hydrogenation. We found at least four pigment components. We propose a linear polyenal structure comparable with the molecules tetradecahexenal, hexadecaheptenal, octadecaoctenal and eicosanonenal.

Separation and identification of carotenoids in bird's plumage by high-performance liquid chromatography-diode-array detection

The coloured feathers of Carduelis spinus (Siskin), C. flammea (Redpoll), Serinus serinus (Serin), Loxia curvirostra (Crossbill), Pinicola enucleator (Grossbeak), Carpodacus roseus (Pallas Rosefinch) and Pyrrhula pyrrhula (Bullfinch) have been extracted with a new procedure using mild conditions (a few minutes at room temperature). After the separation of melanines and proteins, the extracts were analyzed by HPLC-MS and HPLC-UV-Vis. The main components of the pigments were identified in all the species examined; moreover, UV-Vis and MS data were collected also for the minor components. These data suggest that minor components are generally cis isomers accompanying the predominant all-trans isomers.

Carotenoids in bird plumage: the complement of red pigments in the plumage of wild and captive bullfinch (Pyrrhula pyrrhula)

We have studied the carotenoid pigments in the red plumage of male bullfinch (Pyrrhula pyrrhula) immediately following capture and after the completion of the moult in captivity under dietary control. Astaxanthin, adonirubin, and alpha-doradexanthin, as well as papilioeritrinone and canthaxanthin (in lower amounts) are in every case the dominant carotenoids in the plumage pigment of wild individuals. alpha-Doradexanthin is responsible for the reddish-rose colour, which captive individuals adopt after a diet consisting mainly of lutein as disposable carotenoid. The red pigmentation biogenesis of captive bullfinch is compared with those of other red pigmented Carduelinae in which male individuals usually lose the red colour in captivity, namely Carpodacus roseus, Carpodacus rubricilloides, Uragus sibiricus, Carduelis cannabina, Carduelis flammea, Loxia curvirostra and Pinicola enucleator.

CAROTENOIDS IN BIRD PLUMAGE : THE PATTERN IN A SERIES OF RED-PIGMENTED CARDUELINAE

We studied the carotenoid pigments in the red plumage of a series of palearctic Carduelinae (Carduelis cannabina, Carduelis flammea, Carduelis hornemanni, Carpodacus roseus, Carpodacus rubricilloides, Carpodacus trifasciatus, Carpodacus vinaceus and Uragus sibiricus). The pigments were extracted under mild conditions and the extract analysed by HPLC coupled with mass and UV-vis spectroscopy. 4-Oxo-carotenoids are responsible for the red colour in these species. 3-Hydroxy-echinenone is, in every case, the dominant carotenoid in the pigment followed by astaxanthin and adonirubin in variable amounts. 4-Oxo-rubixanthin and 4-oxo-gazaniaxanthin are also present in substantial amounts in some individuals of C. hornemanni and C. roseus. In C. roseus and in C. vinaceus, α-doradexanthin was also identified as an important component of the red colour.

Carotenoids in bird plumage: the complement of yellow and red pigments in true woodpeckers (Picinae)

Woodpeckers typically have colorful, multipatterned plumages. To understand the biochemical basis of the species-specificity of coloration in woodpecker, the complement of carotenoids in the red and yellow feathers of 13 species of true woodpeckers (Picinae) was determined. The pigments were extracted under mild conditions. The extracts were analyzed by HPLC coupled with mass and UV-vis spectroscopy. The 4-oxo-carotenoids (particularly astaxanthin and α-doradexanthin) were responsible for the red colors in these species. Picofulvins were the dominant carotenoids in the yellow feathers of some species. Unmodified lutein, zeaxanthin and β-cryptoxanthin were responsible for the yellow and green colors in other species. Tentative molecular structures for the three main picofulvins are proposed based on the results of spectroscopy (UV-vis, MS) and chemical tests.

Quinazolines by electrocyclic ring closure of 1,3-diaza-1,3-dienes

N-imidoyliminotripheny]phosphorane reacts with aliphatic and aromatic aldehydes to give via an 1,3-diaza-1,3-diene intermediate 3,4-dihydro quinazolines and quinazolines. The ratio between the reaction products depends from the aldehyde employed.