The muscle regeneration marker FOXP3 is associated with muscle injury in Duchenne muscular dystrophy.

BACKGROUND: In Duchenne muscular dystrophy (DMD), the immune system cells (ISC) synthesize molecules to regulate inflammation, a process needed to regenerate muscle. The relationship between those molecules and the muscle injury is unknown. Monocytes belonging to ISC are regulated by omega-3 fatty acids (ω-3 LCPUFAs) in DMD, but whether those fatty acids influence other ISC like T-cells is unknown. OBJECTIVE: We analyzed the expression of the muscle regeneration markers (FOXP3 and AREG) in circulating leukocytes of DMD patients with different lower limb muscle functions and whether ω-3 LCPUFAs regulate the expression of those markers, and the populations of circulating T-cells, their intracellular cytokines, and disease progression (CD69 and CD49d) markers. METHODS: This placebo-controlled, double-blind, randomized study was conducted in DMD boys supplemented with ω-3 LCPUFAs (n = 18) or placebo (sunflower oil, n = 13) for six months. FOXP3 and AREG mRNA expression in leukocytes, immunophenotyping of T-cell populations, CD49d and CD69 markers, and intracellular cytokines in blood samples were analyzed at baseline and months 1, 2, 3, and 6 of supplementation. RESULTS: Patients with assisted ambulation expressed higher (P = 0.015) FOXP3 mRNA levels than ambulatory patients. The FOXP3 mRNA expression correlated (Rho = -0.526, P = 0.03) with the Vignos scale score at month six of supplementation with ω-3 LCPUFAs. CD49d + CD8 + T-cells population was lower (P = 0.037) in the ω -3 LCPUFAs group than placebo at month six of supplementation. CONCLUSION: FOXP3 is highly expressed in circulating leukocytes of DMD patients with the worst muscle function. Omega-3 LCPUFAs might modulate the synthesis of the adhesion marker CD49d + CD8 + T-cells, but their plausible impact on FOXP3 needs more research.

Circulating Nrf2, Glutathione, and Malondialdehyde Correlate with Disease Severity in Duchenne Muscular Dystrophy.

Oxidative stress (OS) plays an essential role in the pathophysiology of Duchenne muscular dystrophy (DMD). However, the actors that regulate OS need to be better studied. We aimed to evaluate whether NFE2-like bZIP transcription factor 2 (Nrf2), glutathione, malondialdehyde (MDA), and protein carbonyl concentrations change according to the disease severity in DMD patients. Moreover, we assessed whether OS correlated with muscle injury, clinical characteristics, physical activity, and antioxidant food consumption (AFC). A total of 28 DMD patients participated in this study. OS markers, metabolic indicators, and enzymatic markers of muscle injury were measured in circulation. Muscle injury was measured with clinical scales, and physical activity and AFC were evaluated with questionnaires. Nrf2 concentration was lower (p ≤ 0.01), and malondialdehyde concentration was higher (p < 0.05) in non-ambulatory patients than in ambulatory patients. Nrf2 correlated with age (rho = -0.387), Vignos scale (rho = -0.328), GMFCS scale (rho = -0.399), and Brooke scale scores (rho = -0.371) (p < 0.05). MDA correlated with Vignos (rho = 0.317) and Brooke scale scores (rho = 0.414) (p ≤ 0.05). In conclusion, DMD patients with the worst muscle function had more significant oxidative damage and lower antioxidant function than DMD patients with better muscle function.

Offspring plumage coloration as a condition-dependent signal in the blue tit.

In many species, offspring display conspicuous coloration already early in life, even though they might be very vulnerable to predation at this stage. However, most attention has been drawn to the conspicuous plumage displayed by adult individuals in a sexual context, while other signaling functions have been explored much less. Here, we investigated whether the yellow breast plumage of blue tit (Cyanistes caeruleus) nestlings shows patterns of condition dependence and hence signals individual quality, as has been described for adult birds. During three consecutive breeding seasons, we, therefore, explored the association between nestling body mass and three color components of the yellow breast plumage (i.e., UV chroma, carotenoid chroma, and total brightness), considering both within and among nest effects. Variation in carotenoid chroma was not related to body mass. However, UV chroma and total brightness varied with body mass on an among-nest level, suggesting that they might signal aspects of genetic quality or parental rearing capacity. Interestingly, we also found a within-nest effect of body mass on total brightness, suggesting that this is a good candidate for a condition-dependent signal within the family. Thus, other family members could rely on brightness to adjust their behavioral strategies, such as feeding behavior in parents. Our study thus reveals that certain color components of the yellow breast plumage might signal different aspects of offspring quality, and they might have a correlated signaling value across life-history stages.

When parents play favorites: brood demand shapes parental preference for offspring UV color.

Parents might initially produce more offspring than they might be able to raise. However, when offspring demand exceeds their parents´ rearing capacity, parents might shift care towards the offspring which yield greater fitness returns to achieve their optimal brood size via brood reduction. Such favoritism could rely on offspring signaling traits if these inform parents about offspring quality and hence about the pay-offs of their investment. Here we investigated whether favoritism of blue tit (Cyanistes caeruleus) parents for an offspring signal (i.e., ultraviolet (UV) plumage coloration) varies with brood demand. To test this, we experimentally blocked the UV reflectance of yellow breast feathers in half of the nestlings of each brood, and then we sequentially performed two opposing brood size manipulations to vary nestling demand below or above parental rearing capacity. In reduced broods, nestlings begged overall less intensely and gained more body mass, supporting that parental rearing capacities sufficed to satisfy brood demand. Moreover, in reduced broods, UV-blocked nestlings (i.e., low-quality offspring) were fed and prey-tested more often. Yet, they begged more than control nestlings, suggesting that they were perhaps treated differently by other family members or which they may exploit parental preferences beyond actual need (at least in reduced nests). Parents flexibly shifted their feeding rate and favoritism in response to short-term changes in family size, as there was no parental preference for enlarged broods. Such flexible parental feeding rules may allow parents to gain the upper hand in parent-offspring conflict. However, we did not find evidence that parental favoritism facilitated brood reduction, at least in conditions where demand was temporally enhanced.

Relocation to avoid costs: A hypothesis on red carotenoid-based signals based on recent CYP2J19 gene expression data.

In many vertebrates, the enzymatic oxidation of dietary yellow carotenoids generates red keto-carotenoids giving color to ornaments. The oxidase CYP2J19 is here a key effector. Its purported intracellular location suggests a shared biochemical pathway between trait expression and cell functioning. This might guarantee the reliability of red colorations as individual quality signals independent of production costs. We hypothesize that the ornament type (feathers vs. bare parts) and production costs (probably CYP2J19 activity compromising vital functions) could have promoted tissue-specific gene relocation. We review current avian tissue-specific CYP2J19 expression data. Among the ten red-billed species showing CYP2J19 bill expression, only one showed strong hepatic expression. Moreover, a phylogenetically-controlled analysis of 25 red-colored species shows that those producing red bare parts are less likely to have strong hepatic CYP2J19 expression than species with only red plumages. Thus, both production costs and shared pathways might have contributed to the evolution of red signals.

Sexual selection, feather wear, and time constraints on the pre-basic molt explain the acquisition of the pre-alternate molt in European passerines.

Avian feathers need to be replaced periodically to fulfill their functions, with natural, social, and sexual selection presumably driving the evolution of molting strategies. In temperate birds, a common pattern is to molt feathers immediately after the breeding season, the pre-basic molt. However, some species undergo another molt in winter-spring, the pre-alternate molt. Using a sample of 188 European passerine species, Bayesian phylogenetic mixed models, and correlated evolution analyses, we tested whether the occurrence of the pre-alternate molt was positively associated with proxies for sexual selection (sexual selection hypothesis) and nonsexual social selection (social selection hypothesis), and with factors related to feather wear (feather wear hypothesis) and time constraints on the pre-basic molt (time constraints hypothesis). We found that the pre-alternate molt was more frequent in migratory and less gregarious species inhabiting open/xeric habitats and feeding on the wing, and marginally more frequent in species with strong sexual selection and those showing a winter territorial behavior. Moreover, an increase in migratory behavior and sexual selection intensity preceded the acquisition of the pre-alternate molt. These results provide support for the feather wear hypothesis, partial support for the sexual selection and time constraints hypotheses, and no support for the social selection hypothesis.

Influence of Maternal Body Fat on Levels of Insulin, Insulin-Like Growth Factor-1, and Obestatin.

BACKGROUND: Insulin, insulin-like Growth Factor-1 (IGF-1), and obestatin in human milk originate from the circulation. There is also limited knowledge about the influence of body fat on the levels of these hormones in human milk. RESEARCH AIM: To determine (1) the influence of body fat on levels of insulin, IGF-1, and obestatin in human milk and serum/plasma during the postpartum period; (2) the changes in the levels of these hormones in human milk and serum/plasma postpartum; and (3) the presence of IGF-1 mRNA in human milk. METHODS: In this prospective, longitudinal, observational cohort study, levels of insulin, IGF-1, and obestatin were measured up to 30 days postpartum in milk and serum/plasma of 58 participants with adequate (≤ 32%) or excess (> 32%) total body fat determined by electrical bioimpedance. Student's t test and repeated-measures analysis of variance were used to evaluate the differences between groups. Pearson's test was used to analyze the associations. RESULTS: The milk from participants with excess body fat had higher insulin and IGF-1 levels and lower obestatin levels than that of participants with adequate body fat at 3-7, 14-15, and 30 days postpartum (adjusted p < .001). The levels of insulin, IGF-1, and obestatin were significantly higher in human milk than in serum/plasma (p < .05) and correlated with maternal body fat (p < .001). CONCLUSIONS: Maternal body fat was associated with elevated insulin and IGF-1 levels and decreased obestatin levels in human milk up to 30 days postpartum.

The early maternal environment shapes the parental response to offspring UV ornamentation.

Parents allocate resources to offspring to increase their survival and to maximize their own fitness, while this investment implies costs to their condition and future reproduction. Parents are hence expected to optimally allocate their resources. They should invest equally in all their offspring under good conditions, but when parental capacity is limited, parents should invest in the offspring with the highest probability of survival. Such parental favouritism is facilitated by the fact that offspring have evolved condition-dependent traits to signal their quality to parents. In this study we explore whether the parental response to an offspring quality signal depends on the intrinsic capacity of the parents, here the female. We first manipulated the intrinsic capacity of blue tit (Cyanistes caeruleus) females through lutein-supplementation during egg laying, and we subsequently blocked the UV/yellow reflectance of breast feathers on half of the nestlings in each brood. We did not find evidence that the female intrinsic capacity shaped parental feeding or sibling competition according to offspring UV/yellow colouration. However, nestling UV/yellow colour affected costly behavioural interactions in the form of prey-testings (when a parent places a prey item into a nestling's gape but removes it again). In lutein-supplemented nests, fathers but not mothers favoured UV-blocked chicks by testing them less often, supporting previous results. Accordingly, in lutein-supplemented nests, UV-blocked nestlings gained more mass than their siblings, while in control nests we found the opposite effect and UV-blocked nestlings gained less. Our results emphasize that the prenatal environment shaped the role of offspring UV/yellow colour during certain family interactions and are indicative for sex-specific parental care strategies.

Circulating markers of oxidative stress are associated with a muscle injury in patients with muscular dystrophy Duchenne.

BACKGROUND: A small number of studies have confirmed the presence of oxidative damage in patients with Duchenne muscular dystrophy (DMD). Nevertheless, it is unknown if there a relationship of circulating markers of oxidative stress with a muscle injury. OBJECTIVE: We evaluated if oxidative damage and anti-oxidant markers are associated with muscle damage in DMD. METHODS: This cross-sectional study included 24 patients with DMD classified in ambulatory and non-ambulatory. Markers of muscle damage (creatine kinase [CK]), oxidative damage (malondialdehyde [MDA], and 8-isoprostane), anti-oxidant function (Thiol and mRNA of NRF2 and NF-κB) and nitric oxide (NO) were quantified in circulation. RESULTS: Total NO, MDA, and 8-isoprostane concentrations were significantly (p < 0.05) higher, and thiol concentration was lower in non-ambulatory than ambulatory patients. A significant correlation (p < 0.05) between muscle injury (evaluated by Vignos scale) with CK (r = -0.382), NO (r = 0.444), MDA (r = 0.503), 8-isoprostanes (r = 0.435) and thiol (r = -0.430) was observed. CONCLUSION: These findings suggest that non-ambulatory have high oxidative damage and low anti-oxidant function than ambulatory patients with DMD. Total nitric oxide and oxidative damage plasma markers increase, but the anti-oxidant marker thiol decreases with a muscle injury in boys with DMD. The findings of this study suggest that these markers could be considered as goods indicators of oxidative damage in longitudinal studies to evaluate the muscle injury during DMD progression. Additionally, these findings add new information about the pathophysiology of DMD.

Eggshell Biliverdin as an Antioxidant Maternal Effect: Biliverdin as an Antioxidant Resource in Oviparous Animals.

In this essay, the hypothesis that biliverdin pigment plays an antioxidant role in the avian eggshell is proposed. Due to its ability to scavenge free radical species and to reduce mutation, biliverdin potentially counteracts the oxidative action of pathogens that penetrate the eggshell and/or protects the shell membrane from oxidation, thus promoting the proven antioxidant and antimicrobial capacities of the shell membrane itself. Additionally, biliverdin may be able to inhibit viral replication in the eggshell due to its ascribed antiviral properties. Moreover, previous results in other taxa leave open the question of whether biliverdin can be absorbed by the embryo from the eggshell and play a role in embryogenesis. These mechanisms of antioxidant action of eggshell biliverdin remain totally unexplored in birds and in other oviparous animals. The main assumptions and predictions of the antioxidant hypothesis are developed, and directions for future research are proposed.

Dietary carotenoid supplementation facilitates egg laying in a wild passerine.

During egg laying, females face a trade-off between self-maintenance and investment into current reproduction, since providing eggs with resources is energetically demanding, in particular if females lay one egg per day. However, the costs of egg laying not only relate to energetic requirements, but also depend on the availability of specific resources that are vital for egg production and embryonic development. One of these compounds are carotenoids, pigments with immuno-stimulatory properties, which are crucial during embryonic development. In this study, we explore how carotenoid availability alleviates this trade-off and facilitates egg laying in a small bird species, the blue tit (Cyanistes caeruleus). Blue tits have among the largest clutch size of all European passerines and they usually lay one egg per day, although laying interruptions are frequent. We performed a lutein supplementation experiment and measured potential consequences for egg laying capacity and egg quality. We found that lutein-supplemented females had less laying interruptions and thus completed their clutch faster than control females. No effects of treatment were found on the onset of egg laying or clutch size. Experimentally enhanced carotenoid availability did not elevate yolk carotenoid levels or egg mass, but negatively affected eggshell thickness. Our results provide hence evidence on the limiting role of carotenoids during egg laying. However, the benefits of laying faster following lutein supplementation were counterbalanced by a lower accumulation of calcium in the eggshell. Thus, even though single components may constrain egg laying, it is the combined availability of a range of different resources which ultimately determines egg quality and thus embryonic development.

Nance-Horan syndrome in females due to a balanced X;1 translocation that disrupts the NHS gene: Familial case report and review of the literature.

The Nance-Horan syndrome is an X-linked disorder characterized by congenital cataract, facial features, microcornea, microphthalmia, and dental anomalies; most of the cases are due to NHS gene mutations on Xp22.13. Heterozygous carrier females generally present less severe features, and up to 30% of the affected males have intellectual disability. We describe two patients, mother and daughter, manifesting Nance-Horan syndrome. The cytogenetic and molecular analyses demonstrated a 46,X,t(X;1)(p22.13;q22) karyotype in each of them. No copy-number genomic imbalances were detected by high-density microarray analysis. The mother had a preferential inactivation of the normal X chromosome; expression analysis did not detect any mRNA isoform of NHS. This is the first report of Nance-Horan syndrome due to a skewed X chromosome inactivation resulting from a balanced translocation t(X;1) that disrupts the NHS gene expression, with important implications for clinical presentation and genetic counseling.

Trisomy 1q41-qter and monosomy 3p26.3-pter in a family with a translocation (1;3): further delineation of the syndromes.

BACKGROUND: Trisomy 1q and monosomy 3p deriving from a t(1;3) is an infrequent event. The clinical characteristics of trisomy 1q41-qter have been described but there is not a delineation of the syndrome. The 3p25.3-pter monosomy syndrome (MIM 613792) characteristics include low birth weight, microcephaly, psychomotor and growth retardation and abnormal facies. CASE PRESENTATION: A 2 years 8 months Mexican mestizo male patient was evaluated due to a trisomy 1q and monosomy 3p derived from a familial t(1;3)(q41;q26.3). Four female carriers of the balanced translocation and one relative that may have been similarly affected as the proband were identified. The implicated chromosomal regions were defined by microarray analysis, the patient had a trisomy 1q41-qter of 30.3 Mb in extension comprising about 240 protein coding genes and a monosomy 3p26.3-pter of 1.7 Mb including only the genes CNTN6 (MIM 607220) and CHL1 (MIM 607416), which have been implicated in dendrite development. Their contribution to the phenotype, regarding the definition of trisomy 1q41-qter and monosomy 3p26.3-pter syndromes are discussed. CONCLUSION: We propose that a trisomy 1q41-qter syndrome should be considered in particular when the following characteristics are present: postnatal growth delay, macrocephaly, wide fontanelle, triangular facies, frontal bossing, thick eye brows, down slanting palpebral fissures, hypertelorism, flat nasal bridge, hypoplasic nostrils, long filtrum, high palate, microretrognathia, ear abnormalities, neural abnormalities (in particular ventricular dilatation), psychomotor developmental delay and mental retardation. Our patient showed most of these clinical characteristics with exception of macrocephaly, possibly due to a compensatory effect by haploinsufficiency of the two genes lost from 3p. The identification of carriers has important implications for genetic counseling as the risk of a new born with either a der(3) or der(1) resulting from an adjacent-1 segregation is of 25% for each of them, as the products of adjacent-2 or 3:1 segregations are not expected to be viable.

Large-scale geographical variation in eggshell metal and calcium content in a passerine bird (Ficedula hypoleuca).

Birds have been used as bioindicators of pollution, such as toxic metals. Levels of pollutants in eggs are especially interesting, as developing birds are more sensitive to detrimental effects of pollutants than adults. Only very few studies have monitored intraspecific, large-scale variation in metal pollution across a species' breeding range. We studied large-scale geographic variation in metal levels in the eggs of a small passerine, the pied flycatcher (Ficedula hypoleuca), sampled from 15 populations across Europe. We measured 10 eggshell elements (As, Cd, Cr, Cu, Ni, Pb, Zn, Se, Sr, and Ca) and several shell characteristics (mass, thickness, porosity, and color). We found significant variation among populations in eggshell metal levels for all metals except copper. Eggshell lead, zinc, and chromium levels decreased from central Europe to the north, in line with the gradient in pollution levels over Europe, thus suggesting that eggshell can be used as an indicator of pollution levels. Eggshell lead levels were also correlated with soil lead levels and pH. Most of the metals were not correlated with eggshell characteristics, with the exception of shell mass, or with breeding success, which may suggest that birds can cope well with the current background exposure levels across Europe.

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

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 ß-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 ß-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 ß-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.

Megacystis-microcolon-intestinal hypoperistalsis syndrome (MMIHS): report of a case with prolonged survival and literature review.

Megacystis-microcolon-intestinal hypoperistalsis syndrome (MMIHS) was first described in 1976. A rare congenital autosomal recessive alteration that predominantly affects females (4:1 ratio), it is characterized by the presence of distended bladder (without distal urinary tract obstruction), microcolon, and decreased or absent intestinal peristalsis. Inconsistent and non-specific histological changes affecting the bladder and intestinal smooth muscle, and intrinsic innervations, have been reported most frequently. MMIHS usually has a fatal prognosis in the first year of life; nevertheless there are some case reports of longer survival. Here is presented the case report of a boy with a diagnosis of MMIHS who has achieved prolonged survival, followed by a review of the literature.

Nest ectoparasites increase physiological stress in breeding birds: an experiment.

Parasites are undoubtedly a biotic factor that produces stress. Heat shock proteins (HSPs) are important molecules buffering cellular damage under adverse conditions. During the breeding season, blue tit Cyanistes caeruleus (L.) adults are affected by blood parasites, nest-dwelling parasites and biting flies, potentially affecting their HSP-mediated responses. Here, we treated females with primaquine to reduce blood parasites and fumigated nests with permethrin to reduce nest-dwelling parasites to test whether these treatments affect HSP60 level during the breeding season. Medicated females, but not controls, had a significant reduction of the intensity of infection by Haemoproteus spp. blood parasites. However, final intensity of infection did not differ significantly between groups, and we did not find an effect of medication on change in HSP60 level. Fumigation reduced the abundance of nest-dwelling parasites (mites, fleas and blowfly larvae) and engorged biting midges in nests. Females breeding in non-fumigated nests increased HSP60 levels during the season more than those breeding in fumigated nests. Furthermore, the change in HSP60 level was positively correlated with the abundance of biting midges. These results show how infections by nest ectoparasites during the breeding period can increase the level of HSPs and suggest that biting midges impose physiological costs on breeding female blue tits. Although plausible, the alternative that biting midges prefer to feed on more stressed birds is poorly supported by previous studies.

Yolk testosterone reduces oxidative damages during postnatal development.

Conditions experienced during early life can influence the development of an organism and several physiological traits, even in adulthood. An important factor is the level of oxidative stress experienced during early life. In birds, extra-genomic egg substances, such as the testosterone hormone, may exert a widespread influence over the offspring phenotype. Interestingly, testosterone can also upregulate the bioavailability of certain antioxidants but simultaneously increases the susceptibility to oxidative stress in adulthood. However, little is known about the effects of maternally derived yolk testosterone on oxidative stress in developing birds. Here, we investigated the role of yolk testosterone on oxidative stress of yellow-legged gull chicks during their early development by experimentally increasing yolk testosterone levels. Levels of antioxidants, reactive oxygen species and lipid oxidative damage were determined in plasma during nestlings' growth. Our results revealed that, contrary to control chicks, birds hatched from testosterone-treated eggs did not show an increase in the levels of oxidative damage during postnatal development. Moreover, the same birds showed a transient increase in plasma antioxidant levels. Our results suggest that yolk testosterone may shape the oxidative stress-resistance phenotype of the chicks during early development owing to an increase in antioxidant defences and repair processes.

Parental conflict and blue egg coloration in a seabird.

When both parents provide offspring care, equal sharing of costly parental duties may enhance reproductive success. This is crucial for longlived species, where increased parental effort in current reproduction profoundly affects future reproduction. Indication of reproductive value or willingness to invest in reproduction may promote matching responses by mates, thus reducing the conflict over care. In birds with biparental care, blue-green eggshell color may function as a signal of reproductive value that affects parental effort, as predicted by the signaling hypothesis of blue-green eggshell coloration. However, this hypothesis has not been explored during incubation, when the potential stimulus of egg color is present, and has been little studied in longlived birds. We experimentally studied if egg color affected incubation patterns in the blue-footed booby, a longlived species with biparental care and blue eggs. We exchanged fresh eggs between nests of the same laying date and recorded parental incubation effort on the following 4 days. Although egg color did not affect male effort, original eggshell color was correlated with pair matching in incubation. Exchanged eggshell color did not affect incubation patterns. This suggests that biliverdin-based egg coloration reflects female quality features that are associated with pair incubation effort or that blue-footed boobies mate assortatively high-quality pairs incubating more colorful clutches. An intriguing possibility is that egg coloration facilitates an equal sharing of incubation, the signal being functional only during a short period close to laying. Results also suggest that indication of reproductive value reduces the conflict over care.

The blood parasite Haemoproteus reduces survival in a wild bird: a medication experiment.

While avian chronic haemoparasite infections induce reproductive costs, infection has not previously been shown to affect survival. Here, we experimentally reduced, through medication, the intensity of infection by Haemoproteus parasites in wild-breeding female blue tits Cyanistes caeruleus. However, this treatment did not reduce the intensity of infection in males or the intensity of infection by Leucocytozoon. Medicated females, but not males, showed increased local survival until the next breeding season compared with control birds. To our knowledge, this is the first empirical evidence showing long-term direct survival costs of chronic Haemoproteus infections in wild birds.