Cross-fostering Study Research Articles

Social, not genetic, programming of development and stress physiology of a colonial seabird.

Phenotypic differences often stem from genetic/maternal differences and/or early-life adaptations to local environmental conditions. In colonial animals, little is known on how variation in the social environment is embedded into individual phenotypes, nor what the consequences are on individual fitness. We conducted an experimental cross-fostering study on king penguins (Aptenodytes patagonicus), exchanging eggs among 134 pairs breeding in high-density (67 pairs) or low-density (67 pairs) areas of the same breeding colony. We investigated differences in parent and chick phenotypes and survival in relation to the density of their origin and foster environment. Adults breeding in colony areas of high density exhibited decreased resting behaviour and increased aggression and vigilance, increased hypometabolism during incubation fasts, and more moderate corticosterone responses shaped by exposure to chronic stressors (e.g. constant aggression by neighbours). Chick phenotypes were more influenced by the environment in which they were raised than their genetic/maternal origin. Chicks raised in high-density colonial environments showed enhanced weight gain and survival rates regardless of the density of their genetic parents' breeding areas. Our study experimentally shows advantages to breeding in colonial areas of higher breeder densities in king penguins, and highlights the importance of social settings in shaping phenotype expression in colonial seabirds.

Effects of the prenatal and postnatal nurturing environment on the phenotype and gut microbiota of mice with polycystic ovary syndrome induced by prenatal androgen exposure: a cross-fostering study.

The gut microbiome is implicated in the pathogenesis of polycystic ovary syndrome (PCOS), and prenatal androgen exposure is involved in the development of PCOS in later life. Our previous study of a mouse model of PCOS induced by prenatal dihydrotestosterone (DHT) exposure showed that the reproductive phenotype of PCOS appears from puberty, followed by the appearance of the metabolic phenotype after young adulthood, while changes in the gut microbiota was already apparent before puberty. To determine whether the prenatal or postnatal nurturing environment primarily contributes to these changes that characterize prenatally androgenized (PNA) offspring, we used a cross-fostering model to evaluate the effects of changes in the postnatal early-life environment of PNA offspring on the development of PCOS-like phenotypes and alterations in the gut microbiota in later life. Female PNA offspring fostered by normal dams (exposed to an abnormal prenatal environment only, fostered PNA) exhibited less marked PCOS-like phenotypes than PNA offspring, especially with respect to the metabolic phenotype. The gut microbiota of the fostered PNA offspring was similar to that of controls before adolescence, but differences between the fostered PNA and control groups became apparent after young adulthood. In conclusion, both prenatal androgen exposure and the postnatal early-life environment created by the DHT injection of mothers contribute to the development of PCOS-like phenotypes and the alterations in the gut microbiota that characterize PNA offspring. Thus, both the pre- and postnatal environments represent targets for the prevention of PCOS and the associated alteration in the gut microbiota in later life.

A short pre-conception bout of predation risk affects both children and grandchildren

Traumatic events that affect physiology and behavior in the current generation may also impact future generations. We demonstrate that an ecologically realistic degree of predation risk prior to conception causes lasting changes in the first filial (F1) and second filial (F2) generations. We exposed male and female mice to a live rat (predator stress) or control (non-predator) condition for 5 min. Ten days later, stressed males and females were bred together as were control males and females. Adult F1 offspring from preconception-stressed parents responded to a mild stressor with more anxiety-like behavior and hyperarousal than offspring from control parents. Exposing these F1 offspring to the mild stressor increased neuronal activity (cFOS) in the hippocampus and altered glucocorticoid system function peripherally (plasma corticosterone levels). Even without the mild stressor, F1 offspring from preconception-stressed parents still exhibited more anxiety-like behaviors than controls. Cross-fostering studies confirmed that preconception stress, not maternal social environment, determined offspring behavioral phenotype. The effects of preconception parental stress were also unexpectedly persistent and produced similar behavioral phenotypes in the F2 offspring. Our data illustrate that a surprisingly small amount of preconception predator stress alters the brain, physiology, and behavior of future generations. A better understanding of the ‘long shadow’ cast by fearful events is critical for understanding the adaptive costs and benefits of transgenerational plasticity. It also suggests the intriguing possibility that similar risk-induced changes are the rule rather than the exception in free-living organisms, and that such multigenerational impacts are as ubiquitous as they are cryptic.

The developmental consequences of early adverse care on infant macaques: A cross-fostering study

Early life adversity/stress (ELA/ELS), particularly adverse caregiving experiences such as child maltreatment (MALT), is a main risk factor for psychopathology, including psychiatric disorders such as anxiety, depression, ADHD, and substance abuse. Yet how these alterations unfold during development and the underlying mechanisms remain poorly understood, as it is difficult to prospectively and longitudinally study early developmental phases in humans, and nearly impossible to disentangle postnatal caregiving effects from heritable traits. This study examined the specific effects of “nurture” (maternal care) versus “nature” (heritable, biological maternal factors) on nonhuman primate infant socioemotional, stress neuroendocrine, and physical development. For this we used a translational and naturalistic macaque model of infant maltreatment by the mother with randomized assignment at birth to either mothers with a history of maltreating their infants (MALT group, n = 22) or to competent mothers (Control group, n = 20). Over the first 6 months of life (roughly equivalent to 2 years in humans), we examined the development of the mother-infant relationship, as well as infants’ social behavior and emotional reactivity. In parallel, we assessed hypothalamic-pituitary-adrenal (HPA) axis function longitudinally, using measures of hair cortisol accumulation, and basal morning plasma cortisol. We identified broad impairments in maternal care exhibited by MALT foster mothers, beyond maltreatment (physical abuse, rejection) events, suggesting that MALT foster mothers provide an overall lower quality of care to their infants compared to Controls. MALT infants exhibited alterations in their initiations and breaks of proximity towards their mothers, as well as heightened emotional reactivity in comparison to Controls. Most striking are the HPA axis findings, with MALT infants showing higher levels of plasma cortisol across the first 6 postnatal months as well as higher hair cortisol accumulation from birth through month 6 (a signature of chronic stress) than Controls. No caregiving effects were detected on physical growth, which ruled out confounding effects of maternal nutrition, metabolism, etc. Taken together, these results suggest that the developmental trajectory of MALT and Control infants is different, marked by heightened levels of emotional reactivity, increased HPA activity and alterations in mother-infant interactions in MALT animals. These findings appear to be due to specific effects of postnatal maternal care, and not to biological/ behavioral traits inherited from the mother, or due to prenatal programming caused by prenatal stress, as the cross-fostering design controlled for these potential factors. However, we also detected a couple of interesting biological effects suggesting heritable transmission of some phenotypes. The prolonged HPA axis activation during the first 6 postnatal months of life is expected to have long-term consequences for brain, physiological, and behavioral development in MALT offspring.

P21-07 How to elucidate the cause of postnatal effects: differentiation of intrauterine and lactation-based exposure – an exemplary cross-foster study

P21-07 How to elucidate the cause of postnatal effects: differentiation of intrauterine and lactation-based exposure – an exemplary cross-foster study

Maternal gut microbiome regulates immunity to RSV infection in offspring.

Development of the immune system can be influenced by diverse extrinsic and intrinsic factors that influence the risk of disease. Severe early life respiratory syncytial virus (RSV) infection is associated with persistent immune alterations. Previously, our group had shown that adult mice orally supplemented with Lactobacillus johnsonii exhibited decreased airway immunopathology following RSV infection. Here, we demonstrate that offspring of mice supplemented with L. johnsonii exhibit reduced airway mucus and Th2 cell-mediated response to RSV infection. Maternal supplementation resulted in a consistent gut microbiome in mothers and their offspring. Importantly, supplemented maternal plasma and breastmilk, and offspring plasma, exhibited decreased inflammatory metabolites. Cross-fostering studies showed that prenatal Lactobacillus exposure led to decreased Th2 cytokines and lung inflammation following RSV infection, while postnatal Lactobacillus exposure diminished goblet cell hypertrophy and mucus production in the lung in response to airway infection. These studies demonstrate that Lactobacillus modulation of the maternal microbiome and associated metabolic reprogramming enhance airway protection against RSV in neonates.

Maternal stress in pregnancy and child autism spectrum disorder: evaluating putative causal associations using a genetically informed design

AimsPrenatal adversity is hypothesized to increase risk of Autism Spectrum Disorder (ASD) via epigenetic changes. Maternal stress in late pregnancy may alter offspring neurodevelopmental outcomes by disrupting a unique period of rapid neurogenesis. Observational studies reporting an environmentally mediated programming pathway face challenges in drawing causal inferences including passive gene-environment correlation. This project aims to use a quasi-experimental genetically informed design to assess if reported correlations between maternal prenatal stress and offspring ASD traits were due to maternally inherited factors or consistent with a potentially causal prenatal exposure effect. No previous cross-fostering studies have assessed the effects of prenatal stress on childhood ASD.MethodThis study used an in-vitro fertilization cross-fostering sample with pregnant mothers related (n = 365) or unrelated (n = 111) to their offspring (mean age = 9.84 years). Prenatal stress was assessed using a subjective Likert scale during pregnancy. Questionnaires examined maternally rated offspring ASD traits using the Social and Communication Disorders Checklist. Birth weight and gestational age from medical records were used as comparison outcomes to validate the measure of stress as evidence suggests they are influenced by environmental factors. Correlations from multiple regression models were examined in relation to magnitude of effect size as well as significance. This is partly due to small sample size and that cross-fostering designs rely on comparing magnitudes of associations between related and unrelated groups. An interaction term was used to test the difference in the strength of association between related and unrelated mother-child groups.ResultSubjective assessment of prenatal maternal stress showed construct validity as it was associated with low birth weight (β = –0.297, p = 0.005) and reduced gestational age (β= –0.320, p = 0.001). Subjective late pregnancy stress was associated with increased offspring ASD traits in the whole sample (β = 0.089, p = 0.073) and in the related (β=0.045, p = 0.424) and unrelated mother-child (β=0.233, p = 0.029) subgroups. Non-significant interaction terms demonstrated that the mechanisms underlying the association between maternal stress and ASD and birth outcomes are likely to be similar and environmentally driven in the different conception groups.ConclusionFindings demonstrate the utility of genetically informed designs in disentangling inherited factors from environmental influences in the study of prenatal risk factors. Correlations between maternal prenatal stress and offspring ASD being present in both related and unrelated mother-child groups indicate an environmental link that is consistent with a potential causal effect. Associations detected are of imperative use for clinicians and policymakers, as they can guide the implementation of early psychosocial care for families at high liability.

Early life RSV infection in neonatal mice leads to exacerbated allergic asthma due to persistent Th2 pulmonary responses that are abrogated by maternal supplementation with a L. johnsonii probiotic

The development of immune responses in infants is central to establishing a balanced system that reacts appropriately to infectious stimuli but does not induce altered disease states with potential long term sequelae. Studies have linked severe RSV infection during early-life with an enhanced likelihood of developing childhood asthma. We have previously shown that supplementing adult mice with a probiotic species identified in allergen-protected animals, L. johnsonii, can attenuate pathologic responses in animals with viral and allergen induced disease. In these studies, we supplemented female mice with L. johnsonii by oral gavage prior to breeding and during pregnancy. The neonatal mice were infected with RSV at day 6 of age after 8 days of infection (day 14) some were evaluated. Subsequently, some of the neonatal miss were sensitized with allergen into the airway 4 or 12 weeks later and examined after a final challenge at 3 weeks post-sensitization. Our studies show that early-life RSV infection leads to long-term effects leaving mice prone to exacerbation upon secondary allergen exposure at 4 to 12 weeks post-infection. Offspring from the L. johnsonii supplemented mice were protected from an early life RSV infection and from the subsequent allergen-induced exacerbated responses. These early life protective responses reduced Th2 responses and mucus and were associated with an altered neonatal microbiome. Using cross-fostering studies we were able to demonstrate both in utero and post natal protective effects on the offspring that were dependent upon the supplementation of the mother with L. johnsonii. Assessment of the plasma and milk metabolic profiles identified an altered metabolite phenotype in the different cross-fostered neonates that may be useful in assessing allergen susceptible and/or protected early immune environments during early life. Thus, we have identified a maternal microbiome associated metabolomic effect associated with protective in offspring that is related to an altered immune phenotype in the lung during RSV infection and subsequent allergic asthma responses. These results identify that maternal environments on offspring have both in utero and post-natal effects and may help guide future clinical research toward evaluating the maternal impact on development of the infant's immune/allergic responses.

Novel sources of (co)variation in nestling begging behavior and hunger at different biological levels of analysis

Abstract Biological hypotheses predicting patterns of offspring begging typically concern the covariance with hunger and/or development at specific hierarchical levels. For example, hunger drives within-individual patterns of begging, but begging also drives food intake among individuals within broods, and begging and food intake can covary positively or negatively among genotypes or broods. Testing biological phenomena that occur at multiple levels, therefore, requires the partitioning of covariance between traits of interest to ensure that each level-specific relationship is appropriately assessed. We performed a partial cross-fostering study on a wild population of great tits (Parus major), then used multivariate mixed models to partition variation and covariation in nestling begging effort and two metrics of nestling hunger within versus among individual nestlings and broods. At the within-individual level, we found that nestlings begged more intensely when hungrier (positive correlation between begging and hunger). However, among individuals, nestlings that were fed more frequently also begged more intensely on average (negative correlation between begging and hunger). Variation in nestling mass did not give rise to the negative correlation between begging and hunger among nestlings, but we did find that lighter nestlings begged more intensely than their heavier biological siblings, suggesting that this effect may be driven by a genetic component linked to offspring size. Our study illustrates how patterns of covariance can differ across biological levels of analysis and addresses biological mechanisms that could produce these previously obscured patterns.

Within-Family Environment and Cross-Fostering Stress Affect Behavior and Physiology in Wild Cavies (Cavia aperea).

Stability of personality traits is well-documented for a wide variety of animals. However, previous results also suggest that behavioral phenotypes are plastic during early ontogeny and can be adaptively shaped to the social environment. In cavies (Cavia aperea), it has already been documented that the size at birth relative to siblings (size rank) greatly influences various behavioral and physiological traits that last at least until independence. The aim of the current study was (1) to investigate if behavioral and physiological differences between pups of the same litter persist until after independence and influence development long-lasting, (2) to determine the potential plasticity in response to changes in the early within-family environment by cross-fostering pups either to the same, a lower, or a higher size rank in a foster-family. We measured three behavioral traits (number of interactions with a novel object, distance moved in an open field, struggle docility) and two physiological traits (resting metabolic rate and basal cortisol levels). We predicted that cross-fostering into a litter where pups occupy the same size rank would not change the expression of traits. Cross-fostering to a different size rank should not influence the expression of traits if repeatability measures indicate low plasticity. Alternatively, if the traits are plastic, animals should adjust trait expression to fit with the size rank occupied in the foster litter. Initial differences in struggle docility, distance moved in an open field and in baseline cortisol concentration between pups of different size-ranks did not remain stable beyond independence. In addition, we found remarkable plasticity of the measured traits in response to cross-fostering to the same, a smaller or larger size-rank, suggesting that differences between pups are more the result of social constraints leading to adaptive shaping of individual phenotypes within a family. We also found a significant influence of the cross-fostering procedure itself. Cross-fostered individuals were less bold, grew slower and showed elevated resting metabolic rates. This finding suggests a cautious interpretation of previous cross-fostering studies and stresses the need for proper control groups to reliably separate the effect of cross-fostering per se from those induced by an experimental treatment.

Imprinting sets the stage for speciation.

Sexual imprinting-a phenomenon in which offspring learn parental traits and later use them as a model for their own mate preferences-can generate reproductive barriers between species1. When the target of imprinting is a mating trait that differs among young lineages, imprinted preferences may contribute to behavioural isolation and facilitate speciation1,2. However, in most models of speciation by sexual selection, divergent natural selection is also required; the latter acts to generate and maintain variation in the sexually selected trait or traits, and in the mating preferences that act upon them3. Here we demonstrate that imprinting, in addition to mediating female mate preferences, can shape biases in male-male aggression. These biases can act similarly to natural selection to maintain variation in traits and mate preferences, which facilitates reproductive isolation driven entirely by sexual selection. Using a cross-fostering study, we show that both male and female strawberry poison frogs (Oophaga pumilio) imprint on coloration, which is a mating trait that has diverged recently and rapidly in this species4. Cross-fostered females prefer to court mates of thesame colour as their foster mother, and cross-fostered males are more aggressive towards rivals that share the colour of their foster mother. We also use a simple population-genetics model to demonstrate that when both male aggression biases and female mate preferences are formed through parental imprinting, sexual selection alone can (1) stabilize a sympatric polymorphism and (2) strengthen the trait-preference association that leads to behavioural reproductive isolation. Our study provides evidence of imprinting in an amphibian and suggests that this rarely considered combination of rival and sexual imprinting can reduce gene flow between individuals that bear divergent mating traits, which sets the stage for speciation by sexual selection.

The influence of maternal nesting behaviour on offspring survival: evidence from correlational and cross-fostering studies

The maternal effect of nesting behaviour is important in oviparous species because choice of microhabitat (e.g. shade cover, temperature) can determine the environment in which embryos develop. In turn, this maternal choice can influence developmental trajectories and offspring phenotypes and survival. We studied maternal nesting behaviour in a western painted turtle, Chrysemys picta, population in northern Idaho, U.S.A. During 2013–2016, we examined maternal choice of nest microhabitat and used correlational data to quantify consequences on egg survival. In 2017, we conducted a cross-fostering experiment to decouple the effects of intrinsic maternal effects from extrinsic environmental factors on egg survival, while simultaneously manipulating the level of nest shade cover and distance from water using artificial nests. Females chose nest sites that were more open and warmer than randomly available habitat. Additionally, of three nesting areas, the coolest area with the most shade cover was used least by nesting females. Egg survival was associated with nest temperature in some, but not all, years. In the cross-fostering experiment, egg survival did not differ between natal and foster eggs, but was greater in maternal nests than in artificial nests. Additionally, egg survival increased with canopy openness and minimum nest temperature, especially for eggs in artificial nests. Overall, these results suggest that females select nesting conditions (warm and open nest sites) that positively affect hatching success.

Developmental Thyroid Hormone Insufficiency Induces a Cortical Brain Malformation and Learning Impairments: A Cross-Fostering Study.

Thyroid hormones (THs) are essential for brain development, but few rodent models exist that link TH inefficiency to apical neurodevelopmental endpoints. We have previously described a structural anomaly, a heterotopia, in the brains of rats treated in utero with propylthiouracil (PTU). However, how the timing of an exposure relates to this birth defect is unknown. This study seeks to understand how various temporal treatments of the mother relates to TH insufficiency and adverse neurodevelopment of the offspring. Pregnant rats were exposed to PTU (0 or 3 ppm) through the drinking water from gestational day 6 until postnatal day (PN) 14. On PN2 a subset of pups was cross-fostered to a dam of the opposite treatment, to create 4 conditions: pups exposed to PTU prenatally, postnatally, during both periods, or not at all (control). Both PTU and TH concentrations were characterized in the mother and offspring over time, to capture the dynamics of a developmental xenobiotic exposure. Brains of offspring were examined for heterotopia presence and severity, and adult littermates were assessed for memory impairments. Heterotopia were observed under conditions of prenatal exposure, and its severity increased in animals in the most prolonged exposure group. This malformation was also permanent, but not sex biased. In contrast, behavioral impairments were limited to males, and only in animals exposed to PTU during both the gestational and postnatal periods. This suggests a distinct TH-dependent etiology for both phenotypes, and illustrates how timing of hypothyroxinemia can induce abnormal brain structure and function.

Evidence suggests vocal production learning in a cross-fostered Risso's dolphin (Grampus griseus).

Vocal learning is a rare skill in mammals, and we have limited information about the contexts in which they use it. Previous studies suggested that cetaceans in general are skilled at imitating sounds, but only few species have been studied to date. To expand this investigation to another species and to investigate the possible influence of the social environment on vocal learning, we studied the whistle repertoire of a female Risso's dolphin (Grampus griseus) that was stranded at an early age and was subsequently raised in a group of bottlenose dolphins (Tursiops truncatus). We show that this cross-fostered animal produced vocal signals more akin to those of its Tursiops poolmates than those of Risso's dolphins in the wild. This is one of very few systematic cross-fostering studies in cetaceans and the first to suggest vocal production learning in the Risso's dolphin. Our findings also suggest that social experience is a major factor in the development of the vocal repertoire in this species.

Interaction does Count: A Cross-Fostering Study on Transgenerational Effects of Pre-reproductive Maternal Enrichment.

Pre-reproductive environmental enrichment of female rats influences sensorimotor development and spatial behavior of the offspring, possibly through the changed maternal nurturing. Nevertheless, maternal care could be not the solely responsible for changing offspring developmental trajectories. To disentangle the specific contribution to the transgenerational inheritance of pre- and post-natal factors, a cross-fostering study was performed. Female rats were reared in an enriched environment from weaning to sexual maturity, while control female rats were reared under standard conditions. Following mating with standard-reared males, all females were housed individually. Immediately after delivery, in- or cross-fostering manipulations were performed so that any foster dams received pups born to another dam of the same (in-fostering) or the opposite (cross-fostering) pre-reproductive rearing condition. In lactating dams maternal care and nesting activities were assessed, while in their male pups spatial abilities were assessed through Morris Water Maze (MWM) test at post-natal day 45. Moreover, the expression of Brain-Derived-Neurotrophic-Factor (BDNF) was evaluated in the hippocampus and frontal cortex of dams and pups at weaning. Pre-reproductive maternal environmental enrichment, followed by adoption procedures, loosened its potential in modifying maternal care and offspring developmental trajectories, as indicated by the lack of differences between in-fostered groups of dams and pups. In addition, enriched dams rearing standard pups showed the least complex maternal repertoire (the highest sniffing duration and the lowest nest quality), and their pups showed a reduced spatial learning in the MWM. Nevertheless, pre-reproductive maternal enrichment kept influencing neurotrophic pattern, with enriched dams expressing increased frontal BDNF levels (regardless of the kind of fostered pups), and their offspring expressing increased hippocampal BDNF levels. The present findings enlighten the crucial importance of the early mother-pups interactions in influencing maternal care and offspring phenotype, with the enriched dam-standard pups couple resulting in the most maladaptive encounter. Our study thus sustains that the bidirectional interactions between mother and pups are able to deeply shape offspring phenotype.

Structural abnormalities and learning impairments induced by low level thyroid hormone insufficiency: A cross-fostering study

Structural abnormalities and learning impairments induced by low level thyroid hormone insufficiency: A cross-fostering study

Early postpartum pup preference is altered by gestational cocaine treatment: Associations with infant cues and oxytocin expression in the MPOA

Cross-fostering studies suggest cocaine-induced deficits in maternal behavior could be associated with altered behavior of offspring following prenatal cocaine-exposure. Neonatal vocalizations are an important offspring cue facilitating early interactions between dam and rodent pup offspring and have been shown to be altered following prenatal cocaine-exposure. It is unclear how variations in acoustic parameters of USVs impact maternal behavior and the mechanism(s) underlying these processes. The present study examined differences in cocaine-exposed and control rodent dam maternal preference of cocaine-exposed or untreated pups in a dual choice apparatus. Relationship of preference-like behavior with pup USVs and dam oxytocin expression was explored. Gestational cocaine-exposure interfered with preference-like behavior of dams on postpartum day 1 with cocaine-exposure associated with decreased time spent on the cocaine-exposed pup side compared to the control pup side, and decreases in preference-like behavior associated in part with decreased number of USVs being emitted by cocaine-exposed pups. On postpartum day 5, decreased oxytocin expression in the medial preoptic area was associated with altered preference-like behavior in cocaine-exposed dams, including frequency and latency to touch/sniff pups. Results indicate cocaine's effects on the mother–infant relationship is likely synergistic, in that cocaine influences mother and offspring both independently and concertedly and that variations within pup vocalizations and the oxytocin system may be potential mechanism(s) underlying this synergistic relationship during the postpartum period.

A single immunization with inactivated H1N1 influenza vaccine formulated with delta inulin adjuvant (Advax™) overcomes pregnancy-associated immune suppression and enhances passive neonatal protection

Pregnant women and neonates represent high-risk groups for influenza infection, and in general have suppressed responses to standard influenza vaccines due to pregnancy-associated immune suppression and immune system immaturity, respectively. We therefore wished to test whether addition of Advax™, a polysaccharide adjuvant based on delta inulin, to an inactivated influenza vaccine (A/H1N1/PR8) administered during pregnancy would safely enhance vaccine immunogenicity and thereby provide improved protection of pregnant mothers and their newborns. Pregnant mice received a single intramuscular injection of β-propiolactone-inactivated H1N1 antigen alone or with Advax adjuvant. Pregnant dams receiving Advax-adjuvanted vaccine exhibited significantly increased serum and breast milk anti-influenza IgG titers. This translated into higher serum anti-influenza IgG titers in the pups of these dams. Complete protection was seen in pups of dams that received Advax-adjuvanted vaccine whereas no survival was seen in pups of control mothers or mothers immunized with unadjuvanted influenza vaccine. Cross-fostering studies confirmed that enhanced protection of pups of dams that received Advax-adjuvanted vaccine was mediated by enhanced transfer of maternal IgG to the pups via breast-feeding. The delta inulin adjuvant was not associated with any reproductive or developmental adverse effects. This study shows that Advax adjuvant was safe when administered with influenza vaccine during pregnancy and provided protection of pups via enhanced breast milk transfer of anti-influenza antibodies, not seen with administration of unadjuvanted vaccine.

On the coadaptation of offspring begging and parental supply—a within-individual approach across life stages

Parental care is often characterized by complex behavioral interactions between offspring soliciting for food and parents providing food. During this interplay both behaviors, offspring begging and parental provisioning, can exert a selective pressure on the expression of the other. It has, therefore, been predicted that traits involved in this interplay may coevolve and ultimately become (genetically) correlated. Such covariation has—at least at the phenotypic level—been found in a number of cross-fostering studies, including evidence from the canary (Serinus canaria), our model species. However, a common challenge for these studies has been to establish a genetic covariation given the difficulty to disentangle the relative contribution of genetic and maternal effects, as the latter may act already before cross-fostering. We addressed this problem by studying within-individual covariation between begging (expressed at the nestling stage) and provisioning (expressed at the adult stage). In addition, we estimated the degree of heritability of these behaviors using parent-offspring regressions, as inheritance forms a prerequisite for any genetic correlation. Both traits showed a low to moderate non-significant heritability, similar to those previously reported in other bird species. However, offspring begging and parental provisioning did not covary at the intra-individual level. Thus, individuals begging intensively as nestlings were not necessarily individuals that provided more food as adults or vice versa. These findings provide important insights for our understanding of coadaptation, suggesting that factors other than genes such as maternal effects may play a role in adjusting offspring begging to the levels of parental provisioning.

Iron deficient toxic milk leads to the mask phenotype in hephaestin knockout mice (907.4)

Iron is an essential element that is required for many cellular functions. Multiple symptoms of iron deficiency have been reported in humans, including anemia, hair loss, stunted growth, and reduced oxygen transport. Mammalian iron intake is mediated in two different ways, across the placenta during fetal growth, and through the intestine during postnatal growth and development. We previously identified hephaestin (Hp), a copper‐iron ferroxidase, which plays a key role in intestinal iron transport. Hephaestin oxidizes iron and works in conjunction with ferroportin to facilitate iron export from enterocytes and its efficient binding to plasma transferrin. Null mutations in the Hp gene cause an accumulation of intracellular iron, specifically in the intestine. During analysis of the Hp null mice, we discovered that neonates born to Hp knockout (Hp KO) dams developed truncal hair loss (the “mask” hair loss phenotype) that resolved after weaning. The same phenotype was also observed in pups born to mothers with intestine‐specific knockout of Hp (even WT (floxed) pups born to these mothers), suggesting that lack of maternal Hp in the intestine alone is responsible for the mask phenotype. In order to determine the stage (ante and/or post natal) at which lack of maternal Hp leads to pup hair loss, we performed cross‐fostering studies. Wild‐type pups fed by Hp KO dams presented with the “mask” phenotype, whereas, all pups fed by the WT dams had normal hair growth. Histology of the affected skin of pups fed by Hp KO dams showed disorientation and keratinization of the follicles, follicular infundibular plugging and some tortuosity to the hair canals. Our findings suggest the involvement of a “toxic milk” phenotype involving low iron levels in the milk causing this phenotype.Grant Funding Source: R01 GM083198‐01A1