Offspring Phenotype Research Articles

Maternal effects in the model system Daphnia: the ecological past meets the epigenetic future.

Maternal effects have been shown to play influential roles in many evolutionary and ecological processes. However, understanding how environmental stimuli induce within-generation responses that transverse across generations remains elusive, particularly when attempting to segregate confounding effects from offspring genotypes. This review synthesizes literature regarding resource- and predation-driven maternal effects in the model system Daphnia, detailing how the maternal generation responds to the environmental stimuli and the maternal effects seen in the offspring generation(s). Our goal is to demonstrate the value of Daphnia as a model system by showing how general principles of maternal effects emerge from studies on this system. By integrating the results across different types of biotic drivers of maternal effects, we identified broadly applicable shared characteristics: 1. Many, but not all, maternal effects involve offspring size, influencing resistance to starvation, infection, predation, and toxins. 2. Maternal effects manifest more strongly when the offspring's environment is poor. 3. Strong within-generation responses are typically associated with strong across-generation responses. 4. The timing of the maternal stress matters and can raise or lower the magnitude of the effect on the offspring's phenotype. 5. Embryonic exposure effects could be mistaken for maternal effects. We outline questions to prioritize for future research and discuss the possibilities for integration of ecologically relevant studies of maternal effects in natural populations with the molecular mechanisms that make them possible, specifically by addressing genetic variation and incorporating information on epigenetics. These small crustaceans can unravel how and why non-genetic information gets passed to future generations.

The effect of moisture during development on phenotypes of egg-laying reptiles: A systematic review and meta-analysis.

The embryonic environment is critical for the development of many ectothermic vertebrates, which makes them highly vulnerable to environmental change. Changes in temperature and moisture, in particular, are known to influence embryo survival and offspring phenotypes. While most papers concerning phenotypic development of terrestrial ectotherms focus on the role of temperature on eggs and embryos, the comparatively small number of studies on the effects of substrate moisture are well suited for quantitative analysis aimed at guiding future research. To accomplish this goal, we compiled data from 37 studies on 28 different reptile species and used a meta-analytic approach to quantify the effect of substrate moisture on several offspring outcomes: hatching success (survival), incubation duration, hatchling mass and length, and sex ratio. We found that substrate moisture had a small effect across most traits but significantly affected body size (i.e., length and mass), with wetter conditions producing longer and heavier hatchlings. Temperature also moderated the effect of moisture on hatching success; with higher temperatures resulting in lower success. Additionally, the effect of moisture on hatching success and hatchling mass was enhanced by larger differences in moisture concentration between treatments, yet the effect was small. Lastly, substrate moisture affected sex ratio in turtles, but not in other squamates. Overall, these analyses provide a foundation for further research investigating the effects of moisture on oviparous reptile development. Increasing the diversity of environmental variables for which we understand their impact on animal phenotype will be beneficial in an era with wide-ranging global change.

Paternal response to novel predator exposure correlates with transgenerational response in offspring of threespined stickleback.

Parental experiences can alter offspring phenotypes via transgenerational plasticity (TGP), which may prime offspring to adaptively respond to novel stressors, including novel predators. However, we know little about the types of sensory cues (e.g. visual, olfactory) that parents use to recognize novel predators and the consequences for offspring. Individuals may respond to novel cues if they mimic historical cues or they may need multiple sensory cues to recognize and respond to novel stimuli. We exposed threespined stickleback (Gasterosteus aculeatus) males to a full factorial of visual and olfactory cues of a novel trout predator prior to fertilization and tested offspring for antipredator behaviour and survival against a live predator. Fathers exposed to visual cues oriented more to and spent time closer to the novel predator post-exposure on the first day. Paternal response to visual cues was echoed in their offspring: offspring of fathers exposed to visual cues were caught faster by a live predator, suggesting that multiple cues are not needed to induce a transgenerational effect. While visual cues elicited responses both within- and transgenerationally, they do not seem to result in adaptive priming in offspring, suggesting the possibility of maladaptive TGP in response to novel cues of predation risk.

Paternal impact on the developmental programming of sexual dimorphism.

Sexual dimorphism involves distinct anatomical, physiological, behavioral, and developmental differences between males and females of the same species, influenced by factors prior to conception and during early development. These sex-specific traits contribute to varied phenotypes and individual disease risks within and across generations and understanding them is essential in mammalian studies. Hormones, sex chromosomes, and imprinted genes drive this dimorphism, with over half of quantitative traits in wildtype mice showing sex-based variation. This review focuses on the impact of paternal non-genetic factors on sexual dimorphism. We synthesize current research on how paternal health before conception affects offspring phenotypes in a sex-specific manner, examining mechanisms such as DNA methylation, paternally imprinted genes, sperm RNA, and seminal plasma. Additionally, we explore how paternal influences indirectly shape offspring through maternal behavior, uterine environment, and placental changes, affecting males and females differently. We propose mechanisms modulating sexual dimorphism during development, underscoring the need for sex-specific documentation in animal studies.

Environmental change mediates plasticity in offspring traits through maternal effects in a coral reef fish

Wild populations are continuously challenged by natural environmental variation as well as threatened by anthropogenically-induced habitat loss and fragmentation. Non-genetic parental effects may be a key mechanism across taxa to cope with such environmental challenges and threats. However, the way in which environmental change modulates parental and offspring traits remains poorly studied in marine fish, especially in the wild. We empirically test whether environmental change directly affects monthly reproductive output and offspring phenotypes, including egg size, larval size and larval swimming abilities, in a wild population of anemonefish. In addition, we test whether environmentally induced parental physiology (hormones) modify parental traits, as well as offspring traits intergenerationally. First, we demonstrate plasticity in parental reproductive output when habitat size (anemone surface area) was experimentally manipulated. Second, we show intergenerational plasticity in wild anemonefish offspring traits. When habitat size increased, offspring traits were unchanged, but reproductive output was increased. Maternal reproductive hormones, such as 17ß-estradiol, showed a trend to increase when habitat size increased and 17ß-estradiol correlates positively with reproductive output. When habitat size decreased, reproductive output decreased, and smaller eggs and larvae were produced, however, these larvae swam faster. Our results provide evidence for marine fish plasticity in both reproductive output and offspring traits. In addition, the maternal reproductive hormone 17ß-estradiol plays a role in determining reproductive output and larval phenotypic traits. Through our study conducted in the wild, we show how changes in habitat size affect fitness of both parents and offspring in different ways. We highlight how parental and offspring plasticity, via intergenerational maternal effects, may ensure population persistence under environmental change.

Prenatal Acoustic Signals Influence Nestling Heat Shock Protein Response to Heat and Heterophil-to-Lymphocyte Ratio in a Desert Bird.

Heat shock proteins (HSPs) are essential to cellular protection against heat stress. However, the causes of inter-individual variation in HSP regulation remain unclear. This study aimed to test the impact of early-life conditions on the HSP response to heat in zebra finches. In this arid-adapted bird, incubating parents emit "heat-calls" at high temperatures, which adaptively alter offspring's phenotypes. Embryos were exposed to heat-calls or control-calls, and at 13 days post-hatch nestlings were separated into two different experiments to test responses to either chronic nest temperature ("in-nest" experiment) or an acute "heat-challenge". Blood samples were collected to measure levels of heat shock cognate 70, heat shock protein 90α, corticosterone and the heterophil-to-lymphocyte (H/L) ratio. In the in-nest experiment, both HSPs were upregulated in response to increasing nest temperatures only in control-calls nestlings (HSC70: p = 0.010, HSP90α: p = 0.050), which also had a marginally higher H/L ratio overall than heat-call birds (p = 0.066). These results point to a higher heat sensitivity in control-call nestlings. Furthermore, comparing across experiments, only the H/L ratio differed, being higher in heat-challenged than in in-nest nestlings (p = 0.009). Overall, this study shows for the first time that a prenatal acoustic signal of heat affects the nestling HSP response to postnatal temperature.

How does parental diet affect offspring locomotor capacity in the bean bug, Riptortus pedestris?

AbstractParental environments have profound consequences for offspring fitness through transgenerational transmission of resources and epigenetic factors. Locomotor activity is a functional trait of considerable ecological importance, as it determines the ability of animals to find food and mates and to disperse to more favourable environments. Although there have been studies demonstrating that animals can plastically increase their locomotor capacity in response to nutritionally stressful environments, it remains largely unexplored whether and how parental diet can adjust offspring locomotor capacity and its related traits. In this study, we tested the hypothesis that the parental intake of a nutritionally suboptimal diet would induce hyperactivity in the offspring and that this transgenerational effect could lead to improved offspring performance in an insect herbivore, the bean bug (Riptortus pedestris Fabricius) (Hemiptera: Alydidae). We compared the locomotor activity, metabolic phenotype and performance traits of two groups of R. pedestris nymphs born to parents raised on soybeans [Glycine max (L.) Merr, Fabaceae; standard diet] or peanuts (Arachis hypogaea L., Fabaceae; high‐fat diet). Despite being smaller at birth, the offspring of peanut‐fed parents moved faster and more frequently than those of soybean‐fed parents during their early development. The newly hatched offspring born to peanut‐fed parents had higher relative energy reserves in somatic tissues than those born to soybean‐fed parents, indicating that differential parental provisioning could underpin this parental effect on offspring locomotor activity. Possibly through increased foraging activity, the hyperactive offspring of peanut‐fed parents grew faster into heavier adults than the offspring of soybean‐fed parents, implying that parentally induced increase in offspring locomotor activity is adaptive. This study provides experimental evidence for diet‐mediated transgenerational plasticity of locomotor activity in invertebrates and sheds novel insights into the role of parental diet history in shaping offspring phenotype.

Fetal programming by the parental microbiome of offspring behavior, and DNA methylation and gene expression within the hippocampus.

The microorganisms colonizing the gastrointestinal tract of animals, collectively referred to as the gut microbiome, affect numerous host behaviors dependent on the central nervous system (CNS). Studies comparing germ-free mice to normally colonized mice have demonstrated influences of the microbiome on anxiety-related behaviors, voluntary activity, and gene expression in the CNS. Additionally, there is epidemiologic evidence supporting an intergenerational influence of the maternal microbiome on neurodevelopment of offspring and behavior later in life. There is limited experimental evidence however directly linking the maternal microbiome to long-term neurodevelopmental outcomes, or knowledge regarding mechanisms responsible for such effects. Here we show that that the maternal microbiome has a dominant influence on several offspring phenotypes including anxiety-related behavior, voluntary activity, and body weight. Adverse outcomes in offspring were associated with features of the maternal microbiome including bile salt hydrolase activity gene expression ( bsh ), abundance of certain bile acids, and hepatic expression of Slc10a1 . In cross-foster experiments, offspring resembled their birth dam phenotypically, despite faithful colonization in the postnatal period with the surrogate dam microbiome. Genome-wide methylation analysis of hippocampal DNA identified microbiome- associated differences in methylation of 196 loci in total, 176 of which show conserved profiles between mother and offspring. Further, single-cell transcriptional analysis revealed accompanying differences in expression of several differentially methylated genes within certain hippocampal cell clusters, and vascular expression of genes associated with bile acid transport. Inferred cell-to-cell communication in the hippocampus based on coordinated ligand-receptor expression revealed differences in expression of neuropeptides associated with satiety. Collectively, these data provide proof-of-principle that the maternal gut microbiome has a dominant influence on the neurodevelopment underlying certain offspring behaviors and activities, and selectively affects genome methylation and gene expression in the offspring CNS in conjunction with that neurodevelopment.

Seminal plasma uterine priming alters uterine transcriptomics and negatively impacts embryo growth and uterine artery resistance but not offspring liver transcriptomics in beef cattle.

Seminal plasma uterine priming is important for pregnancy and offspring phenotype in mice and swine; however, impacts on the uterus of the dam and her offspring in cattle are unknown. We sought to determine the effects of seminal plasma uterine priming at estrus on uterine transcriptomics, early gestation (days 35, 40, and 45) embryo morphometrics, mid- to late-gestation (days 140 to 220) uterine artery hemodynamics, birth morphometrics, and liver transcriptomics in offspring at 30 d of age. Multiparous Angus-based commercial beef cows were randomly assigned to receive treatment at estrus: 0.5mL pooled seminal plasma in the uterine body (n = 31, seminal plasma primed) or no treatment (n = 31, control). Seven days later a subset of cows (n = 4/treatment) underwent uterine biopsies, and the remaining cows underwent embryo transfer. Embryo crown-rump length and uterine artery hemodynamics were measured during gestation using ultrasonography. Morphometrics of the calf were collected within 24h of parturition. Liver biopsies were collected at 30 d of age. Data were analyzed by analysis of variance (ANOVA) in a completely randomized design for the effect of treatment. Myosin heavy chain I (JSP.1) was downregulated [Benjamin-Hochberg adj P (BH) ≤ 0.05] and ABO alpha 1-3-N-acetylgalactosaminyltransferase and alpha 1-3-galactosyltransferase (ABO) was upregulated (BH adj P ≤ 0.05) in the uterus of seminal plasma primed cows 7 d after treatment. Embryo crown-rump length was less (P < 0.05) in seminal plasma primed cows. Mid- to late-gestation (days 140 to 220) uterine artery resistance was increased (P < 0.05) in seminal plasma primed cows. Seminal plasma priming did not alter birth weights or curve-crown-rump length, but heart girth was increased (P < 0.05) in offspring from seminal plasma primed cows. There were no differentially expressed genes (BH adj P ≤ 0.05) in offspring liver at 30 d of age; however, myosin light chain, phosphorylatable, fast skeletal muscle (MYLPF) was absent in all liver samples from calves from seminal plasma primed cows. In contrast, vomeronasal 1 receptor bosTauV1R414 (BOSTAUV1R414) was present in 6 of the 7 liver samples from calves from seminal plasma primed cows. Seminal plasma uterine priming alters uterine transcriptomics, negatively impacts early gestation embryo growth, and mid- to late-gestation uterine artery resistance suggesting downstream vascular anomalies. However, these in utero conditions did not impact offspring from birth to 30 d of age.

Advanced paternal age exacerbates neuroinflammation in offspring via m6A modification-mediated intergenerational inheritance

BackgroundThe trend of postponing childbearing age is prevalent worldwide. Advanced paternal age (APA) is associated with adverse pregnancy outcomes and offspring health. However, the underlying mechanism by which paternal aging affects the risk of offspring neuropsychiatric disorders is unclear. Our study aims to explore the behavioral phenotypes and the pathologic epigenetic alterations of APA offspring inherited from aging sperm.MethodsBehavioral tests, ELISA assay, immunofluorescence and western blotting were performed on offspring mice. Methylated RNA immunoprecipitation sequencing (MeRIP-seq) and RNA immunoprecipitation sequencing (RIP-seq) were used to investigate the modified N6-methyladenosine (m6A) profiles of paternal sperm and offspring hippocampus. Intervention of gene expression by lentivirus and adeno-associated virus in both vivo and vitro examined the potential therapeutic targets of intergenerational inherited neuroinflammation.ResultsIn our study, APA offspring exhibit cognitive impairment and autism-like behavior. An increase in neuroinflammation in APA offspring is associated with microglial overactivation, which manifests as abnormal morphology and augmented engulfment. MeRIP-seq of F0 sperm and F1 hippocampus reveal that Nr4a2 is hypermethylated with decreased expression in APA offspring involving in synaptic plasticity and microglial function. In addition, Ythdc1, an m6A reader protein, is markedly elevated in aging sperm and remains elevated in adult hippocampus of APA group. Enhanced Ythdc1 recognizes and suppresses the hypermethylated Nr4a2, thereby contributing to the abnormal phenotype in offspring. The overexpression of Ythdc1 triggers microglial activation in vitro and its suppression in the hippocampus of APA progeny alleviates behavioral aberrations and attenuates neuroinflammation.ConclusionOur study provides additional evidence of the abnormal behavioral phenotypes of APA offspring and reveals potential epigenetic inheritance signatures and targeted genes for future research.

Maternal effects and its importance in the genetic evaluations of preweaning live weight traits of beef cattle. A review.

Maternal effects in cattle genetics are defined as the causal influence of the phenotype or maternal genotype on the offspring's phenotype by effects occurring when the genetic and environmental characteristics of the mother influence the phenotype of the offspring beyond the direct inheritance of genes. Its relevance has been strongly described in genetic models focused on the genetic improvement of preweaning traits in cow-calf beef cattle production systems. Here, basic concepts and the importance of maternal effects when using linear and animal model procedures for genetic evaluations of growth and live-weight traits in beef cattle are reviewed and discussed. A brief history of estimation methods from classical studies to recent studies used for the development of animal models for studying maternal effects is also provided. Some important biometric concepts for maternal effect estimation are described, and the antagonism between direct genetic effects and maternal effects, its biological basis, and sources of error in the estimation of direct genetic and maternal covariance are discussed. Finally, some genomic perspectives are presented.

Noncanonical inheritance of phenotypic information by protein amyloids.

All known heritable phenotypic information in animals is transmitted by direct inheritance of nucleic acids, their covalent modifications or histone modifications that modulate expression of associated genomic regions. Nonetheless, numerous familial traits and disorders cannot be attributed to known heritable molecular factors. Here we identify amyloid-like protein structures that are stably inherited in wild-type animals and influence traits. Their perturbation by genetic, environmental or pharmacological treatments leads to developmental phenotypes that can be epigenetically passed onto progeny. Injection of amyloids isolated from different phenotypic backgrounds into naive animals recapitulates the associated phenotype in offspring. Genetic and proteomic analyses reveal that the 26S proteasome and its conserved regulators maintain heritable amyloids across generations, which enables proper germ cell sex differentiation. We propose that inheritance of a proteinaceous epigenetic memory coordinates developmental timing and patterning with the environment to confer adaptive fitness.

Stressful Body Temperatures as a Maternal Effect on Lizard Reproduction.

AbstractUnderstanding the relationship between the environment parents experience during reproduction and the environment embryos experience in the nest is essential for determining the intergenerational responses of populations to novel environmental conditions. Thermal stress has become commonplace for organisms inhabiting areas affected by rising temperatures. Exposure to body temperatures that approach, but do not exceed, upper thermal limits often induces adverse effects in organisms, but the propensity for these temperatures to have intergenerational consequences has not been explored in depth. Here, we quantified the effects of thermal stress on the reproductive physiology and development of brown anoles (Anolis sagrei) when thermal stress is experienced by mothers and by eggs during incubation. Mothers exposed to thermal stress produced smaller eggs and smaller offspring with reduced growth rates, while egg stress reduced developmental time and offspring mass. Hatchling survival and growth were negatively affected by thermal stress experienced by mothers but not by thermal stress experienced as eggs. We found mixed evidence for an additive effect of thermal stress on offspring; rather, thermal stress had specific (and most often negative) effects on different components of offspring phenotypes and fitness proxies when experienced either by mothers or by eggs. Stressful body temperatures therefore can function in a similar manner to other types of maternal effects in reptiles; however, this maternal effect has predominantly negative consequences on offspring.

Preconception and/or preimplantation exposure to a mixture of environmental contaminants altered fetoplacental development and placental function in a rabbit model

Pregnant women are daily exposed to environmental contaminants, including endocrine disruptors that can impact the offspring's health. This study aimed to evaluate the effects of maternal oral exposure to a mixture of contaminants at a dose mimicking women's exposure, during folliculogenesis and/or preimplantation period (FED and ED groups, respectively) on the fetoplacental phenotype in a rabbit model. The mixture (DEHP, pp’DDE, β-HCH, HCB, BDE-47, BPS, PFOS, PFOA) was defined based on data from HELIX and INMA cohorts. FED and ED females or unexposed females (control) were inseminated, their embryos were collected and transferred to unexposed control recipient rabbits at 80 h post-insemination. The effects of maternal FED and ED exposure were evaluated on fetoplacental growth and development by ultrasound, fetoplacental biometry, fetal metabolism, placental structure and function. The results demonstrated that the mixture weakly affected ultrasound measurements, as only placental volume increased significantly in FED vs ED. Analysis of placental structure demonstrated that the volume fraction of the maternal blood space was increased in FED vs control. Pre- and/or periconception exposure did not affect biometric at the end of gestation, but affected FED fetal biochemistry. Plasma triglyceride concentration was reduced compared to control. However, total cholesterol, urea, ASAT and ALAT in fetal blood were affected in both exposed groups. Multiple factor analysis, including biometric, biochemical, and stereological datasets, indicated that the three groups were significantly different. Additionally, several placental genes were differentially expressed between groups, compared two by two, in a sex-specific manner, with more difference in females than in males. The differentially expressed genes were involved in lipid, cholesterol, and drug/xenobiotic metabolism in both sexes. These results indicate that maternal exposure to environmental contaminants during crucial developmental windows only mildly impaired fetoplacental development but disturbed fetal blood biochemistry and placental gene expression with potential long-term effects on offspring phenotype.

Maternal high-fat or low-protein diets promote autism-related behavior and altered social behavior within groups in offspring male mice

Maternal malnutrition has been associated with neurodevelopmental deficits and long-term implications on the offspring’s health and behavior. Here, we investigated the effects of maternal low-protein diet (LPD) or obesity-inducing maternal high-fat diet (HFD) on dyadic social interactions, group organization and autism-related behaviors in mice. We found that maternal HFD induced an autism-related behavioral phenotype in the male offspring, including a robust decrease in sociability, increased aggression, cognitive rigidity and repetitive behaviors. Maternal LPD led to a milder yet significant effect on autism-related symptoms, with no effects on olfactory-mediated social behavior. Under naturalistic conditions in a group setting, this manifested in altered behavioral repertoires, increased magnitude in dominance relations, and reduced interactions with novel social stimuli in the HFD male offspring, but not in the LPD offspring. Finally, we found HFD-induced transcriptomic changes in the olfactory bulbs of the male offspring. Together, our findings show that maternal malnutrition induces long-lasting effects on aggression and autism-related behaviors in male offspring, and potential impairments in brain regions processing chemosensory signals.

Within the optimal thermal range, temperature fluctuations with similar means have little effect on offspring phenotypes: A comparison of two approaches that simulate natural nest conditions

Temperature influences nearly every aspect of organismal function. Because aspects of global change such as urbanization and climate change influence temperature, researchers must consider how altering thermal regimes will impact biodiversity across the planet. To do so, they often measure temperature in natural and/or human-modified habitats, replicate those temperatures in laboratory experiments to understand organismal responses, and make predictions under models of future change. Consequently, accurately representing temperature in the laboratory is an important concern, yet few studies have assessed the consequences of simulating thermal conditions in different ways. We used nest temperatures for two urban-dwelling, invasive lizards (Anolis sagrei and A. cristatellus) to create two egg incubation treatments in the laboratory. Like most studies of thermal developmental plasticity, we created daily repeating thermal fluctuations; however, we used different methods to create temperature treatments that differed in the magnitude and breadth of thermal cycles, and then evaluated the effects of these different approaches on embryo development and hatchling phenotypes. Additionally, we measured embryo heart rate, a proxy for metabolism, across temperature to understand the immediate effects of treatments. We found that treatments had minimal effect on phenotypes likely because temperatures were within the optimal thermal range for each species and were similar in mean temperature. We conclude that slight differences in thermal treatments may be unimportant so long as temperatures are within a range appropriate for development, and we make several recommendations for future studies of developmental plasticity.

Maternal stress effects across generations in a precocial bird.

Prenatal maternal stress (PMS) is known to shape the phenotype of the first generation offspring (F1) but according to some studies, it could also shape the phenotype of the offspring of the following generations. We previously showed in the Japanese quail that PMS increased the emotional reactivity of F1 offspring in relation to (i) a variation in the levels of some histone post-translational modification (H3K27me3) in their brains and (ii) a modulation of the hormonal composition of the eggs from which they hatched. Here, we wondered whether PMS could also influence the behaviour of the second (F2) and third (F3) generation offspring due to the persistence of the specific marks we identified. Using a principal component analysis, we found that PMS influenced F2 and F3 quail profiles with subtle differences between generations. It increased F2 neophobia, F3 fearfulness and F3 neophobia but only in females. Interestingly, we did not find any variations in the level of histone post-translational modification in F3 brains and we observed inconsistent modulations of androstenedione levels in F1 and F2 eggs. Although they may vary over generations, our results demonstrate that PMS can have phenotypical effects into the third generation.

Effects of maternal androgens and their metabolite etiocholanolone on prenatal development in birds.

Offspring phenotypes can be affected by maternal testosterone and androstenedione (A4), which are considered a tool of mothers to adjust offspring to a fluctuating environment. Yet testosterone and A4 are very rapidly metabolized by developing avian embryos, suggesting that either the maternal testosterone and A4 have potent organizational effects on the embryos extremely early before being metabolized or it is the metabolites that evoke phenotypic variation in the offspring. One of the metabolites, etiocholanolone, increases substantially during early embryonic development and is a likely candidate for mediating maternal effects as it can promote erythropoiesis. To investigate and compare the effects of testosterone and A4 with the possible effects of etiocholanolone during prenatal embryonic development, we increased their levels in black-headed gull eggs (Larus ridibundus), and used sham-injected eggs as controls. This species usually has 3-egg clutches in which maternal androgen levels increase with the egg-laying sequence. We analysed embryonic heart rate, peri-hatching biometric traits, the ratio of white to red blood cells (W/R ratio) and bursa development. We found that testosterone and A4 treatment increased embryonic heart rate irrespective of egg-laying sequence and decreased bill length and W/R ratio, whereas etiocholanolone did not mimic these effects. Instead, etiocholanolone treatment decreased tarsus length and brain mass. Our finding that etiocholanolone does not mimic the effects induced by testosterone and A4 suggests that the embryonic metabolism of maternal testosterone and A4 can potentially diversify the function of these maternal androgens.

Prenatal broad-spectrum cannabidiol administration prevents an autism-like phenotype in male offspring from a maternal stress/terbutaline rat model

Recently, the diagnosis of autism spectrum disorder (ASD) has increased from 1 in 150 to every 1 in 36 children in the United States, warranting a need for novel prevention and therapeutic strategies. Broad-spectrum cannabidiol oil, free from delta-9-tetrahydrocannabinol, the psychoactive component of cannabis, may be one such therapeutic. It has a high safety profile and is frequently used as a complementary and integrative intervention by persons experiencing symptoms of anxiety, stress, and inflammation. Using a neurodevelopmental rat model of ASD (based on neuroinflammation induced by stress and terbutaline exposure during pre- and postnatal development), we sought to prevent the development of ASD-like behaviors in male offspring by administering broad-spectrum cannabidiol oil to dams throughout pregnancy (10 mg/kg, i.p., daily, embryonic days 3–16). To assess an ASD-like phenotype in the offspring, we used three behavioral measures relevant to three core ASD symptoms: 1) social communication (time spent vocalizing when alone); 2) repetitive behavior (marbles buried during a marble burying test); and 3) social interaction (time spent interacting with a novel conspecific during the three-chamber social interaction test). Broad-spectrum cannabidiol oil given during pregnancy decreased scores for all three ASD-related behavioral responses, resulting in an overall significant prevention of the ASD-like phenotype. These findings highlight the potential of broad-spectrum cannabidiol oil as a complementary and integrative approach for prevention of stressor-induced sequelae relevant to development of an ASD-like phenotype.

Differential effects of purified low molecular weight Poly(I:C) in the maternal immune activation model depend on the laboratory environment

The Poly (I:C) (polyriboinosinic-polyribocytidilic acid) paradigm of maternal immune activation (MIA) is most widely used as experimental model for the evaluation of the effects of gestational infection on the brain and behavior of the progeny. We have previously reported significant batch-to-batch variability in the effects of Poly (I:C), purchased from the same supplier (Sigma–Aldrich), on maternal and fetal immune responses and found these differences to be dependent on the relative amount of synthetic double-stranded RNA fragments in the high versus low molecular weight (LMW) range contained in the compound. We here resorted to Poly (I:C) purified for LMW dsRNA fragments to establish a MIA paradigm with increased reproducibility and enhanced standardization in an effort to refine the MIA paradigm and characterize its effect on offspring behavior. We found that the parallel application of LMW Poly (I:C) in two different MIA-experienced laboratories (Vienna and Zurich) yielded differential outcomes in terms of maternal immune responses and behavioral phenotypes in the offspring generation. In both experimental sites, administration of LMW Poly (I:C) induced a significant sickness response and cytokine induction in the pregnant dam and fetal brains, while the expected deficit in sociability as one main behavioral outcome parameter in the MIA progeny, was only present in the Zurich, but not the Vienna cohort. We conclude that although using Poly (I:C) purified for a defined molecular weight range reduces batch-to-batch variability, it does not make the MIA model more reliable and robust. The differential response in behavioral phenotypes of the MIA offspring between the two laboratories illustrates the highly complex interaction between prenatal and postnatal milieus - including the laboratory environment - that determine offspring phenotypic outcomes after MIA. Consequently, establishing a new MIA protocol or implementing the MIA model firstly under new or changed environmental conditions must include the assessment of offspring behavior to ensure solid and reproducible experimental outcomes.