Predicting yolk testosterone allocation using ecological contexts and species-specific traits.

The prenatal transfer of testosterone (T) from mother to offspring is an important source of phenotypic plasticity. In birds, exposure to ecologically relevant stimuli, such as social competition or an attractive mate, can cause females to deposit more T into their egg yolks. Exposure to elevated yolk T can modify the expression of several fitness-related traits in offspring (e.

Maternal social environment shapes yolk testosterone allocation and embryonic neural gene expression in tree swallows.

Offspring from females breeding in competitive social environments are often exposed to more testosterone (T) during embryonic development, which can affect traits from growth to behavior in potentially adaptive ways. Despite the important role of maternally derived steroids in shaping offspring development, the molecular mechanisms driving these processes are currently unclear. Here, we use tree swallows (Tachycineta bicolor) to explore the effects of the maternal social environment on yolk T concentrations and genome-wide patterns of neural gene expression in embryos.

Decoupling pioneering traits from latitudinal patterns in a north American bird experiencing a southward range shift.

Ecogeographic rules describe spatial patterns in biological trait variation and shed light on the drivers of such variation. In animals, a consensus is emerging that 'pioneering' traits may facilitate range shifts via a set of bold, aggressive and stress-resilient traits. Many of these same traits are associated with more northern latitudes, and most range shifts in the northern hemisphere indicate northward movement.

Gene expression in the female tree swallow brain is associated with inter- and intra-population variation in glucocorticoid levels.

Studies of the evolutionary causes and consequences of variation in circulating glucocorticoids (GCs) have begun to reveal how they are shaped by selection. Yet the extent to which variation in circulating hormones reflects variation in other important regulators of the hypothalamic-pituitary-adrenal (HPA) axis, and whether these relationships vary among populations inhabiting different environments, remain poorly studied. Here, we compare gene expression in the brain of female tree swallows (Tachycineta bicolor) from populations that breed in environments that differ in their unpredictability.

How experimental competition changes ovarian gene activity in free-living birds: Implications for steroidogenesis, maternal effects, and beyond.

The ovary plays an important role in mediating both a female's response to her social environment and communicating it to her developing offspring via maternal effects. Past work has focused on how ovarian hormones respond to competition, but we know little about how the broader ovarian transcriptomic landscape changes, either during or after competition, giving us a narrow perspective on how socially induced phenotypes arise. Here, we experimentally generated social competition among wild, cavity-nesting female birds (tree swallows, Tachycineta bicolor), a species in which females lack a socially induced rise in circulating testosterone but they nevertheless increase allocation to eggs.

Testing hormonal responses to real and simulated social challenges in a competitive female bird.

Competitive interactions often occur in series; therefore animals may respond to social challenges in ways that prepare them for success in future conflict. Changes in the production of the steroid hormone testosterone (T) are thought to mediate phenotypic responses to competition, but research over the past few decades has yielded mixed results, leading to several potential explanations as to why T does not always elevate following a social challenge. Here, we measured T levels in tree swallows (), a system in which females compete for limited nesting cavities and female aggression is at least partially mediated by T.

Experimental competition induces immediate and lasting effects on the neurogenome in free-living female birds.

Periods of social instability can elicit adaptive phenotypic plasticity to promote success in future competition. However, the underlying molecular mechanisms have primarily been studied in captive and laboratory-reared animals, leaving uncertainty as to how natural competition among free-living animals affects gene activity. Here, we experimentally generated social competition among wild, cavity-nesting female birds (tree swallows, ).

Prenatal testosterone triggers long-term behavioral changes in male zebra finches: unravelling the neurogenomic mechanisms.

Background: Maternal hormones, like testosterone, can strongly influence developing offspring, even generating long-term organizational effects on adult behavior; yet, the mechanisms facilitating these effects are still unclear. Here, we experimentally elevated prenatal testosterone in the eggs of zebra finches (Taeniopygia guttata) and measured male aggression in adulthood along with patterns of neural gene expression (RNA-seq) and DNA methylation (MethylC-Seq) in two socially relevant brain regions (hypothalamus and nucleus taenia of the amygdala). We used enrichment analyses and protein-protein interaction networks to find candidate processes and hub genes potentially affected by the treatment.

Corticosterone and testosterone treatment influence expression of gene pathways linked to meiotic segregation in preovulatory follicles of the domestic hen.

Decades of work indicate that female birds can control their offspring sex ratios in response to environmental and social cues. In laying hens, hormones administered immediately prior to sex chromosome segregation can exert sex ratio skews, indicating that these hormones may act directly on the germinal disc to influence which sex chromosome is retained in the oocyte and which is discarded into an unfertilizable polar body. We aimed to uncover the gene pathways involved in this process by testing whether treatments with testosterone or corticosterone that were previously shown to influence sex ratios elicit changes in the expression of genes and/or gene pathways involved in the process of meiotic segregation.

The neurogenomic transition from territory establishment to parenting in a territorial female songbird.

Background: The brain plays a critical role in upstream regulation of processes central to mating effort, parental effort, and self-maintenance. For seasonally breeding animals, the brain is likely mediating trade-offs among these processes within a short breeding season, yet research thus far has only explored neurogenomic changes from non-breeding to breeding states or select pathways (e.g.

Tissue-specific expression profiles and positive selection analysis in the tree swallow (Tachycineta bicolor) using a de novo transcriptome assembly.

Tree swallows (Tachycineta bicolor) are one of the most commonly studied wild birds in North America. They have advanced numerous research areas, including life history, physiology, and organismal responses to global change; however, transcriptomic resources are scarce. To further advance the utility of this system for biologists across disciplines, we generated a transcriptome for the tree swallow using six tissues (brain, blood, ovary, spleen, liver, and muscle) collected from breeding females.

How research on female vertebrates contributes to an expanded challenge hypothesis.

The bi-directional links between hormones and behavior have been a rich area of research for decades. Theory on the evolution of testosterone (T) was greatly advanced by the challenge hypothesis, which presented a framework for understanding interspecific, seasonal, and social variation in T levels in males, and how they are shaped by the competing demands of parental care and male-male competition. Female competition is also widespread in nature, although it is less clear whether or how the challenge hypothesis applies to females.

Predation risk affects egg mass but not egg steroid hormone concentrations in yellow-legged gulls.

Predators have both direct, consumptive effects on their prey and non-lethal effects on physiology and behavior, including reproductive decisions, with cascading effects on prey ecology and evolution. Here, we experimentally tested such non-lethal effects of exposure to increased predation risk on clutch size, egg mass, and the concentration of yolk steroid hormones in the yellow-legged gull . We simulated increased predation risk by displaying stuffed predators (adult fox , and adult buzzard ) to breeding adults before egg laying.

Evaluating testosterone as a phenotypic integrator: From tissues to individuals to species.

Hormones have the potential to bring about rapid phenotypic change; however, they are highly conserved over millions of years of evolution. Here, we examine the evolution of hormone-mediated phenotypes, and the extent to which regulation is achieved via independence or integration of the many components of endocrine systems. We focus on the sex steroid testosterone (T), its cognate receptor (androgen receptor) and related endocrine components.

Why go to the emergency department? Perspectives from persons with borderline personality disorder.

Through this qualitative study, we explored frequent emergency department use by persons with borderline personality disorder from their perspective. Interpretive description guided the study design, and data were collected through interviews with six individuals diagnosed with borderline personality disorder who had at least 12 emergency department visits for reasons related to their mental illness within a 1-year timeframe. Using thematic data analysis, we articulate the participants' experiences through two broad themes: cyclic nature of emergency department use and coping skills and strategies.

Comparison of Cardiovascular Outcomes Between Statin Monotherapy and Fish Oil and Statin Combination Therapy in a Veteran Population.

A study that compared the use of statin therapies with and without fish oil in a veteran population found an insignificant difference between the 2 arms.

Tissue-specific gene regulation corresponds with seasonal plasticity in female testosterone.

Testosterone (T) is a sex steroid hormone that often varies seasonally and mediates trade-offs between territorial aggression and parental care. Prior work has provided key insights into the 'top-down' hypothalamic control of this seasonal plasticity in T, yet mechanisms acting outside of the brain may also influence circulating T levels. We hypothesized that peripheral mechanisms may be especially critical for females, because peripheral regulation may mitigate the costs of systemically elevated T.

Livestock abundance predicts vampire bat demography, immune profiles and bacterial infection risk.

Human activities create novel food resources that can alter wildlife-pathogen interactions. If resources amplify or dampen, pathogen transmission probably depends on both host ecology and pathogen biology, but studies that measure responses to provisioning across both scales are rare. We tested these relationships with a 4-year study of 369 common vampire bats across 10 sites in Peru and Belize that differ in the abundance of livestock, an important anthropogenic food source.

Behavioral phenotype predicts physiological responses to chronic stress in proactive and reactive birds.

Animal species display significant variation in personality traits among individuals, and two main coping styles have been identified and termed "proactive" and "reactive". Further, these coping styles appear to correlate directly with the strength of the physiological stress response exhibited by those individuals. In our study system, white laying hens are reactive, flighty, and exhibit large hormonal and behavioral responses to acute stress, while brown laying hens are proactive, exploratory, and exhibit low hormonal and behavioral responses to acute stress.

Predictors and immunological correlates of sublethal mercury exposure in vampire bats.

Mercury (Hg) is a pervasive heavy metal that often enters the environment from anthropogenic sources such as gold mining and agriculture. Chronic exposure to Hg can impair immune function, reducing the ability of animals to resist or recover from infections. How Hg influences immunity and susceptibility remains unknown for bats, which appear immunologically distinct from other mammals and are reservoir hosts of many pathogens of importance to human and animal health.

Evolutionary implications of interspecific variation in a maternal effect: a meta-analysis of yolk testosterone response to competition.

Competition between conspecifics during the breeding season can result in behavioural and physiological programming of offspring via maternal effects. For birds, in which maternal effects are best studied, it has been claimed that exposure to increased competition causes greater deposition of testosterone into egg yolks, which creates faster growing, more aggressive offspring; such traits are thought to be beneficial for high-competition environments. Nevertheless, not all species show a positive relationship between competitive interactions and yolk testosterone, and an explanation for this interspecific variation is lacking.

Relationship between maternal environment and DNA methylation patterns of estrogen receptor alpha in wild Eastern Bluebird (Sialia sialis) nestlings: a pilot study.

There is mounting evidence that, across taxa, females breeding in competitive environments tend to allocate more testosterone to their offspring prenatally and these offspring typically have more aggressive and faster-growing phenotypes. To date, no study has determined the mechanisms mediating this maternal effect's influence on offspring phenotype. However, levels of estrogen receptor alpha (ER α) gene expression are linked to differences in early growth and aggression; thus, maternal hormones may alter gene regulation, perhaps via DNA methylation, of ER α in offspring during prenatal development.

Justified follow-up: a final intraoperative parathyroid hormone (ioPTH) Over 40 pg/mL is associated with an increased risk of persistence and recurrence in primary hyperparathyroidism.

Introduction: After parathyroidectomy for sporadic primary hyperparathyroidism (PHPT), overall rates of persistence/recurrence are extremely low. A marker of increased risk for persistence/recurrence is needed. We hypothesized that final intraoperative parathyroid hormone (FioPTH) ≥40 pg/mL is indicative of increased risk for disease persistence/recurrence, and can be used to selectively determine the degree of follow-up.

Ultra-soft PDMS-based magnetoactive elastomers as dynamic cell culture substrata.

Mechanical cues such as extracellular matrix stiffness and movement have a major impact on cell differentiation and function. To replicate these biological features in vitro, soft substrata with tunable elasticity and the possibility for controlled surface translocation are desirable. Here we report on the use of ultra-soft (Young's modulus <100 kPa) PDMS-based magnetoactive elastomers (MAE) as suitable cell culture substrata.