Avian Model Research Articles

A simple methodology for creating and applying replicable, photograph‐accurate coloration to 3D‐printed models for animal behavior studies

AbstractResearchers often use artificial models of animals to elicit and study behavior. Until recently, these models were typically handcrafted; however, 3D‐printing technology has been adopted by researchers looking to create accurate and consistent animal models from scans of living animals, taxidermies, or existing models. While 3D‐printing techniques create models with accurate and repeatable shape and size, applying coloration to these models is still typically achieved with traditional methods, such as painting by hand. These approaches can be time‐consuming and require high levels of artistic skill, creating a barrier to producing realistic models, especially when more than one model or standardized coloration is required. Here, we present a simple workflow to avoid these issues by creating a photograph‐accurate paper “skin” that can be glued onto 3D‐printed animal models to provide surface coloration. We have used this methodology to create avian models for several experiments, and found that it can create highly detailed and standardized models with minimal training and is independent of artistic skill. Additionally, this method allows the files needed to accurately recreate models to be shared digitally with other researchers, further enhancing repeatability in the field.

A generic avian physiologically-based kinetic (PBK) model and its application in three bird species

Physiologically-based kinetic (PBK) models are effective tools for designing toxicological studies and conducting extrapolations to inform hazard characterization in risk assessment by filling data gaps and defining safe levels of chemicals. In the present work, a generic avian PBK model for male and female birds was developed using PK-Sim and MoBi from the Open Systems Pharmacology Suite (OSPS). The PBK model includes an ovulation model (egg development) to predict concentrations of chemicals in eggs from dietary exposure. The model was parametrized for chicken (Gallus gallus), bobwhite quail (Colinus virginianus) and mallard duck (Anas platyrhynchos) and was tested with nine chemicals for which in vivo studies were available. Time-concentration profiles of chemicals reaching tissues and egg compartment were simulated and compared to in vivo data. The overall accuracy of the PBK model predictions across the analyzed chemicals was good. Model simulations were found to be in the range of 22–79% within a 3-fold and 41–89% were within 10- fold deviation of the in vivo observed data. However, for some compounds scarcity of in-vivo data and inconsistencies between published studies allowed only a limited goodness of fit evaluation. The generic avian PBK model was developed following a “best practice” workflow describing how to build a PBK model for novel species. The credibility and reproducibility of the avian PBK models were scored by evaluation according to the available guidance documents from WHO (2010), and OECD (2021), to increase applicability, confidence and acceptance of these in silico models in chemical risk assessment.

Effect of Blood Flow on Cardiac Morphogenesis and Formation of Congenital Heart Defects

Congenital heart disease (CHD) affects about 1 in 100 newborns and its causes are multifactorial. In the embryo, blood flow within the heart and vasculature is essential for proper heart development, with abnormal blood flow leading to CHD. Here, we discuss how blood flow (hemodynamics) affects heart development from embryonic to fetal stages, and how abnormal blood flow solely can lead to CHD. We emphasize studies performed using avian models of heart development, because those models allow for hemodynamic interventions, in vivo imaging, and follow up, while they closely recapitulate heart defects observed in humans. We conclude with recommendations on investigations that must be performed to bridge the gaps in understanding how blood flow alone, or together with other factors, contributes to CHD.

Empirical evidence of coevolution between the channel-billed cuckoo and its host, the pied currawong

Abstract Avian obligate brood parasites and their hosts exhibit coevolution, where parasites respond to the evolution of host defences with counter-adaptations, such as egg mimicry, which can then lead to the evolution of more efficient host defences. Using objective measurements and avian visual modelling, we quantified the degree of similarity between the eggs of the channel-billed cuckoo (Scythrops novaehollandiae) and the eggs of three host species from the hosts’ visual perspective. We found no evidence that this cuckoo species has host-specific egg types, but it does appear to mimic one of its primary hosts, the pied currawong (Strepera graculina), in both colour and pattern. Currawongs showed significantly higher interclutch variation in colour and luminance than the other two hosts and had significantly lower intraclutch variation in pattern than interclutch variation. High interclutch and low intraclutch variation in a host could make it more difficult for a cuckoo to match closely any particular host clutch, potentially allowing a host to detect a parasitic egg more easily. This is the first empirical study using objective measurements to quantify the degree of egg mimicry in the channel-billed cuckoo and the results suggest a potential host defence to egg mimicry that merits further investigation.

Development and Validation of the Metric-Based Assessment of a Robotic Dissection Task on an Avian Model.

The introduction of robot-assisted surgical devices requires the application of objective performance metrics to verify performance levels. To develop and validate (face, content, response process, and construct) the performance metrics for a robotic dissection task using a chicken model. In a procedure characterization, we developed the performance metrics (i.e., procedure steps, errors, and critical errors) for a robotic dissection task, using a chicken model. In a modified Delphi panel, 14 experts from four European Union countries agreed on the steps, errors, and critical errors (CEs) of the task. Six experienced surgeons and eight novice urology surgeons performed the robotic dissection task twice on the chicken model. In the Delphi meeting, 100% consensus was reached on five procedure steps, 15 errors and two CEs. Novice surgeons took 20min to complete the task on trial 1 and 14min during trial two, whereas experts took 8.2min and 6.5min. On average, the Expert Group completed the task 56% faster than the Novice Group and made 46% fewer performance errors. Sensitivity and specificity for procedure errors and time were excellent to good (i.e., 1.0-0.91) but poor (i.e., 0.5) for step metrics. The mean interrater reliability for the assessments by two robotic surgeons was 0.91 (Expert Group inter-rater reliability=0.92 and Novice Group=0.9). We report evidence which supports the demonstration of face, content, and construct validity for a standard and replicable basic robotic dissection task on the chicken model.

Bromoacetic acid induces neurogenic injury in the chicken brain by activating oxidative stress and NF-κB inflammatory pathway

The bromoacetic acid (BAA) is one of the most teratogenic and neurotoxic disinfection byproducts. Birds take environmental water as their habitat and are inevitably affected by BAA in the environment. However, the neurotoxicity caused by BAA in birds has not been reported and the mechanism remains unclear. In this study, we chose chickens as the avian model to explore the effects of different concentrations of BAA on the brain tissues. Here, we selected the 3 μg/L dose of BAA detected in Tai Lake basin as a reference, and designed 1-, 100-, and 1000-fold of the environmental exposure dose as the experimental doses to explore the neurotoxicity of BAA in birds. Results showed that BAA increased the number of pyknotic nuclear neurons, deformed vascular sheaths, and glial cells in the brain. BAA inhibited the activity of antioxidant enzymes and the expression of antioxidant genes. With the increase of BAA concentration, the oxidative stress-responsive transcription factor NF-κB was activated. Furthermore, BAA remarkably changed the expression of lipid metabolism related genes (i.e., acc, gpat, hmgr, pparα, cpt1, and ampkα). Importantly, BAA decreased the mRNA and protein expression levels of autophagy-related genes (i.e., atg5, ulk1, beclin1, and lc3). Meantime, BAA increased the mRNA and protein levels of apoptotic and pro-apoptotic genes, such as p53, bax, cytochrome c, caspase-9, and caspase-3. Overall, our study provided new insights into the potential neurotoxic effects of BAA in birds, which was important for the clinical monitoring and prevention of BAA.

Phylogenomic Diversity Elucidates Mechanistic Insights into Lyme Borreliae-Host Association.

ABSTRACTHost association—the selective adaptation of pathogens to specific host species—evolves through constant interactions between host and pathogens, leaving a lot yet to be discovered on immunological mechanisms and genomic determinants. The causative agents of Lyme disease (LD) are spirochete bacteria composed of multiple species of the Borrelia burgdorferi sensu lato complex, including B. burgdorferi (Bb), the main LD pathogen in North America—a useful model for the study of mechanisms underlying host-pathogen association. Host adaptation requires pathogens’ ability to evade host immune responses, such as complement, the first-line innate immune defense mechanism. We tested the hypothesis that different host-adapted phenotypes among Bb strains are linked to polymorphic loci that confer complement evasion traits in a host-specific manner. We first examined the survivability of 20 Bb strains in sera in vitro and/or bloodstream and tissues in vivo from rodent and avian LD models. Three groups of complement-dependent host-association phenotypes emerged. We analyzed complement-evasion genes, identified a priori among all strains and sequenced and compared genomes for individual strains representing each phenotype. The evolutionary history of ospC loci is correlated with host-specific complement-evasion phenotypes, while comparative genomics suggests that several gene families and loci are potentially involved in host association. This multidisciplinary work provides novel insights into the functional evolution of host-adapted phenotypes, building a foundation for further investigation of the immunological and genomic determinants of host association.IMPORTANCE Host association is the phenotype that is commonly found in many pathogens that preferential survive in particular hosts. The Lyme disease (LD)-causing agent, B. burgdorferi (Bb), is an ideal model to study host association, as Bb is mainly maintained in nature through rodent and avian hosts. A widespread yet untested concept posits that host association in Bb strains is linked to Bb functional genetic variation conferring evasion to complement, an innate defense mechanism in vertebrate sera. Here, we tested this concept by grouping 20 Bb strains into three complement-dependent host-association phenotypes based on their survivability in sera and/or bloodstream and distal tissues in rodent and avian LD models. Phylogenomic analysis of these strains further correlated several gene families and loci, including ospC, with host-specific complement-evasion phenotypes. Such multifaceted studies thus pave the road to further identify the determinants of host association, providing mechanistic insights into host-pathogen interaction.

Re: Development and Validation of the Metric-based Assessment of a Robotic Dissection Task on an Avian Model

Re: Development and Validation of the Metric-based Assessment of a Robotic Dissection Task on an Avian Model

Pharmacological intervention of the FGF-PTH axis as a potential therapeutic for craniofacial ciliopathies.

ABSTRACTCiliopathies represent a disease class characterized by a broad range of phenotypes including polycystic kidneys and skeletal anomalies. Ciliopathic skeletal phenotypes are among the most common and most difficult to treat due to a poor understanding of the pathological mechanisms leading to disease. Using an avian model (talpid2) for a human ciliopathy with both kidney and skeletal anomalies (orofaciodigital syndrome 14), we identified disruptions in the FGF23–PTH axis that resulted in reduced calcium uptake in the developing mandible and subsequent micrognathia. Although pharmacological intervention with the U.S. Food and Drug Administration (FDA)-approved pan-FGFR inhibitor AZD4547 alone rescued expression of the FGF target SPRY2, it did not significantly rescue micrognathia. In contrast, treatment with a cocktail of AZD4547 and teriparatide acetate, a PTH agonist and FDA-approved treatment for osteoporosis, resulted in molecular, cellular and phenotypic rescue of ciliopathic micrognathia in talpid2 mutants. Together, these data provide novel insight into pathological molecular mechanisms associated with ciliopathic skeletal phenotypes and a potential therapeutic strategy for a pleiotropic disease class with limited to no treatment options.

Disruption of the Cellular and Extracellular Morphogenesis of Cardiac Tissues in Avian Models of Cyanotic Heart Defects

Disruption of the Cellular and Extracellular Morphogenesis of Cardiac Tissues in Avian Models of Cyanotic Heart Defects

Gull Plumages are, and are Not, What They Appear to Human Vision

Clear correlations between human and bird visual assessments of color have been documented, and are often assumed, despite fundamental differences in human and avian visual physiology and morphology. Analyses of plumage colors with avian perceptual models have shown widespread hidden inter-sexual and inter-specific color variation among passerines perceived as monochromatic to humans, highlighting the uncertainty of human vision to predict potentially relevant variation in color. Herein, we use reflectance data from 13 Larus gull species as an exemplar data set to study concordance between human vision and avian visual modeling of feather colors near, or below, the human threshold for discrimination. We found little evidence among gulls for sexual dichromatism hidden from human vision, but did find inter-specific color variation among gulls that is not seen by humans. Neither of these results were predictable a priori, and we reassert that reflectance measurements of actual feather colors, analyzed with avian relevant visual models, represent best practice when studying bird coloration.

Revisiting TSHβ's Role in Avian Seasonal Reproduction, Insights, and Challenges from Mammalian Models.

The core neuroendocrine pathways regulating seasonal reproduction in vertebrates were characterized over a decade ago. This has led to the development of a "consensus" model of seasonal reproduction that appears to be largely conserved across mammals, birds, amphibians, reptile and fish. This model centers around the photoinduced increase in TSHβ expression in the pars tuberalis of the anterior pituitary gland as the key transducer of photic information from sensory cells to the critical switch in hypothalamic deiodinase enzyme expression that drives changes in localized thyroid hormone signaling. These changes in localized thyroid hormone signaling in the medial basal hypothalamus ultimately activate the reproductive axis. This model has in turn, been consistently supported by studies in a variety of taxa. As such, it has become the standard against which subsequent work is compared, particularly in the non-mammalian literature. However, as new studies move away from the handful of canonical model systems and begin to explore the effects of naturalistic rather than artificial photoperiod manipulations, a more nuanced picture has begun to emerge. Yet, progress in elucidating the detailed events of reproductive photostimulation has been uneven across the research community. In this perspective, I draw on emerging data from studies in free living animals that challenges some of the established assumptions of the avian consensus model of reproduction. Specifically, the role of TSHβ and its dissociation from deiodinase signaling. I then discuss how these apparently surprising findings can be contextualized within the context of the mammalian seasonal literature. In turn, this ability to contextualize from the mammalian literature highlights the breadth of the current gap versus our understanding of the molecular neuroendocrine mechanisms of seasonality in mammals versus birds and other non-mammalian seasonal breeders.

Realism, Conservatism, and Tiered Ecological Risk Assessment.

Recent research has provided valuable momentum for the development and use of population models for ecological risk assessment (ERA). In general, ERA proceeds along a tiered strategy, with conservative assumptions deployed at lower tiers that are relaxed at higher tiers with ever more realistic models. As the tier increases, so do the levels of time and effort required by the assessor. When faced with many stressors, species, and habitats, risk assessors need to find efficiencies. Conservative lower-tier approaches are well established, but higher-tier models often prioritize accuracy, and conservative approaches are relatively unexplored at higher tiers. A principle of efficiency for ecological modeling for population-level ecological risk assessment is articulated and evaluated against a conceptual model and an existing set of avian models for chemical risk assessment. Here, four published avian models are reviewed in increasing order of realism (risk quotient → Markov chain nest productivity model → endogenous lifecycle model → spatially explicit population model). Models are compared in a pairwise fashion according to increasing realism and evaluated as to whether conservatism increases or decreases with each step. The principle of efficiency is shown to be a challenging ideal, though some cause for optimism is identified. Strategies are suggested for studying efficiency in tiered ecological model deployment.

SS18-SSX drives CREB activation in synovial sarcoma

PurposeSynovial sarcoma (SySa) is a rare soft tissue tumor characterized by a reciprocal t(X;18) translocation. The chimeric SS18-SSX fusion protein represents the major driver of the disease, acting as aberrant transcriptional dysregulator. Oncogenic mechanisms whereby SS18-SSX mediates sarcomagenesis are incompletely understood, and strategies to selectively target SySa cells remain elusive. Based on results of Phospho-Kinase screening arrays, we here investigate the functional and therapeutic relevance of the transcription factor CREB in SySa tumorigenesis.MethodsImmunohistochemistry of phosphorylated CREB and its downstream targets (Rb, Cyclin D1, PCNA, Bcl-xL and Bcl-2) was performed in a large cohort of SySa. Functional aspects of CREB activity, including SS18-SSX driven circuits involved in CREB activation, were analyzed in vitro employing five SySa cell lines and a mesenchymal stem cell model. CREB mediated transcriptional activity was modulated by RNAi-mediated knockdown and small molecule inhibitors (666-15, KG-501, NASTRp and Ro 31-8220). Anti-proliferative effects of the CREB inhibitor 666-15 were tested in SySa avian chorioallantoic membrane and murine xenograft models in vivo.ResultsWe show that CREB is phosphorylated and activated in SySa, accompanied by downstream target expression. Human mesenchymal stem cells engineered to express SS18-SSX promote CREB expression and phosphorylation. Conversely, RNAi-mediated knockdown of SS18-SSX impairs CREB phosphorylation in SySa cells. Inhibition of CREB activity reduces downstream target expression, accompanied by suppression of SySa cell proliferation and induction of apoptosis invitro and in vivo.ConclusionIn conclusion, our data underline an essential role of CREB in SySa tumorigenesis and provides evidence for molecular targeted therapies.

Analysis of differential morphology of the anterior fontanelle in an embryonic avian model of induced thyrotoxicosis

Craniosynostosis (CS) occurs when the cranial sutures of the skull fuse prematurely, and this results in intracranial pressure during development and skull deformities. Maternal hyperthyroidism during embryonic development has been linked to the development of CS. Our lab is currently establishing a model of thyroxine-induced CS to study the mechanism involved in thyroxine-enhanced cranial ossification. Two groups of fertilized chicken eggs were injected with saline or 25 ng T4 into the air cell on embryonic days 11 and 15. Skulls from each group were collected on embryonic days 17 through 19 (n = 17-21 per day). They were fixed in formalin and processed using Alizarin Red whole-mount staining to image and quantify any morphological differences in the ossifying membrane of the anterior fontanelle between the treatment and control groups. We hypothesize that thyroxine exposure will alter skull morphology. Geometric morphometric analysis using MorphoJ was performed to identify shape variation between treatment groups of the fibrous space and ossifying region of the anterior fontanelle. Significance was determined by Procrustes ANOVA. Results demonstrated a significant variation in shape of the fibrous gap between developing sutures on embryonic days 17, 18 and 19 (p<0.05) and a significant variation in the shape of the ossifying region on embryonic days 18 and 19 (p<0.001). In conclusion, we determined our model of induced thyrotoxicosis successfully altered skull morphology visualized in the anterior fontanelle. These findings support that our model is successful in promoting the fusing of the cranial bones with thyroxine exposure in our avian model.
 Acknowledgment of NASA West Virginia Space Grant Consortium (Grant #80NSSC20M0055) and the Genomics Core Facility and WV-INBRE (NIH grant P20GM103434).

Thyroxine Metabolism in an Avian Model of Induced Thyrotoxicosis

Craniosynostosis (CS) is the premature fusion of cranial sutures which leads to abnormal cranial structure and causes abnormal neurocognition and behavior. Maternal thyroid disorders are associated with incidence of CS in infants. However, the mechanism of TH-induced CS is still obscure. Thyroxine (T4) metabolism is regulated by the expression of deiodinases. Type I and type II deiodinases (DIO1 and DIO2) remove iodine from T4 producing active triiodothyronine (T3). Deiodinase III (DIO3) inactivates both T4 and T3. Our lab is establishing a model to study the effects of thyrotoxicosis induced CS using fertilized chicken eggs. Eggs were injected into the air cell with either saline or 25 ng T4 on days E11 and E15 of embryonic development. Heart rates were measured daily from EKG recordings and on E19, tissue samples were collected for qRT-PCR analysis. The main objective was to validate the induced state of thyrotoxicosis by evaluating negative feedback mechanisms of thyroid hormone regulation following exposure by measuring expression of DIO1 and DIO3 in embryonic livers. Since livers are the main site of metabolism, we hypothesize that levels of DIO3 will increase following thyroxine exposure. Results demonstrated a significant upregulation of DIO3 2 days after exposure and a significant downregulation 4 days following exposure. No significant differences were observed in DIO1 on any of the days after exposure. These results, along with correlating heart rates, support our model by of induced thyrotoxicosis by demonstrating the metabolism of thyroxine in response to our treatment regimen.
 
 
 Acknowledgment of NASA West Virginia Space Grant Consortium (Grant #80NSSC20M0055) and the Genomics Core Facility and WV-INBRE (NIH grant P20GM103434).

Identifying Positive Cases in an Avian Model of Induced-Thyrotoxicosis

Thyrotoxicosis is a condition of excess circulating thyroid hormones. Maternal thyrotoxicosis has been related to the development of craniosynostosis (CS) in approximately 3% of births. CS occurs when the cranial sutures of the skull fuse prematurely. However, the mechanism for thyroid hormone-induced CS in those cases is unclear. Currently, we are establishing an avian model of thyroxine-induced CS to study these mechanisms. Two groups of fertilized chicken eggs were injected with saline or 25 ng T4 (thyroxine) on embryonic days 11 and 15 and collected on 19 prior to hatching. Data were collected from each group including: body mass and length, tibia and femur length, liver and heart mass, and circulating T4 concentrations. Our study aimed to characterize all possible physiological changes associated with our treatment and determine the subset of positive cases. Following thyroxine exposure, 19-day old embryos were 4% shorter (p<0.05) with a corresponding 8% decrease in tibia length (p<0.01) and 9% decrease in femur length (p<0.01) compared to the controls. Measured T4 concentrations were 88% higher in serum samples following thyroxine-exposure compared to the controls (p<0.01). Body, heart, and liver mass were not different between groups. We were then able to isolate positive cases from correlation plots based on clustering observed in anticipated regions. In conclusion these results support that there is a subset of samples within the treatment group that display the expected phenotypes. It is in this subgroup of data that our focus can be shifted to study the mechanism of thyroxine-induced CS.
 Acknowledgment of NASA West Virginia Space Grant Consortium (Grant #80NSSC20M0055) and the Genomics Core Facility and WV-INBRE (NIH grant P20GM103434).

An avian influenza model with nonlinear incidence and recovery rates in deterministic and stochastic environments

An avian influenza model with nonlinear incidence and recovery rates in deterministic and stochastic environments

Host community-wide patterns of post-fledging behavior and survival of obligate brood parasitic brown-headed cowbirds.

The antagonistic arms races between obligate brood parasites and their hosts provide critical insights into coevolutionary processes and constraints on the evolution of life history strategies. In avian brood parasites-a model system for examining host-parasite dynamics-research has primarily focused on the egg and nestling stage, while far less is known about the behavior and ecology of fledgling and juvenile brood parasites. To provide greater insights into the post-fledging period of generalist brood parasites, we used handheld and automated telemetry systems to examine the behavior and survival of fledgling brown-headed cowbirds (Molothrus ater). Our host community-wide analysis (data on cowbirds fledged from different host species were pooled) shows that fledgling cowbirds' follow patterns of movement and survival found across the post-fledging literature on parental passerine species. Cowbird fledgling survival was lowest during the first 3days post-fledging, whereas daily rates of survival neared 100% after about 16days post-fledging. Cowbird daytime post-fledging activity rates, perch heights, and distance from the natal area all increased with fledging age and young generally gained independence from host parents at 3-4weeks post-fledging, with approximately the same latency as has been observed in studies on fledglings of cowbird host species. Our research demonstrates how automated telemetry systems can overcome past methodological limitations in post-fledging research and provides an important foundation for future studies examining adaptations that cowbirds and other brood parasites use to exploit hosts during the post-fledging period.

Developmental Plasticity in Primate Coordinated Song: Parallels and Divergences With Duetting Songbirds

Homeothermic animals (birds and mammals) are prime model systems for investigating the developmental plasticity and neural mechanisms of vocal duetting, a cooperative acoustic signal that prevails in family-living and pair-bonded species including humans. This review focuses on the nature of this trait and its nurturing during ontogeny and extending into adulthood. I begin by outlining the underpinning concepts of duet codes and pair-specific answering rules as used by birds to develop their learned coordinated song, driven by a complex interaction between self-generated and socially mediated auditory feedback. The more tractable avian model of duetting helps identify research gaps in singing primates that also use duetting as a type of intraspecific vocal interaction. Nevertheless, it has become clear that primate coordinated song—whether overlapping or antiphonal—is subject to some degree of vocal flexibility. This is reflected in the ability of lesser apes, titi monkeys, tarsiers, and lemurs to adjust the structure and timing of their calls through (1) social influence, (2) coordinated duetting both before and after mating, (3) the repair of vocal mistakes, (4) the production of heterosexual song early in life, (5) vocal accommodation in call rhythm, (6) conditioning, and (7) innovation. Furthermore, experimental work on the neural underpinnings of avian and mammalian antiphonal duets point to a hierarchical (cortico-subcortical) control mechanism that regulates, via inhibition, the temporal segregation of rapid vocal exchanges. I discuss some weaknesses in this growing field of research and highlight prospective avenues for future investigation.