Heatwave-induced synchrony within forage fish portfolio disrupts energy flow to top pelagic predators.

During the Pacific marine heatwave of 2014-2016, abundance and quality of several key forage fish species in the Gulf of Alaska were simultaneously reduced throughout the system. Capelin (Mallotus catervarius), sand lance (Ammodytes personatus), and herring (Clupea pallasii) populations were at historically low levels, and within this community abrupt declines in portfolio effects identify trophic instability at the onset of the heatwave. Although compensatory changes in age structure, size, growth or energy content of forage fish were observed to varying degrees among all these forage fish, none were able to fully mitigate adverse impacts of the heatwave, which likely included both top-down and bottom-up forcing. Notably, changes to the demographic structure of forage fish suggested size-selective removals typical of top-down regulation. At the same time, changes in zooplankton communities may have driven bottom-up regulation as copepod community structure shifted toward smaller, warm water species, and euphausiid biomass was reduced owing to the loss of cold-water species. Mediated by these impacts on the forage fish community, an unprecedented disruption of the normal pelagic food web was signaled by higher trophic level disruptions during 2015-2016, when seabirds, marine mammals, and groundfish experienced shifts in distribution, mass mortalities, and reproductive failures. Unlike decadal-scale variability underlying ecosystem regime shifts, the heatwave appeared to temporarily overwhelm the ability of the forage fish community to buffer against changes imposed by warm water anomalies, thereby eliminating any ecological advantages that may have accrued from having a suite of coexisting forage species with differing life-history compensations.

Harmonized Cross-Species Assessment of Endocrine and Metabolic Disruptors by Ecotox FACTORIAL Assay.

Environmental pollution is a threat to humans and wildlife species. Of particular concern are endocrine disrupting chemicals (EDCs). An important target of EDCs is nuclear receptors (NRs) that control endocrine and metabolic responses through transcriptional regulation. Owing in part to structural differences of NRs, adverse effects of EDCs vary significantly among species. Here, we describe a multiplexed reporter assay (the Ecotox FACTORIAL) enabling parallel assessment of compounds' effects on estrogen, androgen, thyroid, and PPARγ receptors of representative mammals, birds, reptiles, amphibians, and fish. The Ecotox FACTORIAL is a single-well assay comprising a set of species-specific, one-hybrid GAL4-NR reporter constructs transiently transfected into test cells. To harmonize cross-species assessments, we used a combination of two approaches. First, we used the same type of test cells for all reporters; second, we implemented a parallel detection of reporter RNAs. The assay demonstrated excellent quality, reproducibility, and insignificant intra-assay variability. Importantly, the EC50 values for NR ligands were consistent with those reported for conventional assays. Using the assay allowed ranking the hazard potential of environmental pollutants (e.g., bisphenols, polycyclic aromatic hydrocarbons, and synthetic progestins) across species. Furthermore, the assay permitted detecting taxa-specific effects of surface water samples. Therefore, the Ecotox FACTORIAL enables harmonized assessment of the endocrine and metabolic disrupting activity of chemicals and surface water in humans as well as in wildlife species.

An exogenous retrovirus isolated from koalas with malignant neoplasias in a US zoo.

Leukemia and lymphoma account for more than 60% of deaths in captive koalas (Phascolarctos cinereus) in northeastern Australia. Although the endogenizing gammaretrovirus koala endogenous retrovirus (KoRV) was isolated from these koalas, KoRV has not been definitively associated with leukemogenesis. We performed KoRV screening in koalas from the San Diego Zoo, maintained for more than 45 y with very limited outbreeding, and the Los Angeles Zoo, maintained by continuously assimilating captive-born Australian koalas. San Diego Zoo koalas are currently free of malignant neoplasias and were infected with only endogenous KoRV, which we now term subtype "KoRV-A," whereas Los Angeles Zoo koalas with lymphomas/leukemias are infected in addition to KoRV-A by a unique KoRV we term subtype "KoRV-B." KoRV-B is most divergent in the envelope protein and uses a host receptor distinct from KoRV-A. KoRV-B also has duplicated enhancer regions in the LTR associated with increased pathology in gammaretroviruses. Whereas KoRV-A uses the sodium-dependent phosphate transporter 1 (PiT1) as a receptor, KoRV-B employs a different receptor, the thiamine transporter 1 (THTR1), to infect cells. KoRV-B is transmitted from dam to offspring through de novo infection, rather than via genetic inheritance like KoRV-A. Detection of KoRV-B in native Australian koalas should provide a history, and a mode for remediation, of leukemia/lymphoma currently endemic in this population.

Species distribution modeling of northern sea otters (Enhydra lutris kenyoni) in a data-limited ecosystem.

Species distribution models (SDMs) are used to map and predict the geographic distributions of animals based on environmental covariates. Typically, SDMs require high-resolution habitat data and time series information on animal locations. For data-limited regions, defined as having scarce habitat or animal survey data, modeling is more challenging, often failing to incorporate important environmental attributes. For example, for sea otters (Enhydra lutris), a federally protected keystone species with variable population trends across the species' range, predictive modeling of distributions has been successfully conducted in areas with robust sea otter population and habitat data. We used open-access data and employed a presence-only model, maximum entropy (MaxEnt), to investigate subtidal habitat associations (substrate and algal cover, bathymetry, and rugosity) of northern sea otters (E. lutris kenyoni) for a data-limited ecosystem, represented by Kachemak Bay, Alaska. Habitat association results corroborated previous findings regarding the importance of bathymetry and understory kelp as predictors of sea otter presence. Novel associations were detected as filamentous algae and shell litter were positively and negatively associated with northern sea otter presence, respectively, advancing existing knowledge of sea otter benthic habitat associations useful for predicting habitat suitability. This study provides a quantitative framework for conducting species distribution modeling with limited temporal and spatial animal distribution and abundance data. Utilizing drop camera information, our novel approach allowed for a better understanding of habitat requirements for a stable northern sea otter population, including bathymetry, understory kelp, and filamentous algae as positive predictors of sea otter presence in Kachemak Bay, Alaska.

Acute Toxicity of Copper to Three Species of Pacific Salmon Fry in Water with Low Hardness and Low Dissolved Organic Carbon.

Proposed development of a mine within Alaska's Bristol Bay watershed (USA) has raised concerns about the potential impact of copper (Cu) on Pacific salmon (Oncorhynchus spp.). We conducted 96-h flow-through bioassays using low-hardness and low dissolved organic carbon water to determine the acute lethal toxicity of Cu to sockeye (Oncorhynchus nerka), Chinook (Oncorhynchus tshawytscha), and coho salmon (Oncorhynchus kisutch) fry. We aimed to determine Cu toxicity under field-relevant water quality conditions and to assess three methods of calculating ambient Cu criteria: the biotic ligand model (BLM), a multiple linear regression model endorsed by the US Environmental Protection Agency, and the hardness-based model currently used by the State of Alaska. The criteria generated by all models were below 20% lethal Cu concentrations by factors ranging from 2.2 to 54.3, indicating that all criteria would be protective against mortality. The multiple linear regression-based criteria were the most conservative and were comparable to BLM-based criteria. The median lethal concentrations (LC50s) for sockeye, Chinook, and coho were 35.2, 23.9, and 6.3 µg Cu/L, respectively. We also used the BLM to predict LC50s for each species. Model predictions differed from empirical LC50s by factors of 0.7 for sockeye and Chinook salmon, and 1.1 for coho salmon. These differences fell within the acceptable range of ±2, indicating the model's accuracy. We calculated critical lethal Cu accumulation values for each species to account for differing water chemistry in each bioassay; the present study revealed that coho salmon were most sensitive to Cu, followed by sockeye and Chinook salmon. Our findings underscore the importance of considering site- and species-specific factors when modeling Cu toxicity. The empirical data we present may enhance Cu risk assessments for Pacific salmon. Environ Toxicol Chem 2023;42:2440-2452. © 2023 SETAC.

Corticosterone predicts foraging behavior and parental care in macaroni penguins.

Corticosterone has received considerable attention as the principal hormonal mediator of allostasis or physiological stress in wild animals. More recently, it has also been implicated in the regulation of parental care in breeding birds, particularly with respect to individual variation in foraging behavior and provisioning effort. There is also evidence that prolactin can work either inversely or additively with corticosterone to achieve this. Here we test the hypothesis that endogenous corticosterone plays a key physiological role in the control of foraging behavior and parental care, using a combination of exogenous corticosterone treatment, time-depth telemetry, and physiological sampling of female macaroni penguins (Eudyptes chrysolophus) during the brood-guard period of chick rearing, while simultaneously monitoring patterns of prolactin secretion. Plasma corticosterone levels were significantly higher in females given exogenous implants relative to those receiving sham implants. Increased corticosterone levels were associated with significantly higher levels of foraging and diving activity and greater mass gain in implanted females. Elevated plasma corticosterone was also associated with an apparent fitness benefit in the form of increased chick mass. Plasma prolactin levels did not correlate with corticosterone levels at any time, nor was prolactin correlated with any measure of foraging behavior or parental care. Our results provide support for the corticosterone-adaptation hypothesis, which predicts that higher corticosterone levels support increased foraging activity and parental effort.

Seasonal patterns of prolactin and corticosterone secretion in an Antarctic seabird that moults during reproduction.

In avian species that have evolved life-history strategies wherein molt and breeding overlap, there are potential conflicts between the regulatory roles of baseline prolactin and corticosterone in parental care (positive) and moult (negative). We describe seasonal patterns of hormonal secretion, moult, and parental behaviour in sibling species of giant petrels (Macronectes spp.) which begin moult during the incubation/early chick-rearing stage of reproduction. With the exception of male Southern giant petrels (Macronectes giganteus), prolactin secretion and moult in Northern (Macronectes halli) and female Southern giant petrels conformed to those observed in all other avian species, with the initiation of moult coincident with decreases from peak prolactin levels. However, male Southern giant petrels began moulting early in incubation when prolactin was increasing and had not yet peaked, which suggests a requirement of prolactin for incubation behaviour and a dissociation of prolactin from moult. Corticosterone showed little seasonal variation and no relationship with moult. When comparing prolactin, corticosterone, and moult in failed vs. active breeders, we found that failed breeding enabled a more rapid down-regulation of prolactin, thus facilitating a more rapid moult. We present specific examples of the behavioural ecology of giant petrels which we conclude help mediate any potential hormonal conflicts between parental care and moult.

The genetic epidemiology of idiopathic scoliosis.

PURPOSE: Idiopathic scoliosis is a complex developmental syndrome defined by an abnormal structural curvature of the spine. High treatment costs, chronic pain/discomfort, and the need for monitoring at-risk individuals contribute to the global healthcare burden of this musculoskeletal disease. Although many studies have endeavored to identify underlying genes, little progress has been made in understanding the etiopathogenesis. The objective of this comprehensive review was to summarize genetic associations/linkages with idiopathic scoliosis, as well as explore the strengths and weaknesses of each study, such that it may serve as a guide for the design and interpretation of future genetic studies in scoliosis. METHODS: We searched PubMed and Human Genome Epidemiology (HuGE) Navigator using the search terms "gene and scoliosis". Linkage or association studies published in English and available full-text were further analyzed as regards results, experimental design, and statistical approach. RESULTS: We identified and analyzed 50 studies matching our criteria. These consisted of 34 candidate gene studies (6 linkage, 28 association) and 16 genome-wide studies [14 pedigree-based linkage, 2 genome-wide association studies (GWAS)]. Findings involved genes related to connective tissue structure, bone formation/metabolism, melatonin signaling pathways, puberty and growth, and axon guidance pathways. Variability in results between studies suggested ethnic and/or genetic heterogeneity. CONCLUSIONS: The major difficulty in idiopathic scoliosis research is phenotypic and genetic heterogeneity. Genetic research was overrepresented by underpowered studies. The use of biological endophenotypes, as well as restricted clinical definitions, may help to partition variation and increase the power of studies to detect or confirm an effect.

Altered mechanotransduction in adolescent idiopathic scoliosis osteoblasts: an exploratory in vitro study.

Adolescent idiopathic scoliosis (AIS) is the most prevalent pediatric spinal deformity. We previously demonstrated elongated cilia and an altered molecular mechanosensory response in AIS osteoblasts. The purpose of this exploratory study was to characterize the mechanosensory defect occurring in AIS osteoblasts. We found that cilia length dynamics in response to flow significantly differ in AIS osteoblasts compared to control cells. In addition, strain-induced rearrangement of actin filaments was compromised resulting in a failure of AIS osteoblasts to position or elongate in function of the bidirectional-applied flow. Contrary to control osteoblasts, fluid flow had an inhibitory effect on AIS cell migration. Moreover, flow induced an increase in secreted VEGF-A and PGE2 in control but not AIS cells. Collectively our data demonstrated that in addition to the observed primary cilium defects, there are cytoskeletal abnormalities correlated to impaired mechanotransduction in AIS. Thus, we propose that the AIS etiology could be a result of generalized defects in cellular mechanotransduction given that an adolescent growing spine is under constant stimulation for growth and bone remodeling in response to applied mechanical forces. Recognition of an altered mechanotransduction as part of the AIS pathomechanism must be considered in the conception and development of more effective bracing treatments.

Implementing Root Cause Analysis and Action: Integrating Human Factors to Create Strong Interventions and Reduce Risk of Patient Harm.

OBJECTIVES: The goal of this study was to develop a systems approach for root cause analysis and action to achieve strong, sustainable interventions. The team integrated human factors principles into the design of interventions to ensure solutions maintain compatibility with human capabilities and limitations resulting in stronger solutions to prevent reoccurrence. METHODS: This study was conducted at a 7-hospital health system located in southwestern Virginia. Including human factors in a new root cause analysis and action process allowed the team to design strong interventions. To assess the results of this process, a team evaluated all interventions over a 4-year period (2.75-y preimplementation and 1.4-y postimplementation). Interventions were initially blind coded and then consensus coding was executed to finalize the strength of each intervention according to the VA National Center for Patient Safety evaluation tool. RESULTS: The new process resulted in an efficient method to address adverse events with increased staff satisfaction and interventions more resilient to human error. The number of events with strong interventions increased from 43% to 69% after implementation of the new process. CONCLUSIONS: Tailoring an event investigation process to an organizational culture is critical to implementation success. Adding human factors into the design of interventions helped facilitate intervention implementation and sustainability. Blinded ratings showed that with the integration of human factors, there was improved strength of interventions. This indicates that a focus on strong system improvement (rather than weaker individual human-based solutions) will lead to improved staff satisfaction and patient safety.

Comprehensive assessment of NR ligand polypharmacology by a multiplex reporter NR assay.

Nuclear receptors (NR) are ligand-modulated transcription factors that regulate multiple cell functions and thus represent excellent drug targets. However, due to a considerable NR structural homology, NR ligands often interact with multiple receptors. Here, we describe a multiplex reporter assay (the FACTORIAL NR) that enables parallel assessment of NR ligand activity across all 48 human NRs. The assay comprises one-hybrid GAL4-NR reporter modules transiently transfected into test cells. To evaluate the reporter activity, we assessed their RNA transcripts. We used a homogeneous RNA detection approach that afforded equal detection efficacy and permitted the multiplex detection in a single-well format. For validation, we examined a panel of selective NR ligands and polypharmacological agonists and antagonists of the progestin, estrogen, PPAR, ERR, and ROR receptors. The assay produced highly reproducible NR activity profiles (r > 0.96) permitting quantitative assessment of individual NR responses. The inferred EC50 values agreed with the published data. The assay showed excellent quality ( = 0.73) and low variability ( = 7.2%). Furthermore, the assay permitted distinguishing direct and non-direct NR responses to ligands. Therefore, the FACTORIAL NR enables comprehensive evaluation of NR ligand polypharmacology.

A major QTL controls susceptibility to spinal curvature in the curveback guppy.

BACKGROUND: Understanding the genetic basis of heritable spinal curvature would benefit medicine and aquaculture. Heritable spinal curvature among otherwise healthy children (i.e. Idiopathic Scoliosis and Scheuermann kyphosis) accounts for more than 80% of all spinal curvatures and imposes a substantial healthcare cost through bracing, hospitalizations, surgery, and chronic back pain. In aquaculture, the prevalence of heritable spinal curvature can reach as high as 80% of a stock, and thus imposes a substantial cost through production losses. The genetic basis of heritable spinal curvature is unknown and so the objective of this work is to identify quantitative trait loci (QTL) affecting heritable spinal curvature in the curveback guppy. Prior work with curveback has demonstrated phenotypic parallels to human idiopathic-type scoliosis, suggesting shared biological pathways for the deformity. RESULTS: A major effect QTL that acts in a recessive manner and accounts for curve susceptibility was detected in an initial mapping cross on LG 14. In a second cross, we confirmed this susceptibility locus and fine mapped it to a 5 cM region that explains 82.6% of the total phenotypic variance. CONCLUSIONS: We identify a major QTL that controls susceptibility to curvature. This locus contains over 100 genes, including MTNR1B, a candidate gene for human idiopathic scoliosis. The identification of genes associated with heritable spinal curvature in the curveback guppy has the potential to elucidate the biological basis of spinal curvature among humans and economically important teleosts.

Evolution of embryonic developmental period in the marine bird families Alcidae and Spheniscidae: roles for nutrition and predation?

BACKGROUND: Nutrition and predation have been considered two primary agents of selection important in the evolution of avian life history traits. The relative importance of these natural selective forces in the evolution of avian embryonic developmental period (EDP) remain poorly resolved, perhaps in part because research has tended to focus on a single, high taxonomic-level group of birds: Order Passeriformes. The marine bird families Alcidae (auks) and Spheniscidae (penguins) exhibit marked variation in EDP, as well as behavioural and ecological traits ultimately linked to EDP. Therefore, auks and penguins provide a unique opportunity to assess the natural selective basis of variation in a key life-history trait at a low taxonomic-level. We used phylogenetic comparative methods to investigate the relative importance of behavioural and ecological factors related to nutrition and predation in the evolution of avian EDP. RESULTS: Three behavioural and ecological variables related to nutrition and predation risk (i.e., clutch size, activity pattern, and nesting habits) were significant predictors of residual variation in auk and penguin EDP based on models predicting EDP from egg mass. Species with larger clutch sizes, diurnal activity patterns, and open nests had significantly shorter EDPs. Further, EDP was found to be longer among birds which forage in distant offshore waters, relative to those that foraged in near shore waters, in line with our predictions, but not significantly so. CONCLUSION: Current debate has emphasized predation as the primary agent of selection driving avian life history diversification. Our results suggest that both nutrition and predation have been important selective forces in the evolution of auk and penguin EDP, and highlight the importance of considering these questions at lower taxonomic scales. We suggest that further comparative studies on lower taxonomic-level groups will continue to constructively inform the debate on evolutionary determinants of avian EDP, as well as other life history parameters.

The Tyranny of Content: "Content Coverage" as a Barrier to Evidence-Based Teaching Approaches and Ways to Overcome It.

Instructors have inherited a model for conscientious instruction that suggests they must cover all the material outlined in their syllabus, and yet this model frequently diverts time away from allowing students to engage meaningfully with the content during class. We outline the historical forces that may have conditioned this teacher-centered model as well as the disciplinary pressures that inadvertently reward it. As a way to guide course revision and move to a learner-centered teaching approach, we propose three evidence-based strategies that instructors can adopt: 1) identify the core concepts and competencies for your course; 2) create an organizing framework for the core concepts and competencies; and 3) teach students how to learn in your discipline. We further outline examples of actions that instructors can incorporate to implement each of these strategies. We propose that moving from a content-coverage approach to these learner-centered strategies will help students better learn and retain information and apply it to new situations.

Idiopathic-type scoliosis is not exclusive to bipedalism.

Human familial/idiopathic-type scoliosis (IS) is a complex genetic disorder for which the cause is unknown. The curve phenotype characteristically demonstrates pronounced morphological and developmental variability that is likely a consequence of biomechanical, environmental, and genetic differences between individuals. In addition, risk factors that affect the propensity for curves to progress to severity are unknown. Progress in understanding the fundamental biology of idiopathic-type scoliosis has been limited by the lack of a genetic/developmental animal model. Prior to consideration of teleosts, developmental idiopathic-type scoliosis has been considered to be exclusive to humans. Consequently, there is the notion that the syndrome is a result of bipedalism, and many studies try to explain the deformity from this anthrocentric viewpoint. This perspective has been reinforced by the choice of animals used for study, in that chickens and bipedal rats and mice demonstrate idiopathic-type curvature when made melatonin-deficient, but quadrupedal animals do not. Overlooked is the fact that teleosts also demonstrate similar curvature when made melatonin-deficient. Our characterization of the guppy curveback has demonstrated that non-induced idiopathic-type curvature is not exclusive to humans, nor bipedalism. We hypothesize that unique morphological, developmental and genetic parallels between the human and guppy syndromes are due to common molecular pathways involved in the etiopathogenesis of both phenotypes. We explore established gene conservation between human and teleost genomes that are in pathways hypothesized to be involved in the IS syndrome. We present non-induced vertebral wedging as a unique shared feature in IS and curveback that suggests a similar interaction between a molecular phenotype on the level of the vertebral anatomy, and biomechanics. We propose that rather than bipedalism per se, expression of idiopathic-type scoliosis is dependent on normal spinal loading applied along the cranio-caudal axis that interacts with an unknown factor causing the primary curve. In this regard, a comparative biological approach using a simplified teleost model will promote discovery of basic processes integral to idiopathic-type scoliosis in teleosts and humans, and highlight human-specific aspects of the deformity.

A unique protein kinase C-dependent pathway for tissue factor downregulation in pericytes.

Essentials Many mediators increase tissue factor (TF) expression in a wide variety of cell types. The only known example of TF downregulation is by pericytes during wound healing angiogenesis. Downregulation of TF mRNA and protein in cultured pericytes is Protein Kinase C (PKC) dependent. Pericyte TF regulation is unique, since PKC mediates increased TF in all other cell types tested. SUMMARY: Background Embryonic and tumor-associated angiogenesis are linked to elevated expression of the procoagulant transmembrane receptor tissue factor (TF). In contrast, we have reported that high baseline TF expression by perivascular cells (pericytes) is dramatically reduced during angiogenesis at sites of wound healing. This is the only setting in which active TF downregulation has been reported, thus revealing a novel mechanism of TF regulation. Objectives To define the mechanisms underlying the unique pattern of TF expression in pericytes. Methods TF expression in primary cultures of human pericytes is not altered by angiogenic cytokines or growth factors, but is actively downregulated by phorbol 12-myristate 13-acetate (PMA). We characterized TF transcription, protein stability and trafficking in response to PMA. Results Exposure to PMA reduced TF mRNA synthesis and shortened the half-life of TF protein from 11 h to 4.5 h. Addition of PMA rapidly triggered endocytosis of cell surface TF, followed by degradation in lysosomes. Cell surface TF coagulant activity was maintained until internal stores were depleted. Reduction of TF transcription, TF endocytosis and enhanced degradation of TF protein were all blocked by broad-spectrum inhibitors of protein kinase C (PKC). This was a surprising finding, because PKC activation increases TF expression in other cell types that have been tested. Conclusions The unique PKC-dependent pathway of TF downregulation in pericytes suggests that TF downregulation may play a functional role in angiogenesis. Distinct pathways regulating pathological and physiological TF expression could be utilized to modulate TF expression for therapeutic purposes.

Association of Circulating YKL-40 Levels and CHI3L1 Variants with the Risk of Spinal Deformity Progression in Adolescent Idiopathic Scoliosis.

The cellular and molecular mechanisms underlying spinal deformity progression in adolescent idiopathic scoliosis (AIS) remain poorly understood. In this study, 804 French-Canadian patients and 278 age- and sex-matched controls were enrolled and genotyped for 12 single nucleotide polymorphisms (SNPs) in the chitinase 3-like 1 (CHI3L1) gene or its promoter. The plasma YKL-40 levels were determined by ELISA. We showed that elevation of circulating YKL-40 levels was correlated with a reduction of spinal deformity progression risk. We further identified significant associations of multiple CHI3L1 SNPs and their haplotypes with plasma YKL-40 levels and scoliosis severity as a function of their classification in a specific endophenotype. In the endophenotype FG3 group, we found that patients harboring the haplotype G-G-A-G-G-A (rs880633|rs1538372|rs4950881|rs10399805|rs6691378|rs946261), which presented in 48% of the cases, showed a positive correlation with the plasma YKL-40 levels (P = 7.6 × 10-6 and coefficient = 36). Conversely, the haplotype A-A-G-G-G-G, which presented in 15% of the analyzed subjects, showed a strong negative association with the plasma YKL-40 levels (P = 2 × 10-9 and coefficient = -9.56). We found that this haplotype showed the strongest association with AIS patients in endophenotype FG2 (P = 9.9 × 10-6 and coefficient = -13.53), who more often develop severe scoliosis compared to those classified in the other two endophenotypes. Of note, it showed stronger association in females (P = 1.6 × 10-7 and coefficient = -10.08) than males (P = 0.0021 and coefficient = -9.01). At the functional level, we showed that YKL-40 treatments rescued Gi-coupled receptor signalling dysfunction occurring in primary AIS osteoblasts. Collectively, our findings reveal a novel role for YKL-40 in AIS pathogenesis and a new molecular mechanism interfering with spinal deformity progression.

A Differential Hypofunctionality of Gαi Proteins Occurs in Adolescent Idiopathic Scoliosis and Correlates with the Risk of Disease Progression.

Adolescent idiopathic scoliosis is the most prevalent spine deformity and the molecular mechanisms underlying its pathophysiology remain poorly understood. We have previously found a differential impairment of melatonin receptor signaling in AIS osteoblasts allowing the classification of patients into three biological endophenotypes or functional groups (FG1, FG2 and FG3). Here, we provide evidence that the defect characterizing each endophenotype lies at the level of Gαi proteins leading to a systemic and generalized differential impairment of Gi-coupled receptor signaling. The three Gαi isoforms exhibited a selective serine phosphorylation patterns for each AIS endophenotype resulting in a differential reduction in Gαi protein activity as determined by cellular dielectric spectroscopy and small interfering RNA methods. We found that one endophenotype (FG2) with phosphorylated Gαi1 and Gαi2 was consistently associated with a significantly high risk of spinal deformity progression when compared to the other two endophenotypes (FG1 and FG3). We further demonstrated that each endophenotype is conserved among affected family members. This study expands our understanding of the mechanism underlying the Gi-coupled receptor signaling dysfunction occurring in AIS and provides the first evidence for its hereditary nature. Collectively, our findings offers a new perspective on Gαi hypofunctionality in a human disease by revealing specific serine phosphorylation signatures of Gαi isoforms that may facilitate the identification of AIS patients at risk of spinal deformity progression.

Identification of Elongated Primary Cilia with Impaired Mechanotransduction in Idiopathic Scoliosis Patients.

The primary cilium is an outward projecting antenna-like organelle with an important role in bone mechanotransduction. The capacity to sense mechanical stimuli can affect important cellular and molecular aspects of bone tissue. Idiopathic scoliosis (IS) is a complex pediatric disease of unknown cause, defined by abnormal spinal curvatures. We demonstrate significant elongation of primary cilia in IS patient bone cells. In response to mechanical stimulation, these IS cells differentially express osteogenic factors, mechanosensitive genes, and signaling genes. Considering that numerous ciliary genes are associated with a scoliosis phenotype, among ciliopathies and knockout animal models, we expected IS patients to have an accumulation of rare variants in ciliary genes. Instead, our SKAT-O analysis of whole exomes showed an enrichment among IS patients for rare variants in genes with a role in cellular mechanotransduction. Our data indicates defective cilia in IS bone cells, which may be linked to heterogeneous gene variants pertaining to cellular mechanotransduction.

Genetic diversity of koala retroviral envelopes.

Genetic diversity, attributable to the low fidelity of reverse transcription, recombination and mutation, is an important feature of infectious retroviruses. Under selective pressure, such as that imposed by superinfection interference, gammaretroviruses commonly adapt their envelope proteins to use alternative receptors to overcome this entry block. The first characterized koala retroviruses KoRV subgroup A (KoRV-A) were remarkable in their absence of envelope genetic variability. Once it was determined that KoRV-A was present in all koalas in US zoos, regardless of their disease status, we sought to isolate a KoRV variant whose presence correlated with neoplastic malignancies. More than a decade after the identification of KoRV-A, we isolated a second subgroup of KoRV, KoRV-B from koalas with lymphomas. The envelope proteins of KoRV-A and KoRV-B are sufficiently divergent to confer the ability to bind and employ distinct receptors for infection. We have now obtained a number of additional KoRV envelope variants. In the present studies we report these variants, and show that they differ from KoRV-A and KoRV-B envelopes in their host range and superinfection interference properties. Thus, there appears to be considerable variation among KoRVs envelope genes suggesting genetic diversity is a factor following the KoRV-A infection process.