Matthew Harris

Heterotopic ossification is the inappropriate formation of bone in soft tissues of the body. It can manifest spontaneously in rare genetic conditions or as a response to injury, known as acquired heterotopic ossification. There are several experimental models for studying heterotopic ossification from different sources of damage. However, their tenuous mechanistic relevance to the human condition, invasive and laborious nature and/or lack of amenability to chemical and genetic screens, limit their utility. To address these limitations, we developed a simple zebrafish injury model that manifests heterotopic ossification in response to micro-fractures in combination with muscle injury. These findings indicate that clinically-emulated injuries in zebrafish can lead to osteo-induction and proliferation as observed in heterotopic ossification in myositis ossificans traumatica. Exploiting this model, we analysed the penetrance and expressivity of heterotopic ossification and defined the transcriptional response to trauma, identifying differentially regulated genes. Taking advantage of defined mutants in several of these candidates, we explored their impact on heterotopic bone formation. Our findings revealed that an increase in potassium channel Kcnk5b activity potentiates injury response. In contrast, we demonstrate that inflammatory responses are essential for the ectopic bone growth, as mutations in Interleukin 11 receptor paralogue (Il11ra) exhibit a drastically reduced ossification response. Based on these findings, we postulate that enhanced ionic signaling, specifically through Kcnk5b, regulates the intensity of the skeletogenic injury response, which, in part …

Any organism's health and disease is inseparably intertwined with its evolutionary history and its development from fertilized egg to adult–and, of course, humans are no exception. In 1890, the British surgeon and zoologist John Bland Sutton published the forward‐thinking monograph Evolution and Disease, which remains highly relevant to this day (Bland Sutton, 1890). Providing detailed and richly illustrated accounts of naturally occurring morphological quirks and malformations from the animal kingdom, his survey predated by a few years William Bateson's similar, yet much more famous Materials for the Study of Variation (Bateson, 1894). Bland Sutton's work had the foresight to make explicit connections between healthy, adaptive phenotypes in animals and disease states in humans. He wrote:“And in many instances we shall find conditions which we regard as abnormal in man, presenting themselves as …

• Unintentional THC ingestions range in symptoms and can present in groups, such as a family, and should be included in the differential diagnosis for the acutely altered patient.• Unintentional THC ingestions in children are preventable and it is the responsibility of medical providers to treat such incidents as sentinel events, and educate our communities to create safe environments for the children that we care for.

The skull roof, or calvaria, is comprised of interlocking plates of bone. Premature suture fusion (craniosynostosis, CS) or persistent fontanelles are common defects in calvarial development. Although some of the genetic causes of these disorders are known, we lack an understanding of the instructions directing the growth and migration of progenitors of these bones, which may affect the suture patency. Here, we identify graded expression of Fibronectin (FN1) protein in the mouse embryonic cranial mesenchyme (CM) that precedes the apical expansion of calvarial osteoblasts. Syndromic forms of CS exhibit dysregulated FN1 expression, and we find FN1 expression is altered in a mouse CS model as well. Conditional deletion of Fn1 in CM causes diminished frontal bone expansion by altering cell polarity and shape. To address how osteoprogenitors interact with the observed FN1 prepattern, we conditionally ablate …

Ecological and evolutionary transitions offer an excellent opportunity to examine the molecular basis of adaptation. Fishes of the order Beloniformes include needlefishes, flyingfishes, halfbeaks, and allies, and comprise over 200 species occupying a wide array of habitats—from the marine epipelagic zone to tropical rainforest rivers. These fishes also exhibit a diversity of diets, including piscivory, herbivory, and zooplanktivory. We investigated how diet and habitat affected the molecular evolution of cone opsins, which play a key role in bright light and colour vision and are tightly linked to ecology and life history. We analyzed a targeted-capture dataset to reconstruct the evolutionary history of beloniforms and assemble cone opsin sequences. We implemented codon-based clade models of evolution to examine how molecular evolution was affected by habitat and diet. We found high levels of positive selection in …

The transition from fins to limbs has been a rich source of discussion for more than a century. One open and important issue is understanding how the mechanisms that pattern digits arose during vertebrate evolution. In this context, the analysis of Hox gene expression and functions to infer evolutionary scenarios has been a productive approach to explain the changes in organ formation, particularly in limbs. In tetrapods, the transcription of Hoxd genes in developing digits depends on a well-characterized set of enhancers forming a large regulatory landscape1,2. This control system has a syntenic counterpart in zebrafish, even though they lack bona fide digits, suggestive of deep homology3 between distal fin and limb developmental mechanisms. We tested the global function of this landscape to assess ancestry and source of limb and fin variation. In contrast to results in mice, we show here that the deletion of the homologous control region in zebrafish has a limited effect on the transcription of hoxd genes during fin development. However, it fully abrogates hoxd expression within the developing cloaca, an ancestral structure related to the mammalian urogenital sinus. We show that similar to the limb, Hoxd gene function in the urogenital sinus of the mouse also depends on enhancers located in this same genomic domain. Thus, we conclude that the current regulation underlying Hoxd gene expression in distal limbs was co-opted in tetrapods from a preexisting cloacal program. The orthologous chromatin domain in fishes may illustrate a rudimentary or partial step in this evolutionary co-option.

Fins are not limbs. However, findings from comparative developmental and genetic analyses show that many of the processes essential in establishing a limb are similar for fin formation. Nevertheless, due to their structural differences, fins are not often used as models to understand the causes or potential treatment of limb disorders.Split hand/foot malformation (SHFM) presents with loss or mis-patterning of elements of hands or feet leading to a ‘clefting-like’phenotype, often with joining of the digits. This rare disorder is genetically and phenotypically heterogeneous, and knowledge of its etiology remains largely incomplete. Recent work by Truong et al. provides new insight into SHFM by identifying new genetic variants within three different families, predicted to cause changes in function of the PRDM1/Blimp1 gene. PRDM1 is a transcription factor known to be essential for early appendage development in both …

Methods:Pre-season testing of bilateral CMJ without arm-swing (dual force plates) and unilateral maximum isometric ankle inversion and eversion strength (hand-held dynamometer) was undertaken for 23 sub-elite female netball athletes. Eligible athletes were free from injury and participating in the NSW Netball Premier League competition. Maximum CMJ vertical height, left and right limb CMJ kinetics and ankle inversion and eversion peak force were analysed. Between-limb asymmetry was calculated using bilateral asymmetry index (BAI) for CMJ kinetics and percentage difference (PD) for unilateral ankle strength. Players were categorised by position as either non-circle (WA, C, WD) or circle (GS, GA, GD, GK). Descriptive statistics were reported due the study’s preliminary nature. To aid comparisons between position categories, threshold values were calculated as one standard deviation above and below the …

Objectives:Arteriovenous malformation (AVM) is a congenital lesion with a nidus of irregular blood vessels connecting arteries to veins instead of a normal capillary bed. Somatic MAP2K1 activating mutations in endothelial cells cause extracranial AVM. The purpose of this study was to create a MAP2K1 AVM animal model using zebrafish and to test pharmacotherapy.Methods:Single-cell casper Tg (gata1a: DsRed) zebrafish embryos were injected with plasmid DNA (control [pTol2-Fli: GFP]; mutant [pTol2-Fli: GFP-kdrl: MAP2K1 K57N]) and Tol2 transposase mRNA to mosaically express activated MAP2K1 in endothelial cells. Two cohorts of fish were examined: group 1 (n= 161) established phenotypes and group 2 (n= 126) tested MEK inhibition. Blood flow was visualized using DsRed fluorescence of erythrocytes. Embryos were imaged 72 hours postfertilization.Results:Group 1 exhibited abnormal arteriovenous …

Kryptolebias marmoratus (Kmar), a teleost fish of the order Cyprinodontiformes, has a suite of unique phenotypes and behaviors not observed in other fishes. Many of these phenotypes are discrete and highly plastic—varying over time within an individual, and in some cases reversible. Kmar and its interfertile sister species, K. hermaphroditus, are the only known self‐fertile vertebrates. This unusual sexual mode has the potential to provide unique insights into the regulation of vertebrate sexual development, and also lends itself to genetics. Kmar is easily adapted to the lab and requires little maintenance. However, its internal fertilization and small clutch size limits its experimental use. To support Kmar as a genetic model, we compared alternative husbandry techniques to maximize recovery of early cleavage‐stage embryos. We find that frequent egg collection enhances yield, and that protease treatment promotes …

Recent adaptive radiations are powerful evolutionary case studies which can be parsed to reveal the relationship between genomic variation and the origin of distinct phenotypes. Sympatric radiations of the charr complex (genus Salvelinus), present a trove for comparative genomics of craniofacial evolution as charrs have repeatedly diversified into multiple sympatric morphs with distinct feeding specializations, with species flocks frequently manifesting as stereotypical assemblages of two to three resident lineages. In such repeated variation, commonalities in adaptive response can highlight potential constraints in biasing the type of phenotypes available for evolutionary change. A species flock of Dolly Varden charr (Salvelinus malma) in Lake Kronotskoe constitutes a unique case study of charrs as it contains at least seven true-breeding lineages, each with defining morphological and ecological traits. This is the most extensive radiation described for the genus. Here, we performed the first genome-wide analyses of variation within this species flock to provide a working foundation in which to address genetic foundations for adaptive change in character. Our data support distinct reproductively isolated lineages within the lake environment suggesting true breeding morphs and little hybridization. Analysis of changes within the lacustrine lineages, we find specific selection on thyroid and craniofacial genes as key shared genetic basis for the lake radiation. Further, we find a shift in thyroid signaling as a key modulator of subsequent lineage specification. Our data delineate a clear genetic basis for diversification of specialized lineages and provide a …

The mission of the Society for Craniofacial Genetics and Developmental Biology (SCGDB) is to promote education, research, and communication about normal and abnormal development of the tissues and organs of the head. The SCGDB welcomes as members undergraduate students, graduate students, post doctoral researchers, clinicians, orthodontists, scientists, and academicians who share an interest in craniofacial biology. Each year our members come together to share their novel findings, build upon, and challenge current knowledge of craniofacial biology. © 2016 Wiley Periodicals, Inc.

Somatic mutations occur frequently and can arise during embryogenesis, resulting in the formation of a patchwork of mutant clones. Such mosaicism has been implicated in a broad range of developmental anomalies; however, their etiology is poorly understood. Patients carrying a common somatic oncogenic mutation in either PIK3CA or AKT1 can present with disproportionally large digits or limbs. How mutant clones, carrying an oncogenic mutation that often drives unchecked proliferation, can lead to controlled and coordinated overgrowth is unknown. We use zebrafish to explore the growth dynamics of oncogenic clones during development. Here, in a subset of clones, we observed a local increase in proportion of the fin skeleton closely resembling overgrowth phenotypes in patients. We unravel the cellular and developmental mechanisms of these overgrowths, and pinpoint the cell type and timing of …

Longevity is a defining, heritable trait that varies dramatically between species. To resolve the genetic regulation of this trait, we have mined genomic variation in rockfishes, which range in longevity from 11 to over 205 years. Multiple shifts in rockfish longevity have occurred independently and in a short evolutionary time frame, thus empowering convergence analyses. Our analyses reveal a common network of genes under convergent evolution, encompassing established aging regulators such as insulin signaling, yet also identify flavonoid (aryl-hydrocarbon) metabolism as a pathway modulating longevity. The selective pressures on these pathways indicate the ancestral state of rockfishes was long lived and that the changes in short-lived lineages are adaptive. These pathways were also used to explore genome-wide association studies of human longevity, identifying the aryl-hydrocarbon metabolism pathway to …

The Koras Group is a bimodal volcanosedimentary group located in post-tectonic grabens in a foreland thrust complex in the Kaaien Terrane of the Mesoproterozoic Namaqua-Natal Province of southern Africa. It contains two sequences of mafic and felsic volcanic rocks with an unconformity between them, only the lower sequence being slightly folded. The Koras Group was long regarded as having formed at the end of the 1 210 to 1 000 Ma Namaqua Orogeny, because it lacks the severe deformation and metamorphism of the underlying rocks, with igneous minerals preserved in many samples. Following years of unsuccessful attempts to precisely date the volcanic rocks, the first two ion probe U-Pb zircon studies both reported ages of ~1 172 Ma for the Swartkopsleegte Formation felsic lava in the slightly folded lower sequence (based on relatively few dated zircons) and ~1 100 Ma for the Leeuwdraai …

Longevity is a defining, heritable trait that varies dramatically between species. To resolve the genetic regulation of this trait, we have mined genomic variation in rockfishes, ranging in longevity from 11 to over 205 years. Multiple shifts in rockfish longevity have occurred independently, and in a short evolutionary time frame, thus empowering convergence analyses. Our analyses reveal a common network of genes under convergent restricted evolution in long-lived lineages, encompassing established aging regulators such as insulin-signaling, yet also identify flavonoid (aryl-hydrocarbon) metabolism as a novel pathway modulating longevity. Further, these genes were used to refine human longevity GWAS, identifying the aryl-hydrocarbon metabolism pathway to be significantly associated with human survival to the 99th percentile. This evolutionary intersection defines and cross-validates a novel, conserved genetic architecture that associates with the evolution of longevity across vertebrates.

Low-density Lipoprotein Receptor-related Protein 5 (LRP5) functions as a co-receptor for Wnt ligands, controlling expression of genes involved in osteogenesis. In humans, loss-of-function mutations in LRP5 cause Osteoporosis-Pseudoglioma syndrome, a low bone mass disorder, while gain-of-function missense mutations have been observed in individuals with high bone mass. Zebrafish (Danio rerio) is a popular model for human disease research, as genetic determinants that control bone formation are generally conserved between zebrafish and mammals. We generated lrp5- knock-out zebrafish to study its role in skeletogenesis and homeostasis. Loss of lrp5 in zebrafish leads to craniofacial deformities and low bone mineral density (total body and head) at adult ages. To understand the mechanism and consequences of the observed phenotypes, we performed transcriptome analysis of the cranium of adult lrp5 mutants and siblings. Enrichment analysis revealed upregulation of genes significantly associated with hydrolase activity: mmp9, mmp13a, acp5a. acp5a encodes Tartrate-resistant acid phosphatase (TRAP) which is commonly used as an osteoclast marker, while Matrix metalloprotease 9, Mmp9, is known to be secreted by osteoclasts and stimulate bone resorption. These genes point to changes in osteoclast differentiation regulated by lrp5. To analyze these changes functionally, we assessed osteoclast dynamics in mutants and observed increased TRAP staining, significantly larger resorption areas, and developmental skeletal dysmorphologies in the mutant, suggesting higher resorptive activity in the absence of Lrp5 signaling. Our …

Methods: Adolescent basketball, volleyball and Australian Rules football athletes aged 11-14 years were recruited between March and November 2017. Data collection occurred biannually over a 2.5-year period or until ceased with the covid-19 pandemic. Bilateral UTC scans of the patellar tendon were collected at each time point. Tendon structure was quantified into four echotypes (echotype I to IV), with echotype I representing the highest structural integrity and echotype IV representing the least amount of structural integrity. The proportion of each echotype was calculated using UTC software for a region of interest (2cm distal from the disappearance of the inferior patella pole). Statistical analysis was conducted for athletes who presented at the initial data collection session with a PTA (s). Maturity status was defined by Mirwald et al.(2002). Generalised additive modelling and generalised additive mixed …

Localized somatic overgrowth disorders that occur during development can be debilitating, and most often require surgical intervention. Although underlying genetic changes associated with overgrowth have been identified in the majority of cases, the cause of the dysregulated growth and its presentation is unknown. Here we detail current work on a specific overgrowth disorder, macrodactyly, in which overgrowth is localized and shows integration with developmental patterning of the limb, providing coordination of the resulting overgrowth structure. We provide clinical analysis of presentation of macrodactyly in a cohort of patients and provide experimental evidence for nerve and vascular-biased regulation of growth. We provide the first animal model that recapitulates macrodactyly and provide evidence that genetic modifiers may underlie the development of this disorder. The unique presentation of macrodactyly provides a framework to identify the causes and regulatory activities that shape hyperplastic signals that lead to integrated patterning in overgrowth. Use of our experimental model suggests potential for genetic modifiers as important for the particular presentation of this disorder over other PIK3CA-related growth disorders.

Methods: 173 athletes were recruited from the specialised sporting programs of basketball, volleyball, and Australian Rules football. Athletes were tested biannually for up to 2.5 years or until data collection ceased due to the covid-19 pandemic. To be eligible for inclusion, athletes had to be active in a selected sporting program and be between the ages of 11-14 at the initial data collection. Bilateral patellar tendon ultrasound tissue characterisation scans were conducted at each data collection point for each athlete to identify patellar tendon abnormality. Descriptive analysis was conducted for any athlete that had or went to develop a patellar tendon abnormality during the longitudinal study period. Maturity status of each athlete was calculated via the maturity offset equations (Mirwald et al (2002).Results: Seventeen of the 173 (9.8%) athletes developed a patellar tendon abnormality during this longitudinal study …