Dental Dynamics: A Fast New Tool for Quantifying Tooth and Jaw Biomechanics in 3D Slicer.

Teeth reveal how organisms interact with their environment. Biologists have long looked at the diverse form and function of teeth to study the evolution of feeding, fighting, and development. The exponential rise in the quantity and accessibility of computed tomography (CT) data has enabled morphologists to study teeth at finer resolutions and larger macroevolutionary scales. Measuring tooth function is no easy task, in fact, much of our mechanical understanding is derived from dental shape. Categorical descriptors of tooth shape such as morphological homodonty and heterodonty, overlook nuances in function by reducing tooth diversity for comparative analysis. The functional homodonty method quantitatively assesses the functional diversity of whole dentitions from tooth shape. This method uses tooth surface area and position to calculate the transmission of stress and estimates a threshold for functionally homodont teeth through bootstrapping and clustering techniques. However, some vertebrates have hundreds or thousands of teeth and measuring the shape and function of every individual tooth can be a painstaking task. Here, we present Dental Dynamics, a module for 3D Slicer that allows for the fast and precise quantification of dentitions and jaws. The tool automates the calculation of several tooth traits classically used to describe form and function (i.e., aspect ratio, mechanical advantage, force, etc.). To demonstrate the usefulness of our module we used Dental Dynamics to quantify 780 teeth across 20 salamanders that exhibit diverse ecologies. We coupled these data with the functional homodonty method to investigate the hypothesis that arboreal Aneides salamanders have novel tooth functions. Dental Dynamics provides a new and fast way to measure teeth and increases the accessibility of the functional homodonty method. We hope Dental Dynamics will encourage further theoretical and methodological development for quantifying and studying teeth.

Los dientes revelan cómo los organismos interactúan con su entorno. Los biólogos llevan mucho tiempo observando las diversas formas y funciones de los dientes para estudiar la evolución de la alimentación, la lucha y el desarrollo. El aumento exponencial en la cantidad y accesibilidad de los datos de la tomografía computarizada (CT) ha permitido a los morfólogos estudiar los dientes con resoluciones más finas y escalas macroevolutivas más grandes. Medir la función dental no es una tarea fácil; de hecho, gran parte de nuestro conocimiento mecánico se deriva de la forma dental. Los descriptores categóricos de la forma de los dientes, como la homodoncia y la heterodoncia morfológicas, pasan por alto los matices funcionales al reducir la diversidad de los dientes para el análisis comparativo. El método de la homodoncia funcional cuantitativamente evalúa la diversidad funcional de denticiones enteras a partir de la forma del diente. Sin embargo, algunos vertebrados tienen cientos o miles de dientes y medir la forma y función de cada uno de los dientes individuales puede ser una tarea minuciosa. Aquí te presentamos Dental Dynamics, un módulo para 3D Slicer que permite la cuantificación rápida y precisa de denticíon y mandíbulas. La herramienta automatiza el cálculo de varios rasgos dentales utilizados clásicamente para describir forma y función (es decir, relación de aspecto, ventaja mecánica, fuerza, etc.). Para demostrar la utilidad de nuestros módulos utilizamos Dental Dynamics para cuantificar 780 dientes en 20 salamandras que exhiben ecologías diversas. Combinamos estos datos con el método de homodoncia funcional para investigar la hipótesis de que las salamandras arbóreas Aneides tienen nuevas funciones dentales. Dinámica Dental proporciona una forma nueva y rápida de medir los dientes y aumenta la accesibilidad de los método funcionales de homodoncia. Esperamos que Dental Dynamics fomente más conocimientos teóricos y desarrollo metodológico para la cuantificación y estudio de los dientes.

Motor skill competence and moderate- and vigorous-intensity physical activity: a linear and non-linear cross-sectional analysis of eight pooled trials.

BACKGROUND: Few studies have examined the relationship between motor skill competence and device-measured physical activity in large samples and none have used non-linear modelling. This study assessed the linear and non-linear associations between motor skill competence and physical activity in children using pooled data from eight studies. METHODS: Cross-sectional ActiGraph accelerometer and motor skills competence data from 988 children (50.8% boys) aged 3-11 years were included. Total, object control and locomotor skill competence were assessed using the Test of Gross Motor Skill Development. Linear mixed models were fitted to examine linear associations between motor skill competence and physical activity. Then, restricted cubic splines models were used to assess potential non-linear relationships. Interactions by sex and age were assessed. RESULTS: There was evidence of positive linear associations between total skill, and object control and locomotor skills, with moderate- and vigorous-intensity physical activity; however, the associations with total skill competence and object control better fitted a non-linear model. Non-linear models indicated associations were positive but relatively weak in the low to mid ranges of TGMD/object control scores but at high ranges (~ > 70 out of 100/ and ~ 35 out of 50) the association strength increased for both moderate- and vigorous-intensity physical activity. There were sex interactions for locomotor skills only, specifically for vigorous activity with boys having a stronger positive association than girls. CONCLUSIONS: There appears to be a threshold for object control skill proficiency that children need to reach to enhance their physical activity levels which provides support for a motor skill "proficiency barrier". This provides a tangible benchmark for children to achieve in motor competence programs.

True grit? Comparative anatomy and evolution of gizzards in fishes.

Gut morphology frequently reflects the food organisms digest. Gizzards are organs of the gut found in archosaurs and fishes that mechanically reduce food to aid digestion. Gizzards are thought to compensate for edentulism and/or provide an advantage when consuming small, tough food items (e.g., phytoplankton and algae). It is unknown how widespread gizzards are in fishes and how similar these structures are among different lineages. Here, we investigate the distribution of gizzards across bony fishes to (1) survey different fishes for gizzard presence, (2) compare the histological structure of gizzards in three species, (3) estimate how often gizzards have evolved in fishes, and (4) explore whether anatomical and ecological traits like edentulism and microphagy predict gizzard presence. According to our analyses, gizzards are rare across bony fishes, evolving only six times in a broad taxonomic sampling of 51 species, and gizzard presence is not clearly correlated with factors like gut length or dentition. We find that gizzard morphology varies among the lineages where one is present, both macroscopically (presence of a crop) and microscopically (varying tissue types). We conclude that gizzards likely aid in the mechanical reduction of food in fishes that have lost an oral dentition in their evolutionary past; however, the relative scarcity of gizzards suggests they are just one of many possible solutions for processing tough, nutrient-poor food items. Gizzards have long been present in the evolutionary history of fishes, can be found in a wide variety of marine and freshwater clades, and likely have been overlooked in many taxa.

The moment of tooth: rate, fate and pattern of Pacific lingcod dentition revealed by pulse-chase.

Tooth replacement rates of polyphyodont cartilaginous and bony fishes are hard to determine because of a lack of obvious patterning and maintaining specimens long enough to observe replacement. Pulse-chase is a fluorescent technique that differentially colours developing mineralized tissue. We present in situ tooth replacement rate and position data for the oral and pharyngeal detentions of Ophiodon elongatus (Pacific lingcod). We assessed over 10 000 teeth, in 20 fish, and found a daily replacement rate of about two teeth (3.6% of the dentition). The average tooth is in the dental battery for 27 days. The replacement was higher in the lower pharyngeal jaw (LPJ). We found no difference between replacement rates of feeding and non-feeding fish, suggesting feeding was not a driver of tooth replacement. Lingcod teeth have both a size and location fate; smaller teeth at one spot will not grow into larger teeth, even if a large tooth nearby is lost. We also found increased rates of replacement at the posterior of the LPJ relative to the anterior. We propose that lingcod teeth do not migrate in the jaw as they develop; their teeth are fated in size and location, erupting in their functional position.

The Role of Developmental Integration and Historical Contingency in the Origin and Evolution of Cypriniform Trophic Novelties.

While functional morphologists have long studied the evolution of anatomical structures, the origin of morphological novelties has received less attention. When such novelties first originate they must become incorporated into an integrated system to be rendered fully functional. Thus, developmental integration is key at the origin of morphological novelties. However, given enough evolutionary time such integration may be broken, allowing for a division of labor that is facilitated by subsequent decoupling of structures. Cypriniformes represent a diverse group of freshwater fishes characterized by several trophic novelties that include: kinethmoid-mediated premaxillary protrusion, a muscular palatal and post-lingual organ, hypertrophied lower pharyngeal jaws that masticate against the base of the neurocranium, novel pharyngeal musculature controlling movement of the hypertrophied lower pharyngeal jaws, and in a few species an incredibly complex epibranchial organ used to aggregate filtered phytoplankton. Here, we use the wealth of such trophic novelties in different cypriniform fishes to present case studies in which developmental integration allowed for the origin of morphological innovations. As proposed in case studies 1 and 2 trophic innovations may be associated with both morphological and lineage diversification. Alternatively, case studies 3 and 4 represent a situation where ecological niche was expanded but with no concomitant increase in species diversity.

Effects of a 'school-based' physical activity intervention on adiposity in adolescents from economically disadvantaged communities: secondary outcomes of the 'Physical Activity 4 Everyone' RCT.

BACKGROUND/OBJECTIVES: Obesity prevention during adolescence is a health priority. The 'Physical Activity 4 Everyone' (PA4E1) study tested a multi-component physical activity intervention in 10 secondary schools from socio-economically disadvantaged communities. This paper aimed to report the secondary outcomes of the study; to determine whether the intervention impacted on adiposity outcomes (weight, body mass index (BMI), BMI z-score), and whether any effect was moderated by sex, baseline BMI and baseline physical activity level, at 12 and 24 months. SUBJECTS/METHODS: A cluster randomised controlled trial was conducted in New South Wales, Australia. The school-based intervention included seven physical activity strategies targeting the following: curriculum (strategies to maximise physical activity in physical education, student physical activity plans, an enhanced school sport programme); school environment (physical activity during school breaks, modification of school policy); and parents and the community (parent engagement, links with community physical activity providers). Students' weight (kg), BMI and BMI z-score, were collected at baseline (Grade 7), 12 and 24 months. Linear Mixed Models were used to assess between-group mean difference from baseline to 12 and 24 months. Exploratory sub-analyses were undertaken according to three moderators of energy balance. RESULTS: A total of 1150 students (mean age=12 years) provided outcome data at baseline, 1051 (91%) at 12 months and 985 (86%) at 24 months. At 12 months, there were group-by-time effects for weight (mean difference=-0.90 kg (95% confidence interval (CI)=-1.50, -0.30), P<0.01) and BMI (-0.28 kg m-2 (-0.50, -0.06), P=0.01) in favour of the intervention group, but not for BMI z-score (-0.05 (-0.11; 0.01), P=0.13). These findings were consistent for weight (-0.62 kg (-1.21, 0.03), P=0.01) and BMI (-0.28 kg m-2 (-0.49, -0.06), P=0.01) at 24 months, with group-by-time effects also found for BMI z-score (-0.08 (-0.14; -0.02), P=0.02) favouring the intervention group. CONCLUSION: The PA4E1 school-based intervention achieved moderate reductions in adiposity among adolescents from socio-economically disadvantaged communities. Multi-component interventions that increase adolescents' engagement in moderate-to-vigorous physical activity (MVPA) may assist in preventing unhealthy weight gain.

Clinical evaluation of the IONA test: a non-invasive prenatal screening test for trisomies 21, 18 and 13.

OBJECTIVE: To evaluate the clinical accuracy of the IONA® test for aneuploidy screening. METHODS: This was a multicenter blinded study in which plasma samples from pregnant women at increased risk of trisomy 21 underwent cell-free DNA analysis utilizing the IONA test. For each sample, the IONA software generated a likelihood ratio and a maternal age-adjusted probability risk score for trisomies 21, 18 and 13. All results from the IONA test were compared against accepted diagnostic karyotyping. RESULTS: A total of 442 maternal samples were obtained, of which 437 had test results available for analysis and assessment of clinical accuracy. The IONA test had a detection rate of 100% for trisomies 21 (n = 43; 95% CI, 87.98-100%), 18 (n = 10; 95% CI, 58.72-100%) and 13 (n = 5; 95% CI, 35.88-100%) with cut-offs applied to likelihood ratio (cut-off > 1 considered high risk for trisomy) and probability risk score incorporating adjustment for maternal age (cut-off ≥ 1/150 considered high risk for trisomy). The false-positive rate (FPR) was 0% for trisomies 18 and 13 with both analysis outputs. For trisomy 21, a FPR of 0.3% was observed for the likelihood ratio, but became 0% with adjustment for maternal age. CONCLUSION: This study indicates that the IONA test is suitable for trisomy screening in a high-risk screening population. The result-interpretation feature of the IONA software should facilitate wider implementation, particularly in local laboratories, and should be a useful addition to the current screening methods for trisomies 21, 18 and 13.