Initiation and emerging complexity of the collagen network during prenatal skeletal development

The establishment of a complex collagen network is critical for the architecture and mechanical properties of cartilage and bone. However, when and how the key collagens in cartilage and bone develop has not been characterised in detail. The study provides a detailed qualitative characterisation of the spatial localisations of collagens I-III, V-VI and IX-XI in the mouse and their regional architecture variation over three developmentally significant time points: when the rudiment starts to form at E13.5 [Theiler stage (TS) 22], when mineralisation is present at E16.5 (TS25) and during the latest prenatal stage at E18.5 (TS27). Dynamic changes in collagen distribution between stages with the progression of the growth plate and mineralisation (particularly collagens I, II, V, X and XI) and dramatic changes in collagen structural organisation and complexity with maturation, especially for collagens II and XI, were observed. The future articular cartilage region was demarcated by pronounced collagens II and VI expression at TS27 and the emergence of collagens I, III, V, IX and XI in the tendon and its insertion site was observed. The present study revealed, for the first time, the emergence and maturation of key cartilage and bone collagens, in high resolution, at multiple locations across the entire rudiment, including the joint regions, at three of the most developmentally significant stages of skeletogenesis, furthering the understanding of disease and regeneration of skeletal tissues

Putting the Earth into Science: Resource, Workshop and Field Trip for High School Science Teachers at GeoCanada 2010

Putting the Earth into Science is a classroom resource that takes an interdisciplinary approach to expanding Earth science content in Canadian high schools. In recent history, Earth science has struggled to be identified as a core subject in school curricula. Differing approaches of whether it is placed in social studies (geography) or science has resulted in identity confusion. Alternatively, it is often seen as a specialist area of study, and hence optional. As a solution to this problem, the National EdGEO Workshop Program has developed a series of curricula-based lesson plans to integrate Earth science topics into the core subjects of physics, chemistry, biology and mathematics. The program will attract teachers of diverse science disciplines, and deliver a meaningful educational experience and important career information to high school students who are largely unaware of how Earth science impacts their daily lives. Putting the Earth into Science was launched during a workshop and field trip offered to teachers across Canada in conjunction with GeoCanada 2010. Sommaire La Terre en science est une source référence d’activités pédagogiques interdisciplinaires visant à accroître le contenu en sciences de la Terre du programme secondaire des écoles canadiennes. Ces dernières années, les sciences de la Terre ont peiné s’imposer comme matière essentielle du programme scolaire. Selon l’approche, elles étaient tantôt incorporées aux sciences sociales (géographie), tantôt aux sciences physiques, d’où la confusion. Elles sont aussi perçues comme matière spécialisée, et optionnelles à ce titre. Comme solution, le National EdGEO Workshop Program a mis au point une série de plans de cours permettant d’intgérer des thèmes de sciences de la Terre aux matières obligatoires comme la physique, la chimie, la biologie et les mathématiques. Le programme intéressera les enseignants de diverses disciplines scientifiques, et leur proposera une démarche éducationnelle riche, et offrira aux éléves du secondaire les informations essentielles sur la profession, eux qui ignorent en grande partie l’impact des sciences de la Terre dans leur vie quotidienne. La Terre en sciences a été lancée officiellement à l’occasion de la tenue d’un atelier et d’une excursion offerts aux enseignants canadiens lors du congrès GeoCanada 2010

Prenatal murine skeletogenesis partially recovers from absent skeletal muscle as development progresses

Skeletal muscle contractions are critical for normal skeletal growth and morphogenesis but it is unclear how the detrimental effects of absent muscle on the bones and joints change over time. Joint shape and cavitation as well as rudiment length and mineralisation were assessed in multiple rudiments at two developmental stages [Theiler stage (TS)24 and TS27] in the splotch-delayed “muscle-less limb” mouse model and littermate controls. Chondrocyte morphology was quantified in 3D in the distal humerus at the same stages. As development progressed, the effects of absent muscle on all parameters except for cavitation become less severe. All major joints in muscle-less limbs were abnormally shaped at TS24, while, by TS27, most muscle-less limb joint shapes were normal or nearly normal. In contrast, any joints that were fused at TS24 did not cavitate by TS27. At TS24, chondrocytes in the distal humerus were significantly smaller in the muscle-less limbs than in controls, while by TS27, chondrocyte volume was similar between the two groups, offering a cell-level mechanism for the partial recovery in shape of muscle-less limbs. Mineralisation showed the most pronounced changes over gestation. At TS24, all muscle-less rudiments studied had less mineralisation than the controls, while at TS27, muscle-less limb rudiments had mineralisation extents equivalent to controls. In conclusion, the effects of muscle absence on prenatal murine skeletogenesis reduced in severity over gestation. Understanding how mammalian bones and joints continue to develop in an environment with abnormal fetal movements provides insights into conditions including hip dysplasia and arthrogryposis

Conodonts from the Cow Head Group, western Newfoundland

At its type section near the village of Cow Head on the Great Northern Peninsula, Newfoundland, the Cow Head Group consists of carbonate breccias, micrites, graded bioclastic limestones and non-calcareous shales with minor sandstones, shaly limestones and non-calcareous siltstones. Many of the limestones are laminated and bioturbated, and some are partially to completely dolomitised. The section is only 300m. thick and ranges in age from Middle Cambrian to Middle Ordovician. It was transported westward by gravity sliding during the Middle Ordovician and it now overlies shelf facies limestones. The sequence was carefully logged and sampled for conodonts in order to determine the existence and extent of conodont zones, and to define the transition between the Cambrian and Ordovician Systems in terms of conodont biostratigraphy. -- Yields of conodonts from the samples are generally sparse and the faunas are rarely diverse. The conodonts are classified using multielement taxonomy wherever possible, and those elements which do not fit into any known multielement species are listed under form taxonomy. -- The Cow Head Group is divided into 14 Units primarily on the basis of conodonts. No conodonts were recovered from the Middle Cambrian and thus it is correlated on the basis of previously reported trilobite faunas. Reasonable correlation can be made with the conodont zones of Balto-Scandia erected by Lindström and Bergström for the Lower Ordovician, however not all of these zones have been recognised. The zones erected by Lindström for the Volkhovian and Kundan Stages of the Baltic Shield (Baltoniodus triangularis Zone to the Amorphognathus variabilis Zone) are not recognised in the Cow Head sequence. Tentative correlations are likewise made with the Australian Lower Ordovician conodont zones. Only a very poor correlation of the Cow Head Group with the conodont zones of the mid-western United States exists, emphasising the difficulty of correlating cratonic and extra-cratonic conodont faunas. -- The Cow Head Group was deposited near the base of the Lower Paleozoic continental slope of eastern North America. It was laid down as a series of mass gravity slides which flowed from the outer shelf and upper slope into an area of active deposition and redistribution of thin carbonate and non-calcareous muds

Effects of imbalanced muscle loading on hip joint development and maturation

The mechanical loading environment influences the development and maturation of joints. In this study, the influence of imbalanced muscular loading on joint development was studied using localized chemical denervation of hip stabilizing muscle groups in neonatal mice. It was hypothesized that imbalanced muscle loading, targeting either Gluteal muscles or Quadriceps muscles, would lead to bilateral hip joint asymmetry, as measured by acetabular coverage, femoral head volume and bone morphometry, and femoral-acetabular shape. The contralateral hip joints as well as age-matched, uninjected mice were used as controls. Altered bone development was analyzed using micro-computed tomography, histology, and image registration techniques at post-natal days (P) 28, 56, and 120. This study found that unilateral muscle unloading led to reduced acetabular coverage of the femoral head, lower total volume, lower bone volume ratio, and lower mineral density, at all three time points. Histologically, the femoral head was smaller in unloaded hips, with thinner triradiate cartilage at P28 and thinner cortical bone at P120 compared to contralateral hips. Morphological shape changes were evident in unloaded hips at P56. Unloaded hips had lower trabecular thickness and increased trabecular spacing of the femoral head compared to contralateral hips. The present study suggests that decreased muscle loading of the hip leads to altered bone and joint shape and growth during post-natal maturation. Statement of Clinical Significance: Adaptations from altered muscle loading during postnatal growth investigated in this study have implications on developmental hip disorders that result from asymmetric loading, such as patients with limb-length inequality or dysplasia. This article is protected by copyright. All rights reserved

Multi-modal detection of fetal movements using a wearable monitor

The importance of Fetal Movement (FM) patterns as a biomarker for fetal health has been extensively argued in obstetrics. However, the inability of current FM monitoring methods, such as ultrasonography, to be used outside clinical environments has made it challenging to understand the nature and evolution of FM. A small body of work has introduced wearable sensor-based FM monitors to address this gap. Despite promises in controlled environments, reliable instrumentation to monitor FM out-of-clinic remains unresolved, particularly due to the challenges of separating FMs from interfering artifacts arising from maternal activities. To date, efforts have been focused almost exclusively on homogenous (single) sensing and information fusion modalities, such as decoupled acoustic or accelerometer sensors. However, FM and related signal artifacts have varying power and frequency bandwidths that homogeneous sensor arrays may not capture or separate efficiently. In this investigation, we introduce a novel wearable FM monitor with an embedded heterogeneous sensor suite combining accelerometers, acoustic sensors, and piezoelectric diaphragms designed to capture a broad range of FM and interfering artifact signal features enabling more efficient isolation of both. We further outline a novel data fusion architecture combining data-dependent thresholding and machine learning to automatically detect FM and separate it from signal artifacts in real-world (home) environments. The performance of the device and the data fusion architecture are validated using 33 h of at-home use through concurrent recording of maternal perception of FM. The FM monitor detected an impressive 82 % of maternally sensed FMs with an overall accuracy of 90 % in recognizing FM and non-FM events. Consistency of detection was strongest from 32 gestational weeks onwards, which overlaps with the critical FM monitoring window for stillbirth prevention. We believe the multi-modal sensor fusion approach presented in this research will be a major milestone in the development of low-cost wearable FM monitors enabling pervasive monitoring of FM in unsupervised environments

Prenatal growth map of the mouse knee joint by means of deformable registration technique.

Joint morphogenesis is the process during which distinct and functional joint shapes emerge during pre- and post-natal joint development. In this study, a repeatable semi-automatic protocol capable of providing a 3D realistic developmental map of the prenatal mouse knee joint was designed by combining Optical Projection Tomography imaging (OPT) and a deformable registration algorithm (Sheffield Image Registration toolkit, ShIRT). Eleven left limbs of healthy murine embryos were scanned with OPT (voxel size: 14.63μm) at two different stages of development: Theiler stage (TS) 23 (approximately 14.5 embryonic days) and 24 (approximately 15.5 embryonic days). One TS23 limb was used to evaluate the precision of the displacement predictions for this specific case. The remaining limbs were then used to estimate Developmental Tibia and Femur Maps. Acceptable uncertainties of the displacement predictions computed from repeated images were found for both epiphyses (between 1.3μm and 1.4μm for the proximal tibia and between 0.7μm and 1.0μm for the femur, along all directions). The protocol was found to be reproducible with maximum Modified Housdorff Distance (MHD) differences equal to 1.9 μm and 1.5 μm for the tibial and femoral epiphyses respectively. The effect of the initial shape of the rudiment affected the developmental maps with MHD of 21.7 μm and 21.9 μm for the tibial and femoral epiphyses respectively, which correspond to 1.4 and 1.5 times the voxel size. To conclude, this study proposes a repeatable semi-automatic protocol capable of providing mean 3D realistic developmental map of a developing rudiment allowing researchers to study how growth and adaptation are directed by biological and mechanobiological factors