miR-133-mediated regulation of the Hedgehog pathway orchestrates embryo myogenesis

Skeletal myogenesis serves as a paradigm to investigate the molecular mechanisms underlying exquisitely regulated cell fate decisions in developing embryos. The evolutionary conserved miR-133 family of microRNAs is expressed in the myogenic lineage, but how it acts remains incompletely understood. Here we performed genome-wide differential transcriptomics of miR-133 knock-down (KD) embryonic somites, the source of vertebrate skeletal muscle. This revealed extensive downregulation of Sonic hedgehog (Shh) pathway components: patched receptors, Hedgehog interacting protein, and the transcriptional activator, Gli1. By contrast Gli3, a transcriptional repressor, was de-repressed and confirmed as a direct miR-133 target. Phenotypically, miR-133 KD impaired myotome formation and growth by disrupting proliferation, extracellular matrix deposition and epithelialization. Together this suggests that miR-133 mediated Gli3 silencing is critical for embryonic myogenesis. Consistent with this idea we found that activation of Shh signalling by either purmorphamine, or KD of Gli3 by antisense morpholino (MO) rescued the miR-133 KD phenotype. We identify a novel Shh/MRF/miR-133/Gli3 axis that connects epithelial morphogenesis with myogenic fate specification

Caudal Fgfr1 disruption produces localised spinal mis-patterning and a terminal myelocystocele-like phenotype in mice

Closed spinal dysraphisms are poorly understood malformations classified as neural tube (NT) defects. Several, including terminal myelocystocele, affect the low spine. We previously identified a NT closure-initiating point, Closure 5, in the distal spine of mice. Here we document equivalent morphology of the caudal-most closing posterior neuropore (PNP) in mice and humans. Closure 5 forms in a region of active FGF signalling and pharmacological FGF receptor blockade impairs its formation in cultured mouse embryos. Conditional genetic deletion of Fgfr1 in caudal embryonic tissues with Cdx2Cre diminishes neuroepithelial proliferation, impairs Closure 5 formation and delays PNP closure. After closure, the distal NT of Fgfr1-disrupted embryos dilates to form a fluid-filled sac overlying ventrally flattened spinal cord. This phenotype resembles terminal myelocystocele. Histological analysis reveals regional and progressive loss of SHH and FOXA2-positive ventral NT domains, resulting in OLIG2-labelling of the ventral-most NT. The OLIG2-domain is also subsequently lost, eventually producing a NT entirely positive for the dorsal marker PAX3. Thus, a terminal myelocystocele-like phenotype can arise after completion of NT closure with localised spinal mis-patterning caused by disruption of FGFR1 signalling

Synchronisation of apical constriction and cell cycle progression is a conserved behaviour of pseudostratified neuroepithelia informed by their tissue geometry

Neuroepithelial cells balance tissue growth requirement with the morphogenetic imperative of closing the neural tube. They apically constrict to generate mechanical forces which elevate the neural folds, but are thought to apically dilate during mitosis. However, we previously reported that mitotic neuroepithelial cells in the mouse posterior neuropore have smaller apical surfaces than non-mitotic cells. Here, we document progressive apical enrichment of non-muscle myosin-II in mitotic, but not non-mitotic, neuroepithelial cells with smaller apical areas. Live-imaging of the chick posterior neuropore confirms apical constriction synchronised with mitosis, reaching maximal constriction by anaphase, before division and re-dilation. Mitotic apical constriction amplitude is significantly greater than interphase constrictions. To investigate conservation in humans, we characterised early stages of iPSC differentiation through dual SMAD-inhibition to robustly produce pseudostratified neuroepithelia with apically enriched actomyosin. These cultured neuroepithelial cells achieve an equivalent apical area to those in mouse embryos. iPSC-derived neuroepithelial cells have large apical areas in G2 which constrict in M phase and retain this constriction in G1/S. Given that this differentiation method produces anterior neural identities, we studied the anterior neuroepithelium of the elevating mouse mid-brain neural tube. Instead of constricting, mid-brain mitotic neuroepithelial cells have larger apical areas than interphase cells. Tissue geometry differs between the apically convex early midbrain and flat posterior neuropore. Culturing human neuroepithelia on equivalently convex surfaces prevents mitotic apical constriction. Thus, neuroepithelial cells undergo high-amplitude apical constriction synchronised with cell cycle progression but the timing of their constriction if influenced by tissue geometry

Characterising open chromatin in chick embryos identifies cis-regulatory elements important for paraxial mesoderm formation and axis extension

Somites arising from paraxial mesoderm are a hallmark of the segmented vertebrate body plan. They form sequentially during axis extension and generate musculoskeletal cell lineages. How paraxial mesoderm becomes regionalised along the axis and how this correlates with dynamic changes of chromatin accessibility and the transcriptome remains unknown. Here, we report a spatiotemporal series of ATAC-seq and RNA-seq along the chick embryonic axis. Footprint analysis shows differential coverage of binding sites for several key transcription factors, including CDX2, LEF1 and members of HOX clusters. Associating accessible chromatin with nearby expressed genes identifies cis-regulatory elements (CRE) for TCF15 and MEOX1. We determine their spatiotemporal activity and evolutionary conservation in Xenopus and human. Epigenome silencing of endogenous CREs disrupts TCF15 and MEOX1 gene expression and recapitulates phenotypic abnormalities of anterior–posterior axis extension. Our integrated approach allows dissection of paraxial mesoderm regulatory circuits in vivo and has implications for investigating gene regulatory networks

The (re)construction of scientific knowledge in school: sociolinguistic analysis of educational practices

AbstractThe study lies on the socio-semiotic approach to language, as proposed by the Systemic Functional Linguistics (SFL), according to which educational discourse’s lexicogrammatical choices play a crucial role in the (re)construing of students’ experience towards educational/scientific knowledge (Halliday, 1999∙ Halliday & Martin, 2004∙ Painter, 1999). From this aspect, school textbooks as educational practices constitute a rather interesting area for the investigation of socio-semiotic realizations.The main question of the study is how the transition from the first to the latest grades of elementary education implies the school texts’ stepwise academic recontextualization towards the different scientific disciplines. Our concern is to highlight the lexicogrammatical resources through which the textbooks of science and history construe specialized knowledge.For the investigation of these linguistic practices, we adopt the conceptual and analytical framework of SFL that has been used in a wide range οf research around different aspects of school discourse. As the English-speaking bibliography regards, research has shown education’s special socio-semiotic nature mainly through the investigation of the school textbooks’ formal speech (Coffin, 2006; Halliday, 2004α, 2004b, 2004c; Halliday & Martin, 2004; Martin, 2004a, 2004b, 2004c; Schleppegrell, 2004). An amount of research following SFL also regards the discourse of various aspects of greek education (Giannisi & Kondyli, 2013∙ Κονδύλη & Αρχάκης, 2004∙ Κονδύλη & Δούκα, 2006∙ Kondyli & Lykou, 2008∙ Κονδύλη & Μανιού, 2007∙ Μανιού & Κονδύλη, 2011∙ Παϊζη & Κονδύλη, 2011∙ Παπαγιαννόπουλος & Κονδύλη, 2014).The corpus of the study, which consists of 201 chapters drawn from the Environmental Study, Science and History textbooks – from first to sixth grade of elementary school -, was analyzed in terms of transitivity (ch.5), grammatical metaphor (ch.6), conjunction (ch. 7) and lexical density (ch. 9), while in a sample of these was studied the parameter of thematic choices (ch. 8). The findings were at the same time regarded on the basis of different school genres (ch. 10), aiming at the parallel consideration of the two linguistic layers, register and genre. The recontextualization of the English grammar’s semantic and lexicogrammatical classes into the greek linguistic system for the aims of the study has been considered of particular importance.The study of the textbooks moved along with the investigation of the relevant texts of the formal linguistic planning of Pedagogic Institute (ch.3.) and provided us an overall view of the continuous reconstructions of the two school subjects during elementary education. The analysis of the textbooks confirms the continuous reconstruction of the scientific fields since for the realization of the different instructional discourses specialized lexicogrammatical syndromes emerge (ch. 12 – 16). The analysis, (both “in” and “above” clause) shows the distinct lexicogrammatical choices by which different kinds of meaning are realized, construing thus technical taxonomies of science and abstractive interpretation of history. In this way, the linguistic recourses that determine – but largely remain obscure – particular educational practices are highlighted.ΠερίληψηΗ παρούσα έρευνα κινείται στο πλαίσιο της κοινωνιοσημειωτικής θεώρηση της γλώσσας που προτείνει η συστημική λειτουργική γλωσσολογία (ΣΛΓ), σύμφωνα με την οποία η λεξικογραμματική του εκπαιδευτικού λόγου κατέχει καίριο ρόλο στην αναμόρφωση της εμπειρίας των μαθητριών/-τών προς την κατεύθυνση της σχολικής/επιστημονικής γνώσης (ενδ. Halliday, 1999∙ Halliday & Martin, 2004∙ Painter, 1999). Υπ’ αυτό το πρίσμα, τα σχολικά εγχειρίδια ως εκπαιδευτικές πρακτικές αποτελούν σημαντικές περιοχές (ανα)συγκρότησης της γνώσης και εξαιρετικά ενδιαφέρουσα ευκαιρία ανάδειξης κοινωνιοσημειωτικών πραγματώσεων.Βασικό ζητούμενο της έρευνας είναι το πώς η σταδιακή μετάβαση από τις πρώτες στις τελευταίες τάξεις της πρωτοβάθμιας εκπαίδευσης συνεπάγεται την κλιμακούμενη ακαδημαϊκή αναπλαισίωση των κειμένων των διδακτικών εγχειριδίων στην κατεύθυνση των επιμέρους επιστημονικών πεδίων. Κεντρικό ερευνητικό μέλημα είναι η ανάδειξη των λεξικογραμματικών πόρων με τους οποίους τα εγχειρίδια της Μελέτης Περιβάλλοντος, της Φυσικής και της Ιστορίας του Δημοτικού σχολείου κατασκευάζουν εξειδικευμένη γνώση στην κατεύθυνση της φυσικής και ιστορικής επιστήμης.Για την ανάλυση και την περιγραφή των παραπάνω γλωσσικών πρακτικών αξιοποιήθηκαν τα εννοιολογικά και αναλυτικά εργαλεία της συστημικής λειτουργικής γλωσσολογίας, τα οποία έχουν αξιοποιηθεί σε σημαντικό φάσμα ερευνών γύρω από τις διάφορες εκφάνσεις του λόγου της εκπαίδευσης. Στην αγγλόφωνη βιβλιογραφία, η σχετική έρευνα έχει αναδείξει την ιδιαίτερη κοινωνιο-σημειωτική φύση της εκπαιδευτικής διαδικασίας, καθώς έχει εξετάσει χαρακτηριστικές όψεις του σχολικού λόγου – με έμφαση στον επίσημο λόγο των σχολικών εγχειριδίων (ενδ. Coffin, 2006∙ Halliday, 2004α, 2004β, 2004γ∙ Halliday & Martin, 2004∙ Martin, 2004α, 2004β, 2004γ∙ Schleppegrell, 2004). Οι έρευνες που σύμφωνα με το υπόδειγμα της ΣΛΓ μελετούν τον εκπαιδευτικό λόγο στις διαφορετικές βαθμίδες του ελληνικού σχολείου, αφορούν τον προφορικό λόγο στο νηπιαγωγείο (ενδ. Giannisi & Kondyli, 2013∙ Κονδύλη & Αρχάκης, 2004∙ Κονδύλη & Δούκα, 2006∙ Kondyli & Lykou, 2008) καθώς και∙τα γραπτά κείμενα των εγχειριδίων και τα γραπτά κείμενα των μαθητών (Κονδύλη & Μανιού, 2007∙ Μανιού & Κονδύλη, 2011∙ Παϊζη & Κονδύλη, 2011∙ Παπαγιαννόπουλος & Κονδύλη, 2014).Το σώμα των δεδομένων της έρευνας αποτελείται από 201 κεφάλαια από τα εγχειρίδια της Μελέτης Περιβάλλοντος, της Φυσικής και της Ιστορίας από την Α΄ έως τη ΣΤ΄ τάξη, τα οποία αναλύθηκαν ως προς το σύστημα της μεταβιβαστικότητας (κεφ. 5), τη γραμματική μεταφορά (κεφ. 6), τη συνδετικότητα (κεφ. 7) και τη λεξική πυκνότητα (κεφ. 9), ενώ σε ένα δείγμα από αυτά εξετάστηκε η παράμετρος της θεματικής οργάνωσης (κεφ. 8). Παράλληλα, μελετήθηκαν τα παραπάνω λεξικογραμματικά ευρήματα υπό το πρίσμα των διαφορετικών σχολικών κειμενικών ειδών, με σκοπό τη συνεξέταση των δύο γλωσσικών στρωμάτων, της λειτουργικής ποικιλίας και του κειμενικού είδους (κεφ. 10). Ιδιαίτερη σημασία έχει η «αναπλαισίωση» των σημασιολογικών και γραμματικών κατηγοριών της αγγλικής γλώσσας στο ελληνικό γλωσσικό σύστημα για τους σκοπούς της έρευνας.Η μελέτη των εγχειριδίων των έξι τάξεων κινήθηκε παράλληλα με την εξέταση των κειμένων του επίσημου γλωσσικού σχεδιασμού του (τότε) Παιδαγωγικού Ινστιτούτου (ΔΕΠΠΣ, ΑΠΣ, βιβλία δασκάλου) (κεφ. 3), και επέτρεψε τη δημιουργία μιας συνολικής εικόνας για τις συνεχείς ανασυγκροτήσεις των δύο γνωστικών αντικειμένων στη διάρκεια της πρωτοβάθμιας εκπαίδευσης.Από την ανάλυση των κειμένων των σχολικών εγχειριδίων επιβεβαιώνεται η συνεχής ανασυγκρότηση των επιστημονικών πεδίων, καθώς καταγράφονται ειδικότερα σύνδρομα λεξικογραμματικής πραγμάτωσης των επιμέρους διδακτικών λόγων (κεφ. 12 – 16). Η ανάλυση - τόσο στο εσωτερικό της πρότασης όσο και στο επίπεδο του κειμένου - αναδεικνύει τις διαφορετικές λεξικογραμματικές επιλογές με τις οποίες πραγματώνονται τα διαφορετικά είδη νοήματος σύμφωνα με τα πρότυπα της τεχνικής ταξινόμησης των φυσικών επιστημών και της αφαιρετικής ερμηνείας της Ιστορίας, αντίστοιχα. Με αυτόν τον τρόπο, επισημαίνονται οι γλωσσικοί πόροι που, ενώ καθορίζουν τις ειδικότερες εκπαιδευτικές πρακτικές, παραμένουν σε μεγάλο βαθμό αδιόρατες

The prevalence of obstructive sleep apnea in Greek young adults in primary care

The syndrome of obstructive sleep apnea (OSA) has for three decades about an identifiable and recognized pathological entity with multiple consequences in the public health.The appearance of the OSA is estimated 2-4% of the world population while some of the diseases associated with such obesity and cardiovascular diseases are growing faster even by the younger age. The aim of the present study was to identify the prevalence of obstructive sleep apnea syndrome (OSA) in a sample of students of Technological Educational Institute of Crete.Material and Method: The sample consisted of 400 students. Obstructive sleep apnea was quantified using the Berlin questionnaire which apart from the demographic data, it included three categories (10 questions) designed to illicit information regarding snoring (category 1), daytime somnolence (category 2) and the presence of obesity and/or hypertension(category 3). Somatometric measurements (Height, Weight, hip and waist circumference) and arterial blood pressure were carried out. Also, apprised parameters that concern the heredity the habit of smoking, nasal congestion, sudden awakenings and respiratory problems. BMI was calculated as the body weight divided by the square of height (expressed in kg/m2). Analysis included Kruskal Wallis test, the Mann Whitney test analysis, the non-parametric Mann Whitney test analysis, the Spearman correlation coefficient and the Coefficients of Cronbach's. The data analysis was performed using the statistical programme IBM SPSS 19.0.Results: The prevalence of OSA was found 1.0% of the sample. Only 4 students were diagnosed with high risk and 48 (12.0%) students with low risk according to Berlin Questionnaire. Snoring had the highest frequency 8% and followed by obesity with 5.3%. Also, snoring have all the people with increased risk for OSA in contrast to those with low or no risk (100% vs. 33.3% and 3.4% respectively, p = 0,008). Significantly more women were at high risk than men (1.5% vs. 0.5%, p = 0,040) but fewer low (8.1% vs 15,8%, p = 0,040). In addition, older students had significantly higher prevalence of low and high risk (p-trend = 0,005) while those with a high or low risk had significantly higher average levels of obesity indices, p <0,001. Smoking, nasal congestion and heredity do not associated with the risk for OSA as opposed to sudden awakenings, p = 0,005 and respiratory problems, p <0,001. Conclusions: Although the very low frequency of OSA, snoring, obesity, the age and the gender consists strong predictors of OSA

Two-Photon Cell and Tissue Level Laser Ablation Methods to Study Morphogenetic Biomechanics

Laser ablation is routinely performed to infer mechanical tension in cells and tissues. Here we describe our method of two-photon laser ablation at the cellular and tissue level in mouse embryos. The primary outcome of these experiments is initial retraction following ablation, which correlates with, and so can be taken as a measure of, the tensile stress that structure was under before ablation. Several experimental variables can affect interpretation of ablation tests. Pre-test factors include differences in physical properties such as viscoelasticity between experimental conditions. Factors relevant during the test include viability of the cells at the point of ablation, image acquisition rate and the potential for overzealous ablations to cause air bubbles through heat dissipation. Post-test factors include intensity-biased image registration that can artificially produce apparent directionality. Applied to the closing portion of the mouse spinal neural tube, these methods have demonstrated long-range biomechanical coupling of the embryonic structure and have identified highly contractile cell populations involved in its closure process