Development of the early axon scaffold in the rostral brain of the small spotted cat shark (<i>Scyliorhinus canicula</i>) embryo

International audienceThe cat shark is increasingly used as a model for Chondrichthyes, an evolutionarily important sister group of the bony vertebrates that include teleosts and tetrapods. In the bony vertebrates, the first axon tracts form a highly conserved early axon scaffold. The corresponding structure has not been well characterised in cat shark and will prove a useful model for comparative studies. Using pan-neural markers, the early axon scaffold of the cat shark, Scyliorhinus canicula, was analysed. Like in other vertebrates, the medial longitudinal fascicle was the first axon tract to form from a small cluster of neurones in the ventral brain. Subsequently, additional neuronal clusters and axon tracts emerged which formed an array of longitudinal, transversal, and commissural axons tracts in the Scyliorhinus canicula embryonic brain. The first structures to appear after the medial longitudinal fascicle were the tract of the postoptic commissure, the dorsoventral diencephalic tract, and the descending tract of the mesencephalic nucleus of the trigeminal nerve. These results confirm that the early axon scaffold in the embryonic brain is highly conserved through vertebrate evolution

Appreciative Advising and ePortfolios: An Example of Technology-Mediated Pedagogy

The evolution of technology in higher education calls for advisors to develop technology-mediated advising pedagogies to better inform their advising practice in the technology rich 21st century. Using an Appreciative Advising framework integrated with ePortfolio technology, an example of a technology-mediated advising pedagogy is discussed. 

Analysis of the initial nerve connections in the embryonic vertebrate brain

The complex organisation of the vertebrate brain starts off as a simple arrangement of axon tracts in the early embryo termed the early axon scaffold. These initial axon tracts were important for the correct guidance of later, follower axons. Yet, little is known about the temporal and spatial control of neuronal differentiation, or the control of axon guidance for the early axon scaffold. The aim of this study was to provide a detailed anatomical description of the early axon scaffold as a basis for functional experiments, to identify candidate genes involved in the differentiation of the early neurones, and to gain insight into the axon guidance for a particular early tract. The anatomical formation of the early axon scaffold in the chick embryonic brain has been analysed in detail using immunohistochemistry and axon tracing. The early tracts in the chick were directly compared with cat shark, Xenopus, zebra finch and mouse. These results highlight the conservation of early axon scaffold development. The medial longitudinal fascicle (MLF) was shown to be the most conserved tract forming first in all vertebrates, apart from mouse where it forms later. Since the genes involved in specification of neurones to an MLF fate are unknown, microarray analysis was used to identify candidate genes with a possible role in MLF neurone specification. CRABPI was shown by in situ hybridisation to be specifically expressed by the MLF neurones. Another highly conserved early tract is the tract of the posterior commissure (TPC). Its neurones were shown to be located in the ventral diencephalon of the chick embryonic brain. While the TPC neurones were intermingled with the MLF neurones, their axons project along very separate paths, suggesting that their outgrowth is directed by different guidance cues present. Netrin1 and Netrin2 were identified as candidate genes for repelling the TPC axons along their correct path. Gain-of-function experiments led to reduction or loss of the TPC, suggesting that Netrins act as repellents on the TPC axons in the chick embryonic brain.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Abnormal Photic Entrainment to Phase-Delaying Stimuli in the R6/2 Mouse Model of Huntington's Disease, despite Retinal Responsiveness to Light.

The circadian clock located in the suprachiasmatic nucleus (SCN) in mammals entrains to ambient light via the retinal photoreceptors. This allows behavioral rhythms to change in synchrony with seasonal and daily changes in light period. Circadian rhythmicity is progressively disrupted in Huntington's disease (HD) and in HD mouse models such as the transgenic R6/2 line. Although retinal afferent inputs to the SCN are disrupted in R6/2 mice at late stages, they can respond to changes in light/dark cycles, as seen in jet lag and 23 h/d paradigms. To investigate photic entrainment and SCN function in R6/2 mice at different stages of disease, we first assessed the effect on locomotor activity of exposure to a 15 min light pulse given at different times of the day. We then placed the mice under five non-standard light conditions. These were light cycle regimes (T-cycles) of T21 (10.5 h light/dark), T22 (11 h light/dark), T26 (13 h light/dark), constant light, or constant dark. We found a progressive impairment in photic synchronization in R6/2 mice when the stimuli required the SCN to lengthen rhythms (phase-delaying light pulse, T26, or constant light), but normal synchronization to stimuli that required the SCN to shorten rhythms (phase-advancing light pulse and T22). Despite the behavioral abnormalities, we found that Per1 and c-fos gene expression remained photo-inducible in SCN of R6/2 mice. Both the endogenous drift of the R6/2 mouse SCN to shorter periods and its inability to adapt to phase-delaying changes will contribute to the HD circadian dysfunction

Regulation of downstream neuronal genes by proneural transcription factors during initial neurogenesis in the vertebrate brain

International audienceBACKGROUND: Neurons arise in very specific regions of the neural tube, controlled by components of the Notch signalling pathway, proneural genes, and other bHLH transcription factors. How these specific neuronal areas in the brain are generated during development is just beginning to be elucidated. Notably, the critical role of proneural genes during differentiation of the neuronal populations that give rise to the early axon scaffold in the developing brain is not understood. The regulation of their downstream effectors remains poorly defined. RESULTS: This study provides the first overview of the spatiotemporal expression of proneural genes in the neuronal populations of the early axon scaffold in both chick and mouse. Overexpression studies and mutant mice have identified a number of specific neuronal genes that are targets of proneural transcription factors in these neuronal populations. CONCLUSION: Together, these results improve our understanding of the molecular mechanisms involved in differentiation of the first neuronal populations in the brain

Sit-to-Stand Symmetry in Individuals with Hip Pathology

Post-hip fracture patients continue to exhibit asymmetries during sit-to-stand task following rehabilitation. While strength is thoroughly addressed, perceptual deficits may be a missing component to rehabilitation post-hip fracture

Novel genes upregulated when NOTCH signalling is disrupted during hypothalamic development.

International audienceBACKGROUND: The generation of diverse neuronal types and subtypes from multipotent progenitors during development is crucial for assembling functional neural circuits in the adult central nervous system. It is well known that the Notch signalling pathway through the inhibition of proneural genes is a key regulator of neurogenesis in the vertebrate central nervous system. However, the role of Notch during hypothalamus formation along with its downstream effectors remains poorly defined. RESULTS: Here, we have transiently blocked Notch activity in chick embryos and used global gene expression analysis to provide evidence that Notch signalling modulates the generation of neurons in the early developing hypothalamus by lateral inhibition. Most importantly, we have taken advantage of this model to identify novel targets of Notch signalling, such as Tagln3 and Chga, which were expressed in hypothalamic neuronal nuclei. CONCLUSIONS: These data give essential advances into the early generation of neurons in the hypothalamus. We demonstrate that inhibition of Notch signalling during early development of the hypothalamus enhances expression of several new markers. These genes must be considered as important new targets of the Notch/proneural network

Quantifying beliefs regarding telehealth: Development of the Whole Systems Demonstrator Service User Technology Acceptability Questionnaire

Introduction: Telehealth (TH) is a potential solution to the increased incidence of chronic illness in an ageing population.The extent to which older people and users with chronic conditions accept and adhere to using assistive technologies is a potential barrier to mainstreaming the service. This study reports the development and validation of the Whole Systems Demonstrator (WSD) Service User Technology Acceptability Questionnaire (SUTAQ). Methods: Questionnaires measuring the acceptability of TH, quality of life, well-being and psychological processes were completed by 478 users of TH. The 22 acceptability items were subject to principal components analysis (PCA) to determine sub-scales. Scale scores, relationships between scales and other patient reported outcome measures (PROMs), and group differences on scales were utilised to check the reliability and validity of the measure. Results: PCAs of SUTAQ items produced 6 TH acceptability scales: enhanced care, increased accessibility, privacy & discomfort, care personnel concerns, kit as substitution, and satisfaction. Scale scores indicated, individuals with long term conditions held beliefs. Significant correlations within these beliefs and between these scales and additional PROMs were coherent and the SUTAQ subscales were able to predict those more likely to refuse TH. Discussion: The SUTAQ is an instrument that can be used to measure user beliefs about the acceptability of TH, and has the ability to discriminate and predict individual differences in beliefs and behaviour. Measuring acceptability beliefs of TH users can provide valuable information to direct and target provision of services to increase uptake and maintain use of TH

Kapsula

This experimental exhibition catalogue was created in collaboration with Gallery 44 Centre for Contemporary Photograpy in Toronto, Canada to document their twenty-first annual exhibition of emergent photography, Proof. The Magazine would like to extend a special thanks to Noa Bronstein, Head of Exhibitions and Publications at Gallery 44, both for her contributions to the document itself and for making this special issue possible

Kapsula

This experimental exhibition catalogue was created in collaboration with Gallery 44 Centre for Contemporary Photograpy in Toronto, Canada to document their twenty-first annual exhibition of emergent photography, Proof. The Magazine would like to extend a special thanks to Noa Bronstein, Head of Exhibitions and Publications at Gallery 44, both for her contributions to the document itself and for making this special issue possible