A vertebrate crossveinless 2 homologue modulates BMP activity and neural crest cell migration

Previous work has revealed that proteins that bind to bone morphogenetic proteins (BMPs) and inhibit their signalling have a crucial role in the spatial and temporal regulation of cell differentiation and cell migration by BMPs. We have identified a chick homologue of crossveinless 2, a Drosophila gene that was identified in genetic studies as a promoter of BMP-like signalling. Chick Cv-2 has a conserved structure of five cysteine-rich repeats similar to those found in several BMP antagonists, and a C-terminal Von Willebrand type D domain. Cv-2 is expressed in the chick embryo in a number of tissues at sites at which elevated BMP signalling is required. One such site of expression is premigratory neural crest, in which at trunk levels threshold levels of BMP activity are required to initiate cell migration. We show that, when overexpressed, Cv-2 can weakly antagonise BMP4 activity in Xenopus embryos, but that in other in vitro assays Cv-2 can increase the activity of co-expressed BMP4. Furthermore, we find that increased expression of Cv-2 causes premature onset of trunk neural crest cell migration in the chick embryo, indicative of Cv-2 acting to promote BMP activity at an endogenous site of expression. We therefore propose that BMP signalling is modulated both by antagonists and by Cv-2 that acts to elevate BMP activity

Talent development for professional rugby league: observations and analysis from a career in rugby’s high-performance environment

Many research theories and frameworks have been proposed to describe the talent development environment in a variety of sports and other high-performance domains. None of these, however, have suitably described the context the first author had experienced in high level rugby league during a career that has spanned 40 years as professional player, club and international coach / manager and more recently as a consultant and researcher. The paper presents current talent development literature in respect to common features that have emerged from this domain. A series of personal reflections then illustrate how these areas are operationalised in rugby league based on the first author’s experiences.What transpires is a clear mis-match between theory and practice and a glaring lack of appropriate support for those who lead in this domain. The paper therefore proposes the need for a new rugby league specific framework which can guide and support those who operate within the rugby league talent development environment

Conserved segmental expression of Krox-20 in the vertebrate hindbrain and its relationship to lineage restriction

6 páginas, 4 figuras.The zinc-finger gene Krox-20 is expressed in two alternating segments, rhombomeres (r) 3 and 5, in the developing mouse hindbrain. This expression pattern is established prior to rhombomere formation in the mouse, but it is not known how the timing of expression relates to cellular events of segmentation, such as lineage restriction. We have cloned Krox-20 sequences from Xenopus and the chick and shown that its alternating expression pattern is conserved in these systems, suggesting that its role in hindbrain development is conserved. Analysis of the early stages of Krox-20 expression in the chick show that both domains of expression precede the restriction of cell lineage to specific rhombomeres, consistent with a role of this gene in early events of hindbrain segmentation. The finding that expression is not coincident with lineage restriction indicates that early expression may not reflect an irreversible commitment of cells to r3 and r5 and/or may be mosaic.Peer reviewe

Relationship between spatially restricted Krox-20 gene expression in branchial neural crest and segmentation in the chick embryo hindbrain

Previous studies have suggested that the rostrocaudal patterning of branchial arches in the vertebrate embryo derives from a coordinate segmental specification of gene expression in rhombomeres (r) and neural crest. However, expression of the Krox-20 gene is restricted to neural crest cells migrating to the third branchial arch, apparently from r5, whereas this rhombomere contributes cells to both the second and third arches. We examined in the chick embryo how this spatially restricted expression is established. Expression occurs in precursors in both r5 and r6, and we show by cell labelling that both rhombomeres contribute to Krox-20-expressing neural crest, emigration occurring first from r6 and later caudally from r5. Krox-20 transcripts are not detected in some precursors in rostral r5, presaging the lack of expression in cells migrating rostrally from this rhombomere. After transposition of r6 to the position of r4 or r5, many Krox-20-expressing cells migrate rostral to the otic vesicle, whereas when r5 is transplanted to the position of r4, only a small number of migrating cells express Krox-20. These results indicate that, in the chick, Krox-20 expression in branchial neural crest does not correlate with rhombomeric segmentation, and that there may be intrinsic differences in regulation between the r5 and r6 Krox-20-expressing populations

An investigation into the talent development knowledge and practice of a rugby high-performance coaching team

The purpose of this study was to investigate Talent Development environments (TDE) within the transition stage of professional rugby. The aim was to explore the knowledge and application of best practice concepts by the coaching teams that work specifically with Academy players to facilitate transition to the first team playing squads. A focus group was established in order to explore TDEs more fully following a series of talent development workshops delivered by the authors, that presented a range of recognised academic theories and concepts. Data were collected and analysed thematically. Findings suggest that those currently working in professional rugby’s talent development transition stage have a series of ‘gaps’ in their theory to practice which are limiting the successful creation and operation of the most conducive TDE for their players. These especially relate to the generated themes of organisational connectivity, philosophical alignment, psycho-social nurturing, workforce development, and legacy building. The paper concludes by recognising the fundamental role that education and training has in any aspiration to create effective TDEs. It also recognises the over-arching responsibility the Academy Manager has in how best to proceed and fill the gaps, not just within this transition stage but throughout the talent pathway

A case study exploration into the professional duties of a Super League Academy Manager: Creating an individualised learning plan using the Talent Development Self Navigation Framework (TDSNF)

This study investigated the professional duties of a professional rugby league Academy Manager (AM) with the explicit aim of identifying bespoke development needs through the operation of the Talent Development Self Navigation Framework (TDSNF). This study adopts an original embodied pedagogy approach grounded in a critical realist view of the participant’s Talent Development domain. The paper presents a full description of the framework’s application as a case study example of the TDSNF in practice. Findings acknowledge how the facilitated TDSNF helped the AM reflect more fully on his ‘real world’ and ‘foundational wants and needs’ to co-create both an individual learning plan for himself and a TD development plan for his Academy team. Feedback on the framework’s content, structure, process and outputs was extremely positive. Significant implications in adopting this approach more widely for coach education and learning are then presente

Scrubbing up: multi-scale investigation of woody encroachment in a southern African savannah

Changes in the extent of woody vegetation represent a major conservation question in many savannah systems around the globe. To address the problem of the current lack of broad-scale cost-effective tools for land cover monitoring in complex savannah environments, we use a multi-scale approach to quantifying vegetation change in Kruger National Park (KNP), South Africa. We test whether medium spatial resolution satellite data (Landsat, existing back to the 1970s), which have pixel sizes larger than typical vegetation patches, can nevertheless capture the thematic detail required to detect woody encroachment in savannahs. We quantify vegetation change over a 13-year period in KNP, examine the changes that have occurred, assess the drivers of these changes, and compare appropriate remote sensing data sources for monitoring change. We generate land cover maps for three areas of southern KNP using very high resolution (VHR) and medium resolution satellite sensor imagery from February 2001 to 2014. Considerable land cover change has occurred, with large increases in shrubs replacing both trees and grassland. Examination of exclosure areas and potential environmental driver data suggests two mechanisms: elephant herbivory removing trees and at least one separate mechanism responsible for conversion of grassland to shrubs, theorised to be increasing atmospheric CO2. Thus, the combination of these mechanisms causes the novel two-directional shrub encroachment that we observe (tree loss and grassland conversion). Multi-scale comparison of classifications indicates that although spatial detail is lost when using medium resolution rather than VHR imagery for land cover classification (e.g., Landsat imagery cannot readily distinguish between tree and shrub classes, while VHR imagery can), the thematic detail contained within both VHR and medium resolution classifications is remarkably congruent. This suggests that medium resolution imagery contains sufficient thematic information for most broad-scale land cover monitoring requirements in heterogeneous savannahs, while having the benefits of being cost-free and providing a longer historical archive of data than VHR sources. We conclude that monitoring of broad-scale land cover change using remote sensing has considerable potential as a cost-effective tool for both better informing land management practitioners, and for monitoring the future landscape-scale impacts of management policies in savannahs

Regularly log-periodic functions and some applications

We prove a Tauberian theorem for the Laplace--Stieltjes transform and Karamata-type theorems in the framework of regularly log-periodic functions. As an application we determine the exact tail behavior of fixed points of certain type smoothing transforms