Retrograde transport pathways utilised by viruses and protein toxins

A model has been presented for retrograde transport of certain toxins and viruses from the cell surface to the ER that suggests an obligatory interaction with a glycolipid receptor at the cell surface. Here we review studies on the ER trafficking cholera toxin, Shiga and Shiga-like toxins, Pseudomonas exotoxin A and ricin, and compare the retrograde routes followed by these protein toxins to those of the ER trafficking SV40 and polyoma viruses. We conclude that there is in fact no obligatory requirement for a glycolipid receptor, nor even with a protein receptor in a lipid-rich environment. Emerging data suggests instead that there is no common pathway utilised for retrograde transport by all of these pathogens, the choice of route being determined by the particular receptor utilised

Syntaxin 16 and syntaxin 5 are required for efficient retrograde transport of several exogenous and endogenous cargo proteins

Retrograde transport allows proteins and lipids to leave the endocytic pathway to reach other intracellular compartments, such as trans-Golgi network (TGN)/Golgi membranes, the endoplasmic reticulum and, in some instances, the cytosol. Here, we have used RNA interference against the SNARE proteins syntaxin 5 and syntaxin 16, combined with recently developed quantitative trafficking assays, morphological approaches and cell intoxication analysis to show that these SNARE proteins are not only required for efficient retrograde transport of Shiga toxin, but also for that of an endogenous cargo protein - the mannose 6-phosphate receptor - and for the productive trafficking into cells of cholera toxin and ricin. We have found that the function of syntaxin 16 was specifically required for, and restricted to, the retrograde pathway. Strikingly, syntaxin 5 RNA interference protected cells particularly strongly against Shiga toxin. Since our trafficking analysis showed that apart from inhibiting retrograde endosome-to-TGN transport, the silencing of syntaxin 5 had no additional effect on Shiga toxin endocytosis or trafficking from TGN/Golgi membranes to the endoplasmic reticulum, we hypothesize that syntaxin 5 also has trafficking-independent functions. In summary, our data demonstrate that several cellular and exogenous cargo proteins use elements of the same SNARE machinery for efficient retrograde transport between early/recycling endosomes and TGN/Golgi membranes

Evaluating weaknesses of "perceptual-cognitive training" and "brain training" methods in sport: An ecological dynamics critique

The recent upsurge in "brain training and perceptual-cognitive training," proposing to improve isolated processes, such as brain function, visual perception, and decision-making, has created significant interest in elite sports practitioners, seeking to create an "edge" for athletes. The claims of these related "performance-enhancing industries" can be considered together as part of a process training approach proposing enhanced cognitive and perceptual skills and brain capacity to support performance in everyday life activities, including sport. For example, the "process training industry" promotes the idea that playing games not only makes you a better player but also makes you smarter, more alert, and a faster learner. In this position paper, we critically evaluate the effectiveness of both types of process training programmes in generalizing transfer to sport performance. These issues are addressed in three stages. First, we evaluate empirical evidence in support of perceptual-cognitive process training and its application to enhancing sport performance. Second, we critically review putative modularized mechanisms underpinning this kind of training, addressing limitations and subsequent problems. Specifically, we consider merits of this highly specific form of training, which focuses on training of isolated processes such as cognitive processes (attention, memory, thinking) and visual perception processes, separately from performance behaviors and actions. We conclude that these approaches may, at best, provide some "general transfer" of underlying processes to specific sport environments, but lack "specificity of transfer" to contextualize actual performance behaviors. A major weakness of process training methods is their focus on enhancing the performance in body "modules" (e.g., eye, brain, memory, anticipatory sub-systems). What is lacking is evidence on how these isolated components are modified and subsequently interact with other process "modules," which are considered to underlie sport performance. Finally, we propose how an ecological dynamics approach, aligned with an embodied framework of cognition undermines the rationale that modularized processes can enhance performance in competitive sport. An ecological dynamics perspective proposes that the body is a complex adaptive system, interacting with performance environments in a functionally integrated manner, emphasizing that the inter-relation between motor processes, cognitive and perceptual functions, and the constraints of a sport task is best understood at the performer-environment scale of analysis

Application of a constraints-led approach to pedagogy in schools: embarking on a journey to nurture physical literacy in primary physical education

Background: Oversimplified, reductionist approaches to operationalising Physical Literacy (PL) have been a barrier to the development of a complex, dynamic and embodied understanding of the individual Physical Literacy journey. Further, there has been no appropriate approach that might allow practitioners to integrate Physical Literacy in Physical Education (PE). Whilst popular approaches, such as Teaching Games for Understanding (TGfU) and Game Sense (GS), for operationalising learner-centred and problem-based learning, have gained professional traction in the last three decades, the development of a comprehensive theoretical basis to underpin pedagogical principles has been neglected – particularly in Physical Education. Pedagogical approaches grounded in play have gained popularity as a vehicle for Physical Literacy development in Physical Education. Despite the prominence of a Constraint-Led Approach (CLA) in sport pedagogy to assist in developing ‘the intelligent, autonomous individual’ in sport, application to Physical Education is limited. Purpose: In this article, we propose key pedagogical principles of a Constraints-Led Approach (CLA) in primary physical education, underpinned by the theoretical framework of Ecological Dynamics (ED). Driven by the challenge of designing affordance landscapes for learning, we present our reflections on a recently designed PE curriculum for primary schools, Boing, which could facilitate the development of movement capacities in play-based curricula designed to nurture the Physical Literacy journey for individuals. An articulation of support for the key theoretical ideas is provided in this paper. Design: This is achieved through reflections on the play-based curriculum (BOING) founded on the principles of Ecological Dynamics (ED) underpinning a Constraints-Led approach (CLA) to better serve the implementation of a Physical Literacy focussed Physical Education in a Primary school setting based on key principles for delivery. Findings: Summarising the findings, the we were able to highlight the importance of developing key principles for delivering a theoretically informed curriculum that elicits key principles of Physical Literacy. Whilst movement skills are key, these approaches are able to elicit the intended outcomes in learners of confidence, motivation and competence (Whitehead 2010, 2016). Conclusions: A CLA affords the theoretical design of play-based curricula beyond just play or sport towards purposeful, inclusive learning environments. Practitioners should look to underpin their practice with key theoretical ideas. This paper is of particular interest to those coaches and teachers tasked with designing practical environments for learning beyond the rhetoric of skill development in sport

Cas9+ conditionally-immortalized macrophages as a tool for bacterial pathogenesis and beyond.

Macrophages play critical roles in immunity, development, tissue repair, and cancer, but studies of their function have been hampered by poorly-differentiated tumor cell lines and genetically-intractable primary cells. Here we report a facile system for genome editing in non-transformed macrophages by differentiating ER-Hoxb8 myeloid progenitors from Cas9-expressing transgenic mice. These conditionally immortalized macrophages (CIMs) retain characteristics of primary macrophages derived from the bone marrow yet allow for easy genetic manipulation and a virtually unlimited supply of cells. We demonstrate the utility of this system for dissection of host genetics during intracellular bacterial infection using two important human pathogens: Listeria monocytogenes and Mycobacterium tuberculosis

On the frequency of N2H+ and N2D+

Context : Dynamical studies of prestellar cores search for small velocity differences between different tracers. The highest radiation frequency precision is therefore required for each of these species. Aims : We want to adjust the frequency of the first three rotational transitions of N2H+ and N2D+ and extrapolate to the next three transitions. Methods : N2H+ and N2D+ are compared to NH3 the frequency of which is more accurately known and which has the advantage to be spatially coexistent with N2H+ and N2D+ in dark cloud cores. With lines among the narrowests, and N2H+ and NH3 emitting region among the largests, L183 is a good candidate to compare these species. Results : A correction of ~10 kHz for the N2H+ (J:1-0) transition has been found (~0.03 km/s) and similar corrections, from a few m/s up to ~0.05 km/s are reported for the other transitions (N2H+ J:3-2 and N2D+ J:1-0, J:2-1, and J:3-2) compared to previous astronomical determinations. Einstein spontaneous decay coefficients (Aul) are included

Mahi-mahi (Coryphaena hippurus) life development: morphological, physiological, behavioral and molecular phenotypes.

BackgroundMahi-mahi (Coryphaena hippurus) is a commercially and ecologically important fish species that is widely distributed in tropical and subtropical waters. Biological attributes and reproductive capacities of mahi-mahi make it a tractable model for experimental studies. In this study, life development of cultured mahi-mahi from the zygote stage to adult has been described.ResultsA comprehensive developmental table has been created reporting development as primarily detailed observations of morphology. Additionally, physiological, behavioral, and molecular landmarks have been described to significantly contribute in the understanding of mahi life development.ConclusionRemarkably, despite the vast difference in adult size, many developmental landmarks of mahi map quite closely onto the development and growth of Zebrafish and other warm-water, active Teleost fishes