Astroglial-axonal interactions during early stages of myelination in mixed cultures using in vitro and ex vivo imaging techniques

<b>Background</b><p></p> Myelination is a very complex process that requires the cross talk between various neural cell types. Previously, using cytosolic or membrane associated GFP tagged neurospheres, we followed the interaction of oligodendrocytes with axons using time-lapse imaging in vitro and ex vivo and demonstrated dynamic changes in cell morphology. In this study we focus on GFP tagged astrocytes differentiated from neurospheres and their interactions with axons.<p></p> <b>Results</b><p></p> We show the close interaction of astrocyte processes with axons and with oligodendrocytes in mixed mouse spinal cord cultures with formation of membrane blebs as previously seen for oligodendrocytes in the same cultures. When GFP-tagged neurospheres were transplanted into the spinal cord of the dysmyelinated shiverer mouse, confirmation of dynamic changes in cell morphology was provided and a prevalence for astrocyte differentiation compared with oligodendroglial differentiation around the injection site. Furthermore, we were able to image GFP tagged neural cells in vivo after transplantation and the cells exhibited similar membrane changes as cells visualised in vitro and ex vivo.<p></p> <b>Conclusion</b><p></p> These data show that astrocytes exhibit dynamic cell process movement and changes in their membrane topography as they interact with axons and oligodendrocytes during the process of myelination, with the first demonstration of bleb formation in astrocytes

Multimodal engagement strategies in science dissemination: A case study of TED talks and YouTube science videos

The growing interest on science dissemination offers new opportunities to communicate science openly to various audiences, but also brings on the challenge of adapting to an audience that does not share the same academic background. This adaptation has been referred to as recontextualization. In the case of the formats that concern this study, that is, TEDx Talks and YouTube science dissemination videos, their multimodal nature suggests that recontextualization, and therefore engagement as a crucial aspect of this process, is likely to go way beyond purely linguistic aspects. The aim of this study is to unveil how engagement strategies in two science dissemination formats (a face to face talk and an online video) are realized through complex multimodal ensembles, and to highlight differences across them. In order to fulfill this aim, two talks by the same presenter and dealing with similar content were selected for analysis: a TEDx talk and a YouTube science dissemination video from the channel PBS Space Time. The recordings were annotated using the software Multimodal Video Analysis. The annotation included engagement strategies; embodied modes, that is, modes carried out using the body; and, in the case of the YouTube video, filmic modes, that is, modes triggered by the editing process of the recorded video. Our results show that the role of both embodied and filmic modes is paramount in the realization of engagement strategies. Our findings also bring to the fore significant differences in the ways in which the two distinct audiences are engaged, concerning the frequency and use of both semiotic modes and engagement strategies

Reduced axonal diameter of peripheral nerve fibres in a mouse model of Rett syndrome

Rett syndrome (RTT) is a neurological disorder characterized by motor and cognitive impairment, autonomic dysfunction and a loss of purposeful hand skills. In the majority of cases, typical RTT is caused by de novo mutations in the X-linked gene, MECP2. Alterations in the structure and function of neurons within the central nervous system of RTT patients and Mecp2-null mouse models are well established. In contrast, few studies have investigated the effects of MeCP2-deficiency on peripheral nerves. In this study, we conducted detailed morphometric as well as functional analysis of the sciatic nerves of symptomatic adult female Mecp2+/- mice. We observed a significant reduction in the mean diameter of myelinated nerve fibers in Mecp2+/- mice. In myelinated fibers, mitochondrial densities per unit area of axoplasm were significantly altered in Mecp2+/- mice. However, conduction properties of the sciatic nerve of Mecp2 knockout mice were not different from control. These subtle changes in myelinated peripheral nerve fibers in heterozygous Mecp2 knockout mice could potentially explain some RTT phenotypes

Minimally Invasive Microscopy Using GRIN Lens Microendoscopes

We report a custom epi-fluorescent microscope setup using GRIN lens microendoscopes for minimally invasive microscopic imaging in rodents. A simple scanning system and deconvolution provides high quality wide field-of-view images through these highly aberrated endoscopes

Evaluación de Spalangia endius y Muscidifurax sp. (Hymenoptera, Pteromalidae) como controladores de Musca domestica en el Perú

In this work we compared the parasitoid activity of the microhymenopterans Spalangia endius and Muscidifurax sp. on the pupae of Musca domestica. The better temperature for the reared was of 25 °C. The cycle of S. endius was completed in 22,6 days, while in Muscidifurax sp. in 14,8 days. The cycle duration was inversely related to temperature, in the females was highest than males. The longevity was similar in both microhymenopterans species (20,7 days in S. endius and 18,6 days in Muscifurax sp.). Spalangia endius oviposited on 175 pupae of M. domestica in 15 days; this value was highest than Muscidifurax that oviposited 140 pupae in 16 days. In both species the highest posture occurred in the third day. Musca domestica pupae with two maturation days were the more parasited; S. endius with 66,4% and Muscidifurax sp. with 60,2% of effective parasitism. The better number of M. domestica pupae was 10 (10:1). We conclude that under laboratory conditions, S. endius can be an efficient biological controller of pustules of M. domestica.En el presente trabajo se comparó la actividad parasitoide de las microavispas Spalangia endius y Muscidifurax sp. sobre el estadio pupal de Musca domestica. La mejor temperatura para la crianza fue de 25 °C. El ciclo de S. endius se completó en 22,6 días, mientras en Muscidifurax sp. en 14,8 días. La duración del ciclo fue inversamente relacionada con la temperatura, siendo mayor en las hembras que en los machos. La longevidad fue similar en ambas especies de microavispas (20,7 días en S. endius y 18,6 días en Muscifurax sp.).La oviposicion de S. endius a los 15 días fue sobre 175 pupas de M. domestica, valor mayor que Muscidifurax que parasitó 140 pupas en 16 días. En ambas especies la mayor postura ocurrió al tercer día. Las pupas de M. domestica de dos días de maduración fueron las mas parasitadas con 66,4% de parasitismo efectivo por S. endius y 60,2% por Muscidifurax sp. El número óptimo de pupas de M. domestica fue 10 (10:1). Se concluye que en condiciones de laboratorio, Spalangia endius puede ser un eficiente controlador biológico de pupas de Musca domestica

Evaluación de Spalangia endius y Muscidifurax sp. (Hymenoptera, Pteromalidae) como controladores de Musca domestica en el Perú

In this work we compared the parasitoid activity of the microhymenopterans Spalangia endius and Muscidifurax sp. on the pupae of Musca domestica. The better temperature for the reared was of 25 °C. The cycle of S. endius was completed in 22,6 days, while in Muscidifurax sp. in 14,8 days. The cycle duration was inversely related to temperature, in the females was highest than males. The longevity was similar in both microhymenopterans species (20,7 days in S. endius and 18,6 days in Muscifurax sp.). Spalangia endius oviposited on 175 pupae of M. domestica in 15 days; this value was highest than Muscidifurax that oviposited 140 pupae in 16 days. In both species the highest posture occurred in the third day. Musca domestica pupae with two maturation days were the more parasited; S. endius with 66,4% and Muscidifurax sp. with 60,2% of effective parasitism. The better number of M. domestica pupae was 10 (10:1). We conclude that under laboratory conditions, S. endius can be an efficient biological controller of pustules of M. domestica.En el presente trabajo se comparó la actividad parasitoide de las microavispas Spalangia endius y Muscidifurax sp. sobre el estadio pupal de Musca domestica. La mejor temperatura para la crianza fue de 25 °C. El ciclo de S. endius se completó en 22,6 días, mientras en Muscidifurax sp. en 14,8 días. La duración del ciclo fue inversamente relacionada con la temperatura, siendo mayor en las hembras que en los machos. La longevidad fue similar en ambas especies de microavispas (20,7 días en S. endius y 18,6 días en Muscifurax sp.).La oviposicion de S. endius a los 15 días fue sobre 175 pupas de M. domestica, valor mayor que Muscidifurax que parasitó 140 pupas en 16 días. En ambas especies la mayor postura ocurrió al tercer día. Las pupas de M. domestica de dos días de maduración fueron las mas parasitadas con 66,4% de parasitismo efectivo por S. endius y 60,2% por Muscidifurax sp. El número óptimo de pupas de M. domestica fue 10 (10:1). Se concluye que en condiciones de laboratorio, Spalangia endius puede ser un eficiente controlador biológico de pupas de Musca domestica

The axon-myelin unit in development and degenerative disease

Axons are electrically excitable, cable-like neuronal processes that relay information between neurons within the nervous system and between neurons and peripheral target tissues. In the central and peripheral nervous systems, most axons over a critical diameter are enwrapped by myelin, which reduces internodal membrane capacitance and facilitates rapid conduction of electrical impulses. The spirally wrapped myelin sheath, which is an evolutionary specialisation of vertebrates, is produced by oligodendrocytes and Schwann cells; in most mammals myelination occurs during postnatal development and after axons have established connection with their targets. Myelin covers the vast majority of the axonal surface, influencing the axon's physical shape, the localisation of molecules on its membrane and the composition of the extracellular fluid (in the periaxonal space) that immerses it. Moreover, myelinating cells play a fundamental role in axonal support, at least in part by providing metabolic substrates to the underlying axon to fuel its energy requirements. The unique architecture of the myelinated axon, which is crucial to its function as a conduit over long distances, renders it particularly susceptible to injury and confers specific survival and maintenance requirements. In this review we will describe the normal morphology, ultrastructure and function of myelinated axons, and discuss how these change following disease, injury or experimental perturbation, with a particular focus on the role the myelinating cell plays in shaping and supporting the axon

Porcine congenital splayleg is characterised by muscle fibre atrophy associated with relative rise in MAFbx and fall in P311 expression

BACKGROUND: Porcine congenital splayleg (PCS) is the most important congenital condition of piglets, associated with lameness and immobility, of unknown aetiology and pathogenesis, hence the need to better understand the condition by defining, in the first instance, its histopathology and molecular pathology. RESULTS: Semitendinosus, longissimus dorsi, and gastrocnemius muscles were removed from 4 sets of 2-day-old splayleg piglets, each with a corresponding normal litter mate. Based on immunohistochemistry and histological image analysis, PCS piglets showed significantly smaller fibre size without any accompanying sign of inflammation. Although there was no dramatic change in fibre type composition in affected muscles, several structural myosin heavy chain genes were significantly down-regulated. MAFbx, a major atrophy marker, was highly up-regulated in nearly all PCS muscles, in comparison with controls from normal litter mates. In contrast, P311, a novel 8 kDa protein, was relatively down-regulated in all the PCS muscles. To investigate a functional role of P311 in skeletal muscle, its full-length cDNA was over-expressed in murine C2C12 muscle cells, which resulted in enhanced cell proliferation with reduced myotube formation. Hence, reduced P311 expression in PCS piglets might contribute to atrophy through reduced muscle cell proliferation. P311, predictably, was down-regulated by the over-expression of calcineurin, a key signalling factor of muscle differentiation. CONCLUSION: We demonstrated that PCS is a condition characterised by extensive fibre atrophy and raised fibre density, and propose that the combined differential expression of MAFbx and P311 is of potential in the diagnosis of subclinical PCS

Do weaner pigs need in-feed antibiotics to ensure good health and welfare?

peer-reviewedThis study was part of the WELPIG project which was funded from internal Teagasc funds. During the writing of this paper JACD’s position was funded by the Department of Agriculture Food and the Marine under the Research Stimulus Fund (PathSurvPigs 14/S/832) as part of the National Development PlanAntibiotics (AB) are used in intensive pig production systems to control infectious diseases and they are suspected to be a major source of antibiotic resistance. Following the ban on AB use as growth promoters in the EU, their prophylactic use in-feed is now under review. The aim of this study was to evaluate the effect of removing prophylactic in-feed AB on pig health and welfare indicators. Every Monday for six weeks, a subset of 70 pigs were weaned, tagged and sorted into two groups of 35 pigs according to weight (9.2 ± 0.6 kg). AB were removed from the diet of one group (NO, n=6) and maintained in the other group (AB, n=6) for nine weeks. Ten focal pigs were chosen per group. After c. five weeks each group was split into two pens of c.17 pigs for the following 4 weeks. Data were recorded weekly. Skin, tail, ear, flank and limb lesions of focal pigs were scored according to severity. The number of animals per group affected by health deviations was also recorded. The number of fights and harmful behaviours (ear, tail bites) per group was counted during 3×5min observations once per week. Data were analysed using mixed model equations and binomial logistic regression. At group level, AB pigs were more likely to have tail (OR=1.70; P=0.05) but less likely to have ear lesions than NO pigs (OR=0.46; P<0.05). The number of ear bites (21.4±2.15 vs. 17.3±1.61; P<0.05) and fights (6.91±0.91 vs. 5.58±0.72; P=0.09) was higher in AB than in NO pigs. There was no effect of treatment on health deviations and the frequency of these was low. Removing AB from the feed of weaner pigs had minimal effects on health and welfare indicators