The avian tectobulbar tract: development, explant culture, and effects of antibodies on the pattern of neurite outgrowth

The tectobulbar tract is the first long-distance projecting fiber pathway to appear during the development of the avian optic tectum (dorsal half of the mesencephalon). Immunologically stained wholemounts of the E3 mesencephalon reveal that the early tectobulbar axons course in a dorsal-to-ventral direction and abruptly turn in a caudal direction shortly before reaching the ventral midline. During subsequent development, more tectobulbar axons are generated that form a parallel array of thick fascicles coursing ventrally within the mesencephalon. At this later stage of development, the tectobulbar tract bifurcates into an ipsilateral and contralateral pathway, both growing in a caudal direction near the mesencephalic ventral midline. Bifurcation and change in direction of growth is accompanied by a complete loss of the fasciculated growth pattern. Each tectobulbar axon is thus divided into a proximal fasciculated and a distal unfasciculated segment. Tectobulbar fascicles occupy the most superficial surface layer of the mesencephalon at early stages and are displaced deeper into the tissue beginning at embryonic day 5. In both of these locations, tectobulbar axons express molecules involved in axon-axon and axon-substrate interactions like the G4 antigen, neural cell adhesion molecule (N-CAM), neurofascin, and T61 antigen as revealed by immunohistochemistry and immunoblotting. Stripes of the mesencephalon explanted onto a basal lamina substratum show vigorous outgrowth of neurites. These processes grow in fascicles at a growth rate of 40 microns/h. Staining of the neurites with specific antibodies, as well as the position of the retrogradely labeled cell bodies, is in agreement with these processes being tectobulbar axons. This in vitro explant system was used to investigate the expression and possible functional involvement of N-CAM, neurofascin, G4 protein, and T61 antigen in the growth of these axons. The presence of antigen- binding fragments of polyclonal anti-G4 antibodies completely blocks fasciculation of the neurites but has no influence on their rate of elongation. Antibodies against N-CAM and neurofascin have no detectable effects. The number and length of the in vitro growing axons are reduced by the monoclonal T61 antibody. This effect is reversible. The elucidation of the exact course in vivo and the accessibility to the axons growing in vitro make the tectobulbar tract an excellent model system for the investigation of the role of these and other proteins in axonal growth and guidance during the development of the CNS

Behavioural Interventions for Obese Adults with Additional Risk Factors for Morbidity : Systematic Review of Effects on Behaviour, Weight and Disease Risk Factors

Peer reviewedPostprin

Precision spectroscopy of the molecular ion HD+: control of Zeeman shifts

Precision spectroscopy on cold molecules can potentially enable novel tests of fundamental laws of physics and alternative determination of some fundamental constants. Realizing this potential requires a thorough understanding of the systematic effects that shift the energy levels of molecules. We have performed a complete ab initio calculation of the magnetic field effects for a particular system, the heteronuclear molecular hydrogen ion HD+. Different spectroscopic schemes have been considered, and numerous transitions, all accessible by modern radiation sources and exhibiting well controllable or negligible Zeeman shift, have been found to exist. Thus, HD+ is a perspective candidate for determination of the ratio of electron-to-nuclear reduced mass, and for tests of its time-independence.Comment: A Table added, references and figures update

Photoelectron spectra of anionic sodium clusters from time-dependent density-functional theory in real-time

We calculate the excitation energies of small neutral sodium clusters in the framework of time-dependent density-functional theory. In the presented calculations, we extract these energies from the power spectra of the dipole and quadrupole signals that result from a real-time and real-space propagation. For comparison with measured photoelectron spectra, we use the ionic configurations of the corresponding single-charged anions. Our calculations clearly improve on earlier results for photoelectron spectra obtained from static Kohn-Sham eigenvalues

Entrepreneurship, Social Capital, And Institutions: Social And Commercial Entrepreneurship Across Nations

We model and test the relationship between social and commercial entrepreneurship drawing on social capital theory. We propose that the country prevalence rate of social entrepreneurship is an indicator of constructible nation-level social capital and enhances the likelihood of individual commercial entry. We further posit that both social and commercial entrepreneurial entry is facilitated by certain formal institutions, namely strong property rights and (low) government activism, albeit the latter impacts each of these types of entrepreneurship differently. We apply bivariate discrete choice multi-level modelling to population-representative samples in 47 countries and find support for these hypotheses

Yorkie and JNK Control Tumorigenesis in Drosophila Cells with Cytokinesis Failure

Summary: Cytokinesis failure may result in the formation of polyploid cells, and subsequent mitosis can lead to aneuploidy and tumor formation. Tumor suppressor mechanisms limiting the oncogenic potential of these cells have been described. However, the universal applicability of these tumor-suppressive barriers remains controversial. Here, we use Drosophila epithelial cells to investigate the consequences of cytokinesis failure in vivo. We report that cleavage defects trigger the activation of the JNK pathway, leading to downregulation of the inhibitor of apoptosis DIAP1 and programmed cell death. Yorkie overcomes the tumor-suppressive role of JNK and induces neoplasia. Yorkie regulates the cell cycle phosphatase Cdc25/string, which drives tumorigenesis in a context of cytokinesis failure. These results highlight the functional significance of the JNK pathway in epithelial cells with defective cytokinesis and elucidate a mechanism used by emerging tumor cells to bypass this tumor-suppressive barrier and develop into tumors. : Cytokinesis failure can be tumorigenic. Gerlach et al. show that JNK represses the expansion of those cells. Yorkie, the Drosophila ortholog of YAP and effector of the Hippo pathway, is able to bypass this barrier in cells with cytokinesis defects and cause neoplastic tumors. Keywords: cytokinesis failure, Drosophila, CDC25, cancer, JNK, Hippo pathway, cell cycle, genomic instabilit

Agrin isoforms and their role in synaptogenesis

Agrin is thought to mediate the motor neuron-induced aggregation of synaptic proteins on the surface of muscle fibers at neuromuscular junctions. Recent experiments provide direct evidence in support of this hypothesis, reveal the nature of agrin immunoreactivity at sites other than neuromuscular junctions, and have resulted in findings that are consistent with the possibility that agrin plays a role in synaptogenesis throughout the nervous system

Is being resolute better than being pragmatic when it comes to breastfeeding? Longitudinal qualitative study investigating experiences of women intending to breastfeed using the Theoretical Domains Framework

Background  In the UK, initiating then discontinuing breastfeeding before two weeks post-partum is common. The aim of this longitudinal qualitative study was to explore which psychosocial factors may influence discontinuation.  Methods  A sample of 10 pregnant women intending to breastfeed were recruited. A longitudinal qualitative design was used to capture views prior to and two weeks following birth. Semi-structured interviews were conducted underpinned by the Theoretical Domains Framework to explore a comprehensive list of psychosocial factors.  Results  Four women discontinued breastfeeding at the time of the second interview. Pre partum differences were identified between maintainers and discontinuers; discontinuers appeared to have stronger intentions to breastfeed based on their self-determination, self-confidence and perception of fewer barriers to breastfeeding. Post partum, discontinuers highlighted how they felt physically unable to carry on; their feeding experiences elicited negative emotions and pain. Negative emotions appeared to be exacerbated by original breastfeeding beliefs and advice given by healthcare professionals.  Conclusions  The women in this study who discontinued breastfeeding showed less cognitive flexibility which appeared to exacerbate post partum emotional distress when they encountered difficulties. Women with strong intentions and self-determination might benefit from support in anticipating potential barriers and identifying ways of overcoming them

Coping among Students: Development and validation of an exploratory measure

Students is a very specific population according to their manner to cope with stress. A coping questionnaire for students was developed and administered to 1100 French students at the beginning of the term (T1). Principal Component Analysis of responses, followed by varimax rotations, yielded three factors accounting for 50.5% of the total variance. Factors were identified as seeking social support, avoidance/emotion-focused coping and festive-addictive coping. Associations were observed between scores on these factors and a general coping scale (WCC-R), personal variables measured at the same time (T1), neuroticism, self-esteem, substance use, and four stress factors, as well as variables measured at the end of the term (T2), somatic symptoms, depressive symptoms, eating disorders, and life satisfaction. It would be very interesting to develop the students' personal competencies, so that they are learning how to adopt functional strategies of coping rather than of the harmful kind