Pharmacological interventions in heat stress based on an animal model

Master'sMASTER OF SCIENC

Distinct subunits in heteromeric kainate receptors mediate ionotropic and metabotropic function at hippocampal mossy fiber synapses

Heteromeric kainate receptors (KARs) containing both glutamate receptor 6 (GluR6) and KA2 subunits are involved in KAR-mediated EPSCs at mossy fiber synapses in CA3 pyramidal cells. We report that endogenous glutamate, by activating KARs, reversibly inhibits the slow Ca2+-activated K+ current I(sAHP) and increases neuronal excitability through a G-protein-coupled mechanism. Using KAR knockout mice, we show that KA2 is essential for the inhibition of I(sAHP) in CA3 pyramidal cells by low nanomolar concentrations of kainate, in addition to GluR6. In GluR6(-/-) mice, both ionotropic synaptic transmission and inhibition of I(sAHP) by endogenous glutamate released from mossy fibers was lost. In contrast, inhibition of I(sAHP) was absent in KA2(-/-) mice despite the preservation of KAR-mediated EPSCs. These data indicate that the metabotropic action of KARs did not rely on the activation of a KAR-mediated inward current. Biochemical analysis of knock-out mice revealed that KA2 was required for the interaction of KARs with Galpha(q/11)-proteins known to be involved in I(sAHP) modulation. Finally, the ionotropic and metabotropic actions of KARs at mossy fiber synapses were differentially sensitive to the competitive glutamate receptor ligands kainate (5 nM) and kynurenate (1 mM). We propose a model in which KARs could operate in two modes at mossy fiber synapses: through a direct ionotropic action of GluR6, and through an indirect G-protein-coupled mechanism requiring the binding of glutamate to KA2

Nurturing shared leaders through internship

The Faculty of Social Sciences (the Faculty) of the University of Hong Kong has offered the very first credit-bearing internships in social sciences amongst all local tertiary institutions. Since September 2009, all students in the discipline have to complete 24 credits (equivalent to 4 courses) of off-campus experiential learning, with 12 credits in local internships and another 12 credits in global internships. In June 2012, the Faculty launched the pilot project of Service Leadership Internship (SLI) under the funding of the Li & Fung Service Leadership Initiative, which supports service leadership training in all eight of Hong Kong’s tertiary institution. The SLI took place in the summer 2012 where student interns worked as a team (groups of 3 – 5) to initiate, develop and implement (a) service task(s). By making use of the interns’ multi-disciplinary knowledge, the student interns contributed as shared leaders and helped community partners to generate innovative solutions to authentic problems under different projects. The Faculty also provided a series of support mechanisms to prepare the interns for the SLI projects. For example, an academic tutor was assigned to take care of each SLI project. Also, a series of workshops using the social cognitive approach were organized so as to enhance the interns’ social and personal competence as shared leaders and at the same time understand the construct of leaderships and social responsibilities through experiential learning and discussions. By completing the pre-workshop readings and actively participating in the workshops, interns internalized the core values of leadership such as enhanced self-awareness, became more competent as shared leaders and developed social responsibilities as an active member of the society. Booster sessions were also provided as a platform for small group sharing and problem-solving. In this paper presentation, the overall structure of the SLI, an overview of the content of the internship training and some of the learning outcome of the interns will be shared. The learning experiences in the pilot project will also help us plan for the upcoming summer of SLI 2013. A revised approach on SLI with an expanded participation of community partners will also be shared with the audience

Correlated Alterations in Serotonergic and Dopaminergic Modulations at the Hippocampal Mossy Fiber Synapse in Mice Lacking Dysbindin

Dysbindin-1 (dystrobrevin-binding protein 1, DTNBP1) is one of the promising schizophrenia susceptibility genes. Dysbindin protein is abundantly expressed in synaptic regions of the hippocampus, including the terminal field of the mossy fibers, and this hippocampal expression of dysbindin is strongly reduced in patients with schizophrenia. In the present study, we examined the functional role of dysbindin in hippocampal mossy fiber-CA3 synaptic transmission and its modulation using the sandy mouse, a spontaneous mutant with deletion in the dysbindin gene. Electrophysiological recordings were made in hippocampal slices prepared from adult male sandy mice and their wild-type littermates. Basic properties of the mossy fiber synaptic transmission in the mutant mice were generally normal except for slightly reduced frequency facilitation. Serotonin and dopamine, two major neuromodulators implicated in the pathophysiology of schizophrenia, can potentiate mossy fiber synaptic transmission probably via an increase in cAMP levels. Synaptic potentiation induced by serotonin and dopamine was very variable in magnitude in the mutant mice, with some mice showing prominent enhancement as compared with the wild-type mice. In addition, the magnitude of potentiation induced by these monoamines significantly correlated with each other in the mutant mice, indicating that a subpopulation of sandy mice has marked hypersensitivity to both serotonin and dopamine. While direct activation of the cAMP cascade by forskolin induced robust synaptic potentiation in both wild-type and mutant mice, this forskolin-induced potentaition correlated in magnitude with the serotonin-induced potentiation only in the mutant mice, suggesting a possible change in coupling of receptor activation to downstream signaling. These results suggest that the dysbindin deficiency could be an essential genetic factor that causes synaptic hypersensitivity to dopamine and serotonin. The altered monoaminergic modulation at the mossy fiber synapse could be a candidate pathophysiological basis for impairment of hippocampus-dependent brain functions in schizophrenia

Organization of sensory feature selectivity in the whisker system

Our sensory receptors are faced with an onslaught of different environmental inputs. Each sensory event or encounter with an object involves a distinct combination of physical energy sources impinging upon receptors. In the rodent whisker system, each primary afferent neuron located in the trigeminal ganglion innervates and responds to a single whisker and encodes a distinct set of physical stimulus properties – features – corresponding to changes in whisker angle and shape and the consequent forces acting on the whisker follicle. Here we review the nature of the features encoded by successive stages of processing along the whisker pathway. At each stage different neurons respond to distinct features, such that the population as a whole represents diverse properties. Different neuronal types also have distinct feature selectivity. Thus, neurons at the same stage of processing and responding to the same whisker nevertheless play different roles in representing objects contacted by the whisker. This diversity, combined with the precise timing and high reliability of responses, enables populations at each stage to represent a wide range of stimuli. Cortical neurons respond to more complex stimulus properties – such as correlated motion across whiskers – than those at early subcortical stages. Temporal integration along the pathway is comparatively weak: neurons up to barrel cortex are sensitive mainly to fast (tens of milliseconds) fluctuations in whisker motion. The topographic organization of whisker sensitivity is paralleled by systematic organization of neuronal selectivity to certain other physical features, but selectivity to touch and to dynamic stimulus properties is distributed in “salt-and-pepper” fashion

IDENTIFICATION AND DISTRIBUTION OF SOFT-BOTTOM BENTHIC BIVALVES OF SINGAPORE

Bachelor'sBACHELOR OF SCIENCE (HONOURS

REASSESSMENT OF THE NUDIBRANCHS OF SINGAPORE

Master'sMASTER OF SCIENC

A generic account of marine soft-bottom benthic bivalves of Singapore

Raffles Bulletin of Zoology442509-53