Development of metabotropic glutamate receptors from trigeminal nuclei to barrel cortex in postnatal mouse

Expression patterns of group I (mGluR1α and mGluR5)and group II (mGluR2/3) metabotropic glutamate receptor subtypes were examined immunocytochemically in the trigeminal system of mice during the first 3 weeks of postnatal development, when somatotopic whisker representations are sequentially established from brainstem through thalamus to cerebral cortex. Immunostaining for all three epitopes formed whisker-related patterns in the trigeminal nuclei from postnatal day (P) 0, in the ventral posterior thalamic nucleus from P2, and in the posteromedial barrel subfield of somatosensory cortex (SI) from P4. The appearance of whisker-related patterns was preceded by increased levels of immunostaining of the neuropil, which subsequently declined from the trigeminal nuclei upward. In SI, mGluR1α-positive neurons were observed in all cortical layers from P2. mGluR5 was localized in neurons, glial cells, and neuropil from P2. mGluR2/3 immunostaining was distributed only in the neuropil at all ages. The three receptor subtypes showed moderate to high expression in deep layer V throughout development. Transient expression peaked in the hollows of layer IV barrels from P4 to P9, and then fell off as expression increased in supragranular layers from P14 to P21. The deep aspect of the cortical subplate (layer VIb) showed dense mGluR5 and less dense mGluR1α immunostaining throughout development. Up-regulation of expression of group I and II mGluRs is correlated with the growth and refinement of connectivity and the establishment of somatotopic patterns in the three main relay stations of the trigeminal system. This finding suggests roles for mGluRs in the early processing of sensory information and in developmental plasticity.

Shh/Boc signaling is required for sustained generation of ipsilateral projecting ganglion cells in the mouse retina

Sonic Hedgehog (Shh) signaling is an important determinant of vertebrate retinal ganglion cell (RGC) development. In mice, there are two major RGC populations: (1) the Islet2-expressing contralateral projecting (c)RGCs, which both produce and respond to Shh; and (2) the Zic2-expressing ipsilateral projecting RGCs (iRGCs), which lack Shh expression. In contrast to cRGCs, iRGCs, which are generated in the ventrotemporal crescent (VTC) of the retina, specifically express Boc, a cell adhesion molecule that acts as a high-affinity receptor for Shh. In Boc −/− mutant mice, the ipsilateral projection is significantly decreased. Here, we demonstrate that this phenotype results, at least in part, from the misspecification of a proportion of iRGCs. In Boc−/− VTC, the number of Zic2-positive RGCs is reduced, whereas more Islet2/Shh-positive RGCs are observed, a phenotype also detected in Zic2 and Foxd1 null embryos.

Best practices for competency development and assessment in higher education

The main objective of this article is to present the results of a study aimed at determining, classifying and evaluating practices of interest for general competency development and assessment in undergraduate programmes. The study encompassed the following phases: (1) focus group in order to establish a starting point regarding competency development and assessment, counting on the opinion of some of the best-rated teachers belonging to the participating universities; (2) collection of best practices; (3) design and validation of a scale for the assessment of best practices; and (4) scale administration (evaluation of good practices) and data analysis.