TY - JOUR AB - To better understand the role of neurotransmitter receptors in neuronal differentiation and maturation a detailed knowledge of their identity, location and function in the plasma membrane of specific neuronal populations during development is required. Combining pre-embedding immunocytochemistry with cell tracking in embryonic brain slice cultures we show that virtually all neurons (∼98%) migrating through the lower intermediate zone (LIZ) on their way from the medial ganglionic eminence to the cerebral cortex, express GABA BR1. Blockade of GABABRs with a specific antagonist, CGP52432, resulted in a concentration-dependent accumulation of these tangentially migrating neurons in the ventricular/subventricular zones (VZ/SVZ) of the cortex and fewer cells were observed in the cortical plate/marginal zone (CP/MZ) and LIZ. Moreover, they had significantly shorter leading processes compared with similar migrating cells in control slices. Electrophysiological recording in LIZ and CP cells revealed no direct effect of either CGP52432 or the GABABR agonist, baclofen, on resting membrane properties suggesting that the effect of CGP52432 on migration might be mediated through a metabotropic action or the regulation of release of factors controlling migration. These results suggest that GABABRs have an important modulatory role in the migration of cortical interneurons. AU - López-Bendito, Guillermina AU - Luján, Rafael AU - Ryuichi Shigemoto AU - Ganter, Paul AU - Paulsen, Ole AU - Molnár, Zoltán ID - 2634 IS - 9 JF - Cerebral Cortex TI - Blockade of GABAB receptors alters the tangential migration of cortical neurons VL - 13 ER - TY - JOUR AB - Taste-metabotropic glutamate receptor 4 (taste-mGluR4) and the heteromers of T1R1 and T1R3 are candidate receptors involved in the sense of umami (monosodium glutamate) taste. Although the expression of group III mGluRs (taste-mGluR4) has been demonstrated in taste tissues, no mention has been made of the expression of group I mGluRs (mGluR1 and mGluR5) in taste tissues. We examined the expression of mGluR1 and mGluR5 in rat gustatory tissues by using reverse transcription-polymerase chain reaction (RT-PCR), in situ hybridization, immunohistochemistry and immunoelectron microscopy. RT-PCR assay showed that mGluR1α and mGluR1β mRNAs were expressed in circumvallate papillae, but mGluR5 mRNA was not expressed. The positive signals of mGluR1 mRNA were detected only in circumvallate taste buds by in situ hybridization analysis. In cryosections of fungiform, foliate and circumvallate papillae, the antibody against mGluRla gave intense labeling on the taste hairs in all taste pores examined. In the developing taste buds, the positive signals of mGluR1α in taste hairs gradually increased with the increase in number of taste bud cells. These results show that, in addition to taste-mGluR4 and the heteromer of T1R1 and T1R3, mGluR1α may function as a receptor for glutamate (umami) taste sensation. AU - Toyono, Takashi AU - Seta, Yuji AU - Kataoka, Shinji AU - Kawano, Shintaro AU - Ryuichi Shigemoto AU - Toyoshima, Kuniaki ID - 2630 IS - 1 JF - Cell and Tissue Research TI - Expression of metabotropic glutamate receptor group I in rat gustatory papillae VL - 313 ER - TY - JOUR AB - While the cholinergic depletion in Alzheimer's disease (AD) has been known for some time, a definitive involvement of other neurotransmitter systems has been somewhat more elusive. Our study demonstrates a clear involvement of both glutamatergic and, to a lesser extent, GABAergic neurons in an early onset transgenic mouse model of AD-like amyloid pathology. Immunohistochemical staining and subsequent quantification has revealed a statistically significant increased density of glutamatergic and GABAergic presynaptic boutons in both the plaque free and plaque adjacent cortical neuropile areas of transgenic mice as compared to non-transgenic controls. Furthermore, amyloid plaque size was shown to have a statistically significant effect on the relative area occupied by dystrophic glutamatergic neurites in the peri-plaque neuropile. These findings support our hypothesis that the amyloid pathology progresses in a time and neurotransmitter specific manner, first in the cholinergic system which appears to be most vulnerable, followed by the glutamatergic presynaptic boutons and finally the somewhat more resilient GABAergic terminals. AU - Bell, Karen F AU - De Kort, G J AU - Steggerda, S AU - Ryuichi Shigemoto AU - Ribeiro-da-Silva, Alfredo AU - Cuello, Augusto C ID - 2637 IS - 2 JF - Neuroscience Letters TI - Structural involvement of the glutamatergic presynaptic boutons in a transgenic mouse model expressing early onset amyloid pathology VL - 353 ER - TY - JOUR AB - We report the results of an experimental study of magnetohydrodynamic damping of sidewall convection in a rectangular enclosure filled with gallium. In particular we investigate the suppression of convection when a steady magnetic field is applied separately in each of the three principal directions of the flow. The strongest damping of the steady flow is found for a vertical magnetic field, which is in agreement with theory. However, we observe that the application of a field transverse to the flow provides greater damping than a longitudinal one, which seems to contradict available theory. We provide a possible resolution of this apparent dichotomy in terms of the length scale of the experiment. AU - Björn Hof AU - Juel, Anne AU - Mullin, Tom P ID - 2784 JF - Journal of Fluid Mechanics TI - Magnetohydrodynamic damping of convective flows in molten gallium VL - 482 ER - TY - JOUR AB - Experimental evidence for the scaling of the finite amplitude of perturbation theory required to promote transition in Poiseuille flow was found. The exponent is -1 and was uncovered using considerable care in the design and execution of the experiment. Interestingly, this exponent was also found in experiments on transition in boundary layers. AU - Björn Hof AU - Juel, Anne AU - Mullin, Tom P ID - 2785 IS - 24 JF - Physical Review Letters TI - Scaling of the turbulence transition threshold in a pipe VL - 91 ER -