TY - JOUR AB - We prove that in an undirected graph there are at most O(n²) cuts of size strictly less than of the size of the minimum cut. AU - Henzinger, Monika H AU - Williamson, David P. ID - 11761 IS - 1 JF - Information Processing Letters SN - 0020-0190 TI - On the number of small cuts in a graph VL - 59 ER - TY - CONF AB - This paper shows how a general technique, called lock-step search, used in dynamic graph algorithms, can be used to improve the running time of two problems arising in program verification and communication protocol design. (1)We consider the nonemptiness problem for Streett automata: We are given a directed graph G = (V, E) with n = ¦V¦ and m = ¦E¦, and a collection of pairs of subsets of vertices, called Streett pairs,〈L i , U i 〉, i = 1.k. The question is whether G has a cycle (not necessarily simple) which, for each 1 ≤ i ≤ k, if it contains a vertex from L i then it also contains a vertex of U i . Let b=Σ i=1..k |L i |+|U i |. The previously best algorithm takes time O((m + b) min{n, k}). We present an algorithm that takes time 𝑂(𝑚min{𝑚𝑙𝑜𝑔𝑛,‾‾‾‾‾‾√𝑘,𝑛}+𝑏𝑚𝑖𝑛{𝑙𝑜𝑔𝑛,𝑘}). (2)In communication protocol pruning we are given a directed graph G = (V, E) with l special vertices. The problem is to efficiently maintain the strongly-connected components of the special vertices on a restricted set of edge deletions. Let m i be the number of edges in the strongly connected component of the ith special vertex. The previously best algorithm repeatedly recomputes the strongly-connected components which leads to a running time of O(Σ i m 2i). We present an algorithm with time 𝑂(𝑙√∑𝑖𝑚1.5𝑖). AU - Henzinger, Monika H AU - Telle, Jan Arne ID - 11804 SN - 0302-9743 T2 - 5th Scandinavian Workshop on Algorithm Theory TI - Faster algorithms for the nonemptiness of streett automata and for communication protocol pruning VL - 1097 ER - TY - CONF AB - We state a new sampling lemma and use it to improve the running time of dynamic graph algorithms. For the dynamic connectivity problem the previously best randomized algorithm takes expected time O(log3 n) per update, amortized over Ω(m) updates. Using the new sampling lemma, we improve its running time to O(log2 n). There exists a lower bound in the cell probe model for the time per operation of Ω(log n/ log log n) for this problem. Similarly improved running times are achieved for 2-edge connectivity, k-weight minimum spanning tree, and bipartiteness. AU - Henzinger, Monika H AU - Thorup, Mikkel ID - 11910 SN - 0302-9743 T2 - 23rd International Colloquium on Automata, Languages, and Programming TI - Improved sampling with applications to dynamic graph algorithms VL - 1099 ER - TY - CONF AB - We are given a set 7 = {Tl , Tz, . . . , Tk} of rooted binary trees, each Ti leaf-labeled by a subset L(x) c {1,2 )...) n}. IfT is a tree on {1,2, . . , n}, we let T]L denote the subtree of T induced by the nodes of L and all their ancestors. The consensus tree problem asks whether there exists a tree T* such that for every I, T’ IC(Ti) is homeomorphic to Ti. We present algorithms which test if a given set of trees has a consensus tree and if so, construct one. The deterministic algorithm takes time min{O(mn’/‘), O(m + n2 logn)}, where m = Ci IZl and uses linear space. The randomized algorithm takes time O(m log3 n) and uses linear space. The previous best for this problem was an 1981 O(mn) algorithm by Aho et al. Our faster deterministic algorithm uses a new efficient algorithm for the following interesting dynamic graph problem: Given a graph G with n nodes and m edges and a sequence of b batches of one or more edge deletions, then after each batch, either find a new component that has just been created or determine that there is no such component. For this problem, we have a simple algorithm with running time O(n2 log n + be min{ n2, m log n}), where be is the number of batches which do not result in a new component. For our particular application, bc 5 1. If all edges are deleted, then the best previously known deterministic algorithm requires time O(mJ;ii) to solve this problem. computational evolutionary biology. The first application is in the problem of inferring consensus of trees when there can be disagreement[l6]. There have, been several models suggested for this problem[2, 3, 4, 8, ?, 11, 17, 181, of which one is called the Local Consensus Tree[l5]. The local consensus tree model presumes that the user provides a local consensus rule which determines the form of the output tree on (perhaps) each triple of leaves, and the objective is to determine whether a tree exists which is consistent with each of the constraints. We will show that we can construct the local consensus tree of k trees on n species in O(kn3) time, improving on the O(lcn3 + n”) running time if we use the Aho et al algorithm. The second application is a heuristic for constructing the maximum likelihood tree based upon combining solutions to small subproblems. This is a simple and yet potentially significantly interesting approach to the evolutionary tree construction problem. AU - Henzinger, Monika H AU - King, Valerie AU - Warnow, Tandy ID - 11927 SN - 0898713668 T2 - 7th Annual ACM-SIAM Symposium on Discrete Algorithms TI - Constructing a tree from homeomorphic subtrees, with applications to computational evolutionary biology ER - TY - CONF AU - Leonid Sazanov AU - Burrows, P AU - Nixon, P J ID - 1942 TI - Presence of a large protein complex containing the ndhK gene product and possessing NADH-specific dehydrogenase activity in thylakoid membranes of higher plant chloroplasts VL - 2 ER - TY - JOUR AB - Two strains of Rhodospirillum rubrum were constructed in which, by a gene dosage effect, the transhydrogenase activity of isolated chromatophores was increased 7-10-fold and 15-20-fold, respectively. The H+/H- ratio (the ratio of protons translocated per hydride ion equivalent transferred from NADPH to an NAD+ analogue, acetyl pyridine adenine dinucleotide), determined by a spectroscopic technique, was approximately 1.0 for chromatophores from the over-expressing strains, but was only approximately 0.6 for wild-type chromatophores. Highly-coupled proteoliposomes were prepared containing purified transhydrogenase from beef-heart mitochondria. Using the same technique, the H+/H- ratio was close to 1.0 for these proteoliposomes. It is suggested that the mechanistic H+/H- ratio is indeed unity, but that a low ratio is obtained in wild-type chromatophores because of inhomogeneity in the vesicle population. AU - Bizouarn, Tania AU - Sazanov, Leonid A AU - Aubourg, Sébastien AU - Jackson, Julie ID - 1952 IS - 1 JF - Biochimica et Biophysica Acta - Bioenergetics SN - 0005-2728 TI - Estimation of the H+/H- ratio of the reaction catalysed by the nicotinamide nucleotide transhydrogenase in chromatophores from over-expressing strains of Rhodospirillum rubrum and in liposomes inlaid with the purified bovine enzyme VL - 1273 ER - TY - JOUR AU - Sazanov, Leonid A AU - Burrows, Paul AU - Nixon, Peter ID - 1951 IS - 3 JF - Biochemical Society Transactions SN - 0300-5127 TI - Detection and characterization of a complex I-like NADH-specific dehydrogenase from pea thylakoids VL - 24 ER - TY - JOUR AB - The metabotropic glutamate receptor subtypes mGluR2 and mGluR5, which are thought to be coupled respectively to the inhibitory cyclic adenosine monophosphate (cAMP) cascade and the phosphatidylinositol hydrolysis/Ca2+ cascade, are known to be expressed on Golgi cells in the granular layer of the rat cerebellar cortex. In the present immunohistochemical study with a monoclonal antibody against mGluR2 and a polyclonal antibody for mGluR5, we examined whether or not mGluR2- and mGluR5-like immunoreactivities were both present in single Golgi cells in the rat cerebellar cortex. In double immunofluorescence histochemistry, no Golgi cells showed mGluR2- and mGluR5-like immunoreactivities simultaneously. Of the total number of Golgi cells immunoreactive for mGluR2 or mGluR5, about 90% were mGluR2-like immunoreactive, and about 10% were mGluR5-like immunoreactive. Golgi cells with mGluR2-like immunoreactivity were distributed evenly in the granular layer of all the cerebellar regions, while those with mGluR5-like immunoreactivity were distributed more frequently in the I, II, VII-X lobules of the vermis and the copula pyramidis of the hemisphere than in other cerebellar regions. The results indicate that Golgi cells containing mGluR2 are segregated from those possessing mGluR5. These two populations of Golgi cells, each equipped with a different metabolic glutamate receptor coupled to a different intracellular signal transduction system, may play different roles in the glutamatergic neuronal circuits in the cerebellar cortex. AU - Neki, Akio AU - Ohishi, Hitoshi AU - Kaneko, Takeshi AU - Shigemoto, Ryuichi AU - Nakanishi, Shigetada AU - Mizuno, Noboru ID - 2492 IS - 3 JF - Neuroscience SN - 0306-4522 TI - Metabotropic glutamate receptors mGluR2 and mGluR5 are expressed in two non-overlapping populations of Golgi cells in the rat cerebellum VL - 75 ER - TY - JOUR AB - The distribution of the neuromedin K receptor (NK3; NKR) in the central nervous system was investigated in the adult rat by using in situ hybridization and immunohistochemical techniques. The rabbit anti-NKR antibody was raised against a bacterial fusion protein containing a C- terminal portion of NKR and affinity purified with a Sepharose 4B column conjugated to the fusion protein. Immunoblot analysis was performed to test the reactivity and specificity of the antibody. Crude membrane was prepared from cDNA-transfected Chinese hamster ovary (CHO) cells expressing each of the rat NKR, substance P receptor (NK1; SPR), and substance K receptor (NK2; SKR) and from the hypothalamus, cerebral cortex, and cerebellum. Immunoreactive bands were observed specifically in the NKR-CHO cells, hypothalamus, and cerebral cortex but not in the SPR- or SKR-CHO cells, nor in the cerebellum. Molecular weights of the immunoreactive bands ranged from 73 to 89 kDa and from 59 to 83 kDa in the NKR-CHO cells and tissues, respectively. The distribution of NKR-like immunoreactivity coincided with that of NKR mRNA. The expression of NKR was indicated on neuronal cell bodies and dendrites. NKR was found to be expressed intensely or moderately in neurons in the glomerular and granule cell layers of the main olfactory bulb; glomerular and mitral cell layers of the accessory olfactory bulb; layers IV and V of the cerebral neocortex; medial septal nucleus; nucleus of the diagonal band; bed nucleus of the stria terminalis; globus pallidus; ventral pallidum; paraventricular nucleus; supraoptic nucleus; zona incerta; dorsal, lateral, and posterior hypothalamic areas; amygdaloid nuclei; medial habenular nucleus; ventral tegmental area; midbrain periaqueductal gray; interpeduncular nuclei; substantia nigra pars compacta; linear, median, dorsal, and pontine raphe nuclei; posteromedial tegmental nucleus; sphenoid nucleus; nucleus of the solitary tract; intermediate and rostroventrolateral reticular nuclei; and lamina II of the caudal spinal trigeminal nucleus and spinal dorsal horn. These findings are discussed in relation to the physiological functions associated with neuromedin K. AU - Ding, Yu AU - Shigemoto, Ryuichi AU - Takada, Masahiko AU - Ohishi, Hitoshi AU - Nakanishi, Shigetada AU - Mizuno, Noboru ID - 2564 IS - 2 JF - Journal of Comparative Neurology SN - 0021-9967 TI - Localization of the neuromedin K receptor (NK3) in the central nervous system of the rat VL - 364 ER - TY - JOUR AB - The present study indicated presynaptic localization of a metabotropic glutamate receptor, mGluR8, in projection neurons of the main olfactory bulb of rat. An antibody was produced by using a peptide corresponding to C-terminal 23 amino acids of mouse mGluR8. It was confirmed that the C-terminal 23 amino acids of rat mGluR8 were the same as those of mouse mGluR8 except for one, and that the antibody specifically recognized mGluR8 in the rat rhinencephalon. In layer Ia of the piriform cortex (a target area of projection fibers from the main olfactory bulb), mGluR8-like immunoreactivity (mGluR8-LI) was reduced after transection of the lateral olfactory tract, and mGluR8-LI was observed in axon terminals which were filled with round synaptic vesicles and made asymmetric synapses with dendritic spines. AU - Kinoshita, Ayae AU - Ohishi, Hitoshi AU - Neki, Akio AU - Nomura, Sakashi AU - Shigemoto, Ryuichi AU - Takada, Masahiko AU - Nakanishi, Shigetada AU - Mizuno, Noboru ID - 2566 IS - 1 JF - Neuroscience Letters SN - 0304-3940 TI - Presynaptic localization of a metabotropic glutamate receptor, mGluR8, in the rhinencephalic areas: A light and electron microscope study in the rat VL - 207 ER - TY - JOUR AB - Immunoreactivity for the metabotropic glutamate receptor 7 (mGluR7) and that for phosphate-activated glutaminase (PAG) were examined in the trigeminal (TG), dorsal root (DRG), nodose (NG), superior cervical, celiac, and pelvic ganglia of the rat. Virtually all neuronal cell bodies showed mGluR7-like immunoreactivity (mGluR7-LI) in these ganglia. On the other hand, PAG-like immunoreactivity (PAG) was seen in almost all neuronal cell bodies in the TG, DRG and NG, but not in the other ganglia. Co-existence of mGluR7- and PAG-LI in the TG, DRG and NG was confirmed by a double-immunofluorescence immunohistochemical method. The results indicate that virtually all sensory ganglion neurons are glutamatergic and equipped with mGluR7. AU - Li, Jin AU - Ohishi, Hitoshi AU - Kaneko, Takeshi AU - Shigemoto, Ryuichi AU - Neki, Akio AU - Nakanishi, Shigetada AU - Mizuno, Noboru ID - 2565 IS - 1-2 JF - Neuroscience Letters SN - 0304-3940 TI - Immunohistochemical localization of a metabotropic glutamate receptor, mGluR7, in ganglion neurons of the rat; with special reference to the presence in glutamatergic ganglion neurons VL - 204 ER - TY - JOUR AB - A monoclonal antibody against a metabotropic glutamate receptor, mGluR2, was produced by using a glutathione S-transferase (GST) fusion protein containing an N-terminal sequence of rat mGluR2. Intense mGluR2-like immunoreactivity (mGluR2-LI) was seen mainly in neuropil of the cerebral cortical regions, hippocampus, olfactory bulb, some diencephalic nuclei, dorsal cochlear nucleus and cerebellar cortex. In the cerebellar cortex, mGluR2-LI was seen only in Golgi cells. In Ammon's hem, mGluR2-LI was marked in the stratum lucidum of CA3 and the stratum lacunosum-moleculare of CA1-CA3, but not detected in the stratum pyramidale. The results indicate that mGluR2 is located not only presynaptically but also postsynaptically. AU - Neki, Akio AU - Ohishi, Hitoshi AU - Kaneko, Takeshi AU - Shigemoto, Ryuichi AU - Nakanishi, Shigetada AU - Mizuno, Noboru ID - 2562 IS - 3 JF - Neuroscience Letters SN - 0304-3940 TI - Pre- and postsynaptic localization of a metabotropic glutamate receptor, mGluR2, in the rat brain: An immunohistochemical study with a monoclonal antibody VL - 202 ER - TY - JOUR AB - Localization of a metabotropic glutamate receptor, mGluR4a, was immunohistochemically examined in the rat cerebellum with an antibody, which was produced by using a synthetic peptide corresponding to a C-terminal sequence of rat mGluR4a. Marked mGluR4a-like immunoreactivity (mGluRLta-LI) was seen in neuropil of the molecular layer of the cerebellar cortex. Electron microscopically, mGluR4a-LI was observed in many axon terminals in the molecular layer. These axon terminals showing mGluR4a-LI were filled with round synaptic vesicles and were in asymmetric synaptic contacts most frequently with dendritic spines. The results indicate that mGluR4a are located presynaptically in the parallel fibers arising from the granule cells in the cerebellar cortex. AU - Kinoshita, Ayae AU - Ohishi, Hitoshi AU - Nomura, Sakashi AU - Shigemoto, Ryuichi AU - Nakanishi, Shigetada AU - Mizuno, Noboru ID - 2568 IS - 3 JF - Neuroscience Letters SN - 0304-3940 TI - Presynaptic localization of a metabotropic glutamate receptor, mGluR4a, in the cerebellar cortex: A light and electron microscope study in the rat VL - 207 ER - TY - JOUR AB - Morphological substrates for interactions between γ-aminobutyric acid (GABA) and substance P upon neurons expressing substance Preceptor (SPR) in the nucleus of the solitary tract (NST) were investigated by immunocytochemical electron microscopy. In the NST of the rat, many GABA-like immunoreactive axon terminals were in symmetric synaptic contacts with dendritic profiles; they were observed on nearly a half of the SPR-like immunoreactive dendritic profiles in the medial part of the caudal half of the NST. AU - Jia, Hong AU - Wang, Bai AU - Rao, Zhi AU - Shi, Ji AU - Shigemoto, Ryuichi AU - Kaneko, Takeshi AU - Mizuno, Noboru ID - 2569 IS - 1 JF - Neuroscience Letters SN - 0304-3940 TI - GABAergic synapses upon neurons expressing substance P receptors in the nucleus of the solitary tract: An immunocytochemical electron microscope study in the rat VL - 210 ER - TY - JOUR AB - Trigeminothalamic and spinothalamic-tact neurons provided with substance P receptor (SPR) were examined in the rat by SPR immunofluorescence histochemistry combined with Fluoro-Gold (FG) fluorescent retrograde labeling. After FG injection in the thalamic regions, FG-labeled cells with SPR-like immunoreactivity were seen mainly in laminae I and m of the medullary and spinal dorsal horns and lateral spinal nucleus. In these regions, about one-fourth to one-third of FG-labeled cells showed SPR-like immunoreactivity. AU - Li, Jin AU - Ding, Yu AU - Shigemoto, Ryuichi AU - Mizuno, Noboru ID - 2567 IS - 1-2 JF - Brain Research SN - 0006-8993 TI - Distribution of trigeminothalamic and spinothalamic-tract neurons showing substance P receptor-like immunoreactivity in the rat VL - 719 ER - TY - JOUR AB - The distribution of the mRNA for a pituitary adenylate cyclase- activating polypeptide (PACAP) receptor (PACAP-R) was examined in the rat brain, and also in the hypophysis and pineal gland, by in situ hybridization with a specific 35S-labeled riboprobe which was generated from a rat PACAP-R cDNA clone. In the brain, expression of PACAP-R mRNA was most prominent in the periglomerular and granule cells of the olfactory bulb, granule cells of the dentate gyrus, supraoptic nucleus, and area postrema. The expression was also intense in the piriform, cingulate, and retrosplenial cortices, pyramidal cells in CA2, non-pyramidal cells in CA1- CA3, neuronal cells in the hilus of the dentate gyrus, lateral septal nucleus, intercalated amygdaloid nucleus, anterodorsal thalamic nucleus, most of the midline and intralaminar thalamic nuclei, many regions of the hypothalamus, dorsal motor nucleus of the vagus nerve, hypoglossal nucleus, and lateral reticular nucleus. No significant expression was detected in the mitral and tufted cells in the olfactory bulb, pyramidal cells in CA1 and CA3, posterior nuclear group of the thalamus, dorsal lateral geniculate nucleus, and Purkinje, Golgi, and granule cells in the cerebellar cortex. Moderate-to-weak expression was further observed in many other regions of the brain. In the cerebellar cortex, presumed Bergmann gila cells showed moderate expression. In the hypophysis, the expression was moderate in the anterior lobe, and weak to moderate in the posterior lobe; no significant expression was observed in the intermediate lobe. In the pineal gland, the expression was very weak, if any. Thus, the expression of PACAP-R was detected not only on neuronal cells but also on some particular glial cells. The present study has shown, for the first time, the exact site of PACAP-R expression in the brain and hypophysis. Although the functional significance of PACAP and PACAP-R in the brain still remains to be clarified, the present results are considered to provide some direction for future functional studies. AU - Hashimoto, Hitoshi AU - Nogi, Hiroyuki AU - Mori, Kensaku AU - Ohishi, Hitoshi AU - Shigemoto, Ryuichi AU - Yamamoto, Kyohei AU - Matsuda, Toshio AU - Mizuno, Noboru AU - Nagata, Shigekazu AU - Baba, Akemichi ID - 2572 IS - 4 JF - Journal of Comparative Neurology SN - 0021-9967 TI - Distribution of the mRNA for a pituitary adenylate cyclase-activating polypeptide receptor in the rat brain: An in situ hybridization study VL - 371 ER - TY - JOUR AB - lonotropic and metabotropic (mGluR1a) glutamate receptors were reported to be segregated from each other within the postsynaptic membrane at individual synapses. In order to establish whether this pattern of distribution applies to the hippocampal principal cells and to other postsynaptic metabotropic glutamate receptors, the mGluR1a/b/c and mGluR5 subtypes were localized by immunocytochemistry. Principal cells in all hippocampal fields were reactive for mGluR5, the strata oriens and radiatum of the CA1 area being most strongly immunolabelled. Labelling for mGluR1b/c was strongest on some pyramids in the CA3 area, weaker on granule cells and absent on CA1 pyramids. Subpopulations of non-principal cells showed strong mGluR1 or mGluR5 immunoreactivity. Electron microscopic pre-embedding immunoperoxidase and both pre- and postembedding immunogold methods consistently revealed the extrasynaptic location of both mGluRs in the somatic and dendritic membrane of pyramidal and granule cells. The density of immunolabelling was highest on dendritic spines. At synapses, immunoparticles for both mGluR1 and mGluR5 were found always outside the postsynaptic membrane specializations. Receptors were particularly concentrated in a perisynaptic annulus around type 1 synaptic junctions, including the invaginations at 'perforated' synapses. Measurements of immunolabelling on dendritic spines showed decreasing levels of receptor as a function of distance from the edge of the synaptic specialization. We propose that glutamatergic synapses with an irregular edge develop in order to increase the circumference of synaptic junctions leading to an increase in the metabotropic to ionotropic glutamate receptor ratio at glutamate release sites. The perisynaptic position of postsynaptic metabotropic glutamate receptors appears to be a general feature of glutamatergic synaptic organization and may apply to other G-protein-coupled receptors. © European Neuroscience Association. AU - Luján, Rafael AU - Nusser, Zoltán AU - Roberts, John AU - Shigemoto, Ryuichi AU - Somogyi, Péter ID - 2574 IS - 7 JF - European Journal of Neuroscience SN - 0953-816X TI - Perisynaptic location of metabotropic glutamate receptors mGluR1 and mGluR5 on dendrites and dendritic spines in the rat hippocampus VL - 8 ER - TY - JOUR AB - Developmental changes of the distribution pattern of substance P receptor (SPR) were investigated immunohistochemically in the rat striatum. The SPR immunoreactivity in the striatum first emerged at postnatal day 1 and transiently showed a patchy pattern of distribution until it displayed the adult pattern of homogeneous distribution by the end of the third postnatal week. The SPR-immunoreactive patches were most marked in the medial and dorsolateral parts of the striatum, as well as in the subcallosal streak. They matched tyrosine hydroxylase-enriched areas and, conversely, avoided calbindin-enriched zones. No neurons within the SPR-immunoreactive patches contained either choline acetyltransferase or somatostatin, which is known to be contained in intrinsic neurons in the striatum. The vast majority of SPR-immunoreactive patch neurons also contained DARPP-32, a phosphoprotein that is expressed in striatal projection neurons with D1 dopamine receptor. The results indicate that SPR-immunoreactive patches which appear transiently in the developing striatum are in register with the striatal patch compartment, and that SPR immunoreactivity within these patches may be expressed on projection neurons rather than intrinsic neurons. Such SPR immunoreactivity in projection neurons in striatal patches may fade out in adulthood. AU - Tokuno, Hironobu AU - Takada, Masahiko AU - Kaneko, Takeshi AU - Shigemoto, Ryuichi AU - Mizuno, Noboru ID - 2573 IS - 1 JF - Developmental Brain Research SN - 0165-3806 TI - Patchy distribution of substance P receptor immunoreactivity in the developing rat striatum VL - 95 ER - TY - JOUR AB - The probability of synaptic neurotransmitter release from nerve terminals is regulated by presynaptic receptors responding to transmitters released from the same nerve terminal or from terminals of other neurons. The release of glutamate, the major excitatory neurotransmitter, is suppressed by presynaptic auto receptors. Here we show that a metabotropic glutamate receptor (mGluR7) in the rat hippocampus is restricted to the presynaptic grid, the site of synaptic vesicle fusion. Pyramidal cell terminals presynaptic to mGluR1α-expressing interneurons have at least a ten-fold higher level of presynaptic mGluR7 than terminals making synapses with pyramidal cells and other types of interneuron. Distinct levels of mGluR7 are found at different synapses made by individual pyramidal axons or even single boutons. These results raise the possibility that presynaptic neurons could regulate the probability of transmitter release at individual synapses according to the postsynaptic target AU - Shigemoto, Ryuichi AU - Kulik, Ákos AU - Roberts, John AU - Ohishi, Hitoshi AU - Nusser, Zoltán AU - Kaneko, Takeshi AU - Somogyi, Péter ID - 2570 IS - 6582 JF - Nature SN - 0028-0836 TI - Target-cell-specific concentration of a metabotropic glutamate receptor in the presynaptic active zone VL - 381 ER - TY - JOUR AB - Subtype 2 of the metabotropic glutamate receptor (mGluR2) is expressed in the presynaptic elements of hippocampal mossy fiber-CA3 synapses. Knockout mice deficient in mGluR2 showed no histological changes and no alterations in basal synaptic transmission, paired-pulse facilitation, or tetanus-induced long-term potentiation (LTP) at the mossy fiber-CA3 synapses. Long-term depression (LTD) induced by low-frequency stimulation, however, was almost fully abolished. The mutant mice performed normally in water maze learning tasks. Thus, the presynaptic mGluR2 is essential for inducing LTD at the mossy fiber-CA3 synapses, but this hippocampal LTD does not seem to be required for spatial learning. AU - Yokoi, Mineto AU - Kobayashi, Kazuto AU - Manabe, Toshiya AU - Takahashi, Tomoyuki AU - Sakaguchi, Isako AU - Katsuura, Goro AU - Shigemoto, Ryuichi AU - Ohishi, Hitoshi AU - Nomura, Sakashi AU - Nakamura, Kenji AU - Nakao, Kazuki AU - Katsuki, Motoya AU - Nakanishi, Shigetada ID - 2571 JF - Science SN - 0036-8075 TI - Impairment of hippocampal mossy fiber LTD in mice lacking mGluR2 VL - 273 ER -