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Tetsuo Yamamori

Publications and source records attributed to Tetsuo Yamamori.

At least 19 recordsLinked to original sources
PubMed2006

Binding and complementary expression patterns of semaphorin 3E and plexin D1 in the mature neocortices of mice and monkeys.

Although axon guidance molecules play critical roles in neural circuit formation during development, their roles in the adult circuit are not well understood. In this study we examined the expression patterns of Semaphorin 3E (Sema3E), a member of the semaphorin family, in the mature neocortices of monkeys and mice by in situ hybridization (ISH). We found that Sema3E mRNA is highly specific to layer VI throughout the macaque monkey neocortex. We further examined the ratio of Sema3E+ cells among the layer VI excitatory neurons in areas M1, S1, TE, and V1 by fluorescence double ISH, using the vesicular glutamate transporter 1 (VGluT1) gene as a specific marker for excitatory neurons. Among these areas, 34-63% of the VGluT1+ neurons expressed Sema3E mRNA. In the mouse cortex, two significant differences were observed in the pattern of Sema3E mRNA distribution. 1) Sema3E mRNA was expressed in layer Vb, in addition to layer VI in mice. 2) A subset of GABAergic interneurons expressed Sema3E mRNA in mice. By an in vitro binding experiment, we provide evidence that Plexin D1 is the specific receptor for Sema3E. Plexin D1 mRNA was preferentially expressed in layers II-V in both monkey and mouse cortices. The detailed lamina analysis by double ISH, however, revealed that Plexin D1 mRNA is expressed in layers II-Va, but not in layer Vb in the mouse cortex. Thus, the Plexin D1 and Sema3E mRNAs exhibit conserved complementary lamina patterns in mice and monkeys, despite the species differences in the pattern of each gene.

Animals↗
PubMed2006

Comparative analysis of layer-specific genes in Mammalian neocortex.

We examined the expression patterns of 4 layer-specific genes in monkey and mouse cortices by fluorescence double in situ hybridization. Based on their coexpression profiles, we were able to distinguish several subpopulations of deep layer neurons. One group was characterized by the expression of ER81 and the lack of Nurr1 mRNAs and mainly localized to layer 5. In monkeys, this neuronal group was further subdivided by 5-HT2C receptor mRNA expression. The 5-HT2C(+)/ER81(+) neurons were located in layer 5B in most cortical areas, but they intruded layer 6 in the primary visual area (V1). Another group of neurons, in monkey layer 6, was characterized by Nurr1 mRNA expression and was further subdivided as Nurr1(+)/connective tissue growth factor (CTGF)(-) and Nurr1(+)/CTGF(+) neurons in layers 6A and 6B, respectively. The Nurr1(+)/CTGF(+) neurons coexpressed ER81 mRNA in monkeys but not in mice. On the basis of tracer injections in 3 monkeys, we found that the Nurr1(+) neurons in layer 6A send some corticocortical, but not corticopulvinar, projections. Although the Nurr1(+)/CTGF(-) neurons were restricted to lateral regions in the mouse cortex, they were present throughout the monkey cortex. Thus, an architectonic heterogeneity across areas and species was revealed for the neuronal subpopulations with distinct gene expression profiles.

Animals↗
PubMed2006

Topological relationships between brain and social networks.

Brains are complex networks. Previously, we revealed that specific connected structures are either significantly abundant or rare in cortical networks. However, it remains unknown whether systems from other disciplines have similar architectures to brains. By applying network-theoretical methods, here we show topological similarities between brain and social networks. We found that the statistical relevance of specific tied structures differs between social "friendship" and "disliking" networks, suggesting relation-type-specific topology of social networks. Surprisingly, overrepresented connected structures in brain networks are more similar to those in the friendship networks than to those in other networks. We found that balanced and imbalanced reciprocal connections between nodes are significantly abundant and rare, respectively, whereas these results are unpredictable by simply counting mutual connections. We interpret these results as evidence of positive selection of balanced mutuality between nodes. These results also imply the existence of underlying common principles behind the organization of brain and social networks.

Animals↗
PubMed2006

Neocortical areas, layers, connections, and gene expression.

Cortical patterns of gene expression provide a new approach to long standing issues of lamination, and area identity and formation. In this review, we summarize recent findings where molecular biological techniques have revealed a small number of area-specific genes in the nonhuman primate cortex. One of these (occ1) is strongly expressed in primary visual cortex and is associated with thalamocortical connections. Another gene, RBP, is more strongly expressed in association areas. It is not clear whether RBP might be linked with any particular connectional system, but several possibilities are raised. We also discuss possible roles of area-specific genes in postnatal development, and conclude with a brief sketch of future directions.

Animals↗
PubMed2006

[Barrel finishing of cobalt-chromium alloy cast plate--basic study on polishing materials and time].

PURPOSE: This study was designed to establish the optimum grinding condition of barrel finishing for cobalt-chromium alloy. Smoothing of the mucosal surface, reduction of labor, and improvement of the working environment were estimated by the application of barrel finishing to cobalt-chromium alloy. METHODS: Tabular test pieces cast in cobalt-chromium alloy whose surface was standardized by waterproof abrasive papers were used in this study with a centrifugal flow barrel finishing machine. The abrasive that was most suitable for the primary polishing was selected, and proper polishing time was then decided by measuring the surface roughness of the test pieces. The abrasive and polishing time for the secondary polishing were decided in the same manner. Finally, the surface texture of the test pieces, which were finished in this condition by the manufacturer's instruction or by the electrolytic polishing method, were compared. Statistic analysis was performed by one-way analysis of variance and the multiple comparison test. RESULTS: A triangular prism-shape abrasive made of Al(2)O(3) and SiO(2) whose one side or height was 6 mm was selected for the primary polishing, and the same kind of abrasive with one side or height of 4 mm was chosen for the secondary one. The optimum polishing time for the primary polishing and the secondary polishing were 60 minutes and 40 minutes, respectively. The surface roughness of the test pieces that were finished in this condition was significantly smaller than that finished following the manufacturer's indication or that finished by the electrolytic polishing method. CONCLUSION: The optimum polishing condition of barrel finishing for cobalt-chromium alloy was established in this study. For the polished surface of cast dentures, polishing by a rotary cutting instrument after barrel finishing in this condition would be needed, as no luster was observed on the finished surface.

Aluminum Oxide↗
PubMed2005

Novel transcription factor zfh-5 is negatively regulated by its own antisense RNA in mouse brain.

Here, we report features of a novel transcription factor zfh-5, which we isolated from the mouse brain; in addition to the mRNA, the antisense strand of zfh-5 is also expressed in the developing brain, in a manner complementary to the expression of zfh-5 mRNA. Although most neurons express zfh-5 mRNA soon after their final mitosis, several types of neurons, such as the pyramidal and granule cells in the hippocampus, express the zfh-5 antisense RNA prior to the mRNA expression. Using gene-targeting approach, we showed that this antisense RNA has a negative regulatory role on the expression of zfh-5 mRNA. These observations suggest that, in specific types of neurons, the expression of zfh-5 is additionally regulated by a mechanism depending on this antisense RNA.

Animals↗
PubMed2005

Activity-dependent expression of occ1 in excitatory neurons is a characteristic feature of the primate visual cortex.

occ1 is a gene whose expression is particularly abundant in neurons in the macaque primary visual cortex (V1). In the present study, we report that the expression of occ1 mRNA in the macaque neocortex can be classified into two modes. The first mode is associated with excitatory neurons distributed in the major thalamocortical recipient layers that exhibit strong cytochrome oxidase activity. This is highly prominent in V1. The second mode is associated with parvalbumin-positive GABAergic interneurons and is distributed across the macaque neocortex. In V1, monocular deprivation showed that occ1 mRNA expression in excitatory neurons was markedly dependent on afferent activity, whereas that in GABAergic interneurons was not. Cross-species comparison showed specific differences in expression. In marmosets, a strong expression was observed in V1 similarly to macaques. The occ1 mRNA expression, however, was generally weak in the mouse neocortex. In rabbit and ferret cortices, the strong expression was observed only in GABAergic interneurons. We conclude that activity-dependent occ1 mRNA expression in the excitatory neurons of V1 was caused by a novel mechanism acquired by primates after their separation from other lineages.

Action Potentials↗
PubMed2004

Local design principles of mammalian cortical networks.

To understand global and local design principles of mammalian cerebral cortical networks, we applied network-theoretical approaches to connectivity data from macaque and cat cortical networks. We first confirmed "small-world" properties and searched for the evidence of hierarchical modularity. To elucidate their local design principles, we then compared these cortical networks, based on the significance profile (SP) of network motifs in the real network compared to randomized networks. We found that SPs of different mammalian cortical networks are highly conserved and robust, suggesting constraints of neocortical development and evolution.

Animals↗
PubMed2004

Behavioral studies of auditory-visual spatial recognition and integration in rats.

Rodents are useful animal models in the study of the molecular and cellular mechanisms underlying various neural functions. For studying behavioral properties associated with multisensory functions in rats, we measured the speed and accuracy of target detection by the reaction-time procedure. In the first experiment, we utilized simple two-alternative-choice tasks, in which spatial cues are visual or auditory modalities, and conducted a cross-modal transfer test in order to determine whether rats recognize amodal spatial information. Rats showed successful performance in the cross-modal transfer test and the speed to respond to sensory stimuli was constant under a rule-consistent condition despite the change in cue modality. In the second experiment, we developed audiovisual two-alternative-choice tasks, in which both auditory and visual stimuli were simultaneously presented but one of the two modalities was task-relevant, in order to determine whether the response to the sensory stimulation of one modality is enhanced by the stimulation of a different modality. If bimodal stimuli were spatially coincident, the speed for detecting the relevant stimulus was shortened and the extent of the effect was comparable to those in past studies of humans and other mammals. These results indicate the cross-modal spatial abilities of rats and our present paradigms may provide useful behavioral tasks for studying the neural bases of multisensory processing and integration in rats.

Acoustic Stimulation↗
PubMed2004

Retinol-binding protein gene is highly expressed in higher-order association areas of the primate neocortex.

The neocortex consists of histochemically, connectionally, and functionally distinguishable areas. Recently, molecular biological techniques have enabled us to find rare types of genes expressed in specific neocortical areas. We previously reported occ1 gene as preferentially expressed in the primary visual cortex (V1), using the differential display method. Here, by differential display, we found selective and strong expression of the serum retinol-binding protein (RBP) gene, in higher-order association areas. In V1, RBP mRNA was expressed only in the superficial part of layer II, but its expression increased, involving deeper layers, along the visual pathway. In visual association areas such as TE, RBP mRNA was strongly expressed in both supra- and infragranular layers. In primary auditory and somatosensory areas, as in V1, RBP expression was low, and restricted to the upper part of the supragranular layers. The laminar pattern of RBP expression is in marked contrast with that of occ1; and in early visual areas where both genes are expressed, these occur in distinct sublayers within the supragranular layers. In neonatal monkeys, the area-specific expression pattern of RBP was less distinct, suggesting that the characteristic expression of RBP in higher-order association areas is mainly established postnatally.

Animals↗
PubMed2004

Activation of syntaxin 1C, an alternative splice variant of HPC-1/syntaxin 1A, by phorbol 12-myristate 13-acetate (PMA) suppresses glucose transport into astroglioma cells via the glucose transporter-1 (GLUT-1).

Syntaxin 1C is an alternative splice variant lacking the transmembrane domain of HPC-1/syntaxin 1A. We found previously that syntaxin 1C is expressed as a soluble protein in human astroglioma (T98G) cells, and syntaxin 1C expression is enhanced by stimulation with phorbol 12-myristate 13-acetate (PMA). However, the physiological function of syntaxin 1C is not known. In this study, we examined the relationship between syntaxin 1C and glucose transport. First, we discovered that glucose transporter-1 (GLUT-1) was the primary isoform in T98G cells. Second, we demonstrated that glucose uptake in T98G cells was suppressed following an increase in endogenous syntaxin 1C after stimulation with PMA, which did not alter the expression levels of other plasma membrane syntaxins. We further examined glucose uptake and intracellular localization of GLUT-1 in cells that overexpressed exogenous syntaxin 1C; glucose uptake via GLUT-1 was inhibited without affecting sodium-dependent glucose transport. The value of Vmax for the dose-dependent uptake of glucose was reduced in syntaxin 1C-expressing cells, whereas there was no change in Km. Immunofluorescence studies revealed a reduction in the amount of GLUT-1 in the plasma membrane in cells that expressed syntaxin 1C. Based on these results, we postulate that syntaxin 1C regulates glucose transport in astroglioma cells by changing the intracellular trafficking of GLUT-1. This is the first report to indicate that a syntaxin isoform that lacks a transmembrane domain can regulate the intracellular transport of a plasma membrane protein.

Alternative Splicing↗
PubMed2003

Occ1 mRNA expression reveals a characteristic feature in the hippocampal CA2 field of adult macaques.

The gene occ1 is preferentially expressed in the primary visual cortex in an activity-dependent and developmentally regulated manner. In this report, we show the characteristic distribution of occ1 transcripts in the CA2 subfield of the hippocampal formation in adult monkeys. occ1 mRNA signals were observed selectively in the pyramidal cell layer of CA2. In addition to these signals, a relatively sparse distribution of occ1 was found in the stratum oriens and, occasionally, in the outermost regions of the pyramidal cell layers of both CA1 and CA2. A few labeled cells were detected in CA3. The elevated expression of occ1 in the CA2 subfield provides a new approach for investigating the function of this subregion, whose role has still not been well clarified.

Animals↗
PubMed2003

Ciliary neurotrophic factor inhibits differentiation of photoreceptor-like cells in rat pineal glands in vitro.

Ciliary neurotrophic factor (CNTF) is a unique member of the interleukin-6 (IL-6) family, whose receptor subunit for ligand binding is exclusively expressed in the nervous system and muscle. The role of CNTF in mammalian development remains unknown. We recently reported the specific expression of CNTF in the pineal gland and eyes. To further examine the expression pattern and role of CNTF in development, we prepared a polyclonal antibody against rat CNTF, performed western blotting with this antibody, and confirmed a strong and specific expression of the CNTF protein in pineal glands and a moderate expression in the eyes among the various tissues examined in newborn rats. In pineal organ cultures of newborn rats, exogenously added recombinant rat CNTF potently inhibited the differentiation of photoreceptor-like cells in a dose-dependent manner, while CNTF did not influence the survival of pineal cells. Among several cell growth factors known to have a similar effect in retinal cultures examined, strong inhibitory effects were seen only with CNTF and the leukemia inhibitory factor (LIF), both of which belong to the IL-6 cytokine family. This inhibitory effect was the strongest during three to 6 days of culture when CNTF was added to these cultures. These results suggest that CNTF plays an inhibitory role in the development of photoreceptor-like cells in early postnatal rat pineal glands.

Animals↗
PubMed2003

Expression of syntaxin 1C, an alternative splice variant of HPC-1/syntaxin 1A, is enhanced by phorbol-ester stimulation in astroglioma: participation of the PKC signaling pathway.

Syntaxin 1C is an alternative splice variant of HPC-1/syntaxin 1A; the latter participates in neurotransmitter release and is assigned to the gene domain responsible for Williams' syndrome (WS). It is expressed in the soluble fraction extracted from human astroglioma cell lines T98G and U87MG. Quantitative immunoblot and indirect immunofluorescence analyses revealed that the expression of syntaxin 1C was upregulated by phorbol 12-myristate 13-acetate (PMA), but not by forskolin. A protein kinase C (PKC) inhibitor suppressed this enhancement. These results suggest that syntaxin 1C expression is regulated via the PKC signal pathway. This is the first report of a signal transduction system that directly affects the expression of syntaxin protein.

Alternative Splicing↗
PubMed2003

Expression of occ1 mRNA in the visual cortex during postnatal development in macaques.

We previously reported that the occ1 gene is specifically expressed in the primary visual cortex of adult monkeys in an activity-dependent manner (Tochitani et al., Eur. J. Neurosci., 3, 297-307, 2001). In this report, we compared occ1 mRNA expression in the primary visual cortex during the development of newborn, 3-month-old and adult monkeys. occ1 mRNA was already expressed preferentially in the primary visual cortex of newborn monkeys, but the laminar pattern of occ1 expression in the visual cortex changed as development proceeded. This suggests the possible importance of experience-dependent developmental regulations of occ1 in the developing primary visual cortex.

Aging↗