Hokkaido University

About: Hokkaido University is a education organization based out in Sapporo, Hokkaidô, Japan. It is known for research contribution in the topics: Population & Catalysis. The organization has 53925 authors who have published 115403 publications receiving 2651647 citations. The organization is also known as: Hokudai & Hokkaidō daigaku.

Cbln1 Is a Ligand for an Orphan Glutamate Receptor δ2, a Bidirectional Synapse Organizer

Abstract: Cbln1, secreted from cerebellar granule cells, and the orphan glutamate receptor delta2 (GluD2), expressed by Purkinje cells, are essential for synapse integrity between these neurons in adult mice. Nevertheless, no endogenous binding partners for these molecules have been identified. We found that Cbln1 binds directly to the N-terminal domain of GluD2. GluD2 expression by postsynaptic cells, combined with exogenously applied Cbln1, was necessary and sufficient to induce new synapses in vitro and in the adult cerebellum in vivo. Further, beads coated with recombinant Cbln1 directly induced presynaptic differentiation and indirectly caused clustering of postsynaptic molecules via GluD2. These results indicate that the Cbln1-GluD2 complex is a unique synapse organizer that acts bidirectionally on both pre- and postsynaptic components.

Geochemical and microbiological evidence for a hydrogen-based, hyperthermophilic subsurface lithoautotrophic microbial ecosystem (HyperSLiME) beneath an active deep-sea hydrothermal field

Abstract: Subsurface microbial communities supported by geologically and abiologically derived hydrogen and carbon dioxide from the Earth's interior are of great interest, not only with regard to the nature of primitive life on Earth, but as potential analogs for extraterrestrial life. Here, for the first time, we present geochemical and microbiological evidence pointing to the existence of hyperthermophilic subsurface lithoautotrophic micro- bial ecosystem (HyperSLiME) dominated by hyper- thermophilic methanogens beneath an active deep-sea hydrothermal field in the Central Indian Ridge. Geo- chemical and isotopic analyses of gaseous components in the hydrothermal fluids revealed heterogeneity of both concentration and carbon isotopic compositions of methane between the main hydrothermal vent (0.08 mM and )13.8& PDB, respectively) and the adjacent diver- gent vent site (0.2 mM and )18.5& PDB, respectively), representing potential subsurface microbial methano- genesis, at least in the divergent vent emitting more 13 C-depleted methane. Extremely high abundance of magmatic energy sources such as hydrogen (2.5 mM) in the fluids also encourages a hydrogen-based, lithoauto- trophic microbial activity. Both cultivation and culti- vation-independent molecular analyses suggested the predominance of Methanococcales members in the superheated hydrothermal emissions and chimney inte- riors along with the other major microbial components of Thermococcales members. These results imply that a HyperSLiME, consisting of methanogens and ferment- ers, occurs in this tectonically active subsurface zone, strongly supporting the existence of hydrogen-driven subsurface microbial communities.

Subtype switching of vesicular glutamate transporters at parallel fibre-Purkinje cell synapses in developing mouse cerebellum.

Abstract: Two subtypes of the vesicular glutamate transporter are expressed differentially in two excitatory afferents synapsing on to Purkinje cells: VGluT1 (BNPI) in axon terminals of cerebellar granule cells (i.e. parallel fibres; PFs) and VGluT2 (DNPI) in those of the inferior olivary neurons (climbing fibres; CFs). In the present study, we examined their expression in the developing mouse cerebellum. By in situ hybridization, the inferior olivary nucleus selectively expressed VGluT2 mRNA through postnatal life. In the cerebellum, both subtypes were transcribed in the external and internal granular layers during the first postnatal week. Thereafter, VGluT1 mRNA showed marked upregulation in the internal granular layer, whereas VGluT2 mRNA disappeared from the external and internal granular layers by the end of the third postnatal week. By immunohistochemistry, CF terminals consistently exhibited VGluT2 immunoreactivity in the postnatal cerebellum. By contrast, in the first 10 days of postnatal life, VGluT2 predominated in PF terminals, despite the transcription of both transporters in developing granule cells. During the second 10 days, VGluT2 in PF terminals was replaced with VGluT1 from deep regions of the molecular layer upwards, correlating with dendritic translocation of CFs. This replacement was accomplished by postnatal day 30. Taking that late-borne PFs are laid down successively on earlier ones in the molecular layer, the deep-to-superficial replacement represents maturation-linked switching from VGluT2 to VGluT1 in individual PFs, and is likely to be regulated at both the transcription and translation levels.