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.

Evolutionary control of leaf element composition in plants

Abstract: Leaf nitrogen (N) and phosphorus (P) concentrations are correlated in plants. Higher-level phylogenetic effects can influence leaf N and P. By contrast, little is known about the phylogenetic variation in the leaf accumulation of most other elements in plant tissues, including elements with quantitatively lesser roles in metabolism than N, and elements that are nonessential for plant growth. Here the leaf composition of 42 elements is reported from a statistically unstructured data set comprising over 2000 leaf samples, representing 670 species and 138 families of terrestrial plants. Over 25% of the total variation in leaf element composition could be assigned to the family level and above for 21 of these elements. The remaining variation corresponded to differences between species within families, to differences between sites which were likely to be caused by soil and climatic factors, and to variation caused by sampling techniques. While the majority of variation in leaf mineral composition is undoubtedly associated with nonevolutionary factors, identifying higher-level phylogenetic variation in leaf elemental composition increases our understanding of terrestrial nutrient cycles and the transfer of toxic elements from soils to living organisms. Identifying mechanisms by which different plant families control their leaf elemental concentration remains a challenge.

Cbln1 is essential for synaptic integrity and plasticity in the cerebellum.

Abstract: Cbln1 is a cerebellum-specific protein of previously unknown function that is structurally related to the C1q and tumor necrosis factor families of proteins. We show that Cbln1 is a glycoprotein secreted from cerebellar granule cells that is essential for three processes in cerebellar Purkinje cells: the matching and maintenance of pre- and postsynaptic elements at parallel fiber–Purkinje cell synapses, the establishment of the proper pattern of climbing fiber–Purkinje cell innervation, and induction of long-term depression at parallel fiber–Purkinje cell synapses. Notably, the phenotype of cbln1-null mice mimics loss-of-function mutations in the orphan glutamate receptor, GluRδ2, a gene selectively expressed in Purkinje neurons. Therefore, Cbln1 secreted from presynaptic granule cells may be a component of a transneuronal signaling pathway that controls synaptic structure and plasticity.

Succession of Sulfur-Oxidizing Bacteria in the Microbial Community on Corroding Concrete in Sewer Systems

Abstract: Microbially induced concrete corrosion (MICC) in sewer systems has been a serious problem for a long time. A better understanding of the succession of microbial community members responsible for the production of sulfuric acid is essential for the efficient control of MICC. In this study, the succession of sulfur-oxidizing bacteria (SOB) in the bacterial community on corroding concrete in a sewer system in situ was investigated over 1 year by culture-independent 16S rRNA gene-based molecular techniques. Results revealed that at least six phylotypes of SOB species were involved in the MICC process, and the predominant SOB species shifted in the following order: Thiothrix sp., Thiobacillus plumbophilus, Thiomonas intermedia, Halothiobacillus neapolitanus, Acidiphilium acidophilum, and Acidithiobacillus thiooxidans. A. thiooxidans, a hyperacidophilic SOB, was the most dominant (accounting for 70% of EUB338-mixed probe-hybridized cells) in the heavily corroded concrete after 1 year. This succession of SOB species could be dependent on the pH of the concrete surface as well as on trophic properties (e.g., autotrophic or mixotrophic) and on the ability of the SOB to utilize different sulfur compounds (e.g., H2S, S0, and S2O32−). In addition, diverse heterotrophic bacterial species (e.g., halo-tolerant, neutrophilic, and acidophilic bacteria) were associated with these SOB. The microbial succession of these microorganisms was involved in the colonization of the concrete and the production of sulfuric acid. Furthermore, the vertical distribution of microbial community members revealed that A. thiooxidans was the most dominant throughout the heavily corroded concrete (gypsum) layer and that A. thiooxidans was most abundant at the highest surface (1.5-mm) layer and decreased logarithmically with depth because of oxygen and H2S transport limitations. This suggested that the production of sulfuric acid by A. thiooxidans occurred mainly on the concrete surface and the sulfuric acid produced penetrated through the corroded concrete layer and reacted with the sound concrete below.