Nitric Oxide Fluxes from Upland Soils in Central Hokkaido, Japan

Symposium Pape

Comparison of Nitrogen Budgets in Agricultural Watersheds

Poster Sessio

Alteration of chondroitin sulfate composition on proteoglycan produced by knock-in mouse embryonic fibroblasts whose versican lacks the A subdomain

Versican/proteoglycan-mesenchymal (PG-M) is a large chondroitin sulfate (CS) proteoglycan of the extracellular matrix (ECM) that is constitutively expressed in adult tissues such as dermis and blood vessels. It serves as a structural macromolecule of the ECM, while in embryonic tissue it is transiently expressed at high levels and regulates cell adhesion, migration, proliferation, and differentiation. Knock-in mouse embryonic (Cspg2Δ3/Δ3) fibroblasts whose versican lack the A subdomain of the G1 domain exhibit low proliferation rates and acquire senescence. It was suspected that chondroitin sulfate on versican core protein would be altered when the A subdomain was disrupted, so fibroblasts were made from homozygous Cspg2Δ3/Δ3 mouse embryos to investigate the hypothesis. Analysis of the resulting versican deposition demonstrated that the total versican deposited in the Cspg2Δ3/Δ3 fibroblasts culture was approximately 50% of that of the wild type (WT), while the versican deposited in the ECM of Cspg2Δ3/Δ3 fibroblasts culture was 35% of that of the WT, demonstrating the lower capacity of mutant (Cspg2Δ3/Δ3) versican deposited in the ECM. The analysis of CS expression in the Cspg2Δ3/Δ3 fibroblasts culture compared with wild-type fibroblasts showed that the composition of the non-sulfate chondroitin sulfate isomer on the versican core protein increased in the cell layer but decreased in the culture medium. Interestingly, chondroitin sulfate E isomer was found in the culture medium. The amount of CS in the Cspg2Δ3/Δ3 cell layer of fibroblasts with mutant versican was dramatically decreased, contrasted to the amount in the culture medium, which increased. It was concluded that the disruption of the A subdomain of the versican molecule leads to lowering of the amount of versican deposited in the ECM and the alteration of the composition and content of CS on the versican molecule

Eco-balance analysis of land use combinations to minimize environmental impacts and maximize farm income in northern Japan

Relationships between global warming potential (GWP), farmland surplus nitrogen (FSN) and income for major land uses in Ikushunbetsu watershed were compared using the eco-balance method. An empirical model was created for carbon dioxide, methane and nitrous oxide for both uplands and paddy rice using monitoring data from 22 fields. The greenhouse gas emissions were converted into GWP, whereas yield and FSN were obtained from farmers' interviews and literature survey. Land use distribution was obtained by ground surveys in 2002, 2005 and 2007. The analysis showed that paddy rice and soybean were characterized by a high GWP, low FSN and high income, whereas onions and vegetables had a high FSN but low GWP and moderate income. Wheat showed a negative GWP in some years and abandoned areas always exhibit negative values. The total GWP for the region was 14184, 11085 and 8337 Mg CO2 yr^[-1] for 2002, 2005 and 2007, respectively. The contribution of paddy rice to GWP was highest, ranging from 40% to 75%. To find optimal land use combinations that have higher income and lower GWP and FSN than present, all possible land use combination was analyzed by changing the land use proportion from 0 - 100% at an interval of 10%. The number of land use combinations meeting the requirements in the three investigated years was 205. Abandoned area which had the smallest environmental load was included in every land use combination, indicating that land uses with low environmental impacts should be maintained at a certain proportion to mitigate the environmental load accompanying land uses with high production

Effects of environmental factors on temporal variation in annual carbon dioxide and nitrous oxide emissions from an unfertilized bare field on Gray Lowland soil in Mikasa, Hokkaido, Japan

Soil is one of the important sources of atmospheric carbon dioxide (CO2) and nitrous oxide (N2O). Studies of CO2 and N2O emission from bare soil may explain the annual change of carbon (C) in soil organic matter (SOM) and help analyzing the N2O production from SOM. Therefore, CO2 and N2O emissions associated with the decomposition of SOM from bare soil are important factors for assessing the C budget and N2O emission in agricultural field. We conducted a study over seven years to assess the controlling factors of CO2 and N2O emissions from unplanted and unfertilized soil in Mikasa, Hokkaido, Japan. Carbon dioxide flux increased in the summer, and there were significant positive correlations between the CO2 flux and soil temperature in the first four years. However, apparent relationships between CO2 flux and WFPS, soil NH4 and NO3 concentrations were not observed. The slope of monthly CO2 emission against mean monthly temperature was positively correlated with monthly precipitation. These results suggest that the response of CO2 production to increase in soil temperature becomes more sensitive in wet soils. The average CO2 emission during the study period was 2.53 Mg C ha^[-1] year^[-1], and uncertainty of the annual CO2 emission was 24%. Annual precipitation explained the yearly variation (CO2 emission [Mg C ha^[-1] year^[-1]] = 0.0021 x annual precipitation [mm year^[-1]] -0.0499, R = 0.976, P < 0.001). Nitrous oxide flux increased from July to October, and was positively correlated with CO2 flux. Based on the ratio of N2O-N : NO-N of fluxes, N2O appeared to be the main product of denitrification. The average N2O emission in the study period was 4.88 kg N ha^[-1] year^[-1], and uncertainty of annual N2O emission was 58.5%. Strong relationships between the monthly emissions of CO2 and N2O suggest that N2O production by denitrification is strongly affected by SOM decomposition. Unlike the CO2 emission, the relationship between N2O emission and precipitation was not observed because of the multiple pathways of nitrification and denitrification for N2O production induced by SOM decomposition

Chondroitin sulfate synthase-2 is necessary for chain extension of chondroitin sulfate but not critical for skeletal development.

Chondroitin sulfate (CS) is a linear polysaccharide consisting of repeating disaccharide units of N-acetyl-D-galactosamine and D-glucuronic acid residues, modified with sulfated residues at various positions. Based on its structural diversity in chain length and sulfation patterns, CS provides specific biological functions in cell adhesion, morphogenesis, neural network formation, and cell division. To date, six glycosyltransferases are known to be involved in the biosynthesis of chondroitin saccharide chains, and a hetero-oligomer complex of chondroitin sulfate synthase-1 (CSS1)/chondroitin synthase-1 and chondroitin sulfate synthase-2 (CSS2)/chondroitin polymerizing factor is known to have the strongest polymerizing activity. Here, we generated and analyzed CSS2(-/-) mice. Although they were viable and fertile, exhibiting no overt morphological abnormalities or osteoarthritis, their cartilage contained CS chains with a shorter length and at a similar number to wild type. Further analysis using CSS2(-/-) chondrocyte culture systems, together with siRNA of CSS1, revealed the presence of two CS chain species in length, suggesting two steps of CS chain polymerization; i.e., elongation from the linkage region up to Mr ∼10,000, and further extension. There, CSS2 mainly participated in the extension, whereas CSS1 participated in both the extension and the initiation. Our study demonstrates the distinct function of CSS1 and CSS2, providing a clue in the elucidation of the mechanism of CS biosynthesis