Impact of elevated CO<Subscript>2</Subscript> on root traits of a sapling community of three birches and an oak: a free-air-CO<Subscript>2</Subscript> enrichment (FACE) in northern Japan

Key message

The CO ₂ effect on the root production of a broad-leaved community was insignificant when grown in brown forest soil, however, it was positively large when grown in volcanic ash soil.

Abstract

We evaluated the root response to elevated CO₂ fumigation of 3 birches (Betula sp.) and 1 deciduous oak (Quercus sp.) grown in immature volcanic ash soil (VA) or brown forest soil (BF). VA is a nutrient-poor, phosphorus-impoverished soil, broadly distributed in northern Japan. Each species had been exposed to either ambient (375–395 μmol mol^?1) (aCO₂) or elevated (500 μmol mol^?1) (eCO₂) CO₂ during the daytime (more than 70 μmol m^?2 s^?1) over 4 growing seasons. The results suggest that eCO₂ did not cause an increase in total root production when the community had grown in fertile BF soil, however, it did cause a large increase when the community was grown in infertile VA soil. Yet, carbon allocation to plant roots was not affected by eCO₂ in either the BF or VA soils. Rhizo-morphogenesis appeared to occur to a greater extent under eCO₂. It seems that the saplings developed a massive amount of fine roots under the VA and eCO₂ conditions. Unexpectedly, eCO₂ resulted in a larger total root mass when the community was grown in VA soil than when grown in BF soil (eCO₂ × VA vs. eCO₂ × BF). These results may hint to a site-specific potential of communities to sequester future atmospheric carbon. The growing substance of plants is an important factor which root response to eCO₂ depends on, however, further studies are needed for a better understanding.

     

Optimization of the extraction of phenolic compounds from Cyclosorus extensa with solvents of varying polarities

The leaves of Cyclosorus extensa are used in the preparation of rice beer in Assam, India. The optimal conditions of time and temperature of fermentation for extraction of bioactive compounds from the dried leaves were obtained using response surface methodology. The central composite rotatable design was used and 13 experimental runs based on two-factor-five-level design were generated and performed for each of the solvents. The independent variables were extraction time (12 and 48?h) and temperature (25 and 55°C). The responses studied were total polyphenol content, radical scavenging activity, antibacterial activity, and antifungal activity. The analysis of variance of the test data was performed and the sequential sum of squares, F-value, R², and adjusted R² were deduced. The predicted models for all the response variables were adequately fitted to the observed experimental data (p?≤?0.001). The maximum extraction of bioactive compounds under the optimum conditions of extraction temperature and time for hexane, ethyl acetate, methanol, and distilled water were found to be 25°C for 29.43?h, 28.28°C for 41.27?h, 43.95°C for 29.61?h, and 55.00°C for 48.00?h, respectively. It was also observed that the solubility of the polyphenols was higher in methanol, followed by ethyl acetate, and the highest antibacterial activity against Escherichia coli was shown by the ethyl acetate extracts.     

A solid-phase substrate of heparanase: its application to assay of human melanoma for heparan sulfate degradative activity

We found a tumor metastasis-associated heparan sulfate (HS)-degrading endoglycosidase in melanoma cells that is a unique endo-beta-glucuronidase (heparanase) capable of specifically cleaving HS at intrachain sites (M. Nakajima, T. Irimura, N. DiFerrante, and G. L. Nicolson, 1984, J. Biol. Chem. 259, 2283-2290). To perform rapid and microscale quantitative assays of heparanase we developed a solid-phase HS substrate by crosslinking radiolabeled HS onto agarose gel beads using one covalent linkage. The HS from bovine lung was partially N-desulfated and labeled with [14C]acetic anhydride. Free HS amino groups were completely acetylated, and reducing terminal saccharides were reductively aminated. The HS derivatives with amino groups at their reducing termini were coupled to amino-reactive agarose beads. Incubation of the solid-phase HS substrates with B16 melanoma cell extracts in the presence of D-saccharic acid 1,4-lactone (a potent exo-beta-glucuronidase inhibitor) resulted in the time- and dose-dependent release of [14C]HS fragments. Human melanoma cell lines were tested for HS-degrading endoglycosidase using the newly developed solid-phase HS substrates. The human malignant melanoma cells tested had high levels of HS-degrading activity that were comparable to those of highly metastatic murine B16-F10 melanoma cells.     

A preliminary note on the hormonal induction of NADP-linked dehydrogenases in phytohaemagglutinin-stimulated human lymphocytes

Synopsis Human leucocytes were culturedin vitro with either phytohaemagglutin or 17 -oestradiol or both, and the enzyme activities of nicotinamide adenine dinucleotide phosphate-linked glucose-6-phosphate dehydrogenase and isocitrate dehydrogenase were assayed. As a result, it was found that these enzymes were considerably induced by oestradiol in phytohaemagglutinin-stimulated lymphocytes, but not in non-stimulated cells. Electrophoretic studies on glucose-6-phosphate dehydrogenase showed that six molecular forms are demonstrable in normal and phytohaemagglutinin-stimulated leucocytes, and that one of the forms was specifically induced by oestradiol in the presence of phytohaemagglutinin.     

Induction of distamycin A-inducible rare fragile sites and increased sister chromatid exchanges at the fragile site

Summary Expression of distamycin A-inducible rare fragile sites by AT-specific DNA-ligands was examined in lymphoblastoid cell lines derived from heterozygous carriers for the fra(8)(q24), fra(16)(pl2), and fra(16)(q22) sites. The sensitivity of fragile site expression to the inducers was different at these fragile sites. The expression of fra(8)(q24) was induced markedly by Hoechst 33258, but not by distamycin A or berenil. An increased expression of fra(16)(p12) was found following treatment with Hoechst 33258 or berenil, but not with distamycin A. At fra(16)(q22), distamycin A markedly induced the fragile site, but Hoechst 33258 and berenil did not. Since their response to the different inducers was similar to that found in cultured lymphocytes, lymphoblastoid cell lines appear to retain their inherent properties. Although BrdUrd alone did nto induce any fragile sites, concomitant treatment with BrdUrd plus the inducer was synergistically effective in inducing all the fragile sites. An increased frequency of sister chromatid exchanges was observed at fra(16)(p12) following simultaneous treatment with BrdUrd and berenil, mainly when the site was expressed as an isochromatid gap. Thus, the induced fra (16)(pl2) site is a hot spot for the formation of sister chromatid exchanges, as found in other reported fragile sites.     

Coordinated binding of sugar, calcium, and antibody to macrophage C- type lectin

Mouse macrophage galactose/N-acetylgalactosamine-specific C-type lectin (MMGL) is a type II transmembrane glycoprotein belonging to the C-type lectin family. Our development of monoclonal antibodies led us to discover that a calcium-dependent conformational change is detected by an antibody (termed mAb LOM-11) and that the antibody's binding to the respective site locks the lectin in an active conformation. These findings correspond to the divalent cation-mediated regulatory mechanisms in a family of cell adhesion molecule integrins that have gained much attention. We now provide direct evidence that mAb LOM-11 increases the affinity of the lectin for calcium ions as a mechanism for the conformational lock using a soluble recombinant form of MMGL (rML) produced in bacteria. Furthermore, we discovered by using an enzyme-linked immunosorbent assay that specific monosaccharides induced a binding site for mAb LOM-11 on the immobilized rML under low calcium environments. We also demonstrated that cell surface MMGL on a transfectant cell line underwent a conformational change upon addition of calcium or ligands, as detected by the binding of mAb LOM-11. These properties are reminiscent of ligand-induced binding sites defined for integrins. The present results suggest a possibility that the mAb LOM- 11 binding site on the lectin may be a site at which protein-protein interaction helps to fine tune the specificity of the C-type lectins by means of coordinated recognition mechanisms.      

Human DDK rescues stalled forks and counteracts checkpoint inhibition at unfired origins to complete DNA replication

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A Microfibril Formation from Depolymerized Chitosan by N-Acetylation

The geometrical isomers of O-4-tert-butylcyclohexyl methylthiocarbamate were prepared by way of the corresponding dithiocarbonates. The O-trans-isomer was obtained from a mixture of cis- and trans-4-tert-butylcyclohexanols via an alkoxide formation involving biassed equilibration, whereas the O-cis isomer was from the cis-cyclohexanol via an alkoxide formation free from equilibration.

The acid-catalyzed rearrangement of the O-cis thiocarbamate gave a 1:3 mixture of S-cis- and S-trans-4-tert-butylcyclohexyl methylthiocarbamates, whereas that of the O-trans thiocarbamate afforded a 9:1 mixture of S-cis and S-trans products.

These results, together with the data from a study on the reactions of O-cis-3,3,5-tri-methylcyclohexyl methylthiocarbamate and the O-neopentyl analog, indicate that the acid-catalyzed rearrangement proceeded mostly through an S_N2 type of transalkylating mechanism to give the S-isomer in the case where the approach of nucleophiles was not sterically blocked, otherwise the reaction gave S_N1-type products.     

The association between major sialoglycoprotein and spectrin of human erythrocyte membranes as detected by fluorescence resonance energy transfer.

The interactions among the major sialoglycoprotein and peripheral proteins of human erythrocyte membranes were investigated by the long range resonance energy transfer between different fluorescent moieties separately conjugated to proteins. Consequently, direct association between the major sialoglycoprotein and spectrin was observed and divalent cations were required for their association.