Biotic and abiotic processes of nitrogen immobilization in the soil-residue interface     

Naoki Moritsuka  Junta Yanai  Takashi Kosaki 《Soil biology & biochemistry》2004,36(7):1141-1148

The interface between decaying plant residues and soil is a hotspot for microbial immobilization of soil inorganic N. Recent studies on forest and grassland soils have demonstrated that rapid abiotic immobilization of inorganic N is also induced by the presence of plant residues. We, therefore, examined (1) how N immobilization varies with distance from the soil-residue interface and (2) whether abiotic immobilization occurs in agricultural soils. Spatiotemporal changes of N immobilization in the soil-residue interface were evaluated using a box that enabled soil to be sampled in 2 mm increments from a 4 mm-thick residue compartment (RC). The RC was filled with paddy soil containing ground plant residue (rice bran, rice straw or beech leaves) uniformly at a rate of 50 g dry matter kg⁻¹. Soil in the surrounding compartments contained no residue. After aerobic incubation for 5, 15 and 30 days at 25 °C, soils in each compartment were analyzed. After 5 days, significant depletion of inorganic N occurred throughout a volume of soil extending at least 10 mm from the RC in all residue treatments, suggesting extensive diffusion of inorganic N towards the RC. The depletion within 10 mm of the RC amounted to 5.0, 4.3 and 3.4 mg for rice bran, rice straw and beech leaf treatment, respectively. On the other hand, microbial N had increased significantly in the RC of the rice bran and rice straw treatments (11 mg and 5.5 mg, respectively) and insignificantly in the RC of the beech leaf treatment (0.06 mg). This increase amounted to 221% (rice bran), 129% (rice straw) and 1.7% (beech leaves) of the decrease in inorganic N within 10 mm of each RC. Thereafter the rate of N mineralization exceeded that of immobilization, and inorganic N levels had recovered almost to their original level by 15 days (rice bran) and 30 days (rice straw and beech leaves). These results suggested the predominance of biotic immobilization in soil near rice bran and rice straw and of abiotic immobilization in soil near beech leaves. No significant increase in both microbial and soluble organic N in the vicinity of beech leaves after incubation for 5 days further suggested that the abiotic process was responsible for the transformation of inorganic N into the insoluble organic N.  相似文献   

Collection,mapping, and annotation of over 28,000 cDNA clones from japonica rice   总被引：2，自引：0，他引：2  

Rice Full-Length cDNA Consortium;National Institute of Agrobiological Sciences Rice Full-Length cDNA Project Team  Kikuchi S  Satoh K  Nagata T  Kawagashira N  Doi K  Kishimoto N  Yazaki J  Ishikawa M  Yamada H  Ooka H  Hotta I  Kojima K  Namiki T  Ohneda E  Yahagi W  Suzuki K  Li CJ  Ohtsuki K  Shishiki T;Foundation of Advancement of International Science Genome Sequencing & Analysis Group  Otomo Y  Murakami K  Iida Y  Sugano S  Fujimura T  Suzuki Y  Tsunoda Y  Kurosaki T  Kodama T  Masuda H  Kobayashi M  Xie Q  Lu M 《Science (New York, N.Y.)》2003,301(5631):376-379

  相似文献   

Protostellar feedback halts the growth of the first stars in the universe     

Hosokawa T  Omukai K  Yoshida N  Yorke HW 《Science (New York, N.Y.)》2011,334(6060):1250-1253

The first stars fundamentally transformed the early universe by emitting the first light and by producing the first heavy elements. These effects were predetermined by the mass distribution of the first stars, which is thought to have been fixed by a complex interplay of gas accretion and protostellar radiation. We performed radiation-hydrodynamics simulations that followed the growth of a primordial protostar through to the early stages as a star with thermonuclear burning. The circumstellar accretion disk was evaporated by ultraviolet radiation from the star when its mass was 43 times that of the Sun. Such massive primordial stars, in contrast to the often-postulated extremely massive stars, may help explain the fact that there are no signatures of the pair-instability supernovae in abundance patterns of metal-poor stars in our galaxy.  相似文献   

Specialized inhibitory synaptic actions between nearby neocortical pyramidal neurons     

Ren M  Yoshimura Y  Takada N  Horibe S  Komatsu Y 《Science (New York, N.Y.)》2007,316(5825):758-761

We found that, in the mouse visual cortex, action potentials generated in a single layer-2/3 pyramidal (excitatory) neuron can reliably evoke large, constant-latency inhibitory postsynaptic currents in other nearby pyramidal cells. This effect is mediated by axo-axonic ionotropic glutamate receptor-mediated excitation of the nerve terminals of inhibitory interneurons, which connect to the target pyramidal cells. Therefore, individual cortical excitatory neurons can generate inhibition independently from the somatic firing of inhibitory interneurons.  相似文献   

Quantum criticality without tuning in the mixed valence compound beta-YbAlB4     

Matsumoto Y  Nakatsuji S  Kuga K  Karaki Y  Horie N  Shimura Y  Sakakibara T  Nevidomskyy AH  Coleman P 《Science (New York, N.Y.)》2011,331(6015):316-319

Fermi liquid theory, the standard theory of metals, has been challenged by a number of observations of anomalous metallic behavior found in the vicinity of a quantum phase transition. The breakdown of the Fermi liquid is accomplished by fine-tuning the material to a quantum critical point by using a control parameter such as the magnetic field, pressure, or chemical composition. Our high-precision magnetization measurements of the ultrapure f-electron-based superconductor β-YbAlB(4) demonstrate a scaling of its free energy that is indicative of zero-field quantum criticality without tuning in a metal. The breakdown of Fermi liquid behavior takes place in a mixed-valence state, which is in sharp contrast with other known examples of quantum critical f-electron systems that are magnetic Kondo lattice systems with integral valence.  相似文献   

Morphological modifications among oribatid mites (Acari: Oribatida) in relation to habitat differentiation in mangrove forests   总被引：2，自引：0，他引：2  

Shigenori Karasawa  Naoki Hijii 《Pedobiologia》2004,48(4):383-394

We examined morphological modifications among oribatid species in five microhabitats in mangrove forests in the Ryukyu Islands of Japan. A total of 89 oribatid species were recorded from canopy (leaves and branches), bark of flooded trunks (trunks of 0–50 cm high and knee roots), bark of other trunks higher than 50 cm, and littoral algae in mangrove forests, and the forest-floor soil in an adjacent bank forest. There were no significant differences in the body length, body width, and notogastral length among oribatid species from the five microhabitats. The mean sensillus length of the oribatid species from the forest-floor soil was about twice as long as that from the other microhabitats. Claw morphology was characterized by two attributes: number (monodactyly and tridactyly) and length. In the canopy and trunks, the proportion of tridactyl species was higher than that of monodactyl species. On the other hand, the proportion of tridactyl species in the forest-floor soil accounted for only about 20%, and that in the flooded trunks and littoral algae approximated to zero. The mean claw length was larger in the oribatid species from the flooded trunks and littoral algae than in both monodactyl and tridactyl species from every other microhabitat. Trydactyl species with short claws in the arboreal environments might have been selected by a compromise between grip and mobility for unpredictable environmental changes such as wind and rain. The dominance of monodactyl species with a longer claw in the littoral environments implies a consequence of selection for regular tidal flooding, which requires oribatids to grip tighter on the substrate. The modifications in claw morphology of oribatid mites in mangrove forest might be interpreted as adaptations to a difference in the predictability of the environmental conditions of microhabitats.  相似文献   

Inhibitory effects of Zingiber officinale Roscoe derived components on aldose reductase activity in vitro and in vivo     

Kato A  Higuchi Y  Goto H  Kizu H  Okamoto T  Asano N  Hollinshead J  Nash RJ  Adachi I 《Journal of agricultural and food chemistry》2006,54(18):6640-6644

Ginger (Zingiber officinale Roscoe) continues to be used as an important cooking spice and herbal medicine around the world. Scientific research has gradually verified the antidiabetic effects of ginger. Especially gingerols, which are the major components of ginger, are known to improve diabetes including the effect of enhancement against insulin-sensitivity. Aldose reductase inhibitors have considerable potential for the treatment of diabetes, without increased risk of hypoglycemia. The assay for aldose reductase inhibitors in ginger led to the isolation of five active compounds including 2-(4-hydroxy-3-methoxyphenyl)ethanol (2) and 2-(4-hydroxy-3-methoxyphenyl)ethanoic acid (3). Compounds 2 and 3 were good inhibitors of recombinant human aldose reductase, with IC50 values of 19.2 +/- 1.9 and 18.5 +/- 1.1 microM, respectively. Furthermore, these compounds significantly suppressed not only sorbitol accumulation in human erythrocytes but also lens galactitol accumulation in 30% of galactose-fed cataract rat model. A structure-activity relationship study revealed that the applicable side alkyl chain length and the presence of a C3 OCH3 group in the aromatic ring are essential features for enzyme recognition and binding. These results suggested that it would contribute to the protection against or improvement of diabetic complications for a dietary supplement of ginger or its extract containing aldose reductase inhibitors.  相似文献   

Matrix metalloproteinases (MMPs) activity in cultured canine bone marrow stromal cells (BMSCs)     

Haraguchi T  Tani K  Koga M  Oda Y  Itamoto K  Yamamoto N  Terai S  Sakaida I  Nakazawa H  Taura Y 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2012,74(5):633-636

Autologous bone marrow stromal cells (BMSCs) infusion therapy improves the hepatic fibrosis. To investigate the mechanism of remission, we evaluated the matrix metalloproteinase (MMP)-2 and -9 activity in canine BMSCs and the effect of pro-inflammatory cytokines on their expression. The activity and the gene expression of MMPs were analyzed by gelatin zymography and quantitative RT-PCR, respectively. The specific gelatinase bands were indicative effect of MMP-2 and -9 in canine BMSCs. MMP-2 expression seemed to be increased by TNF-α and IL-1β while MMP-9 was enhanced by TNF-α and IL-6. These results suggested that remissive effect on liver fibrosis might be partly attributable to the MMP-2 and -9 activity in BMSCs under the inflammatory condition.  相似文献   

Heterotrophic respiration causes seasonal hysteresis in soil respiration in a warm-temperate forest     

Yuji Kominami  Mayuko Jomura  Mioko Ataka  Koji Tamai  Takafumi Miyama  Masako Dannoura  Naoki Makita  Kenichi Yoshimura 《Journal of Forest Research》2012,17(3):296-304

To assess the effect of changes in organic litter stock on seasonal changes in heterotrophic respiration (R _H), soil respiration (R _S), and total ecosystem respiration (R _E), we measured seasonal changes in leaf litter respiration (R _LL) by the chamber method and estimated the seasonal change in total R _H using the RothC model in a warm-temperate mixed deciduous?Cevergreen forest in Japan. Both R _E and R _S had seasonal hysteresis and were higher in spring than at the same temperature during autumn. Under warm and humid conditions, the rate of decomposition of newly supplied leaf litter in one?year was high (60% loss). Consequently, R _LL and R _H were higher in spring after leaf drop, when more fresh material was available, than in autumn. In this study, 42 and 88% of the difference in R _E and R _S between spring and autumn (soil temperature 16?C18°C) could be accounted for by the difference in R _H, respectively, and 71% of the difference in R _H could be accounted for by the difference in R _LL. This study showed that seasonal changes in heterotrophic respiration (R _LL and R _H) could be a major factor in the seasonal hysteresis of R _E and R _S.  相似文献   

A simple and efficient transient transformation for hybrid aspen (Populus tremula × P. tremuloides)     

N Takata  ME Eriksson 《Plant methods》2012,8(1):30

  相似文献