Mulberry anthracnose antagonists (iturins) produced by Bacillus amyloliquefaciens RC-2

Bacillus amyloliquefaciens strain RC-2 produced seven antifungal compounds (1-7) secreted into the culture filtrate. These compounds inhibited the development of mulberry anthracnose caused by the fungus, Colletotrichum dematium. Chemical structural analyses by NMR and FAB-MS revealed that all these compounds were iturins (cyclic peptides with the following sequence: L-Asn --> D-Tyr --> D-Asn --> L-Gln --> L-Pro --> D-Asn --> L-Ser --> D-beta-amino acid -->) and compounds 1-6 are identical to iturins A-2-A-7, respectively. Compound 7 (iturin A-8) is a new iturin, which has a -(CH(2))(10)CH(CH(3))CH(2)CH(3) group as a side chain in the beta-amino acid in the molecule.     

Form of aluminium for uptake and translocation in buckwheat (Fagopyrum esculentum Moench)

 The forms of Al for uptake by the roots and translocation from the root to the shoot were investigated in a buckwheat (Fagopyrum esculentum Moench, cv. Jianxi) that accumulates Al in its leaves. The Al concentration in the xylem sap was 15-fold higher in the plants exposed to AlCl₃ than in those exposed to an Al-oxalate (1:3) complex, suggesting that the roots take up Al in the ionic form. The Al concentration in the xylem sap was 4-fold higher than that in the external solution after a 1-h exposure to AlCl₃ solution and 10-fold higher after a 2-h exposure. The Al concentration in the xylem sap increased with increasing Al concentration in the external solution. The Al uptake was not affected by a respiratory inhibitor, hydroxylamine, but significantly inhibited by the addition of La. These results suggest that Al uptake by the root is a passive process, and La³⁺ competes for the binding sites for Al³⁺ on the plasma membrane. The form of Al in the xylem sap was identified by ²⁷Al-nuclear magnetic resonance analysis. The chemical shift of ²⁷Al in the xylem sap was around 10.9 ppm, which is consistent with that of the Al-citrate complex. Furthermore, the dominant organic acid in the xylem sap was citric acid, indicating that Al was translocated in the form of Al-citrate complex. Because Al is present as Al-oxalate (1:3) in the root, the present data show that ligand exchange from oxalate to citrate occurs before Al is released to xylem. Received: 10 December 1999 / Accepted: 3 February 2000     

Mucilage strongly binds aluminum but does not prevent roots from aluminum injury in Zea mays

The possible role of mucilage in protecting roots from aluminum (Al) injury was investigated in Zea mays L. (cv. Golden Cross Bantam), focusing on binding of Al with mucilage and effects of mucilage on Al toxicity. Al was bound to mucilage after the treatment of roots with 10–50 μ M Al for 1 h and 30 μ M Al for 30, 60, 90 and 120 min. Using molecular sieve chromatography (Sephadex G-100), Al was co-eluted with a high molecular mass sugar and a low molecular mass sugar. The difficulty in desorbing Al from mucilage with organic acids confirmed the strong binding strength of Al by mucilage revealed by ²⁷Al nuclear magnetic resonance (NMR). Al could not be desorbed completely by succinic, malic, oxalic and citric acid at a molar ratio of 1:1. It could only be completely removed by oxalic acid at a molar ratio of 20:1 (oxalate:Al). Bioassay experiments showed that cell viability and callose formation were unaffected by Al bound to mucilage. However, mucilage deprived roots had only 0.21–0.59 nmol apex⁻¹ higher Al content than control roots after treatment with 30 μ M Al for 1, 1.5 and 2 h. Moreover, inhibition of root elongation by 5 μ M Al for 6, 12, 24 and 36 h was independent of the presence or absence of mucilage prior to the Al treatment. These results indicate that although mucilage affects the accumulation of Al by roots, it does not confer Al resistance to Z. mays root apices.     

Complex Interrelationships Among Aboveground Biomass,Soil Chemical Properties,and Events Caused by Feral Goats and Their Eradication in a Grassland Ecosystem of an Island

This study examined the recovery, via biotic and abiotic pathways, of a grassland ecosystem after eradication of introduced exotic goats. We used path analyses to evaluate the relative strength of relationships among aboveground biomass, soil chemical properties (carbon, nitrogen, and phosphorus content; soil acidity), presence of nesting seabirds after goat eradication, extent of vegetation degraded by goats before their eradication, plant species composition after removal of goats, and topography. Models including the same variables with different paths were constructed using the Bayesian estimation method, and the best-fit models were constructed by comparing deviance information criterion values. Results of the path analyses demonstrated that vegetation degradation and soil erosion prior to goat eradication increased soil exchangeable acidity, which resulted in limitation of aboveground biomass. Seabird nesting after goat eradication increased the quantity of soil nutrients, possibly through inputs of feces, eggshells, and dead chicks or adults. The increase in nutrients was affected indirectly, via seabird nesting, by topography and vegetation type after goat eradication. The direct and indirect relationships demonstrated by our results suggest the existence of complex interrelationships during recovery of ecosystem function after eradication of exotic mammals.     

Nocardioides sp. strain WSN05-2, isolated from a wheat field, degrades deoxynivalenol, producing the novel intermediate 3-epi-deoxynivalenol

The mycotoxin deoxynivalenol (DON) causes serious problems worldwide in the production of crops such as wheat and barley because of its toxicity toward humans and livestock. A bacterial culture capable of degrading DON was obtained from soil samples collected in wheat fields using an enrichment culture procedure. The isolated bacterium, designated strain WSN05-2, completely removed 1,000???g/mL of DON from the culture medium after incubation for 10?days. On the basis of phylogenetic studies, WSN05-2 was classified as a bacterium belonging to the genus Nocardioides. WSN05-2 showed significant growth in culture medium with DON as the sole carbon source. High-performance liquid chromatography analysis indicated the presence of a major initial metabolite of DON in the culture supernatant. The metabolite was identified as 3-epi-deoxynivalenol (3-epi-DON) by mass spectrometry and ¹H and ¹³C nuclear magnetic resonance analysis. The amount of DON on wheat grain was reduced by about 90% at 7?days after inoculation with WSN05-2. This is the first report of a Nocardioides sp. strain able to degrade DON and of the yet unknown 3-epi-DON as an intermediate in the degradation of DON by a microorganism.     

Exploring Dynamics of Molybdate in Living Animal Cells by a Genetically Encoded FRET Nanosensor

Molybdenum (Mo) is an essential trace element for almost all living organisms including animals. Mo is used as a catalytic center of molybdo-enzymes for oxidation/reduction reactions of carbon, nitrogen, and sulfur metabolism. Whilst living cells are known to import inorganic molybdate oxyanion from the surrounding environment, the in vivo dynamics of cytosolic molybdate remain poorly understood as no appropriate indicator is available for this trace anion. We here describe a genetically encoded Förester-resonance-energy-transfer (FRET)-based nanosensor composed of CFP, YFP and the bacterial molybdate-sensor protein ModE. The nanosensor MolyProbe containing an optimized peptide-linker responded to nanomolar-range molybdate selectively, and increased YFP:CFP fluorescence intensity ratio by up to 109%. By introduction of the nanosensor, we have been able to successfully demonstrate the real-time dynamics of molybdate in living animal cells. Furthermore, time course analyses of the dynamics suggest that novel oxalate-sensitive- and sulfate-resistant- transporter(s) uptake molybdate in a model culture cell.     

Sex pheromone and related compounds in the Ishigaki and Okinawa strains of the tussock moth Orgyia postica (Walker) (Lepidoptera: Lymantriidae)

Two distinct electroantennographycally active (EAG-active) components, A and B, and a weakly active component C were found in a solvent extract from virgin females of the Ishigaki strain of the tussock moth, Orgyia postica (Walker). Components A, B, and C were found in the extract of the females at 4.0, 0.5, and 4.0 ng/female respectively. Components A, B, and C were identified as (6Z,9Z,11S,12S)-11,12-epoxyhenicosa-6,9-diene [(11S,12S)-1: posticlure], (6Z)-henicos-6-en-11-one (2), and (6Z,9Z)-henicosa-6,9-diene (3), respectively. Component B was absent in the extract from the Okinawa strain, in which components A and C were present at 2.0 and 1.5 ng/female respectively. (11S,12S)-1 and the racemic mixture showed attractiveness for both the Okinawa and Ishigaki strains, whereas (11R,12R)-1 did not. The addition of 2 significantly reduced the trap catches with (11S,12S)-1 on the Okinawa strain which lacked 2, while there was no significant inhibitory effect on the Ishigaki strain. The addition of 3 to (11S,12S)-1 did not significantly affect trap catches at Ishigaki or Okinawa. This confirmed that the attractant pheromone of O. postica of the Ishigaki strain is also (11S,12S)-1.     

Humification processes of needle litters on forest floors in Japanese cedar (Cryptomeria japonica) and Hinoki cypress (Chamaecyparis obtusa) plantations in Japan

We quantitatively clarified the early humification processes on Japanese cedar and Hinoki cypress forest floors by using a litterbag experiment and the solid-state ¹³C CPMAS NMR technique. There was no significant effect on litter mass loss during early humification between both coniferous litters regardless of the shape of their needles. Carbon composition in both litters showed similar trends during early humification. A/O-A as a humification index was low, around 0.6, in both litters throughout the experiment period although 60% of litter mass was lost. Coniferous litter incubated for 3 years might not be well-humified and would be susceptible to physical fragmentation. Carbon mass loss rates in conifers were in the following order: O-alkyl > aliphatic > aromatic > carbonyl carbons, differing with hardwoods. Conifers had concomitantly higher and lower mass loss rates of aliphatic and aromatic carbons than hardwoods. Soil organic carbon (SOC) accumulated in topsoil for conifers had relatively high and low contents of aliphatic and aromatic carbons than that for hardwood. These compositional differences of SOC among forests could be caused by the high and low supply rates of aliphatic and aromatic carbons from litter to topsoil. Consequently, initial litter nature and humification processes can affect the compositional qualities of SOC accumulated in soil.     

Adrenomedullin: a possible regulator of germinal vesicle breakdown

Adrenomedullin (ADM) is a multifunctional hormone that regulates processes as diverse as blood pressure and cell growth. Although expressed in the ovary, the role of ADM in this organ is not clear. In the present study, we found the expression of ADM receptor and receptor activity-modifying proteins in mouse cumulus cells but not in the oocytes. We report that germinal vesicle breakdown (GVBD), which is required for oocyte maturation, is not inhibited by ADM alone. However, ADM in the presence of the nitric oxide donor sodium nitroprusside (SNP) significantly inhibited GVBD. Furthermore, the ADM- and SNP-dependent inhibition of GVBD was abrogated by Akt blockade. Additionally, Akt expression and phosphorylation was exhibited by ADM, suggesting that Akt signaling upstream in cumulus cells is responsible. Additionally, immunohistochemical analysis revealed that ADM was localized in the granulosa cells of developed follicles, implying the possibility that ADM physiologically affects oocyte maturation in vivo. Our results provide the evidence that ADM can act as a GVBD regulator.     

Soil erosion alters soil chemical properties and limits grassland plant establishment on an oceanic island even after goat eradication

Soil erosion after vegetation degradation induced by disturbance by feral goats, an invasive mammal, can lead to loss or accumulation of soil at a local scale and can alter soil chemical properties. This alteration of soil properties can in turn affect the establishment of plant species. We evaluated relationships among the extent of soil erosion, soil chemical properties, and the distribution of plant species in grassland ecosystems after goat eradication on Nakodo‐jima Island in the northwestern Pacific. In 105 1 × 1–m quadrats, changes were measured in the position of topsoil over 2 years. Surface soils were sampled for analysis of chemical properties, and plant species in the quadrat were recorded. Changes in the position of topsoil were related to the area of bare ground. Soil loss occurred at sites where areas of bare ground were extremely large. Significantly higher values of soil exchange acidity and smaller amounts of available phosphorus, total carbon, and total nitrogen were detected in soils at sites with large soil losses. Most of the 11 dominant plant species were absent from sites with large losses of soil. The presence of eight species was significantly negatively related to soil exchange acidity, and three species were significantly positively related to available phosphorus. Our results indicated that exposure of subsoils at the soil surface after vegetation degradation can increase soil loss, which can alter soil chemical properties, and this alteration can continue to limit the establishment of plant species, even long after goat eradication.