Predicting future invasion of an invasive alien tree in a Japanese oceanic island by process-based statistical models using recent distribution maps

Modelling and predicting the potential habitat and future range expansion of invasive species can help managers to mitigate the impact of such species. Because habitat suitability and the colonization process are key determinants of range expansion, inferences drawn from invasion patterns should be based on both attributes. To predict the potential habitat and expansion rate of the invasive tree Bischofia javanica on Hahajima Island, we used simultaneous models of habitat and dispersal to estimate the effect of environment and dispersal from the source population on the current distribution. We compared the fit and the estimated magnitudes of the environment and dispersal effects in the simultaneous models with those in habitat suitability and colonization kernel models. The values of Akaike’s information criterion for the simultaneous models were better than those of the habitat suitability and colonization kernel models, indicating that the current distribution of Bischofia was determined by both environment and dispersal. The simultaneous models predicted that the potential habitat of Bischofia would be larger than that predicted by the habitat suitability model. The potential habitat distribution and future invasion predicted by the simultaneous models will contribute to the development of specific landscape-scale management plans to control this invasive species.     

Effect of arylidene-cyclopentenedione radiosensitizers on ATP synthesis in mitochondria: action as potent inhibitors of phosphate transport

The effects of the arylidene-cyclopentenedione radiosensitizers, KIH-200, 201 and 202 on ATP synthesis in mitochondria were examined. In spite of the close similarity of their chemical structure to that of the most potent known weakly acidic uncoupler, SF 6847, they did not show any uncoupling activity at concentrations of up to 50 microM. However, these three compounds were found to have very potent inhibitory effects on Pi-transport into mitochondria, all causing 50% inhibition (I50%) at about 7 microM. Thus they are much more potent than the commonly used Pi-transport inhibitors N-ethylmaleimide (I50% = about 40 microM), and mersalyl (I50% = about 30 microM). They may act as SH-reagents, and inhibit Pi-transport by modifying an SH-group(s) in the Pi-transporter.     

Plasma gelsolin facilitates interaction between β2 glycoprotein I and α5β1 integrin

Antiphospholipid syndrome (APS) is characterized by thrombosis and the presence of antiphospholipid antibodies (aPL) that directly recognizes plasma β₂‐glycoprotein I (β₂GPI). Tissue factor (TF), the major initiator of the extrinsic coagulation system, is induced on monocytes by aPL in vitro, explaining in part the pathophysiology in APS. We previously reported that the mitogen‐activated protein kinase (MAPK) pathway plays an important role in aPL‐induced TF expression on monocytes. In this study, we identified plasma gelsolin as a protein associated with β₂GPI by using immunoaffinity chromatography and mass spectrometric analysis. An in vivo binding assay showed that endogenous β₂GPI interacts with plasma gelsolin, which binds to integrin a₅β₁ through fibronectin. The tethering of β₂GPI to monoclonal anti‐β₂GPI autoantibody on the cell surface was enhanced in the presence of plasma gelsolin. Immunoblot analysis demonstrated that p38 MAPK protein was phosphorylated by monoclonal anti‐β₂GPI antibody treatment, and its phosphorylation was attenuated in the presence of anti‐integrin a₅β₁ antibody. Furthermore, focal adhesion kinase, a downstream molecule of the fibronectin‐integrin signalling pathway, was phosphorylated by anti‐β₂GPI antibody treatment. These results indicate that molecules including gelsolin and integrin are involved in the anti‐β₂GPI antibody‐induced MAPK pathway on monocytes and that integrin is a possible therapeutic target to modify a prothrombotic state in patients with APS.     

Estimates of Denitrification and Nitrification in Coastal and Estuarine Sediments

Denitrification and nitrification in sediments of Tama Estuary and Odawa Bay, Japan, were investigated by the combined use of a continuous-flow sediment-water system and a ¹⁵N tracer technique. At Odawa Bay, the nitrification rate was comparable to the nitrate reduction rate, and 70% of the N₂ evolved originated from nitrogenous oxides (nitrate and nitrite) which were produced by the action of nitrifying bacteria in the sediments. At Tama Estuary, the nitrate reduction rate was 11 to 17 times higher than the nitrification rate, and nitrogenous oxides derived from ammonium accounted for only 6 to 9% of the N₂ evolution by denitrification.     

Depolarization-Induced Increase in Surface Binding and Internalization of 125I-Nerve Growth Factor by PC 12 Pheochromocytoma Cells

The binding and internalization of 125I-nerve growth factor (NGF) by PC12 pheochromocytoma cells was studied as a function of extracellular potassium concentration. Both surface-bound and internalized fractions of 125I-NGF associated with the cells under depolarizing conditions (50 mM K+) increased to 144 +/- 28% (average +/- SEM, six different cell preparations) and to 176 +/- 12% (n = 6), respectively, of those observed at 6.0 mM K+. Scatchard-type analysis of the data indicates increased sites for the binding and internalization of iodinated NGF by the cells. Similar enhancement was observed for cells treated with NGF as well. This voltage-dependent phenomenon was reversible, and also observed in the presence of veratridine. Moreover, withdrawal of extracellular Ca2+ abolished high K+-induced modulation of 125I-NGF binding and internalization, indicating that this effect may be mediated by Ca2+.     

Low-molecular-mass proteins in cyanobacterial photosystem II: identification of psbH and psbK gene products by N-terminal sequencing

The O2-evolving photosystem II core complex was isolated from a thermophilic cyanobacterium, Synechococcus vulcanus Copeland. Analysis by SDS-polyacrylamide gel electrophoresis revealed that the complex contained at least seven low-molecular-mass proteins in addition to the well characterized CP47 apoprotein, CP43 apoprotein, 33 kDa extrinsic protein, D1 protein, D2 protein and large subunit of cytochrome b-559. The separation of these low-molecular-mass proteins were very similar between cyanobacterial and higher plant PS II. N-terminal sequences of the 6.5 kDa and 3.9 kDa proteins of cyanobacterial core complex were determined after blotting to a polyvinylidene difluoride membrane. The sequence of the 6.5 kDa protein showed high homology with an internal sequence of plant psbH gene product, so-called 10 kDa phosphoprotein, but did not conserve the Thr residue which is specifically phosphorylated in plants. The sequence of the 3.9 kDa protein corresponded to the K protein of higher plants (mature form of psbK gene product). These results indicate that the products of both psbH and psbK genes are present in cyanobacterial PS II as well as being associated with the O2-evolving core complex.     

Mitochondrial DNA Variation Follows a Geographic Pattern in Japanese Beech Species

The amount and distribution of mitochondrial (mt) DNA restriction fragment length polymorphism was determined among individual tree samples of two Japanese beech species, Fagus crenata and F.japonica. Individual plants were collected from 16 F. crenata populations throughout the range of the species, and from three F. japonica populations. We detected enough variation to characterize eleven and three chondriome types in F. crenata and F.japonica, respectively. The grouping of beech chondriome types based upon the cladistic analysis of mtDNA polymorphism allowed us to recognize the apparent geographical patterns of mtDIMA diversity: the resulting three main groups occupied distinct geographic areas. This geographic differentiation is likely to reflect the history of the Japanese beech forests after the last glacial period of the Pleistocene. In addition, the mtDNA polymorphism encountered within F. crenata encompassed all the variation observed in F.japonica. Our result suggests the need for re-evaluation of their phylogenetic relationships.     

Ecophysiological responses of the larch species in northern Japan to environmental changes as a basis for afforestation

For sustainable use and suitable management of larch plantations, we must clarify the ecophysiological responses of larch species to environmental changes. The physical environment has been changing dramatically, e.g., increase in atmospheric CO₂ concentration ([CO₂]), nitrogen (N) deposition, and atmospheric ozone concentration ([O₃]), and these changes may negatively affect growth of larch species. This review summarizes the previous experimental studies on the ecophysiological responses of larch species to elevated [CO₂], soil acidification, elevated [O₃], and N load. Based on the advanced studies, although elevated [CO₂] will stimulate the productivity of larch, increase of [O₃] and severe soil acidification will reduce it. Increase of N deposition, at least, will not negatively affect larch productivity. Finally, we propose the future direction for investigation to understand the mechanism of the responses of larch species and to predict the associated risk.     

Identification of the Gene Encoding Isoprimeverose-producing Oligoxyloglucan Hydrolase in Aspergillus oryzae

Aspergillus oryzae produces a unique β-glucosidase, isoprimeverose-producing oligoxyloglucan hydrolase (IPase), that recognizes and releases isoprimeverose (α-d-xylopyranose-(1→6)-d-glucopyranose) units from the non-reducing ends of oligoxyloglucans. A gene encoding A. oryzae IPase, termed ipeA, was identified and expressed in Pichia pastoris. With the exception of cellobiose, IpeA hydrolyzes a variety of oligoxyloglucans and is a member of the glycoside hydrolase family 3. Xylopyranosyl branching at the non-reducing ends was vital for IPase activity, and galactosylation at a α-1,6-linked xylopyranosyl side chain completely abolished IpeA activity. Hepta-oligoxyloglucan saccharide (Xyl₃Glc₄) substrate was preferred over tri- (Xyl₁Glc₂) and tetra- (Xyl₂Glc₂) oligoxyloglucan saccharides substrates. IpeA transferred isoprimeverose units to other saccharides, indicating transglycosylation activity. The ipeA gene was expressed in xylose and xyloglucan media and was strongly induced in the presence of xyloglucan endo-xyloglucanase-hydrolyzed products. This is the first study to report the identification of a gene encoding IPase in eukaryotes.