Effects of environmental factors on growth and mortality of Parashorea macrophylla (Dipterocarpaceae) planted on slopes and valleys in a degraded tropical secondary forest in Sarawak,Malaysia

Enrichment planting with climax trees such as dipterocarps is required to rehabilitate degraded tropical forests in Southeast Asia, because these forests have been damaged by various anthropogenic activities. Severely degraded tropical secondary forests are the most important targets for enrichment planting in the region, because secondary forest trees potentially provide moderate conditions for planted seedlings by preventing strong sunlight and high temperatures. In an enrichment planting site located in Sarawak, Malaysia, we explored how variation in secondary forest structure (biomass and stand density) and soil (nutrient and water) conditions influenced the mortality and growth rates of planted dipterocarp seedlings (Parashorea macrophylla, Wyatt-Sm. ex P.S. Ashton) over the period from 2000–2007. Experimental plots were set up on different topographical features (slopes and valleys). Using the data collected, we demonstrated the ways in which environmental factors, such as soil nitrogen content, relate to climax tree seedling growth and mortality in degraded tropical secondary forests dominated by the genera Macaranga, Ficus, and Glochidion. Stand density and total aboveground biomass of secondary forest trees were significantly lower in the valley plots than on the slopes, whereas soil total nitrogen and water contents were significantly higher in valley plots. Over seven years, the total biomass of trees increased, whereas the density of secondary forest trees decreased in all plots. Nutrient stocks (nitrogen, phosphorus, potassium, calcium, and magnesium) in the soil (0–5?cm) also decreased over seven years in all plots. Height, diameter, and mortality of planted seedlings were higher in the valley plots than on slopes. Multiple stepwise regression demonstrated significant positive effects of total soil nitrogen and water content on the relative growth rate of seedlings over seven years. There were no significant relationships between seedling mortality and any of the environmental factors measured, including soil conditions. We conclude that (1) seedling growth was enhanced by soil total nitrogen rather than by available phosphorus or potassium, and (2) planted seedlings grew faster and died more often in the valley plots than on the slopes.     

A meningioma with hyperintensity on T1-weighted images in a dog

A male six-year-old Pomeranian showed recurrent seizures and progressive left hemiparesis. MRI revealed a mass in the right paramedian frontal-temporal region with hyperintensity on T1-weighted (T1W) and mixed-intensity on T2-weighted (T2W) images. After gadolinium enhancement, the mass was enhanced homogenously and demonstrated the dural tail sign. Surgical resection of mass was performed and its histological diagnosis was meningioma. The meningioma of this case had a high cellular density with some lipid contents and intra- and extra-tumor hemorrhage, however, calcification was not found. These cellular characteristics may contribute to a higher signal intensity on T1W imaging.     

Beta-cyanoalanine synthase as a molecular marker for induced resistance by fungal glycoprotein elicitor and commercial plant activators

ABSTRACT The biocontrol agent Pythium oligandrum produces glycoprotein elicitor in the cell wall fraction, designated CWP, and induces resistance to a broad range of pathogens. To understand the mechanism of CWP-induced resistance to pathogens, gene expression at the early stage of CWP treatment in tomato roots was analyzed using a cDNA array. At 4 h after CWP treatment, 144 genes were up-regulated and 99 genes were down-regulated. In the 144 up-regulated genes, nine genes exhibited about eightfold increased expression. Analysis of the response of these nine genes to three commercial plant activators indicated that a high level of one gene, beta-cyanoalanine synthase gene (LeCAS) encoding hydrogen cyanide (HCN) detoxification enzyme, was stably induced in tomato roots by such treatment. However, expression of LeCAS was not significantly induced in tomato roots at 4 h by abiotic stresses, whereas only a very low level of induction of such expression by cold stress was observed. This LeCAS expression was also induced after exogenous treatment with a low level of 1-amino-cyclopropane-1-carboxylate as the precursor of ethylene, but not with either salicylic acid or methyl jas-monate. The induction of LeCAS expression in CWP-treated and plant activator-treated roots is likely to be caused by the detoxification of HCN during ethylene production. Transient activation of LeCAS expression caused by ethylene production in tomato roots may be a general phenomenon in fungal elicitor-induced and synthetic plant activator-induced resistance. LeCAS seems to be useful for screening possible novel plant activators for plant protection against pathogens.     

Synthesis and antifungal activity of the proposed structure of a volatile compound isolated from the edible mushroom Hypsizygus marmoreus

We synthesized the proposed structure of an antifungal compound detected in the culture broth of the edible mushroom Hypsizygus marmoreus. Using the Evans aldol and Abiko–Masamune aldol reactions as the key steps, we synthesized all of the stereoisomers of the compound with high stereoselectivity. The GC retention times and the fragmentation patterns in the mass spectra of the synthesized isomers did not match those of the natural product. Therefore, this result may imply that it is necessary to reisolate the natural product and reconsider its structure. All of the synthesized isomers were found to exhibit antifungal activity against the phytopathogenic fungus Alternaria brassicicola. Due to their simple structures, the obtained isomers could be lead compounds for new pesticides.     

Nonequilibrium mechanics of active cytoskeletal networks

Cells both actively generate and sensitively react to forces through their mechanical framework, the cytoskeleton, which is a nonequilibrium composite material including polymers and motor proteins. We measured the dynamics and mechanical properties of a simple three-component model system consisting of myosin II, actin filaments, and cross-linkers. In this system, stresses arising from motor activity controlled the cytoskeletal network mechanics, increasing stiffness by a factor of nearly 100 and qualitatively changing the viscoelastic response of the network in an adenosine triphosphate-dependent manner. We present a quantitative theoretical model connecting the large-scale properties of this active gel to molecular force generation.     

Bioactive Alkaloids from the Sea: A Review

In our ongoing search for bioactive substances from marine organisms, novel alkaloids have been isolated. Pinnatoxins and pinnamine, potent shellfish poisons, were purified from the Okinawan bivalve Pinna muricata. Pinnatoxins activate Ca²⁺ channels. Halichlorine was isolated from the marine sponge Halichondria okadai. This compound inhibits the induction of VCAM-1. Drugs that block VCAM-1 may be useful for treating coronary artery diseases, angina, and noncardiovascular inflammatory diseases. Pinnaic acids, which are cPLA₂ inhibitors, were also obtained from P. muricata. Interestingly, the structures of pinnaic acids are closely related to that of halichlorine. Norzoanthamine hydrochloride, isolated from the colonial zoanthid Zoanthus sp., suppresses decreases in bone weight and strength in ovariectomized mice, and could be a good candidate for an osteoporotic drug. Ircinamine, purified from the marine sponge Ircinia sp., has a reactive thioester. Aburatubolactams, inhibitors of superoxide anion generation, were isolated from Streptomyces sp. This article covers the bioactive marine alkaloids that have been recently isolated by this research group.     

Sequence and polymerase chain reaction–restriction fragment length polymorphism analysis of the large subunit rRNA gene of bivalve: Simple and widely applicable technique for multiple species identification of bivalve larva

ABSTRACT:   One of the biggest and long-standing difficulties in investigation of larval ecology in the field is species-level identification. In the present study, we developed polymerase chain reaction–restriction fragment length polymorphism (PCR-RFLP) analysis based on the large subunit (LSU) rRNA gene (rDNA) D1/D2/D3 region for identification of multiple species of bivalve larvae using 14 species of bivalve collected from Maizuru Bay. The LSU rDNA D1/D2/D3 region of all analyzed species could be amplified by PCR using bvD1f/bvD3r primers, and RFLP analysis by Hae III digestion on the PCR products showed species-specific fragment patterns. Furthermore, this analysis applied to single bivalve larvae in Maizuru Bay revealed efficient amplification of the target region and the species-specific pattern from 80% of the larvae, 75% of which showed a pattern that matched a certain pattern of the adult bivalves. In addition, the analysis of inter- and intraspecies variation of the LSU rDNA D1/D2/D3 region using the sequence data of the genus Crassostrea from the DDBJ database showed high applicability of this RFLP analysis on closely related species. Because of the wide applicability and technical simplicity, this method can become the standard for the identification of bivalve larvae species once the sequence data of the LSU rDNA D1/D2/D3 region of many bivalve species have been accumulated.     

Genetic analysis of ion-beam induced extremely late heading mutants in rice

Two extremely late heading mutants were induced by ion beam irradiation in rice cultivar ‘Taichung 65’: KGM26 and KGM27. The F₂ populations from the cross between the two mutants and Taichung 65 showed clear 3 early: 1 late segregation, suggesting control of late heading by a recessive gene. The genes identified in KGM26 and KGM27 were respectively designated as FLT1 and FLT2. The two genes were mapped using the crosses between the two mutants and an Indica cultivar ‘Kasalath’. FLT1 was located on the distal end of the short arm of chromosome 8. FLT2 was located around the centromere of chromosome 9. FLT1 might share the same locus as EHD3 because their chromosomal location is overlapping. FLT2 is inferred to be a new gene because no gene with a comparable effect to that of this gene was mapped near the centromere of chromosome 9. In crosses with Kasalath, homozygotes of late heading mutant genes showed a large variation of days to heading, suggesting that other genes affected late heading mutant genes.