Removal of estrogenic activity from endocrine-disrupting chemicals by purified laccase of Phlebia tremellosa

A white-rot basidiomycete, Phlebia tremellosa, produced a laccase that showed increased activity during degradation of phthalates. A laccase was purified through the ion exchange chromatography and preparative gel electrophoresis, and the estimated molecular weight was 75 kDa. The optimum pH and temperature of the purified laccase was pH 4.0 and 20 degrees C, respectively. The K(m) value of the enzyme was 55.7 microM, and the V(max) was 0.0541 OD min(-1) U(-1) for o-tolidine. Purified laccase reduced the estrogenic activity of four different endocrine-disrupting chemicals. However, this effect was reduced by a laccase inhibitor, kojic acid, which confirmed that the laccase was involved in the removal of estrogenic activity.     

Influence of stand density on soil CO2 efflux for a Pinus densiflora forest in Korea

We investigated the influence of stand density [938 tree ha⁻¹ for high stand density (HD), 600 tree ha⁻¹ for medium stand density (MD), and 375 tree ha⁻¹ for low stand density (LD)] on soil CO₂ efflux (R _S) in a 70-year-old natural Pinus densiflora S. et Z. forest in central Korea. Concurrent with R _S measurements, we measured litterfall, total belowground carbon allocation (TBCA), leaf area index (LAI), soil temperature (ST), soil water content (SWC), and soil nitrogen (N) concentration over a 2-year period. The R _S (t C ha⁻¹ year⁻¹) and leaf litterfall (t C ha⁻¹ year⁻¹) values varied with stand density: 6.21 and 2.03 for HD, 7.45 and 2.37 for MD, and 6.96 and 2.23 for LD, respectively. In addition, R _S was correlated with ST (R ² = 0.77–0.80, P < 0.001) and SWC (R ² = 0.31–0.35, P < 0.001). It appeared that stand density influenced R _S via changes in leaf litterfall, LAI and SWC. Leaf litterfall (R ² = 0.71), TBCA (R ² = 0.64–0.87), and total soil N contents in 2007 (R ² = 0.94) explained a significant amount of the variance in R _S (P < 0.01). The current study showed that stand density is one of the key factors influencing R _S due to the changing biophysical and environmental factors in P. densiflora.     

Approaches for enhancement of N2 fixation efficiency of chickpea (Cicer arietinum L.) under limiting nitrogen conditions

Chickpea (Cicer arietinum) is an important pulse crop in many countries in the world. The symbioses between chickpea and Mesorhizobia, which fix N₂ inside the root nodules, are of particular importance for chickpea's productivity. With the aim of enhancing symbiotic efficiency in chickpea, we compared the symbiotic efficiency of C‐15, Ch‐191 and CP‐36 strains of Mesorhizobium ciceri in association with the local elite chickpea cultivar ‘Bivanij’ as well as studied the mechanism underlying the improvement of N₂ fixation efficiency. Our data revealed that C‐15 strain manifested the most efficient N₂ fixation in comparison with Ch‐191 or CP‐36. This finding was supported by higher plant productivity and expression levels of the nifHDK genes in C‐15 nodules. Nodule specific activity was significantly higher in C‐15 combination, partially as a result of higher electron allocation to N₂ versus H⁺. Interestingly, a striking difference in nodule carbon and nitrogen composition was observed. Sucrose cleavage enzymes displayed comparatively lower activity in nodules established by either Ch‐191 or CP‐36. Organic acid formation, particularly that of malate, was remarkably higher in nodules induced by C‐15 strain. As a result, the best symbiotic efficiency observed with C‐15‐induced nodules was reflected in a higher concentration of the total and several major amino metabolites, namely asparagine, glutamine, glutamate and aspartate. Collectively, our findings demonstrated that the improved efficiency in chickpea symbiotic system, established with C‐15, was associated with the enhanced capacity of organic acid formation and the activities of the key enzymes connected to the nodule carbon and nitrogen metabolism.     

ERK/ribosomal S6 kinase (RSK) signaling positively regulates death receptor 5 expression through co-activation of CHOP and Elk1

Death receptor 5 (DR5) is a death domain-containing transmembrane receptor that triggers apoptosis upon binding to its ligand or when overexpressed. Its expression is induced by certain small molecule drugs, including celecoxib, through mechanisms that have not been fully elucidated. The current study has revealed a novel ERK/ribosomal S6 kinase (RSK)-dependent mechanism that regulates DR5 expression primarily using celecoxib as a DR5 inducer. Both C/EBP homologous protein (CHOP) and Elk1 are required for celecoxib-induced DR5 expression based on promoter deletion and mutation analysis and siRNA-mediated gene silencing results. Co-expression of both CHOP and Elk1 exhibited enhanced effects on increasing DR5 promoter activity and DR5 expression, indicating that CHOP and Elk1 co-operatively regulate DR5 expression. Because Elk1 is an ERK-regulated protein, we accordingly found that celecoxib increased the levels of phosphorylated ERK1/2, RSK2, and Elk1. Inhibition of either ERK signaling with a MEK inhibitor or ERK1/2 siRNA, or RSK2 signaling with an RSK2 inhibitor or RSK2 siRNA abrogated DR5 up-regulation by celecoxib as well as other agents. Moreover, these inhibitions suppressed celecoxib-induced CHOP up-regulation. Thus, ERK/RSK-dependent, CHOP and Elk1-mediated mechanisms are critical for DR5 induction. Additionally, celecoxib increased CHOP promoter activity in an ATF4-dependent manner, and siRNA-mediated blockade of ATF4 abrogated both CHOP induction and DR5 up-regulation, indicating that ATF4 is involved in celecoxib-induced CHOP and DR5 expression. Collectively, we conclude that small molecules such as celecoxib induce DR5 expression through activating ERK/RSK signaling and subsequent Elk1 activation and ATF4-dependent CHOP induction.     

Effects of irradiance and spectral quality on seedling development of two Southeast Asian Hopea species

 Seedling developmental responses to understory shade combine the effects of reductions in irradiance and changes in spectral quality. We studied the seedling development of two Southeast Asian dipterocarp trees in response to differences in irradiance (photosynthetic photon flux density, PPFD) and spectral quality (red to far-red ratio, R:FR). The two species, Hopea helferei and H. odorata, are taxonomically closely related but differ in their ecological requirements; H. helferei is more drought-tolerant and typically grows in more open habitats. Seedlings were grown in six different replicated shadehouse treatments varying in percentage of solar PPFD and R:FR. The two species differed in the influence of light variables on most seedling characters, particularly for final height, internode distance, branch/trunk internodes, stem length/mass, leaf area/stem length, petiole length, and growth/mol of photons received. Most of the characters in both taxa were primarily influenced by PPFD, but spectral quality also influenced some characters – more so for H. odorata. The latter species grew more rapidly, particularly in the low PPFD treatments, and its leaves were capable of higher photosynthesis rates. However, growth in H. helferei was not reduced in direct sunlight. The growth of this taxon may be constrained by adaptations, particularly in leaves, for drought tolerance. Received: 14 April 1996 / Accepted: 8 October 1996     

Diversity and decay ability of basidiomycetes isolated from lodgepole pines killed by the mountain pine beetle

When lodgepole pines (Pinus contorta Douglas ex Louden var. latifolia Engelm. ex S. Watson) that are killed by the mountain pine beetle (Dendroctonus ponderosae) and its fungal associates are not harvested, fungal decay can affect wood and fibre properties. Ophiostomatoids stain sapwood but do not affect the structural properties of wood. In contrast, white or brown decay basidiomycetes degrade wood. We isolated both staining and decay fungi from 300 lodgepole pine trees killed by mountain pine beetle at green, red, and grey stages at 10 sites across British Columbia. We retained 224 basidiomycete isolates that we classified into 34 species using morphological and physiological characteristics and rDNA large subunit sequences. The number of basidiomycete species varied from 4 to 14 species per site. We assessed the ability of these fungi to degrade both pine sapwood and heartwood using the soil jar decay test. The highest wood mass losses for both sapwood and heartwood were measured for the brown rot species Fomitopsis pinicola and the white rot Metulodontia and Ganoderma species. The sap rot species Trichaptum abietinum was more damaging for sapwood than for heartwood. A number of species caused more than 50% wood mass losses after 12 weeks at room temperature, suggesting that beetle-killed trees can rapidly lose market value due to degradation of wood structural components.     

Classification of viral zoonosis through receptor pattern analysis

Background  

Viral zoonosis, the transmission of a virus from its primary vertebrate reservoir species to humans, requires ubiquitous cellular proteins known as receptor proteins. Zoonosis can occur not only through direct transmission from vertebrates to humans, but also through intermediate reservoirs or other environmental factors. Viruses can be categorized according to genotype (ssDNA, dsDNA, ssRNA and dsRNA viruses). Among them, the RNA viruses exhibit particularly high mutation rates and are especially problematic for this reason. Most zoonotic viruses are RNA viruses that change their envelope proteins to facilitate binding to various receptors of host species. In this study, we sought to predict zoonotic propensity through the analysis of receptor characteristics. We hypothesized that the major barrier to interspecies virus transmission is that receptor sequences vary among species--in other words, that the specific amino acid sequence of the receptor determines the ability of the viral envelope protein to attach to the cell.     

Ceramide kinase regulates the migration of bone marrow-derived mesenchymal stem cells

Endogenous bone marrow-derived mesenchymal stem cells (BM-MSCs) are mobilized into peripheral blood and injured tissues by various growth factors and cytokines that are expressed in the injured tissues, such as substance P (SP), stromal cell derived factor-1 (SDF-1), and transforming growth factor-beta (TGF-β). Extracellular bioactive lipid metabolites such as ceramide-1-phosphate and sphingosine-1-phosphate also modulate BM-MSC migration as SP, SDF-1, and TGF-β. However, the roles of intrinsic lipid kinases of BM-MSCs in the stem cell migration are unclear. Here, we demonstrated that ceramide kinase mediates the chemotactic migration of BM-MSCs in response to SP, SDF-1, or TGF-β. Furthermore, a specific inhibitor of ceramide kinase inhibited TGF-β-induced migration of BM-MSCs and N-cadherin that is necessary for BM-MSCs migration in response to TGF-β. Therefore, these results suggest that the intracellular ceramide kinase is required for the BM-MSCs migration and the roles of the intrinsic ceramide kinase in the migration are associated with N-cadherin regulation.     

Oncogenic Notch Promotes Long-Range Regulatory Interactions within Hyperconnected 3D Cliques

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Enhancing the Production and Monosaccharide Composition of Exopolysaccharides of Lactobacillus plantarum VAL6 by Applying Thermal Stress and Increased Carbon Dioxide Concentration

Microbiology - Lactobacilli are able to produce exopolysaccharides (EPSs) with a wide diversity in structure and composition. However, changes in EPS production under environmental challenges are...