Management of pine wilt disease in Korea through preventative silvicultural control

Pine wilt disease (PWD) represents a major threat to forest ecosystems worldwide. Although PWD is now better understood, effective control measures for this disease have still not been devised. Here, we report several years of field studies on preventative silvicultural control of PWD. Silvicultural control through preventative clear-cutting and the manual removal of logs was implemented between 2005 and 2009 in 16 Korean districts that had newly PWD-infected stands. Preventative clear-cutting of neighboring asymptomatic pine trees (within a 10-50-m radius of wilt trees) and the removal of felled logs or branches suppressed spread of PWD. Occurrences of PWD wilt pines in districts (city or county) subjected to this silvicultural control method were significantly reduced compared with those in districts using conventional controls (physical or chemical treatment of wilt pine trees). Through silvicultural control, PWD was successfully suppressed in 11 of 16 districts investigated. In contrast, successful control was achieved in only 1 among 18 districts subjected to conventional control. Our results will be of considerable interest to those engaged in the very difficult battle against the global spread of PWD.     

High-affinity monoclonal antibodies for detection of the microbial metabolite, 2-methylisoborneol

The production of 2-methylisoborneol (MIB) by certain fungi and algae can contribute musty off-flavors to foods and water supplies if uncontrolled. The goal of this research was to develop a nonsensory simple method for the detection of MIB. Anti-MIB monoclonal antibodies were produced by immunizing mice with borneol-conjugated protein and selecting positive clones with an MIB-protein conjugate. An indirect competitive immunoassay developed using this antibody had a detection limit of 0.6 microg L(-)(1) and an I(50) value of 5 microg L(-)(1). Detection was relatively specific for MIB and showed 20% cross-reactivity with borneol or isoborneol and 4-5% cross-reactivity with camphor. No cross-reactivity to geosmin was observed.     

Evaluation and validation of a commercially available enzyme-linked immunosorbent assay for the neonicotinoid insecticide imidacloprid in agricultural samples

The performance of a commercially available microtiter plate ELISA kit for the determination of the neonicotinoid insecticide imidacloprid was evaluated for sensitivity, selectivity, influence of organic solvent used for extraction procedure, matrix interference originated from agricultural sample, accuracy, and method comparison with conventional HPLC analysis. The limit of detection for the kit (0.1 or 0.5 ng/mL) was determined. The working range (1-39 ng/mL) experimentally calculated on the basis of a criterion, which is determined as the range from I(20) to I(80), was comparable to that established by the manufacturer (1-50 ng/mL). The linearity of the standard curve based on the kit-assembled standard solutions agreed with the one based on the self-made standard solutions. Specificity studies indicate that the imidacloprid monoclonal antibody can readily distinguish the target compound from other structurally related neonicotinoid analogues and some metabolites, with the exception of clothianidin, the cross-reactivity of which was approximately 12%. To extract imidacloprid from an agricultural sample (apple) as simply and rapidly as possible, some extraction methods were examined. Consequently, the extraction method with hand-shaking for 5 min was the best among the examined methods. For the analysis of imidacloprid in apple samples, it was extracted directly with methanol and the extracts were diluted 10-fold (100-fold in the well) with water prior to ELISA analysis. No significant matrix interference was observed with the dilution factor. Recoveries of imidacloprid from fortified apple samples ranged from 87.7 to 112.0%. The results obtained with the ELISA kit correlated well with those by the reference method (conventional HPLC analysis) for apple samples (r > 0.998). These findings strongly indicate that the ELISA kit may be employed routinely for an on-site imidacloprid residue analysis of apple samples.     

Correlation between Environmental Conditions and the Distribution of Mosses Exposed to Urban Air Pollutants

Moss surveys have several advantages over conventional depositionmonitoring based on precipitation, and allow the study of regional differences and temporal trends of airborne pollution. The purposes of this study were to: (i) describe the moss species growing in one of the largest industrial cities in Asia, (ii) document edaphic and atmospheric conditions at each site, (iii) collect materials and data for a program of regular moss monitoring, previously lacking in the Far East, (iv) uncover correlations among atmospheric and edaphic factors expected to influence moss growth. As a result, a total of fifteen moss species were recorded in twenty-five sites in Seoul, Korea, and most sites had four or five species. Each species' density was affected by soil parameters, but density of Pogonatum nessii and Taxiphyllum taxirameum was also affected by CO. In contrast, SO₂ was the only environmental variablethat significantly affected the composition of moss communities. On the whole, species diversity rather than abundance of specific moss species might be a good indicator of atmospheric contamination in Seoul. This investigation will help fill the gap in knowledge of the interactions between environmental pollution and moss vegetation under field conditions.     

Influence of green tea polyphenol in rats with arginine-induced renal failure

To determine whether green tea polyphenol ameliorates the pathological conditions induced by excessive dietary arginine, green tea polyphenol was administered to rats at a daily dose of 50 or 100 mg/kg body weight for 30 days with a 2% w/w arginine diet. In arginine-fed control rats, urinary and/or serum levels of guanidino compounds, nitric oxide (NO), urea, protein, and glucose increased significantly, while the renal activities of the oxygen species-scavenging enzymes superoxide dismutase (SOD) and catalase decreased, compared with casein-fed rats. However, rats given green tea polyphenol showed significant and dose-dependent decreases in serum levels of creatinine (Cr) and urea nitrogen and urinary excretion of Cr, and they exerted a slight reduction of nitrite plus nitrate, indicating that green tea polyphenol reduced the production of uremic toxins and NO. In addition, in arginine-fed rats the urinary urea, protein, and glucose level increases were reversed by the administration of green tea polyphenol. Moreover, in rats given green tea polyphenol the SOD and catalase activities suppressed by excessive arginine administration increased dose-dependently, implying the biological defense system was augmented as a result of free radical scavenging. These results suggest that green tea polyphenol would ameliorate renal failure induced by excessive dietary arginine by decreasing uremic toxin, and NO production and increasing radical-scavenging enzyme activity.     

Agglomeration and Competition among Chinese Cities: An Investigation of Taiwanese High‐Tech Foreign Direct Investment

The purpose of this study was to investigate how Taiwanese high‐tech firms' foreign direct investment (FDI) leads to agglomeration and competition among cities in China. By using social network analysis to analyze 1,111 subsidiaries affiliated with 270 multinational corporations (MNCs) during the years between 1988 and 2006 in 30 major Chinese cities, this study finds that: 1) agglomeration in Chinese cities falls into three primary categories: the hub cluster, the communication‐extended cluster, and the computer‐extended cluster. Among the aforementioned clusters, the hub cluster is the most critical in terms of firm location, and therefore is often a high‐priority investment site for Taiwanese high‐tech firms. 2) Chinese cities fall into four primary groups, or “blocks”: the core block, the coast block, the inland block, and the periphery block; these groups were determined by applying a structural equivalence analysis of which members of each type are in competition with one another. By linking the findings of the urban network characteristics to Chinese regional economic policies, this study provides guidance to aid executives in determining the optimal location for future FDI. Implications and suggestions for host country governments in terms of firms' investment strategies are also discussed.     

Role of myocardial catecholamines in cardiac contractility

In cats bilateral sympathectomy or administration of reserpine results in a marked reduction in concentration of myocardial catecholamines. The contractility of papillary muscles from such animals is significantly less than that of muscles from untreated animals. These findings demonstrate the importance of normal levels of myocardial catecholamines in the maintenance of normal cardiac contractility.     

Molecular characterization of tetracycline- and quinolone-resistant Aeromonas salmonicida isolated in Korea

The antibiotic resistance of 16 Aeromonas (A.) salmonicida strains isolated from diseased fish and environmental samples in Korea from 2006 to 2009 were investigated in this study. Tetracycline or quinolone resistance was observed in eight and 16 of the isolates, respectively, based on the measured minimal inhibitory concentrations. Among the tetracycline-resistant strains, seven of the isolates harbored tetA gene and one isolate harbored tetE gene. Additionally, quinolone-resistance determining regions (QRDRs) consisting of the gyrA and parC genes were amplified and sequenced. Among the quinolone-resistant A. salmonicida strains, 15 harbored point mutations in the gyrA codon 83 which were responsible for the corresponding amino acid substitutions of Ser⁸³→Arg⁸³ or Ser⁸³→Asn⁸³. We detected no point mutations in other QRDRs, such as gyrA codons 87 and 92, and parC codons 80 and 84. Genetic similarity was assessed via pulsed-field gel electrophoresis, and the results indicated high clonality among the Korean antibiotic-resistant strains of A. salmonicida.