Acidification of Red Pine Forest Soil Due to Acidic Deposition in Chunchon, Korea

The effect of acidic deposition on the soil under red pine forest in Chunchon, Korea was investigated. Precipitation, stream water, and soil solution chemistry were monitored at the watershed from 1997 to 1998. Acidity of the open-bulk precipitation was often neutralized by large amounts of ammonia (NH₃) that might have originated from livestock farming and fertilization. Estimated elemental budget at the watershed showed a positive correlation between loss of base cations and proton (H⁺) production due to nitrogen transformation in soil (ΔH⁺ _NT: ([NH₄ ⁺]_in-[NH₄ ⁺]_out)- ([NO₃ ^?]_in-[NO₃ ^?]_out)). When ΔH⁺ _NT increased, concentrations of nitrate in soil solutions also increased. Consequently, pH values of soil solutions decreased, although ion exchange with base cations contributed to buffer reaction. Since acid buffering capacity of the red pine forest soil was small, it was concluded that the input of ammonium nitrogen enhanced nitrification in soil thus causing soil acidification represented by loss of base cations from the watershed.     

Influence of electron-beam irradiation on bioactive compounds in grapefruits ( Citrus paradisi Macf.)

Phytochemical levels in fruits and vegetables can be affected by several postharvest factors. In the present study, the effect of electron-beam (E-beam) irradiation was studied on grapefruit bioactive compounds. 'Rio Red' and 'Marsh White' grapefruits were irradiated with E-beam at 0, 1.0, 2.5, 5.0, and 10.0 kGy. Changes of various bioactive compounds, such as vitamin C, flavonoids, carotenoids, furocoumarins, and limonoids, were measured. The acidity decreased slightly with an increasing E-beam dose, whereas the total soluble solids were increased. Irradiation did not affect the vitamin C content at 1 kGy; however, doses beyond 1 kGy significantly reduced the vitamin C content. Lycopene and beta-carotene did not change significantly from the irradiation. Lycopene levels decreased as the E-beam dose increased, while the beta-carotene content slightly increased. Dihydroxybergamottin levels exhibited a decreasing trend, while the bergamottin content did not change. Naringin, a major flavonoid of grapefruit, showed a significant increase over the control at 10 kGy in both 'Rio Red' and 'Marsh White'. Nomilin continued to decrease with an increasing dose of E-beam irradiation, while limonin levels remained the same at all of the doses. Low-dose E-beam irradiation has very little effect on the bioactive compounds and offers a safe alternative to existing postharvest treatments for the disinfection and decontamination of grapefruits.     

Organobentonite for Sorption and Degradation of Phenol in the Presence of Heavy Metals

An experimental study was performed to determine the feasibility of usingorganobentonite modified with quarternary ammonium cations (QACs) as a reactive medium in immobilization and biodegradation barriers for mixed contaminants in the subsurface soil. Various factors, including interactions between heavy metals, organic contaminants, and soil microorganisms, were investigated when they coexisted with untreated bentonite and organobentonite. Batch sorption tests for cadmium and lead were conducted to quantify sorption selectivity of these metals on untreated bentonite and organobentonite. Metal concentrations of 50 × 10^-6 M slightly reduced the growth of soil microbes and partially interfered with the biodegradation of phenol. Soil microorganisms tested with untreated bentonite grew after approximately 25 hr of lag period and degraded phenol completely within 350 hr. The results from this study demonstrate that organobentonite could be used as a reactive medium for immobilization and biodegradation of organic contaminants in the presence of heavy metals in the subsurface soil.     

High‐Level Ciprofloxacin‐Resistant Campylobacter jejuni Isolates Circulating in Humans and Animals in Incheon,Republic of Korea

Campylobacter jejuni is one of the major causative pathogens of outbreaks or sporadic cases of diarrhoeal diseases worldwide. In this study, we compared the phenotypic and genetic characteristics of C. jejuni isolates of human and food‐producing animal origins in Korea and examined the genetic relatedness between these two groups of isolates. Regardless of isolation source, all C. jejuni isolates harboured four virulence genes, cadF, cdtB, ciaB and racR, whereas the wlaN and virB11 genes were more frequently observed in human isolates. Antimicrobial susceptibility testing showed that the majority of C. jejuni isolates displayed high‐level resistance to fluoroquinolone (95.2%) or tetracycline (76.2%) antibiotics, and 12.4% of isolates exhibited multidrug resistance (more than three classes of antibiotics tested). Pulsed‐field gel electrophoresis (PFGE) of all Campylobacter isolates revealed 51 different SmaI‐PFGE patterns and six major clusters containing both human and animal isolates. These results indicate that genetically diverse strains of C. jejuni with antimicrobial drug‐resistance and virulence properties have prevailed in Incheon. Nevertheless, some particular populations continue to circulate within the community, providing the evidence for an epidemiological link of C. jejuni infections between humans and food‐producing animals. Therefore, the continued monitoring and surveillance of C. jejuni isolates of human and food‐producing animal origins are required for public health and food safety.     

Rapidly quantitative detection of Nosema ceranae in honeybees using ultra-rapid real-time quantitative PCR

BackgroundThe microsporidian parasite Nosema ceranae is a global problem in honeybee populations and is known to cause winter mortality. A sensitive and rapid tool for stable quantitative detection is necessary to establish further research related to the diagnosis, prevention, and treatment of this pathogen.ObjectivesThe present study aimed to develop a quantitative method that incorporates ultra-rapid real-time quantitative polymerase chain reaction (UR-qPCR) for the rapid enumeration of N. ceranae in infected bees.MethodsA procedure for UR-qPCR detection of N. ceranae was developed, and the advantages of molecular detection were evaluated in comparison with microscopic enumeration.ResultsUR-qPCR was more sensitive than microscopic enumeration for detecting two copies of N. ceranae DNA and 24 spores per bee. Meanwhile, the limit of detection by microscopy was 2.40 × 10⁴ spores/bee, and the stable detection level was ≥ 2.40 × 10⁵ spores/bee. The results of N. ceranae calculations from the infected honeybees and purified spores by UR-qPCR showed that the DNA copy number was approximately 8-fold higher than the spore count. Additionally, honeybees infected with N. ceranae with 2.74 × 10⁴ copies of N. ceranae DNA were incapable of detection by microscopy. The results of quantitative analysis using UR-qPCR were accomplished within 20 min.ConclusionsUR-qPCR is expected to be the most rapid molecular method for Nosema detection and has been developed for diagnosing nosemosis at low levels of infection.     

Effects of Acetylsalicylic Acid and Calcium Chloride on Photosynthetic Apparatus and Reactive Oxygen-Scavenging Enzymes in Chrysanthemum Under Low Temperature Stress with Low Light

The effects of acetylsalicylic acid （ASA）, CaCl2, and ASA ＋ CaCl2 on the photosynthetic apparatus and antioxidant enzyme activities were investigated in chrysanthemum Jinba （a cut flower cultivar） under low temperature stress with low light （TL stress） （16/12℃, day/night, PFD 100 μmol m^-2 s-1）. The results showed that under TL stress, the net photosynthesis rate （Pn）, carboxylation efficiency （CE）, apparent quantum yield （AQY）, maximal photochemical efficiency （Fv/Fm） of PSII, quantum yield of PSII electron transport （ФPSII）, and photochemical quenching （qP） of the chrysanthemum leaves in all treatments were significantly decreased, but the decreases were alleviated by ASA, CaCl2, and ASA ＋ CaCl2 treatments compared with the controls. The alleviating effect of ASA ＋ CaCI2 was better than either ASA or CaCl2 single treatment. Moreover, the ASA ＋ CaCl2 treatment highly improved the chlorophyll content, relatively improved the number and size of chloroplast and starch grain in the leaves of chrysanthemum plants compared with ASA and CaCl2 treatments. It was indicated that ASA and/or CaCI2 could regulate the photosynthetic functions in the leaves of chrysanthemum plants to enhance the resistance against TL stress. On the other hand, reduction in relative conductance rate implied that ASA and/ or CaCl2 could protect from membrane injury in leaves of chrysanthemum plants. The activities of SOD, POD, and CAT in the treated leaves of chrysanthemum were increased as compared with the controls. It was suggested that ASA and/or CaCl2 had positive regulation effects on the defence enzyme activities in chrysanthemum leaves which could protect the photosynthetic apparatus to a certain degree under the TL stress. In brief, the treatment of ASA together with CaCl2 was better for chrysanthemum plants to adapt TL stress than single ASA or CaCl2 treatments.     

Neoamphimedine circumvents metnase-enhanced DNA topoisomerase IIα activity through ATP-competitive inhibition

Type IIα DNA topoisomerase (TopoIIα) is among the most important clinical drug targets for the treatment of cancer. Recently, the DNA repair protein Metnase was shown to enhance TopoIIα activity and increase resistance to TopoIIα poisons. Using in vitro DNA decatenation assays we show that neoamphimedine potently inhibits TopoIIα-dependent DNA decatenation in the presence of Metnase. Cell proliferation assays demonstrate that neoamphimedine can inhibit Metnase-enhanced cell growth with an IC(50) of 0.5 μM. Additionally, we find that the apparent K(m) of TopoIIα for ATP increases linearly with higher concentrations of neoamphimedine, indicating ATP-competitive inhibition, which is substantiated by molecular modeling. These findings support the continued development of neoamphimedine as an anticancer agent, particularly in solid tumors that over-express Metnase.