Prenylated flavanones isolated from flowers of Azadirachta indica (the neem tree) as antimutagenic constituents against heterocyclic amines

Four prenylated flavanones were isolated from the methanol extract of the flowers of Azadirachta indica (the neem tree) as potent antimutagens against Trp-P-1 (3-amino-1,4-dimethyl-5H-pyrido[4,3-b]indole) in the Salmonella typhimurium TA98 assay by activity-guided fractionation. Spectroscopic properties revealed that those compounds were 5,7,4'-trihydroxy-8-prenylflavanone (1), 5,4'-dihydroxy-7-methoxy-8-prenylflavanone (2), 5,7,4'-trihydroxy-3',8-diprenylflavanone (3), and 5,7,4'-trihydroxy-3',5'-diprenylflavanone (4). All isolated compounds were found for the first time in this plant. The antimutagenic IC(50) values of compounds 1-4 were 2.7 +/- 0.1, 3.7 +/- 0.1, 11.1 +/- 0.1, and 18.6 +/- 0.1 microM in the preincubation mixture, respectively. These compounds also similarly inhibited the mutagenicity of Trp-P-2 (3-amino-1-methyl-5H-pyrido[4,3-b]indole) and PhIP (2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine). All of the compounds 1-4 strongly inhibited ethoxyresorufin O-dealkylation activity of cytochrome P450 1A isoforms, which catalyze N-hydroxylation of heterocyclic amines. However, compounds 1-4 did not show significant inhibition against the direct-acting mutagen NaN(3). Thus, the antimutagenic effect of compounds 1-4 would be mainly based on the inhibition of the enzymatic activation of heterocyclic amines.     

Measurement of Indoor Sulfur Dioxide Emission from Coal–Biomass Briquettes

The coal–biomass briquette is an alternative fuel that replaces low-grade coal. It is expected that the use of coal–biomass briquettes will effectively reduce the indoor concentration of sulfur dioxide (SO₂) emitted during raw coal combustion. In this study, indoor concentrations of SO₂ emitted from combustion of either coal–biomass briquettes or low-grade coal in households in Nanchuan, which is in the rural area of Chongqing City, China, were measured. The acidic gases were collected using passive samplers, and the samplers were taken to the laboratory for extraction and measurement. The SO₂ concentrations resulting from the use of coal–biomass briquettes were clearly reduced compared with those resulting from the use of low-grade coal. The concentrations of SO₂ to which the inhabitants (housewives) of the houses were exposed were also measured, and were found to be less with coal–biomass briquettes. Although with coal–biomass briquettes exposure concentrations still exceeded the World Health Organization guideline for SO₂ (125 μ g m^?3), indoor air pollution and adverse effects on human health caused by SO₂ could be decreased by substituting coal–biomass briquettes for low-grade coal as a domestic fuel.     

Effects of elevated carbon dioxide concentration on biological nitrogen fixation, nitrogen mineralization and carbon decomposition in submerged rice soil

Controlled-environment chambers were used to study the effects of elevated CO₂ concentrations on biological N fixation, N mineralization and C decomposition in rice soil. In three chambers, CO₂ concentration was maintained at 353ᆣ/396ᆫ µmol mol^-1 (day/night; ambient CO₂), while in another three, CO₂ was maintained at 667ᆸ/700ᆽ µmol mol^-1 (day/night; elevated CO₂) throughout the growing season. Rice (var. Nipponbare) seedlings were grown under either ambient or elevated CO₂ concentrations, and then transplanted into the soils in the corresponding chambers. At different growth stages, soil samples were taken from surface (0-1cm) and sub-surface (1-10cm) layers at the centre of four hills, then sieved (<1 mm) to remove root residues. Fresh soil was used to measure N fixation activity (using the acetylene reduction assay), NH₄⁺ content and organic C. Separate sets of soil samples were transferred to serum bottles and anaerobically incubated at 30°C for 30 days to measure potential rates of N mineralization and C decomposition. Under an elevated atmospheric CO₂ concentration, acetylene reduction activity significantly increased in the surface soil layer during the early cultivation stages and in the sub-surface soil layer during the latter part of cultivation. There was no difference in the amount of NH₄⁺ in fresh soils between elevated and ambient CO₂ chambers, while the rate of N mineralization was increased by elevated CO₂ during the latter part of cultivation. Soils from the elevated CO₂ chambers had obviously higher rate of C decomposition than that from the ambient CO₂ chambers. CH₄ production gradually increased with the growth of rice plants. These results suggest that elevated CO₂ affected biological N fixation, N mineralization and C decomposition in submerged rice soil during the different growth stages of rice.     

Receptor assay-guided isolation of anti-GABAergic insecticidal alkaloids from a fungal culture

The gamma-aminobutyric acid (GABA) receptor bears sites of action for insecticides. To discover GABA receptor-directed insecticides in natural products, fungal culture extracts were screened for their ability to inhibit specific binding of the radiolabeled noncompetitive antagonist [3H]1-(4-ethynylphenyl)-4-n-propyl-2,6,7-trioxabicyclo[2.2.2]octane to housefly head membranes. The screening efforts led to the isolation of two alkaloids from Aspergillus terreus: PF1198A (alantrypinone) and PF1198B (serantrypinone), which had IC50 values of 0.34 and 2.1 microM, respectively, in this assay. These compounds were ca. 47-61-fold selective for housefly vs rat GABA receptors. Both compounds showed insecticidal activity against Myzus persicae in the range of 100-500 ppm. Binding assay-guided screening should provide significant opportunities for the identification of novel and selective insecticides.     

Determination of neonicotinoid pesticide residues in vegetables and fruits with solid phase extraction and liquid chromatography mass spectrometry

A rapid and simple extraction method for the simultaneous analysis of five neonicotinoid insecticides has been developed. Twelve different fruit and vegetable matrixes were extracted with methanol and cleaned up using a graphitized carbon solid phase extraction cartridge loading with a 20% methanol solution. The concentrated eluate after methanol elution was then analyzed for pesticide residues by liquid chromatography/mass spectrometry in the APCI positive mode. The five pesticides including nitenpyram, thiamethoxam, imidacloprid, acetamiprid, and thiacloprid were recovered at 70-95% at spike levels of 0.1 and 1 mg/kg in bell pepper, cucumber, eggplant, grape, grapefruit, Japanese radish, peach, pear, potato, rice, and tomato. Relative standard deviations were less than 10% for all of the recovery tests. The proposed method is fast, easy to perform, and could be utilized for regular monitoring of pesticide residues.     

PCR-based detection of blood parasites in cattle and adult Rhipicephalus appendiculatus ticks

To ascertain the infection rate for tick-borne pathogens in Zambia, an epidemiological survey of Theileria parva, Babesia bigemina and Anaplasma marginale in traditionally managed Sanga cattle was conducted using PCR. Of the 71 native Zambian cattle, 28 (39.4%) were positive for T. parva, 16 (22.5%) for B. bigemina and 34 (47.9%) for A. marginale. The mixed infection rate in cattle was 8.5% (6/71), 16.9% (12/71), 7.0% (5/71) and 2.8% (2/71) for T. parva/B. bigemina, T. parva/A. marginale, B. bigemina/A. marginale and T. parva/B. bigemina/A. marginale, respectively.To predict the risk for transmission of tick-borne pathogens from ticks to cattle, a total of 74 Rhipicephalus appendiculatus ticks were collected from a location where cattle had been found positive for T. parva. Of the ticks collected, 10 (13.5%) were found to be PCR-positive for T. parva. The results suggest that the infection rate for tick-borne pathogens was relatively high in Sanga cattle and that adult R. appendiculatus ticks were highly infected with T. parva.     

Effects of Elevated Ozone Concentration on Starch and Starch Synthesis Enzymes of Yangmai 16 Under Fully Open-Air Field Conditions

O3 is not only greenhouse gas but also a primary gaseous contaminant in the atmosphere.It has long-lasting effects on crop growth,yield and quality,and brings a series of ecological and environmental problems.A free-air controlled enrichment（FACE） system was applied to study the effect of elevated ozone concentration on activities of key enzymes of starch synthesis of Yangmai 16 in 2009-2010.The main-plot treatment had two levels of O 3 ：ambient level（A-O 3） and 50% higher than ambient level（E-O 3）.The main results were that accumulation rate of amylose,amylopectin and starch were represented in a single peak curve,and their content and accumulation amount rose gradually.The O 3 elevation decreased the accumulation rate of amylose,amylopectin and starch amylase,reduced the accumulation amount of amylopectin and starch,and decreased the content of amylopectin and starch,but increased the content of amylose.With the increase of O 3 concentration,the enzyme activity of grain granule-bound starch synthase（GBSS）,soluble starch synthase（SSS） and starch branching enzyme（SBE） decreased after anthesis.The activities of GBSS and SSS had highly significant correlations with amylose,amylopectin and starch accumulation rate,and the activity of SBE had significant correlations with these items.So the O 3 elevation decreased the activity of key enzymes of starch synthesis,which led to the variation of starch synthesis.     

Comparative endoscopic evaluation of normal and ulcerated gastric mucosae in Thoroughbred foals

To contribute to early diagnosis and treatment of gastric ulcer of foals, we examined the gastric mucosa of healthy and affected foals using an endoscope. In healthy foals, the characteristic changes in the development of the squamous mucosa were seen mainly in the squamous mucosa, and maturation of the squamous mucosa in the greater curvature (GC-S) occurred more slowly than that of the squamous mucosa in the lesser curvature (LC-S). Epithelial desquamation in the LC-S and GC-S was observed between 6 and 90 days but was not observed in the LC-S at about 60 days, whereas it was observed in the GC-S until 90 days old. These findings suggest that there is a difference in the development of the gastric mucosa by region and that desquamation continues over a term longer than studies have reported in the past. In the affected foals, the minimum age at which gastric ulcer was observed was 4 days old. Gastric ulcers formed predominantly in the squamous mucosa (LC-S and GC-S) of foals with an immature mucosa before the weaning period, and the peak incidence occurred between 61 and 90 days old. The differences in the ulceration sites were considered to depend on the difference in the development (maturation) stage of the squamous mucosa. The grading score of the gastric ulcer increased with the growth of the affected foals. The gastric ulcer might be enhanced greatly by stress in the weaning period.     

Clock mutation affects circadian regulation of circulating blood cells

Background  

Although the number of circulating immune cells is subject to high-amplitude circadian rhythms, the underlying mechanisms are not fully understood.