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To obtain basic information for evaluating critical levels of O3 under different nitrogen loads for protecting Japanese beech forests, two-year-old seedlings of Fagus crenata Blume were grown in potted andisol supplied with N as NH4NO3 solution at 0, 20 or 50 kg ha−1 year−1 and exposed to charcoal-filtered air or O3 at 1.0, 1.5 and 2.0 times the ambient concentration from 16 April to 22 September 2004. The O3 induced significant reductions in the whole-plant dry mass, net photosynthetic rate at 380 μmol mol−1 CO2 ( A 380), carboxylation efficiency ( CE) and concentrations of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) and total soluble protein (TSP) in the leaves. The concentrations of Rubisco and TSP were negatively correlated with the concentration of leaf acidic amino acid, suggesting that O3 enhanced the degradation of protein such as Rubisco. The N supply to the soil did not significantly change the whole-plant dry mass and A 380, whereas it significantly increased the CE and concentrations of Rubisco and total amino acid. No significant interactive effects of O3 and N supply to the soil were detected on the growth, photosynthetic parameters and concentrations of protein and amino acid in the leaves. In conclusion, N supply to the soil at ≤50 kg ha−1 year−1 does not significantly change the sensitivity to O3 of growth and net photosynthesis of Fagus crenata seedlings. [ABSTRACT FROM AUTHOR]

Recombinant Rhodopseudomonas palustris, harboring the carotenoid-metabolizing gene crtI (CrtIBS), and whose color changes from greenish yellow to red in response to inorganic As(III), was cultured in transparent microplate wells illuminated with a light emitting diode (LED) array. The cells were seen to grow better under near-infrared light, when compared with cells illuminated with blue or green LEDs. The absorbance ratio of 525 to 425 nm after cultivation for 24 h, which reflects red carotenoid accumulation, increased with an increase in As(III) concentrations. The detection limit of cultures illuminated with near-infrared LED was 5 microgram/l, which was equivalent to that of cultures in test tubes illuminated with an incandescent lamp. A near-infrared LED array, in combination with a microplate, enabled the simultaneous handling of multiple cultures, including CrtIBS and a control strain, for normalization by the illumination of those with equal photon flux densities. Thus, the introduction of a near-infrared LED array to the assay is advantageous for the monitoring of arsenic in natural water samples that may contain a number of unknown factors and, therefore, need normalization of the reporter event.

Cadmium pollution in soil not only affects growth and yield formation of crop plants, but also develops a potential risk to food health. The experiment was conducted to study growth of Cd and mineral nutrient uptake of two wheat cultivars differed in agronomic performance in seedling stage under 5 Cd levels ranged from 0 to 1.0 mg.kg-1 Cd. The results showed that the growth and dry matter accumulation were stimulated in low Cd concentration (0.03 mg.kg-1) for both cultivars, while inhibited significantly under high concentration (> 0.3 mg.kg-1). The inhibited extension was dependence on cultivars and Genguo 534 had higher tolerance to Cd toxicity in comparison with E18513. There was the significant interaction between Cd level and cultivar in the influence of Cd treatment on Cd content in both root and shoot in that Genguo 534 had higher Cd content in lower Cd levels and E81513 showed more rapid increase in higher Cd levels. Cd treatment had significant influence on mineral nutrient uptake and two cultivars showed different response. In the treatment of 0.1 mg.kg-1 Cd, the contents of five macro-nutrients were significant lower for E81513 in comparison with those in control, while Genguo remained little changed.