Beneficial effects of arbuscular mycorrhizae on Cu detoxification in Mimosa pudica L. grown in Cu-polluted soils.

Arbuscular mycorrhizal (AM) fungi are known to have beneficial effects on host plants growing on contaminated soils. The present study aimed at investigating the influence of two different AM fungi (Rhizophagus intraradices and Funneliformis mosseae) on the growth of plants and Cu uptake by Mimosa pudica L. grown in polluted soils containing various levels of Cu (Control, 400, 500, or 600 mg kg-l soil) in pot experiments. Mycorrhizal colonisation rates by the two AM fungi decreased markedly with the increasing Cu levels in soils. This inhibition was more pronounced to F. mosseae than R. intraradices, indicating that R. intraradices was more tolerant to Cu than F. mosseae. Compared with non-mycorrhizal plants, R. intraradices inoculation increased plant growth (including shoot height, numbers of compound leaves and leaflets, and dry biomass) and P concentrations in the shoots and roots of M. pudica at all levels of Cu. Meanwhile, F. mosseae displayed a capability of growth promotion to M. pudica much later and lower than R. intraradices. F. mosseae and R. intraradices markedly decreased Cu concentration in shoots at 400-600 mg kg-1 Cu levels. However, R. intraradices was more efficient than F. mosseae in decreasing the shoot Cu concentrations. As for the increasing Cu tolerance by R. intraradices, possibly it was reached though the improvement of phosphorus nutrition and the decline of Cu transport from roots to shoots of M. pudica. R. intraradices showed a good potential for improving medicinal plants growth and declining toxic effects in Cu-contaminated soils.

Delineation of contaminant plume for an inorganic contaminated site using electrical resistivity tomography: comparison with direct-push technique.

Precise delineation of contaminant plume distribution is essential for effective remediation of contaminated sites. Traditional in situ investigation methods like direct-push (DP) sampling are accurate, but are usually intrusive and costly. Electrical resistivity tomography (ERT) method, as a non-invasive geophysical technique to map spatiotemporal changes in resistivity of the subsurface, is becoming increasingly popular in environmental science. However, the resolution of ERT for delineation of contaminant plumes still remains controversial. In this study, ERT and DP technique were both conducted at a real inorganic contaminated site. The reliability of the ERT method was validated by the direct comparisons of their investigation results that the resistivity acquired by ERT method is in accordance with the total dissolved solid concentration in groundwater and the overall variation of the total iron content in soil obtained by DP technique. After testifying the applicability of ERT method for contaminant identification, the extension of contaminant plume at the study site was revealed by supplementary ERT surveys conducted subsequently in the surrounding area of the contaminant source zone.

[Effects of astragalus injection on extracellular signal-regulated kinase pathway in cultured normal cardiac myocytes].

OBJECTIVE: To investigate the dose-effect relationship and time-effect relationship of astragalus injection on the protein expression of nitric-oxide synthase (NOS) and extracellular signal-regulated kinase (ERK) in cultured cardiac myocytes. METHODS: (1) Ventricular myocytes of Sprague-Dawley rats were isolated, cultured, and incubated with astragalus injection of the concentrations of 0, 20, 100, 200, or 400 ml/L for 8 days. Cell growth curve was drawn. Automatic biochemical analyzer was used to detect the level of creatine kinase (CK). (2) Western blotting was used 2 h after incubation to observe the protein expression of ERK and nitric oxide synthase (NOS). (3) Myocytes were incubated with astragalus injection (200 ml/L) or with astragalus and PD98059, an ERK inhibitor, for 5, 15, 30, 60, and 120 min respectively, and Western blotting was used to detect the protein expression of ERK and NOS. RESULTS: Astragalus of different concentrations showed no effect on the cell proliferation. Only the CK level of the astragalus 200 ml/L group was significantly higher than that of the control group (P < 0.05). Astragalus showed no dose-dependent effect on the ERK expression, and dose-dependently reduced the NOS expression level. 15 min after the co-incubation with astragalus 200 ml/L the ERK level of the myocytes decreased transiently, and then began to increase gradually since 15 min after the co-incubation; the NOS level began to increase since 60 min after the co-incubation (P < 0.05). After the addition of PD98059 the ERK expression significantly decreased (P < 0.05). CONCLUSION: Astragalus injection has modulation effect on ERK and NOS expression. This effect is enhanced time-dependently at appropriate Astragalus concentration, but attenuated by high dose Astragalus injection.