Physiological regulation of salicylic acid on Helianthus tubeuosus upon copper stress and root FTIR analysis / 生物工程学报

Phytoremediation plays an important role in the treatment of heavy metal pollution in soil. In order to elucidate the mechanism of salicylic acid (SA) on copper absorption, seedlings from Xuzhou (with strong Cu-tolerance) and Weifang Helianthus tuberosus cultivars (with weak Cu-tolerance) were selected for pot culture experiments. 1 mmol/L SA was sprayed upon 300 mg/kg soil copper stress, and the photosynthesis, leaf antioxidant system, several essential mineral nutrients and the changes of root upon copper stress were analyzed to explore the mechanism of copper resistance. The results showed that Pn, Tr, Gs and Ci upon copper stress decreased significantly compared to the control group. Meanwhile, chlorophyll a, chlorophyll b and carotenoid decreased with significant increase in initial fluorescence (F0), maximum photochemical quantum yield of PSⅡ (Fv/Fm), electron transfer rate (ETR) and photochemical quenching coefficient (qP) content all decreased. The ascorbic acid (AsA) content was decreased, the glutathione (GSH) value was increased, the superoxide dismutase (SOD), catalase (CAT) and ascorbate peroxidase (APX) activity in the leaves were decreased, and the peroxidase (POD) activity was significantly increased. SA increased the Cu content in the ground and root system, and weakened the nutrient uptake capacity of K, Ca, Mg, and Zn in the root stem and leaves. Spray of exogenous SA can maintain the opening of leaf stomata, improve the adverse effect of copper on photosynthetic pigment and PSⅡ reaction center. Mediating the SOD and APX activity started the AsA-GSH cycle process, effectively regulated the antioxidant enzyme system in chrysanthemum taro, significantly reduced the copper content of all parts of the plant, and improved the ion exchange capacity in the body. External SA increased the content of the negative electric group on the root by changing the proportion of components in the root, promoted the absorption of mineral nutrient elements and the accumulation of osmoregulatory substances, strengthened the fixation effect of the root on metal copper, and avoided its massive accumulation in the H. tuberosus body, so as to alleviate the inhibitory effect of copper on plant growth. The study revealed the physiological regulation of SA upon copper stress, and provided a theoretical basis for planting H. tuberosus to repair soil copper pollution.

Effect of chlorophyll and aqueous extracts of Bacopa monniera and Valeriana wallichii on ischaemia and reperfusion-induced cerebral injury in mice.

Bilateral carotid artery occlusion followed by reperfusion produced significant cerebral infarction and impaired short-term memory, motor co-ordination and lateral push response. Individual pretreatments with chlorophyll and aqueous extracts of B. monniera and V. wallichii markedly attenuated ischaemia-reperfusion induced cerebral injury in terms of decreased infarct size, increase in short-term memory, motor in coordination and lateral push response. The results suggest that chlorophyll and aqueous extracts of B. monniera and V. wallichii prevent ischaemia-reperfusion induced cerebral injury with comparable potency.

Anti-retroviral effect of chlorophyll derivatives (CpD-D) by photosensitization

A new photosensitizer, CpD(chlorophyll derivatives), previously reported as a promising agent for tumor therapy, was studied to determine its inhibitory effects on Gross leukemia virus(GLV), a mouse retrovirus isolated from the GLV-producing TGV cell line, and the cytocidal effect on the GLV infected cells in vitro, following photodynamic treatment with CpD-D and red light, the viral inactivation and infectivity were examined by measuring the reverse transcriptase(RT) activity of the virus itself and that in cell-free culture supernatant of freshly GLV-infected secondary mouse embryo cells respectively. The cytocidal activity was measured by trypan blue exclusion test. Inhibition of GLV associated RT activity resulted from CpD-D and red light treatment. The RT inhibition effect was immediate and the infectivity of these photodynamically treated GLV to mouse embryo cells was also inhibited. However, specific cytotoxicity of GLV infected cells was not found. Thus, it is concluded that CpD-D may be used as an effective antiviral agent.