The changes of three components in coelomic fluid of Urechis unicinctus exposed to different concentrations of sulfide

The changes in heme (associated with hemoglobin), hemoglobin and hematin in the coelomic fluid of marine worm, Urechis unicinctus, exposed to different concentrations of sulfide, were investigated using bio- chemical techniques. When exposed to different sulfide concentrations for up to 96 h, the relative amounts of the three components changed in a regular pattern suggesting that the coelomocytes play an important role in the worm’s tolerance to sulfide. The possible roles of heme compounds in sulfide tolerance of this species are dis- cussed on the basis of our experimental data.

Exogenous Hematin Alleviates Mercury-induced Oxidative Damage in the Roots of Medicago sativa

In the present study, we evaluated the protective effect of exogenous heme oxygenase-1 （HO-1 EC 1.14.99.3） inducer hematin against mercury-induced oxidative damage in the roots of Alfalfa （Medicago sativa L.）. Plants exposed to mercury （HgCl2） exhibited a significant increase of lipid peroxidation, as well as inhibition of root elongation. However, hematin （50 μM） supplementation to HgCl2 （100 μmol/L） treated plants effectively reduced the lipid peroxidation and partially increased the root elongation. These responses were mimicked by the application of aqueous solution of carbon monoxide （CO） with 50% saturation. Also, treatment with hematin could result in the potent induction of HO-1 transcript in the root tissues, as detected 12h following treatment. Moreover, the activation of anti-oxidant enzyme, including glutathione reductase, monodehydroascorbate reductase and superoxide dismutase activities, and the decrease of lipoxygenase activity, were induced by hematin at 12h or 24h, which was further confirmed by histochemical staining for the detection of lipid peroxidation and loss of membrane integrity. Whereas, ascorbate peroxidase and guaiacol peroxidase isozyme activities or their transcripts were reduced, respectively, indicating that hydrogen peroxide might act as a signal to mediate Hg- tolerance at the beginning of treatment. The ameliorating effects of hematin were specific, since the CO scavenger hemoglobin differentially reversed the above actions. Taken together, our results suggested that hematin exhibits a vital role in protecting the plant against Hg-induced oxidative damage.