1,721,106 research outputs found
Hg(2+) and Cu(2+) interfere with agonist-mediated Ca(2+) signaling in isolated Mytilus digestive gland cells
No full textThe effects of mercury and copper on agonist-mediated Ca-signaling were investigated in isolated cells from the marine mussel: Mytilus galloprovincialis Lam., by single cell fluorescence microscopy. In isolated digestive gland cells, short-term exposure (10 min) to both Hg2+, a highly toxic metal and Cu2+, essential metal, in the nano-low mu M range caused a sustained increase in cytosolic [Ca2+]. The effect of mercury on resting [Ca2+] was stronger than that of copper. The Hg-induced elevation in [Ca2+] seemed to be mainly due to an increased influx through Verapamil-sensitive Ca-channels, whereas the effect of Cu2+ was related to a release from thapsigargin-sensitive intracellular stores. Agonists, such as epidermal growth factor (EGF), bradykinin (BK) and ATP, evoked Ca2+ transients in isolated digestive gland cells through different mechanisms similar to those observed in mammalian cells, demonstrating the presence of common pathways of Ca-mediated cell signaling in both invertebrates and vertebrates. The agonist-mediated Ca2+ response was affected by exposure to Hg2+ and Cu2+ in a concentration dependent manner: both metals significantly reduced the amplitude of the Ca2+ spikes elicited by BK and ATP and decreased the percentage of EGF-responsive cells. The effects of Hg2+ and Cu2+ were apparently independent of their different type of interaction with the mechanisms involved in Ca2+ homeostasis. The results clearly demonstrate that, in marine invertebrate cells, short-term exposure to heavy metal concentrations comparable to environmental exposure levels results in alterations of intracellular Ca2+ homeostasis which compromise the cell response to extracellular stimuli involving Ca-mediated signaling. The mechanisms of heavy metal interference with Ca-homeostasis and signaling are discussed. (C) 2000 Elsevier Science B.V. All rights reserved
Growth factor-mediated signal transduction and redox balance in isolated digestive gland cells from Mytilus galloprovincialis Lam
No full textHeavy metals and glutathione metabolism in mussel tissues
No full textData are presented on the tissue glutathione content and on the activity of two of the main enzymes involved in GSH metabolism (γ-glutamyl-cysteine synthetase (GCS), GSH transferase (GST)) in the gills and digestive gland of mussels (Mytilus galloprovincialis Lam.) exposed for 1, 4 and 7 days to sublethal concentrations of copper and of mercury, both in the inorganic form of HgCl2 and in the organic form of CH3HgCl. The results indicate that Cu2+ (0.6 μM) and CH3Hg+ (0.2 μM) can affect, although to a different extent, glutathione metabolism in mussel tissues; common traits were a decrease in tissue glutathione content, stimulation of GST activity and inhibition of GSH synthesis rate; on the other hand, inorganic Hg2+ (0.2 μM) did not significantly affect glutathione content and metabolism in mussel tissues. Exposure to copper (0.6 μM) resulted in a decrease in total glutathione content in both gills and the digestive gland that was maximal after the first day, followed by a tendency to recover at longer exposure times. Such a decrease seemed to be mainly related to a stimulation of GST activity, which was transient in gills and persistent in the digestive gland. The tissue glutathione content was also decreased in mussel exposed to methylmercury (0.2 μM); however, such a decrease seemed to be mainly due to inhibition of the GSH synthesis rate and, to a lesser extent, to an increased GST activity. On the contrary, inorganic Hg2+ (0.2 μM) did not significantly affect glutathione metabolism, although mussel exposure to the same concentration of organic and inorganic Hg2+ resulted in similar total metal tissue load in mussel tissues. The role of glutathione as a potential defense against heavy metals is discussed in relation to different routes of metal toxicity and homeostasis in mussel tissues. Copyright (C) 1999 Elsevier Science B.V
Effects of dioxin exposure in Eisenia andrei: integration of biomarker data by an Expert System to rank the development of pollutant-induced stress syndrome in earthworms
No full textSEASONAL-VARIATIONS IN THE ANTIOXIDANT DEFENSE SYSTEMS AND LIPID-PEROXIDATION OF THE DIGESTIVE GLAND OF MUSSELS
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Biochemical properties of metalloproteinases from the hemocytes of the mussel Mytilus galloprovincialis Lam.
No full textCU, ZN AND CD CONTENT IN DIFFERENT TISSUES OF THE ANTARCTIC SCALLOP ADAMUSSIUM-COLBECKI - ROLE OF METALLOTHIONEIN IN HEAVY-METAL HOMEOSTASIS AND DETOXICATION
No full textIdentification of EGF receptors in Mytilus isolated digestive gland cells by immunoelectron microscopy: effect of ligand binding on intracellular EGFR distribution
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