The influence of nutritional conditions on metal uptake by the mixotrophic dual symbiosis harboring vent mussel Bathymodiolus azoricus.
The vent mussel Bathymodiolus azoricus, host thioautotrophic and methanotrophic bacteria, in their gills and complementary, is able to digest suspended organic matter. But the involvement of nutritional status in metal uptake and storage remains unclear. The influence of B. azoricus physiological condition on its response to the exposure of a mixture of metals in solution is addressed. Mussels from the Menez Gwen field were exposed to 50 μgL(-1) Cd, plus 25 μgL(-1) Cu and 100 μgL(-1) Zn for 24 days. Four conditions were tested: (i) mussels harboring both bacteria but not feed, (ii) harboring only methanotrophic bacteria, (iii) without bacteria but fed during exposure and (iv) without bacteria during starvation. Unexposed mussels under the same conditions were used as controls. Eventual seasonal variations were assessed. Metal levels were quantified in subcellular fractions in gills and digestive gland. Metallothionein levels and condition indices were also quantified. Gill sections were used for fluorescence in situ hybridization (FISH) to assess the temporal distribution of symbiotic associations. Starvation damages metal homeostasis mechanisms and increase the intracellular Zn and MT levels function. There is a clear metallic competition for soluble and insoluble intracellular ligands at each condition. Seasonal variations were observed at metal uptake and storage.
Martins
Inês
I
IMAR, DOP-Department of Oceanography and Fisheries, University of the Azores, 9901-862 Horta, Portugal. imartins@uac.pt
Bettencourt
Raul
R
Colaço
Ana
A
Sarradin
Pierre-Marie
PM
Santos
Ricardo Serrão
RS
Cosson
Richard
R
D000818:Animals; D001419:Bacteria / Q000187:drug effects; D002104:Cadmium / Q000378:metabolism / Q000633:toxicity; D003300:Copper / Q000378:metabolism / Q000633:toxicity; D004064:Digestive System / Q000187:drug effects / Q000378:metabolism / Q000382:microbiology; D005880:Gills / Q000187:drug effects / Q000378:metabolism / Q000382:microbiology; D008670:Metals / Q000378:metabolism* / Q000633:toxicity; D049879:Mytilidae / Q000187:drug effects / Q000378:metabolism*; D012623:Seawater / Q000737:chemistry; D013559:Symbiosis / Q000187:drug effects; D014874:Water Pollutants, Chemical / Q000378:metabolism* / Q000633:toxicity
D008670:Metals; D014874:Water Pollutants, Chemical; D002104:Cadmium; D003300:Copper