Is the digestive gland of Mytilus galloprovincialis a tissue of choice for estimating cadmium exposure by means of metallothioneins?

Abstract

A study performed over 12 months with caged mussels M. galloprovincialis in the coastal marine zone which is under the urban pressure, reveales a temporal variation of digestive gland mass which causes "biological dilution" of cytosolic metallothionein (MT) and trace metal (Cd, Cu, Zn, Fe, Mn) concentrations. The dilution effect was corrected by expressing the cytosolic MT and metal concentrations as the tissue content.

Characterization of the cytosolic distribution of priority pollutant metals and metalloids in the digestive gland cytosol of marine mussels: Seasonal and spatial variability

“…The role of MT in Zn homeostasis is well known (Viarengo and Nott, 1993) so more Zn could have been bound on MT in March to provide a sufficient amount of Zn, which is needed for various biological functions. Such correlation of increased concentration of MTs and essential metals in spring has been noticed also by other authors (Raspor et al, 2004). Besides MT as a possible ligand for Zn binding, another explanation of stronger Zn elution in samples from March obtained at location H compared to location M and R could be some Zn associated enzyme, possibly carbonic anhydrase (CA).…”

“…Therefore, the general trend of higher concentrations of cytosolic metals in March than in August as it was reported in this study for Cu, Cd and Zn (Table 3) could also be related with the possible influence of reproductive status. In addition, increased concentrations of essential elements in mussel tissues in spring are often reported probably as a consequence of increased food availability and higher requirements for essential metals due to gonad development (Raspor et al, 2004). Furthermore, discrepancy between the seawater and cytosolic concentration of the particular metal in this study could be caused by the fact that metals were analyzed in the soluble tissue fraction only, and it is known that some metals (e.g.…”

“…Besides physico-chemical properties of the seawater, other factors related with the reproductive stage of mussels could also affect metal concentrations in the digestive gland (Regoli and Orlando 1994, Raspor et al, 2004, Ivanković et al, 2005. Therefore, the general trend of higher concentrations of cytosolic metals in March than in August as it was reported in this study for Cu, Cd and Zn (Table 3) could also be related with the possible influence of reproductive status.…”

“…In our knowledge cytosolic distribution of metals was not investigated with reference to seasonality. Yet, it is known that the level of total tissue and cytosolic metals show a seasonal variability dependent on the abiotic and biotic factors even when the environmental concentrations of metals remain unchanged (Regoli and Orlando 1994, Raspor et al, 2004, Ivanković et al, 2005. Similarly, it is found that biomarkers are also affected by seasonality (Ivanković et al, 2005; Bocchetti and Regoli , 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 5 organism.…”

Interspecies comparison of selected pollution biomarkers in dreissenid spp. inhabiting pristine and moderately polluted sites

“…This phenomenon is attributed to the close functional relationship between the digestive system and gonad development as periods of food abundance and gonad development (both evolving in the warm season) are often coincident (Mackie, 1984;Sheehan and Power, 1999). Significant increase in MT levels during gametogenesis were reported for several aquatic invertebrates inhabiting unpolluted sites (Raspor et al, 2004;Geffard et al, 2005;Geffard et al, 2007;Bochetti et al, 2008). As for example, fourfold increase in metallothionein-like proteins was reported by Baudrimont et al (1997) for the Asiatic clam (Corbicula fluminea) inhabiting a remote site in France, and this elevation was unrelated to metal exposure but seemed to be strongly correlated with the reproductive cycle of this bivalve.…”