Cadmium detoxification processes in the digestive gland of cephalopods in relation to accumulated cadmium concentrations

Abstract

The high concentrations of cadmium recorded in the digestive gland of cephalopods from various temperate and subpolar waters suggest that these molluscs have developed efficient cadmium detoxification mechanisms. The subcellular distribution of cadmium in the digestive gland cells was investigated in seven cephalopod species from the Bay of Biscay (France) and the Faroe Islands. In most species, cadmium was mainly found in the cytosolic fraction of the digestive gland cells, reaching up to 86% of the total cadmium for the squid Loligo vulgaris from the Bay of Biscay. But species with the highest total level of cadmium showed a higher percentage of cadmium associated to insoluble compounds. The quantification of metallothioneins (MTs) by the polarographic method was performed in order to evaluate the involvement of these proteins in the detoxification of the high amounts of bioaccumulated cadmium. Metallothionein levels in cephalopods ranged form 742 +/- 270 to 3478 +/- 1572 microg/g wet weight. No relationship could be established between total cadmium, cytosolic cadmium and MT levels suggesting the occurrence of other Cd-binding ligands. Although these proteins have not been characterised, as cadmium in the digestive gland of cephalopods is mainly associated with soluble ligands, a high potential transfer to predators can be predicted.

Ocean acidification and temperature rise: effects on calcification during early development of the cuttlefish Sepia officinalis

“…In the octopod Octopus vulgaris however, calcium concentration increases during the oocyte development, suggesting that this essential element could be obtained from seawater intake (Villanueva and Bustamante 2006). It has been previously demonstrated that the eggshell displays a selective permeability to dissolved trace elements, independently of their essential or non-essential character (Bustamante et al 2002, Lacoue-Labarthe et al 2008, and that changes in seawater pCO 2 conditions could affect these properties (Lacoue-Labarthe et al 2009). In this study, it is worth noting that, whatever the treatment, 45 Ca was detected in embryos' cuttlebones revealing that 1) the eggshell is permeable to calcium and 2) the cuttlebone formation is dependent on calcium uptake from seawater.…”

“…Exchange between seawater and PVF is limited and selective in terms of water and molecules (Gomi et al 1986;de Leersnyder and Lemaire 1972), including pollutants (Bustamante et al 2002, Lacoue-Labarthe et al 2009. Due to the egg case serving as a diffusion barrier for respiratory gases (CO 2 , O 2 ), embryos are exposed to low PVF pO 2 (pO 2 < 6 kPa, Cronin andSeymour 2000, Gutowska and and to high pCO 2 in turn (pCO 2 > 0.4 kPa i.e.…”

“…PVF is also slightly hypertonic when compared to seawater (de Leersnyder and Lemaire 1972), which enables the characteristic egg swelling process (Cronin and Seymour 2000). In addition, the eggshell was shown to display a trace element selective permeability (Bustamante et al 2002(Bustamante et al , 2004Lacoue-Labarthe et al 2008. Consequently, the embryo grows under abiotic conditions in the PVF that are very different from those that hatchlings and juveniles encounter in the seawater.…”

Bioaccumulation of PCBs in the cuttlefish Sepia officinalis from seawater, sediment and food pathways

“…These results are particularly surprising for the digestive gland as it (a) has no direct contact with ambient seawater and (b) plays a major role in the digestive processes, including nutrient absorption. However, this organ is also involved in detoxification processes of xenobiotics in cephalopods (Cheah et al 1995, Bustamante et al 2002. Therefore, elevated concentrations in the digestive gland could result more from transfers from other organs accumulating compounds to be detoxified than from actual bioconcentration in the digestive gland itself.…”

Interannual patterns of variation in concentrations of trace elements in arms of Octopus vulgaris

“…2004.11.099 in their tissues (e.g. Miramand and Bentley, 1992;Bustamante, 1998;Bustamante et al, 1998aBustamante et al, ,b, 2000Bustamante et al, , 2002aStorelli and Marcotrigiano, 1999). Among tissues, the digestive gland and branchial hearts appeared to play a major role in bioaccumulation processes of toxic elements such as cadmium and silver, which are detoxified and sequestrated, sometimes over a very long time scale (Bustamante et al, 2002a(Bustamante et al, , 2004Beuerlein et al, 2002).…”