CHAPTER 11
Metallothionein and Glutathione as Stress Indicators in Bivalves in the
Lagoon of Venice
P. Irato, A. Cusini, G. Santovito, F. Cattalini, and V. Albergoni
ABSTRACT
Bivalves are often used as indicators of metal pollution, as their digestive glands and gills are
important target organs for metal accumulation. With the aim of studying the effects of stress
conditions (heavy metal pollution) using metallothionein (MT) and glutathione (GSH) as markers, we studied three species of Bivalvia: Mytilus galloprovincialis, which feeds on suspended
matter filtered from sea water by cilia on the gill surfaces, and Tapes philippinarum and
Scapharca inequiva/vis, which live on sediments. These species were sampled in spring 1998 in
two stations with different pollution levels,at Chioggia and Marghera in the Lagoon of Venice.
Digestive gland MT contents were significantly different in the same station in the three species:
the specimens with the greatest MT contents were T. philippinarum. The same species at
Marghera was also the one with the greatest amounts of Mn, Co and Fe in the digestive gland.
GSH digestive gland contents and Mn, Co and Fe concentrations were statistically greater in M.
galloprovinciaJisfrom Chioggia with respect to M. galloprovincialisfrom Marghera. GSH digestive gland contents of S. inequivalvis were also higher in the species from Chioggia. Comparing
digestive gland results of the three species at the same two stations, M. galloprovincialis and S.
inequiva/vis had significantly greater amounts of GSH than T. philippinarum. As regards gills, M.
galloprovincialis from Chioggia had significantly greater amounts of GSH than M. galloprovincia/is from Marghera; in the latter station S. inequiva/vis had significantly greater amounts of
GSH and metals than M. galloprovincialis. We also looked for relationships between different
parameters: length or weight with MT or GSH.
Introduction
Marine bivalve molluscs are often used as indicators of metal pollution. Since the digestive gland
(a site for storage) and gills (the site of uptake) are
important target organs for metal accumulation.
these tissues were chosen to investigate biological
responses to metals such as levels of metallothionein (MT) and glutathione. In mussels, metals
are primarily complexed by MTs (Viarengo 1989),
low-molecular-weight, cysteine-rich proteins,
which are capable of sequestering and detoxifying excess intra-cellular metal. Consequently, MTs
are regarded as potentially specific indicators of
metal pollution. Glutathione (GSH in its reduced
form) is considered one of the most important
hydrophilic antioxidant agents involved in the
protection of cell membranes from lipid peroxidation by scavenging oxygen radicals (Meister
1989). Mussels exposed to environmentally high
levels of metals undergo an increase in lipid peroxidation, as demonstrated by the enhanced
accumulation of lipofuscin within tertiary lysosomes of specimens found in metal-polluted
environments (Regoli 1992). With the aim of
studying the effects of stress conditions (heavy
metal pollution) using MT and GSH as markers,
we studied three species of Bivalvia: Mytilus galloprovincialis, which feeds on suspended matter
filtered from sea water by cilia on the gill surfaces,
and Tapes philippinarum and Scapharca inequivalvis, which live on organic matter in sediments.
Marine sediments act as sinks for a variety of pollutants which may be concentrated up to 1000
times higher than in background water levels.
Ingested sediment particles are carried into the
Dipartimento di Biologia, Universita ill Padova, Via U. Bassi 58/B. 35121 Padova, Italy
F.M. Faranda, L. Guglielmo, G. Spezie (edo)
Mediterranean Ecosystems: Structures and Processes
@ Springer-Verlag Italia 2001
Metallothionein and Glutathione as Stress Indicators in Bivalves in the
Lagoon of Venice
P. Irato, A. Cusini, G. Santovito, F. Cattalini, and V. Albergoni
ABSTRACT
Bivalves are often used as indicators of metal pollution, as their digestive glands and gills are
important target organs for metal accumulation. With the aim of studying the effects of stress
conditions (heavy metal pollution) using metallothionein (MT) and glutathione (GSH) as markers, we studied three species of Bivalvia: Mytilus galloprovincialis, which feeds on suspended
matter filtered from sea water by cilia on the gill surfaces, and Tapes philippinarum and
Scapharca inequiva/vis, which live on sediments. These species were sampled in spring 1998 in
two stations with different pollution levels,at Chioggia and Marghera in the Lagoon of Venice.
Digestive gland MT contents were significantly different in the same station in the three species:
the specimens with the greatest MT contents were T. philippinarum. The same species at
Marghera was also the one with the greatest amounts of Mn, Co and Fe in the digestive gland.
GSH digestive gland contents and Mn, Co and Fe concentrations were statistically greater in M.
galloprovinciaJisfrom Chioggia with respect to M. galloprovincialisfrom Marghera. GSH digestive gland contents of S. inequivalvis were also higher in the species from Chioggia. Comparing
digestive gland results of the three species at the same two stations, M. galloprovincialis and S.
inequiva/vis had significantly greater amounts of GSH than T. philippinarum. As regards gills, M.
galloprovincialis from Chioggia had significantly greater amounts of GSH than M. galloprovincia/is from Marghera; in the latter station S. inequiva/vis had significantly greater amounts of
GSH and metals than M. galloprovincialis. We also looked for relationships between different
parameters: length or weight with MT or GSH.
Introduction
Marine bivalve molluscs are often used as indicators of metal pollution. Since the digestive gland
(a site for storage) and gills (the site of uptake) are
important target organs for metal accumulation.
these tissues were chosen to investigate biological
responses to metals such as levels of metallothionein (MT) and glutathione. In mussels, metals
are primarily complexed by MTs (Viarengo 1989),
low-molecular-weight, cysteine-rich proteins,
which are capable of sequestering and detoxifying excess intra-cellular metal. Consequently, MTs
are regarded as potentially specific indicators of
metal pollution. Glutathione (GSH in its reduced
form) is considered one of the most important
hydrophilic antioxidant agents involved in the
protection of cell membranes from lipid peroxidation by scavenging oxygen radicals (Meister
1989). Mussels exposed to environmentally high
levels of metals undergo an increase in lipid peroxidation, as demonstrated by the enhanced
accumulation of lipofuscin within tertiary lysosomes of specimens found in metal-polluted
environments (Regoli 1992). With the aim of
studying the effects of stress conditions (heavy
metal pollution) using MT and GSH as markers,
we studied three species of Bivalvia: Mytilus galloprovincialis, which feeds on suspended matter
filtered from sea water by cilia on the gill surfaces,
and Tapes philippinarum and Scapharca inequivalvis, which live on organic matter in sediments.
Marine sediments act as sinks for a variety of pollutants which may be concentrated up to 1000
times higher than in background water levels.
Ingested sediment particles are carried into the
Dipartimento di Biologia, Universita ill Padova, Via U. Bassi 58/B. 35121 Padova, Italy
F.M. Faranda, L. Guglielmo, G. Spezie (edo)
Mediterranean Ecosystems: Structures and Processes
@ Springer-Verlag Italia 2001