218
A. Vidal et al.
Mussels, like other bivalves, can accumulate DSP toxins during algal blooms of
these microalgal species. Accumulation takes place mainly in the digestive gland
(Blanco et al. 2007) and causes a negative economic impact to the shellfishing
industry in the Galician rias on an annual basis. Following ingestion of contaminated
mussels by humans the DSP toxins can cause a gastrointestinal disease and result in
a serious public health problem.
The genetic selection of molluscs with a greater capacity for detoxification, in
order to reduce depuration times, could help to reduce the resultant significant
economic and health problems.
There are few studies concerning the metabolism of biotoxins in bivalves,
although some authors have suggested involvement of detoxification enzymes
(Kodama and Sato 2002; FRS Marine Laboratory 2004) and described the induction
of some antioxidant enzymes in crustaceans and scallops in the presence of toxic
dinoflagellates (Campa-C´ ordova et al. 2009).
This work is a preliminary study of the metabolism of okadaic acid in Mytilus
galloprovincialis. We analysed a diverse range of enzymes potentially involved
in xenobiotic metabolism and follow enzyme activity variation in relation to OA
accumulation during three different toxic blooms of D. acuminata and D. acuta in
the Ria de Vigo.
Material and Methods
Samples
Mussels (Mytillus galloprovincialis) were sampled fortnightly from floating rafts of
the Vigo estuary (NW Spain) from June 2001 until August 2002. For each sampling,
80 adult individuals of 6–8 cm in length were randomly collected. The digestive
glands of 30 mussels were dissected, immediately frozen in liquid nitrogen, pooled
and stored at 80
ı C until the enzymatic assays. A section of mantle tissue was
also dissected, fixed in Bouin’s solution and histologically processed using routine
histological techniques (paraffin embedded, 5 m sectioning, stained with Harris’
haematoxylin-eosin solution and analysed microscopically) to determine the sex of
each mussel.
The soft tissues of the other subsample (50 mussels) were pooled, homogenized,
lyophilized and stored for drying until toxin analysis. In Mytilus, enzymatic activity
varies with the reproductive status, sex and environmental parameters (Borkovic
et al. 2005; Bochetti and Regoli 2006; Monserrat et al. 2007; Verlecar et al. 2008;
Cravo et al. 2009). In this study, the histological analysis showed that most of the
mussels collected on the same date were at the same gametogenic stage. Because
of this and because we separated males and females following collection, we felt
justified in pooling each sample from the same sampling location.
A. Vidal et al.
Mussels, like other bivalves, can accumulate DSP toxins during algal blooms of
these microalgal species. Accumulation takes place mainly in the digestive gland
(Blanco et al. 2007) and causes a negative economic impact to the shellfishing
industry in the Galician rias on an annual basis. Following ingestion of contaminated
mussels by humans the DSP toxins can cause a gastrointestinal disease and result in
a serious public health problem.
The genetic selection of molluscs with a greater capacity for detoxification, in
order to reduce depuration times, could help to reduce the resultant significant
economic and health problems.
There are few studies concerning the metabolism of biotoxins in bivalves,
although some authors have suggested involvement of detoxification enzymes
(Kodama and Sato 2002; FRS Marine Laboratory 2004) and described the induction
of some antioxidant enzymes in crustaceans and scallops in the presence of toxic
dinoflagellates (Campa-C´ ordova et al. 2009).
This work is a preliminary study of the metabolism of okadaic acid in Mytilus
galloprovincialis. We analysed a diverse range of enzymes potentially involved
in xenobiotic metabolism and follow enzyme activity variation in relation to OA
accumulation during three different toxic blooms of D. acuminata and D. acuta in
the Ria de Vigo.
Material and Methods
Samples
Mussels (Mytillus galloprovincialis) were sampled fortnightly from floating rafts of
the Vigo estuary (NW Spain) from June 2001 until August 2002. For each sampling,
80 adult individuals of 6–8 cm in length were randomly collected. The digestive
glands of 30 mussels were dissected, immediately frozen in liquid nitrogen, pooled
and stored at 80
ı C until the enzymatic assays. A section of mantle tissue was
also dissected, fixed in Bouin’s solution and histologically processed using routine
histological techniques (paraffin embedded, 5 m sectioning, stained with Harris’
haematoxylin-eosin solution and analysed microscopically) to determine the sex of
each mussel.
The soft tissues of the other subsample (50 mussels) were pooled, homogenized,
lyophilized and stored for drying until toxin analysis. In Mytilus, enzymatic activity
varies with the reproductive status, sex and environmental parameters (Borkovic
et al. 2005; Bochetti and Regoli 2006; Monserrat et al. 2007; Verlecar et al. 2008;
Cravo et al. 2009). In this study, the histological analysis showed that most of the
mussels collected on the same date were at the same gametogenic stage. Because
of this and because we separated males and females following collection, we felt
justified in pooling each sample from the same sampling location.