explain the differences in CS enzyme activities: the trophic status and the exposure
to micropollutants [38]. Contrary to CS, no significant difference between the two
sites could be observed for DG enzymes (Fig. 3 illustration for amylase). This
contrast between the two organs may be attributed to higher availability of enzymes
that may interact with pollutants in extracellular spaces (such as the style sac and
stomach lumen) than in intracellular spaces (e.g. the digestive cells of the DG). The
water quality along the Seine River (comparison between Marnay-sur-Seine,
Bougival and Triel-sur-Seine) also impacted digestive capacity in transplanted
gammarids [20]. As with Dreissena, the value of digestive enzymes has also been
demonstrated in another model species in ecotoxicology.
3.3.5 Conclusion
The objective of the various actions carried out in the PIREN-Seine programme was
to validate the use of digestive enzymes in invertebrates as biomarkers of the quality
of aquatic environments. The digestive activities were therefore characterised with
respect to certain parameters of the environment; their ecological relevance was
demonstrated; and, finally, their application in biomonitoring proved to be relevant.
3.4 Value of Haemocytes of Zebra Mussels
for the Development of Immune and Genotoxic
Biomarkers
3.4.1 Introduction
Among biomarkers studied in bivalves, those related to the immune system are of
great interest since they can be indicative of the health status of an organism.
Considered as one of the first lines of defence of the body after the physical barrier
of the shell, haemocytes are key cells of individual homeostasis, which can either be
activated to counter a chemical or biological stressor or increase their turnover in
organisms exposed to contaminated sites to guarantee mussel survival. A functional
immune system indicates favourable living conditions for an organism; conversely, a
weak immune system could reveal a degraded environment requiring organisms to
adapt. For this reason, immune markers are developed to qualify not only the
individual’s health but also the quality of their environment. With an opened
circulatory system, haemolymph circulates through the body, bringing nutrients to
the various organs. Drawn from the adductor muscle of bivalves after a small breach
in the shell, haemolymph sampling is not lethal for organisms, a clear advantage for
biomonitoring studies. Several responses involved in the physiological processes
may be measured on haemocytes. For this purpose, a multiple biomarker approach
was adopted on haemocytes of D. polymorpha, including biomarkers of cytotoxicity
(cellular distribution and mortality), genotoxicity (primary DNA strand breaks) and
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M. Bonnard et al.
to micropollutants [38]. Contrary to CS, no significant difference between the two
sites could be observed for DG enzymes (Fig. 3 illustration for amylase). This
contrast between the two organs may be attributed to higher availability of enzymes
that may interact with pollutants in extracellular spaces (such as the style sac and
stomach lumen) than in intracellular spaces (e.g. the digestive cells of the DG). The
water quality along the Seine River (comparison between Marnay-sur-Seine,
Bougival and Triel-sur-Seine) also impacted digestive capacity in transplanted
gammarids [20]. As with Dreissena, the value of digestive enzymes has also been
demonstrated in another model species in ecotoxicology.
3.3.5 Conclusion
The objective of the various actions carried out in the PIREN-Seine programme was
to validate the use of digestive enzymes in invertebrates as biomarkers of the quality
of aquatic environments. The digestive activities were therefore characterised with
respect to certain parameters of the environment; their ecological relevance was
demonstrated; and, finally, their application in biomonitoring proved to be relevant.
3.4 Value of Haemocytes of Zebra Mussels
for the Development of Immune and Genotoxic
Biomarkers
3.4.1 Introduction
Among biomarkers studied in bivalves, those related to the immune system are of
great interest since they can be indicative of the health status of an organism.
Considered as one of the first lines of defence of the body after the physical barrier
of the shell, haemocytes are key cells of individual homeostasis, which can either be
activated to counter a chemical or biological stressor or increase their turnover in
organisms exposed to contaminated sites to guarantee mussel survival. A functional
immune system indicates favourable living conditions for an organism; conversely, a
weak immune system could reveal a degraded environment requiring organisms to
adapt. For this reason, immune markers are developed to qualify not only the
individual’s health but also the quality of their environment. With an opened
circulatory system, haemolymph circulates through the body, bringing nutrients to
the various organs. Drawn from the adductor muscle of bivalves after a small breach
in the shell, haemolymph sampling is not lethal for organisms, a clear advantage for
biomonitoring studies. Several responses involved in the physiological processes
may be measured on haemocytes. For this purpose, a multiple biomarker approach
was adopted on haemocytes of D. polymorpha, including biomarkers of cytotoxicity
(cellular distribution and mortality), genotoxicity (primary DNA strand breaks) and
256
M. Bonnard et al.