Molecular and Histocytological Biomarkers - Ecological Biomarkers: Indicators of Ecotoxicological Effects - page 91

in addition to oxidative stress, the commonly used pesticides atrazine and chlorpyrifos,
separately or as a mixture, cause histopathological effects in the common carp Cyprinus
carpio .

4.3.2 Responses to Metal Contamination

Various histocytological effects have been shown after exposure to metals either in the
field or in the laboratory. In in situ exposure of mussels Mytilus edulis to an effluent of the
titanium dioxide industry, impairments were observed mainly in the absorbing organs
(gills and mantle) by comparison with controls (Ballan-Dufrançais et al. 1990). However,
in all the organs observed, the regression of mitochondrial cristae evokes an alteration
of cellular respiration. The authors hypothesized that this may be due to shell closure in
response to the bad quality of water, thus generating hypoxia. All spermatozoa showed
morphological alterations with swollen membrane systems and a lack of mitochondrial
cristae, suggesting that these spermatozoa may be nonfunctional (Figure 4.2). Structural
alterations of mitochondria (e.g., mitochondria with a swollen external membrane and
deprived of cristae) were also observed in the gill epithelium of oysters Crassostrea gigas
exposed to arsenic in seawater (Ettajani et al. 1996).

M

0.5

N

M

0.5

FIGURE 4.2
Spermatozoa of mussels ( Mytilus edulis ) from a reference population (top) compared to specimens exposed in
the field to effluents of the titanium dioxide industry (bottom). Note the lack of mitochondrial cristae in exposed
mussels. (After Ballan-Dufrançais, C. et al., Ann. Inst. Océanogr ., 66, 1-17, 1990. With permission.)