and several biochemical endpoints suggestive of GBH toxicity were assessed for up
to 8 weeks [24]. Their results revealed the usefulness of the targeted enzymatic
endpoints and antioxidant defences in earthworms for monitoring
GBH-contaminated soil and identified E. eugeniae and L. violaceus as the ones
with higher vermiremediation potential. Another recent study that encompasses
biochemical, mRNA and metabolomics complementary approaches by Zhang
et al. [25] evaluated the effects on E. fetida due to exposure to the fungicide
tebuconazole under artificial soil conditions for 7 days. Amongst the biomarkers
assessed, a confirmation of an oxidative stress condition seen by SOD activity
decreases translationally controlled tumour protein (TCTP) and annetocin (ANN)related genes’ downregulation as well as metabolic affectance of the AMP pathway
(seen as the alteration of 12 endogenous metabolites) using untargeted nuclear
magnetic resonance (NMR) techniques, all pointing to consequences on the reproductive outcome of the exposed earthworms. In the same species, neonicotinoid
dinotefuran was tested, using the filter paper contact test and soil exposures, for
enzymatic and effect oxidative responses including gene expression of Hsp70 and
ANN genes [26] but also the toxicity associated with its metabolites as indicated in
Sect. 9.
4 Biomarkers of Metal Exposure
The field study [27] considered a comprehensive set of biomarkers, in addition to
MT as a specific marker, and pointed out L. terrestris as adequate sentinels of metal
pollution. Furthermore, the same authors using the same species related the response
of MT in the coelomic fluid to that in the whole tissue homogenate in order to
validate the use of an alternative non-destructive marker for metal monitoring
[28]. The naturally occurring species Metaphire posthuma was the species of choice
in a study aimed at assessing toxicity in several metal-contaminated sites from India
[29]. In this case, they also used coelomocytes from the local species to associate
metal exposures to the response observed in biomarkers dealing with the immune
response, ROS formation and antioxidant defences. The naturally occurring soildwelling earthworm A. caliginosa was the sentinel in a field survey conducted in
Slovakia also following a metal-polluted gradient. In this case, the biomarkers
selected and measured in whole tissue homogenates refer to GSH-dependent
enzymes such as GSH content, GST, GPX and GR activities, considered as antioxidant defences [30]. A multidimensional analysis (PCA) of the selected biomarkers
revealed site-dependent depletion on GSH content while showing an increase on the
antioxidant enzyme activities in the local earthworms due to metal exposures. The
same species A. caliginosa was used in a microcosm study with natural soils, and the
consequences of the exposures were evaluated after 21 days in terms of mt gene
expression, enzymatic activities and energy reserves [31]. The closely related anecic
species, Aporrectodea rosea and A. trapezoids, but also the epigeic E. fetida were
contrasted in relation to their sensibility to metal-spiked soils (Pb and Cd nitrates) at
324
M. Solé
to 8 weeks [24]. Their results revealed the usefulness of the targeted enzymatic
endpoints and antioxidant defences in earthworms for monitoring
GBH-contaminated soil and identified E. eugeniae and L. violaceus as the ones
with higher vermiremediation potential. Another recent study that encompasses
biochemical, mRNA and metabolomics complementary approaches by Zhang
et al. [25] evaluated the effects on E. fetida due to exposure to the fungicide
tebuconazole under artificial soil conditions for 7 days. Amongst the biomarkers
assessed, a confirmation of an oxidative stress condition seen by SOD activity
decreases translationally controlled tumour protein (TCTP) and annetocin (ANN)related genes’ downregulation as well as metabolic affectance of the AMP pathway
(seen as the alteration of 12 endogenous metabolites) using untargeted nuclear
magnetic resonance (NMR) techniques, all pointing to consequences on the reproductive outcome of the exposed earthworms. In the same species, neonicotinoid
dinotefuran was tested, using the filter paper contact test and soil exposures, for
enzymatic and effect oxidative responses including gene expression of Hsp70 and
ANN genes [26] but also the toxicity associated with its metabolites as indicated in
Sect. 9.
4 Biomarkers of Metal Exposure
The field study [27] considered a comprehensive set of biomarkers, in addition to
MT as a specific marker, and pointed out L. terrestris as adequate sentinels of metal
pollution. Furthermore, the same authors using the same species related the response
of MT in the coelomic fluid to that in the whole tissue homogenate in order to
validate the use of an alternative non-destructive marker for metal monitoring
[28]. The naturally occurring species Metaphire posthuma was the species of choice
in a study aimed at assessing toxicity in several metal-contaminated sites from India
[29]. In this case, they also used coelomocytes from the local species to associate
metal exposures to the response observed in biomarkers dealing with the immune
response, ROS formation and antioxidant defences. The naturally occurring soildwelling earthworm A. caliginosa was the sentinel in a field survey conducted in
Slovakia also following a metal-polluted gradient. In this case, the biomarkers
selected and measured in whole tissue homogenates refer to GSH-dependent
enzymes such as GSH content, GST, GPX and GR activities, considered as antioxidant defences [30]. A multidimensional analysis (PCA) of the selected biomarkers
revealed site-dependent depletion on GSH content while showing an increase on the
antioxidant enzyme activities in the local earthworms due to metal exposures. The
same species A. caliginosa was used in a microcosm study with natural soils, and the
consequences of the exposures were evaluated after 21 days in terms of mt gene
expression, enzymatic activities and energy reserves [31]. The closely related anecic
species, Aporrectodea rosea and A. trapezoids, but also the epigeic E. fetida were
contrasted in relation to their sensibility to metal-spiked soils (Pb and Cd nitrates) at
324
M. Solé