3.97 Æ 0.43 mg/L [25]. A 14-day exposure of D. magna to IBU (concentration range
20, 40, and 80 mg/L) measuring chronic effects on life history traits and population
performance was performed by Heckmann and coauthors [22]. Population growth
rate was significantly reduced at all the IBU tested concentrations, while D. magna
survival was affected only by the exposure to 80 mg/L of IBU. Reproduction was
influenced by the exposure to low concentrations of IBU, whereby the 14-day EC 50
was calculated as 13.4 mg/L but was utterly inhibited at 80 mg/L. Similar results
were obtained by Hayashi and coauthors [21], who exposed D. magna (5-days old)
to the same range of IBU concentrations than [22] (i.e., 20, 40 and 80 mg/L) for
10 days. Individuals exposed to higher concentrations produced significantly fewer
offspring than controls, while no reproduction occurred at 80 mg/L. Moreover, at
first reproduction was delayed at all the tested IBU concentrations. D. magna
survival was affected after the exposure to 80 mg/L during the 10-day exposure,
while the population growth rates were >1 after the exposure to control, 20 and
40 mg/L of IBU, suggesting and increasing population, <1 at 80 mg/L of IBU,
suggesting a decreasing population trend [39]. A recent study by Wang and coauthors [39] investigated the modulation of the expression of CYP360A, CYP314, and
GST genes involved in the detoxification process and the responses of their associated enzymes activity, as well as in some physiological parameters (e.g., growth and
reproduction) in D. magna exposed to environmentally relevant concentrations of
IBU (0.5, 5, and 50 μg/L). IBU did not affect the total amount of eggs produced per
female, total number of brood per female, and body length of D. magna specimens.
By a molecular and biochemical point of view, IBU treatment inhibited the expression of CYP360A gene at 0.5 μg/L while induced its expression at 50 μg/L. Similar
trend was also noted for GST gene, while the gene CYP314 showed an inhibition
after short time exposure (6 h). Conversely, the gene CYP314 showed an
overexpression after prolonged exposure time (48 h at 0.5 μg/L). Erythromycin Ndemethylase (ERND) and aminopyrine N-demethylase were both inhibited after
short time exposure (6 h). However, they were both overexpressed after prolonged
exposure time (48 h) at 0.5 μg/L. Moreover, an induction of glutathione
S-transferase (GST), superoxide dismutase (SOD), and catalase (CAT) activity
was observed in short-term exposure to IBU, while EROD and methane dicarboxylic
aldehyde (MDA) content increased in a dose-dependent manner [41]. A 7-day
exposure to 10, 100 μg/L, 1.0, and 10 mg/L of IBU did not influence the survival
of H. vulgaris at concentrations up to 1.0 mg/L, while after 17 days neither feeding
nor bud formation nor the ability of dissected polyps to regenerate a hypostome,
tentacles, and foot was affected [28]. However, a further study showed that regeneration was significantly inhibited at 5 mg/L of IBU, while the 96-h IC 50 (i.e., the
concentration that inhibits 50% of the embryos to develop) was calculated as
3.84 mg/L (confidence interval 2.36–6.26 mg/L) [44]. IBU exposure also induced
sublethal effects towards mollusks. The cytogenotoxicity of IBU was investigated
through an in vitro approach by exposing zebra mussel hemocytes for 1 h to 45, 450,
and 909 μg/L [34]. A significant decrease in the stability of lysosomal membranes
was noted after the exposure to 450 and 909 μg/L of IBU, while genotoxicity
occurred after the exposures to all the tested concentrations. A further in vivo
156
M. Parolini
20, 40, and 80 mg/L) measuring chronic effects on life history traits and population
performance was performed by Heckmann and coauthors [22]. Population growth
rate was significantly reduced at all the IBU tested concentrations, while D. magna
survival was affected only by the exposure to 80 mg/L of IBU. Reproduction was
influenced by the exposure to low concentrations of IBU, whereby the 14-day EC 50
was calculated as 13.4 mg/L but was utterly inhibited at 80 mg/L. Similar results
were obtained by Hayashi and coauthors [21], who exposed D. magna (5-days old)
to the same range of IBU concentrations than [22] (i.e., 20, 40 and 80 mg/L) for
10 days. Individuals exposed to higher concentrations produced significantly fewer
offspring than controls, while no reproduction occurred at 80 mg/L. Moreover, at
first reproduction was delayed at all the tested IBU concentrations. D. magna
survival was affected after the exposure to 80 mg/L during the 10-day exposure,
while the population growth rates were >1 after the exposure to control, 20 and
40 mg/L of IBU, suggesting and increasing population, <1 at 80 mg/L of IBU,
suggesting a decreasing population trend [39]. A recent study by Wang and coauthors [39] investigated the modulation of the expression of CYP360A, CYP314, and
GST genes involved in the detoxification process and the responses of their associated enzymes activity, as well as in some physiological parameters (e.g., growth and
reproduction) in D. magna exposed to environmentally relevant concentrations of
IBU (0.5, 5, and 50 μg/L). IBU did not affect the total amount of eggs produced per
female, total number of brood per female, and body length of D. magna specimens.
By a molecular and biochemical point of view, IBU treatment inhibited the expression of CYP360A gene at 0.5 μg/L while induced its expression at 50 μg/L. Similar
trend was also noted for GST gene, while the gene CYP314 showed an inhibition
after short time exposure (6 h). Conversely, the gene CYP314 showed an
overexpression after prolonged exposure time (48 h at 0.5 μg/L). Erythromycin Ndemethylase (ERND) and aminopyrine N-demethylase were both inhibited after
short time exposure (6 h). However, they were both overexpressed after prolonged
exposure time (48 h) at 0.5 μg/L. Moreover, an induction of glutathione
S-transferase (GST), superoxide dismutase (SOD), and catalase (CAT) activity
was observed in short-term exposure to IBU, while EROD and methane dicarboxylic
aldehyde (MDA) content increased in a dose-dependent manner [41]. A 7-day
exposure to 10, 100 μg/L, 1.0, and 10 mg/L of IBU did not influence the survival
of H. vulgaris at concentrations up to 1.0 mg/L, while after 17 days neither feeding
nor bud formation nor the ability of dissected polyps to regenerate a hypostome,
tentacles, and foot was affected [28]. However, a further study showed that regeneration was significantly inhibited at 5 mg/L of IBU, while the 96-h IC 50 (i.e., the
concentration that inhibits 50% of the embryos to develop) was calculated as
3.84 mg/L (confidence interval 2.36–6.26 mg/L) [44]. IBU exposure also induced
sublethal effects towards mollusks. The cytogenotoxicity of IBU was investigated
through an in vitro approach by exposing zebra mussel hemocytes for 1 h to 45, 450,
and 909 μg/L [34]. A significant decrease in the stability of lysosomal membranes
was noted after the exposure to 450 and 909 μg/L of IBU, while genotoxicity
occurred after the exposures to all the tested concentrations. A further in vivo
156
M. Parolini