Detection of early effects of a single herbicide (diuron) and a mix of herbicides and pharmaceuticals (diuron, isoproturon, ibuprofen) on immunological parameters of Pacific oyster (Crassostrea gigas) spat

Abstract

In the context of massive summer mortality events of the Pacific oyster Crassostrea gigas, the aim of this study was to investigate the early effects on genes, enzymes and haemocyte parameters implicated in immune defence mechanisms in C. gigas oysters exposed to a potentially hostile environment, i.e. to an herbicide alone or within a mixture. Following 2 h of exposure to the herbicide diuron at 1 μg L(-1), the repression of different genes implicated in immune defence mechanisms in the haemocytes and the inhibition of enzyme activities, such as laccase-type phenoloxidase (PO) in the plasma, were observed. The inhibition of superoxide dismutase (SOD) activity in the plasma was also observed after 6 and 24 h of exposure. In the mixture with the herbicides diuron and isoproturon, and the pharmaceutical ibuprofen, catecholase-type PO activity in the plasma and the percentage of phagocytosis in the haemocytes were reduced after 6 h of exposure. Our results showed that early effects on molecular, biochemical and cellular parameters can be detected in the presence of diuron alone or within a mixture, giving an insight of its potential effect in situations that can be found in natural environments, i.e. relatively high concentrations for short periods of time.

Are Mussels Always the Best Bioindicators? Comparative Study on Biochemical Responses of Three Marine Invertebrate Species to Chronic Port Pollution

“…Thus, it is probable that PO activity is stimulated in barnacles of the port due to pathogens abundance. However, the increase of PO activity in different marine invertebrates' species has been associated with a variety of contaminants such as metals (Tujula et al 2001), certain PAHs (Coles et al 1994), herbicides and pharmaceuticals (Luna-Acosta et al 2012), not only organic contaminants. Further, Bado-Nilles et al (2008) found increase in PO activity in Pacific oysters exposed to benzo[b]fluoranthene, but did not find modulation of other haemocyte parameters and thus suggest that the increment is produced by a direct influence of the contaminant on the enzyme activity.…”

Involvement of fish immunomarkers in environmental biomonitoring approach: Urban and agri-viticultural context

“…As previously observed with agricultural pressures, an increase of cellular mortality was detected. As many pesticides, diuron and copper may generate reactive oxygen species (ROS) and induce an overwhelming of the antioxidant system (Dautremepuits et al, 2004;Luna-Acosta et al, 2012). This oxidative stress could be accountable to reduction of cellular viability by increasing DNA strand breaks leading to apoptosis (Bopp et al, 2008) or decreasing functional integrity of the lysosomal membrane (Roméo et al, 2000;Krumschnabel et al, 2005) inducing necrosis by release of acid hydrolases (Holtzman, 1989).…”

Suspected endocrine disrupting substances

“…However, stimulation of spawning is common among aquatic organisms when they are transferred to experimental conditions and therefore this endpoint might easily generate false positives (Buisson et al 2008). In another study with oyster the relative expression of seven immune-related genes was an equally sensitive endpoint to study the effects of diuron on mollusc (Luna-Acosta et al 2012). Even more sensitive was the study design set up by Akcha et al (2012) where embryo-larval development of oysters were significantly affected by diuron at a concentration of 0.05 µg/l.…”

“…Other exposure studies with oyster (Crassotrea gigas) have indicated effects of diuron on the reproductive cycle at a concentration of 1 µg/l (Buisson et al 2008). Further, diuron has an immunological effect on oyster and exposure of 0.8 µg/l for 2 hours changes the activity of enzymes implicated in immune defence mechanisms (Luna-Acosta et al 2012).…”

“…However the endocrine systems of these organisms are poorly investigated and hence these effects cannot be taken as proof of diuron acting as an EDC. Diuron causes adverse effects on oysters including effects on spermatozoa (Akacha et al 2012), effects on the reproductive cycle (Buisson et al 2008) and immunological effects (Luna-Acosta et al 2012). Diuron 17 In a strict sence the effects on hormone productive organs, such as testis or ovaries, are not regarded as proof of endocrine disruption.…”