The effect of in situ cadmium contamination on some biomarkers in Cerastoderma glaucum

Abstract

The present study was designed to detect in situ effects of cadmium on marine organisms Cerastoderma glaucum from the gulf of Gabès (Tunisia). Six sampling stations were chosen: one site, relatively far from known local source of pollution, was considered as uncontaminated site and five sites clearly exposed to anthropogenic impact. Metallothionein like protein (MTLP) and sub-cellular metal partitioning were measured in cockles (C. glaucum) gills and digestive gland. Various biomarkers were also measured, including malondialdehyde (MDA) in the digestive gland and acetylcholinesterase activity (AChE) in the remainder. The health status of the cockles was assessed by using the condition index (CI). Significant differences between sites were noted for Cd concentrations, (CI) and also for the three studied biomarkers. Significant higher biomarkers response was measured in cockles from stations located in the northern part of the gulf, which are exposed directly to industrial and urban effluents, whereas the response of most biomarkers was minimal at the reference station. Positive and significant correlations were observed between MTLP and Cd concentrations in the digestive gland and in the gills. However, it must be noted that these correlations were more significant in the digestive gland, suggesting that compared to the gills, the digestive gland of C. glaucum is more suitable for monitoring metal pollution. The subcellular distribution of Cd showed that the soluble fraction was the major compartment for Cd storage, a pattern which is due to the role of MTLP in Cd detoxication. But at the most contaminated site (EH), cadmium in the digestive gland was preferentially accumulated in the insoluble fraction (P1) suggesting that the MTLP capacity in binding metals was not sufficient to avoid the binding of Cd to the insoluble fraction. Furthermore, the MTLP concentrations in the cockles from this site are lower than expected. So in highly polluted sites, MTLP in C. glaucum should not be used as a useful biomarker for metal pollution. The lipid peroxidation as presented by malondialdehyde levels, and MT-like protein concentrations increased in cockles exposed to cadmium contamination. We can, therefore, hypothesize that Cd could induce MTLP synthesis and MDA increase. While AChE had distinct and specific pattern showing that cadmium is not the only factor of the inhibition of cholinesterase activity. There are other polluting inputs engendering this inhibition.

CHOLINESTERASE ACTIVITY IN Crassostrea sp. OF NAYARIT (NW MEXICO) COASTAL WATERS

“…Additionally, they may be affected also by metals, although the effect may be either metal-or species-dependent since, while no effect was observed in mussels exposed to Cu (Regoli and Principato 1995), Machreki-Ajmi et al (2008) and Bonacci et al (2008) observed cholinesterase inhibition in clams when exposed to Cd.…”

Use of oxidative stress biomarkers in Carcinus maenas to assess littoral zone contamination in Tunisia

“…When they are exposed to Cd in company with other metals, Cd values are highest in the digestive gland (Martín-Díaz et al 2005). Cd accumulation was also found to be higher in the digestive gland of the cockle Cerastoderma glaucum from Gabès Gulf than in the gills (Machreki-Ajmi et al 2008). …”

“…Crude phosphate treatments, chemical industries, tanneries, and plastics plants release pollutionloaded effluents into the marine environment; these pollutants include toxic metals, which are washed back by tides to the littoral area (Louati et al 2001, Banni et al 2005, Zaghden et al 2005, MachrekiAjmi et al 2008, Smaoui-Damak et al 2009). Cd from phosphate plants is one of the main contaminants in the Gabès area , SmaouiDamak et al 2003, Machreki-Ajmi et al 2008. Samples were collected from: (1) Bizerte (BIZ) Lagoon, and (2) Gargour (GAR), in Gabès Gulf, both of which areas receive urban, industrial and agricultural pollution, and (3) Teboulba (TEB), with no main contamination sources and considered a reference site in many field studies (Banni et al 2007, Jebali et al 2007, Bouraoui et al 2010.…”

“…This endangers the health of organisms and affects the marine ecosystem and humans consuming food of marine origin. Levels of metals, pesticides and hydrocarbons are increasing along the Tunisian littoral zone, especially at Bizerte Lagoon (Dellali et al 2001, Khessiba et al 2001, Louiz et al 2009, Bouraoui et al 2010 and in the area of Sfax/ Gabès gulf (Louati et al 2001, Zaghden et al 2005, Machreki-Ajmi et al 2008, Bouraoui et al 2010. Although both areas are subject to many ecological pressures, they are, due to the variety of fishing and aquaculture activities, key aquatic resources.…”

Metals and linear alkylbenzene sulphonate as inhibitors of the algae Pseudokirchneriella subcapitata acid phosphatase activity

“…and Cd 2? inhibit algal b-D-galactosidase (Peterson and Stauber 1996) and algal b-glucosidase (Obst 1988), as well as fish phosphatases (El Demerdash and Elagamy 1999;Gill et al 1991) and mollusc acetylcholinesterase (Machreki-Ajmi et al 2008). The activities of glucose-6-phosphate dehydrogenase (Kong and Chen 1995) and phosphatases (Rai et al 1998) were decreased by Al 3?…”