Effects of dietary Pb and Cd and their combination on lysosomal and tissue-level biomarkers and histopathology in digestive gland of the land snail, Cantareus apertus (Born, 1778).

The present study was aimed at determining cell and tissue-level biomarkers and histopathological alterations in the green garden snail, Cantareus apertus (Born, 1778), exposed to different nominal dietary concentrations of Pb (25, 100 and 2500 mg Pb/kg), Cd (5, 10 and 100 mg Cd/kg) and their combination (25 mg Pb + 5 mg Cd/Kg, 100 mg Pb + 10 mg Cd/kg and 2500 mg Pb + 100 mg Cd/ kg) for 1 and 8 weeks. Lead and Cd exerted histopathological effects on the digestive gland in a dose-dependent manner and related to lysosomal and tissue-level biomarkers. The biological responses observed included digestive cell vacuolisation and numerical atrophy, calcium cell hydropic degeneration, excretory cell hypertrophy, inflammatory responses, blood vessel congestion, and disruption of the blood vessel wall and the interstitial connective tissue. Lysosomal enlargement and transient intracellular accumulation of neutral lipids and lipofuscins were also observed, together with alterations in the cell type composition and thinning of the digestive gland epithelium and with diverticular distortion. This response profile fits well with the biological effects reported after metal exposure in gastropods from other regions, as well as with data obtained in parallel studies dealing with metal bioaccumulation and intralysosomal accumulation, mortality, feeding, growth, oxidative stress and neurotoxicity exerted elicited by Pb, Cd and their mixture in green garden snails under the present experimental conditions. Consequently, C. apertus seems to be a suitable model species for the biomarker-based assessment of the biological effects of Pb and Cd, alone or in combinations, thus providing a challenging opportunity to advance in identifying suitable sentinel species for metal pollution biomonitoring and ecosystem health assessment in soil ecosystems in Northern Africa.

Effects of Dietary Pb and Cd and Their Combination on Glutathion-S-Transferase and Catalase Enzyme Activities in Digestive Gland and Foot of the Green Garden Snail, Cantareus apertus (Born, 1778).

The present study was focused on the assessment of glutathion-S-transferase (GST) and catalase (CAT) activities in the digestive gland and foot of the land snail, Cantareus apertus (Born, 1778), exposed to different nominal dietary concentrations of Pb (25 and 2500 mg Pb/Kg), Cd (5 and 100 mg Cd/Kg) and their combination (25 mg Pb + 5 mg Cd/Kg and 2500 mg Pb + 100 mg Cd/Kg) for 7 and 60 days. GST activity was significantly increased after 7 and 60 days exposure to the highest concentration of Pb, Cd and their combination. The levels of CAT activity were different in the two studied organs but in both cases it resulted increased after 7 and 60 days of exposure, which varied significantly between metals and dietary concentrations. Therefore, it can be concluded that GST and CAT enzymes in digestive gland and foot of C. apertus are responsive to Cd, Pb and their combination, whereby they are suitable to be included in a battery of biomarkers for ecosystem health assessment in metal polluted soils using this species as sentinel.

Copper, zinc, and cadmium body concentrations in Hexaplex trunculus collected from the Tunisian coast.

Copper, Zn, and Cd were analyzed in the soft tissues of the edible gastropod Hexaplex trunculus collected from seven localities along the Tunisian coast. The body concentration of these metals was significantly different depending on the gender and site. Copper and Zn varied, respectively, from 47.70 to 343.64 µg/g dry weight (dw) and 149.46 to 530.44 µg/g dw, being higher in males. Cadmium varied from 0.22 to 18.95 µg/g dw and was always higher in females. Overall, the highest concentrations of the three metals were all recorded in Gabès fishing harbor. Comparison of metal concentrations with the European standards compiled by the Food and Agriculture Organization showed that values exceeded standards in several localities. Imposex had been previously recorded in H. trunculus along the Tunisian coast; however, it does not seem to be related with Cu, Zn, and Cd pollution because the body concentration of these metals is not correlated with imposex degree. Nevertheless, interactive effects resulting from the combination of different pollutants and other stressors cannot be disregarded.

Green garden snail, Cantareus apertus, as biomonitor and sentinel for integrative metal pollution assessment in roadside soils.

The present investigation was conceived to study, in a small scale field study, the potential of the green garden snail, Cantareus apertus, as biomonitor and sentinel for integrative metal pollution assessment in soils. For this purpose, we investigated the association between the trace metal (Cd, Pb, As, Fe, Cr, Cu, Ni, and Zn) concentrations in soil, plants (Trifolium repens), and C. apertus depending on the distance (20, 150, and 700 m) from a main roadside in Tunisia as well as between metal concentrations and biomarkers of oxidative stress, oxidative damage, and neurotoxicity in C. apertus. Results revealed a clear association between the concentration of metals such as Ni, Cu, and Zn in snail digestive gland, both amongst them and with oxidative stress and neurotoxicity biomarkers recorded in the same organ. Interestingly, Ni, Pb, and Zn occurred at the highest concentration in soil, plant, and snails and the association appeared related to the immediacy of the roadside and the concentration of these three metals tended to decrease with distance from the roadside in the soil-plant-snail system. Conversely, Cd and Cu were bioaccumulated in plants and snails but their concentrations in soil were not high and did not show a decline in concentration with distance from the roadside. After PCA analysis, PC-01 (56% of the variance) represented metal bioaccumulation and associated toxic effects in snails in the presence of high levels of metal pollution (nearby the roadside) while PC-02 (35% of the variance) represented stress induced by moderate levels of metal pollution (at intermediate distances from the roadside). The four studied sites were clearly discriminated one from each other, depending on how they are affected by traffic pollution. In summary, this field study reveals that (a) C. apertus can be used as biomonitor for metal pollution in roadside soils and as sentinel for pollution effects assessment based on biochemical biomarkers; and (b) that oxidative stress and neurotoxicity biomarkers endow with a powerful biological tool for metal pollution biomonitoring in soils, especially in combination with chemical analysis of the soil-plant-snail transfer system. Moreover, this study provides some baseline data for future impact assessments concerning trace metal pollution in Tunisia.

Bioaccumulation of trace metals in Hexaplex trunculus: spatial and temporal trends from 2004 to 2011 along the Tunisian coast.

Cd, Zn, Cu, As, Fe, Cr, Ni, Al, and Pb were analyzed in the edible and inedible parts of the muricid gastropod Hexaplex trunculus sampled along the Tunisian coast in 2004, 2007, and 2011. The concentration ranges (µg/g dry weight) in the whole soft tissue were 0.1-19.2 for Cd, 198.7-564.6 for Zn, 31.9-363.1 for Cu, 12.8-177.8 for As, 35.4-179.0 for Fe, 0.0-5.8 for Cr, 0.1-4.6 for Ni, 1.0-41.4 for Al, and 0.0-0.6 for Pb. The highest concentrations were recorded in Gabès for Cd, Menzel Jemil for Zn and Cu, Bizerte channel for As, Zarat for Cr and Pb, and Tunis North Lake for Fe, Al, and Ni. The European standards compiled by FAO for mollusks were exceeded in several localities. The temporal trends revealed a decreasing metal contamination in most sampling stations from 2004 to 2011. The calculated intake of metals (µg/week/kg body weight) through human consumption of the snail edible portion varied from 0.0 to 4.4 of Cd, 55.9 to 172.1 of Zn, 8.7 to 92.7 of Cu, 3.0 to 42.6 of As, 9.5 to 49.1 of Fe, 0.0 to 1.52 of Cr, 0.0 to 1.4 of Ni, and 0.3 to 11.4 of Al. Comparison of these metal intakes with those of the standard provisional tolerable weekly intake (PTWI) values stipulated by the WHO recommends precaution in terms of human consumption of this marine snail.

Bioaccumulation and tissue distribution of Pb and Cd and growth effects in the green garden snail, Cantareus apertus (Born, 1778), after dietary exposure to the metals alone and in combination.

The present study was aimed at determining bioaccumulation and cell and tissue distribution of Pb and Cd in the green garden snail, Cantareus apertus (Born, 1778), exposed to different nominal dietary concentrations of Pb (25, 100 and 2500 mg Pb/kg), Cd (5, 10 and 100 mg Cd/kg) and their combination (25mg Pb+10 mg Cd/kg and 2500 mg Pb+100 mg Cd/kg) for 1 and 8 wk. Pb and Cd were bioaccumulated in the digestive gland in a dose-dependent manner and the degree of effects on growth was related to the level of exposure, though metal-metal interactions were observed after treatment with mixtures of Pb and Cd. The present results are absolutely comparable to those obtained in other terrestrial pulmonates in other regions and therefore they absolutely support that C. apertus is suitable as biomonitor for the assessment of the Pb and Cd levels and their biological effects in soil ecosystems in Northern Africa.