Impact of heavy metal pollution on the hemogram and serum biochemistry of the Libyan jird, Meriones libycus

The stress profiles of the hemogram and serum biochemistry were determined in the context of heavy metal (Cd, Cu, Hg, Ni and Pb) exposure in the wild libyan jird, Meriones libycus, from one of Riyadh’s polluted areas versus a reference site. Coupling the pronounced drop in platelets (PLT) (28%) and mean platelet volume (MPV) (17%) with the insignificant responses of other red blood cell indices, suggests bone marrow suppression that is characterized by thrombocytopenia as an initial abnormality. The species-specific stress leukogram for M. libycus is expressed by leukocytosis (66%), monocytosis (40%), lymphocytosis (23%) with eosinopenia (81%) and neutropenia (42%). Hyperglycemia (50%), hyper-low-density-lipoproteinemia (38%), hypocortisolism (85%) and hypotriglyceridemia (55%) depicted serum biochemistry profile. In polluted jirds, the elevated activities of pseudocholinesterase (PChE) and serum marker enzymes (alanine aminotransferase ALT, aspartate aminotransferase AST and creatine kinase CK) strongly suggest functional damage of the liver and/or heart. A potential role of PChE in low-density lipoprotein (LDL) metabolism is implied in the joint rise of both indices and in the recognized relationship between PChE and lipid metabolites. While increased utilization in lipid metabolism and energy synthesis could rationalize the inhibition of the normal patterns of triglycerides and lactate dehydrogenase (LDH), the inhibited activities of LDH could additionally be attributed to its hormetic behavior towards low and high metal concentrations. The overall findings presented here documented the relevance of M. libycus in biomonitoring and predicting the risk imposed on human populations living in polluted areas.     

Risk assessment of heavy metal contamination in soil and wild Libyan jird Meriones libycus in Riyadh, Saudi Arabia

This study was undertaken to document the impact of heavy metal pollution on the Libyan jird, Meriones libycus and to contribute to an environmental impact statement for the rapidly growing City of Riyadh. All metal concentrations in surface soil of a polluted site (within Riyadh City) were higherthan those from a reference site (outside the city).Although Pb declined versus earlier reports on Riyadh soil, Cd (0.97 microg g(-1)) and Hg (0.28 microg g(-1)) were above some of the most stringent quality guidelines (0.07-0.62 microg g(-1) for Cd and 0.14-0.18 microg g(-1) for Hg). Metal distribution in M. libycus proved site-related and organ-specific, recognizing a higher affinity of most tested metals towards the kidneys, liver and brain than the lung and heart. The comparatively lower site-specific accumulation of Pb in soft tissues was attributed primarily to its major hypothetical accumulation in bones, whereas, the transition rate of Hg from the liver was suggested to be lower to the brain than to the kidneys. Although a non hazardous status was assumed for Cu (11.27-13.16 microg g(-1)) and Hg (up to 0.207 microg g(-1)) in tissues of M. libycus, a potential risk was imposed by mean tissue concentrations of Cd (up to 3.29 microg g(01)), Ni (up to 1.48 microg g(-1)) and Pb (up to 1.94 microg g(-1)). On the grounds of the significantly higher metal levels in polluted soft tissues versus reference subjects, Libyan jirds possess high exposure potential and can be useful biomonitors of environmental metal contamination.