Effects of cadmium exposure on the ultrastructural pathology of different pulmonary cells, leukocyte count, and activity of glutathione peroxidase and lactate dehydrogenase in relation to free radical production in Uromastyx aegyptius.

Animal studies on the toxicity of heavy metals have been widely used as model to simulate the impacts of environmental pollution on the human health. In the present study the authors hypothesized that cadmium exposure inducts changes in reactive oxygen species (ROS) and that may be involved in the pathogenesis of lung diseases. The pathological changes of different pulmonary cells of ROS-cadmium-dependent effects were investigated in relation to the activity of lactate dehydrogenase (LDH) and glutathione peroxidase (GPx). Twelve animals were randomly assigned to two groups, control and experimental. The experimental group underwent ingestion of cadmium mixed with diet (200 mg/kg) for 7 weeks. Following the treatment conditions for each group, blood samples were collected and animals were sacrificed and the lung was isolated. Ultrastructure examination showed that cadmium resulted in desquamated pneumocyte type II with degenerated surfactant materials, thickened alveolar wall, and thickening of alveolar septum due to proliferation of endothelial cells lining the pulmonary capillaries as a result of an active transmigration. t-test results showed that cadmium caused a significant (p < .05) rise in leukocytes, lymphocytes, neutrophils, and monocytes, which was a sign for chemotactic activity that enhanced transmigration from pulmonary microcirculation into inflammated tissue. In addition, lung tissue FR production, LDH, and GPx activities increased significantly (p < .05) from the baseline control of 88.17+/-17.70, 183.49+/-29.50, and 4466.79+/-1190.32 to 129.67+/-14.49.14 (Carr U), 339.17+/-75.28 (U/L), and 5943.08+/-695 (U/L) respectively, in the cadmium-treated group. Based on the results of the present study, it can be concluded that long-term cadmium exposure (ingestion mixed with food) results in cadmium deposition in the tissue of the vasculature of the lungs, such as pulmonary capillary endothelial, which induced the buildup of ROS, a possible proposed new mechanism that explains lung inflammation.

A light and electron microscope study of Sarcocystis mitrani (sp. nov.) infecting the skink Scincus mitranus in the central region of Saudi Arabia.

The prevalence of Sarcocystis infection among skinks, Scincus mitranus, was studied for the first time. Grossly macroscopic sarcocysts were found to infect the skeletal muscles of the skink (infection rate: 4.16%). Fecal examination for the presence of sporocysts was negative in this study. Sarcocysts were studied using light and transmission electron microscopes. Mature sarcocysts measuring 0.05-0.3 x 0.5-1.8 mm (mean 0.1 5x 1.2 mm) were observed. The characteristic primary cyst wall, with long, finger-like, non-branched and non-stalked protrusions, is described. The ground substance gives rise to numerous thick septa dividing the interior of the cyst into chamber-like compartments. Zoites, including metrocytes and merozoites, were found to have the main architecture of Apicomplexa. Peculiarities of these elements and the importance of the primary cyst-wall ultrastructure for identification and specification of Sarcocystis are discussed. Secondary cyst wall was completely absent. Alterations in the infected host cell were observed.

Responses to chemical cues from animal and plant foods by actively foraging insectivorous and omnivorous scincine lizards.

If tongue-flicking is important to lizards to sample chemical cues permitting identification of foods, tongue-flicking and subsequent feeding responses should be adjusted to match diet. This hypothesis can be examined for plant foods because most lizards are insectivores, but herbivory/omnivory has evolved independently in many lizard taxa. Here we present experimental data on chemosensory responses to chemical cues from animal prey and palatable plants by three species of the scincine lizards. When tested with chemical stimuli presented on cotton swabs, the insectivorous Eumeces fasciatus responded strongly to prey chemicals but not to chemicals from plants palatable to omnivorous lizards or to pungent or odorless control stimuli. Two omnivorous species, E. schneideri and Scincus mitranus, responded more strongly to chemical cues from both prey and food plants than to the control chemicals. All available data for actively foraging lizards, including these skinks, show that they are capable of prey chemical discrimination, and insectivores do not exhibit elevated tongue-flicking or biting responses to chemical cues from palatable plants. In all of the several species of herbivores/omnivores tested, the lizards show elevated responses to both animal and plant chemicals. We suggest two independent origins of both omnivory and plant chemical discrimination that may account for the evolution of diet and food chemical discriminations in the eight species of skinks studied, five of which are omnivores. All data are consistent with the hypothesis that acquisition of omnivory is accompanied by acquisition of plant chemical discrimination, but data on a broad diversity of taxa are needed for a definitive comparative test of the evolutionary hypothesis. J. Exp. Zool. 287:327-339, 2000.