Cadmium induced oxidative stress in Dunaliella salina

The unicellular green algae Dunaliella salina contains various antioxidants which protect the cell from oxidative damage due to environmental stresses such as heavy metal stress. In the present study, the response of D. salina at the stationary growth phase to oxidative stress generated by cadmium chloride was investigated. Growth, expressed as cell number per ml of culture, did not change up to 75 μM cadmium but decreased significantly at 100 and 150 μM Cd2+. Reduction in chlorophyll content and carotenoids content per ml of culture was observed in the presence of Cd2+. Total antioxidant activity, expressed as μmole Trolox equivalent per 106 cell (μmol TE 106 cell-1) and also total phenolic content (pg GAE, cell-1) were significantly reduced in the presence of Cd2+. Lower Cd2+ concentration had no influence on the activity of ascorbate peroxidase, 100 and 150 μM Cd2+ caused significant reduction in enzyme activity. Lipid peroxidation, reported as malondialdehyde content, was the same as control up to 100 μM Cd2+ but increased at higher Cd2+ concentration. It is concluded that high concentration of cadmium have negative effect on aquatic algae.Keywords: Dunaliella salina, Carotenoids, Antioxidant activity, Cadmium chloride, Lipidperoxidation, Ascorbate peroxidas

Orthostatic Intolerance and Motion Sickness After Parabolic Flight

Orthostatic intolerance is common in astronauts after prolonged space flight. However, the "push-pull effect" in military aviators suggests that brief exposures to transitions between hypo- and hypergravity are sufficient to induce untoward autonomic cardiovascular physiology in susceptible individuals. We therefore investigated orthostatic tolerance and autonomic cardiovascular function in 16 healthy test subjects before and after a seated 2-hr parabolic flight. At the same time, we also investigated relationships between parabolic flight-induced vomiting and changes in orthostatic and autonomic cardiovascular function. After parabolic flight, 8 of 16 subjects could not tolerate a 30-min upright tilt test, compared to 2 of 16 before flight. Whereas new intolerance in non-Vomiters resembled the clinical postural tachycardia syndrome (POTS), new intolerance in Vomiters was characterized by comparatively isolated upright hypocapnia and cerebral vasoconstriction. As a group, Vomiters also had evidence for increased postflight fluctuations in efferent vagal-cardiac nerve traffic occurring independently of any superimposed change in respiration. Results suggest that syndromes of orthostatic intolerance resembling those occurring after space flight can occur after a brief (i.e., 2-hr) parabolic flight