Ozone saps toads' immune systems.The ozone in smog can impair immunity in human lungs. A laboratory study now indicates that the pollutant can do the same in toads. Michael R. Dohm and his colleagues at the University of Hawaii (body, education) University of Hawaii - A University spread over 10 campuses on 4 islands throughout the state. http://hawaii.edu/uhinfo.html. See also Aloha, Aloha Net. at Hilo placed cane toads (Buff) marinus), collected locally, into a chamber for 4 hours with air containing 0.2 to 0.8 part per million (ppm) ozone. That's well above the 0.01 ppm ozone concentration typical of Hilo. But it's within the range of exposures in many major cities worldwide and the air that drifts downwind down·wind adv. In the direction in which the wind blows. down  wind from them. At various intervals over the 2 days following the ozone exposure, Dohm's team collected macrophages Macrophages White blood cells whose job is to destroy invading microorganisms. Listeria monocytogenes avoids being killed and can multiply within the macrophage. from the amphibians' lungs and tested them for ozone damage. Macrophages are immune cells that, among other roles, engulf en·gulf tr.v. en·gulfed, en·gulf·ing, en·gulfs To swallow up or overwhelm by or as if by overflowing and enclosing: The spring tide engulfed the beach houses. bacteria and other microscopic particles. Although ozone didn't affect the number or viability of lung macrophages, it severely impaired the cells' capacity to engulf particles. "Nearly 40 percent of cells failed to [engulf any] particles when the toads were exposed to ozone," the scientists report in the January Environmental Toxicology Chemistry. Many of the rest of the ozone-exposed macrophages collected only a single particle. During the next day most of the cells had recovered their appetites and once again engulfed many particles. What this means, the researchers conclude, is that ozone "may be a significant and now commonplace stressor of wildlife populations." Through immunological suppression, the pollutant may contribute to the perplexing per·plex tr.v. per·plexed, per·plex·ing, per·plex·es 1. To confuse or trouble with uncertainty or doubt. See Synonyms at puzzle. 2. To make confusedly intricate; complicate. worldwide decline of amphibian amphibian, in zoology amphibian, in zoology, cold-blooded vertebrate animal of the class Amphibia. There are three living orders of amphibians: the frogs and toads (order Anura, or Salientia), the salamanders and newts (order Urodela, or Caudata), and the species (SN: 4/15/00, p. 247), say Dohm and his colleagues.--J.R. |
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