Fertilizer Chemicals Linked To Animal Developmental Woes

Fertilizer chemicals may pose a bigger hazard to the environment – specifically to creatures that live in water – than originally foreseen, according to new research from North Carolina State University toxicologists.

在8月27日版发表的一项研究中PLoS One, the NC State researchers show that water fleas take up nitrates and nitrites – common chemicals used primarily in agriculture as fertilizers – and convert those chemicals into nitric oxide. Nitric oxide can be toxic to many organisms.

该研究表明，在水中引入肥料化学物质的水蚤被困扰，并且甚至在氧化氮毒性中均一致，即使在将被认为是低浓度的情况下也是如此。

这提出了关于这些化学物质可能对其他生物体的影响的问题，NC状态的环境和分子毒理学教授和描述结果的纸质作者的环境和分子毒理学教授。他补充说，将需要额外的研究来探索这些问题。

LeBlanc says that some of the study’s results were surprising.

“There’s only limited evidence to suggest that animals could convert nitrates and nitrites to nitric oxide, although plants can,” he says. “Since animals and plants don’t have the same cellular machinery for this conversion, it appears animals use different machinery for this conversion to occur.”

LeBlanc was also dismayed at seeing toxic effects at low chemical concentrations.

“Nitrite concentrations in water vary across the United States, but commonly fall within 1 to 2 milligrams per liter of water,” he says. “We saw negative effects to water fleas at approximately 0.3 milligrams per liter of water.”

Harmful effects of nitric oxide included developmental delay – water flea babies were born on schedule but were underdeveloped; some lacked appendages important for swimming, for instance.

LeBlanc now plans to identify the mechanism behind nitric oxide’s toxic effects; evaluate the relationship between nitrite and nitrate concentrations in the environment and developmental toxicity; and consider possible risks to humans.

“不可能从我们的生活中消除硝酸盐和亚硝酸盐 - 他们在农业作物生产中遇到奇迹，”勒布兰斯说。“但我们可以采取措施，确保这些化学品的益处超出了表面水域来突出其风险。”

The research was funded by the Environmental Protection Agency and the National Science Foundation.

环境和分子毒理学系是大学农业和生命科学学院的一部分。

- kulikowski

Note to editors: An abstract of the paper follows.

“Intracellular Conversion of Environmental Nitrate and Nitrite to Nitric Oxide With Resulting Developmental Toxicity”

作者: Bethany R. Hannas, Parikshit C. Das, Hong Li and Gerald A. LeBlanc, North Carolina State University

发表: Aug. 27, 2010, in PLoS One

Abstract: Nitrate and nitrite (jointly referred to herein as NOx) are ubiquitous environmental contaminants to which aquatic organisms are at particularly high risk of exposure. We tested the hypothesis that NOx undergo intracellular conversion to the potent signaling molecule nitric oxide resulting in the disruption of endocrine-regulated processes. These experiments were performed with insect cells (Drosophila S2) and whole organisms Daphnia magna. We first evaluated the ability of cells to convert nitrate (NO3) and nitrite (NO2) to nitric oxide using amperometric real-time nitric oxide detection. Both NO3 and NO2 were converted to nitric oxide in a substrate concentration-dependent manner. Further, nitric oxide trapping and fluorescent visualization studies revealed that perinatal daphnids readily convert NO2 to nitric oxide. Next, daphnids were continuously exposed to concentrations of the nitric oxide-donor sodium bitroprusside (positive control) and to concentrations of NO3 and NO2. All three compounds interfered with normal embryo development and reduced daphnid fecundity. Developmental abnormalities were characteristic of those elicited by compounds that interfere with ecdysteriod signaling. However, no compelling evidence was generated to indicate that nitric oxide reduced ecdysteriod titers. Results demonstrate that nitrite elicits developmental and reproductive toxicity at environmentally relevant concentrations due likely to its intracellular conversion to nitric oxide.