http://www.eurekalert.org/pub_releas...-fcl082710.php


The Department of Environmental and Molecular Toxicology is part of the
university's College of Agriculture and Life Sciences.
Note to editors: An abstract of the paper follows.

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

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

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also noted in the article:

"It's not possible to eliminate nitrates and nitrites from our lives –
they do wonders in agricultural crop production," LeBlanc says. "But
we can take measures to ensure that the benefits of these chemicals
outweigh their risks by keeping them out of surface waters."