In a study published in the Aug. 27 edition of 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.
The study shows that water fleas introduced to fertilizer chemicals in water were plagued with developmental and reproductive problems consistent with nitric oxide toxicity, even at what would be considered low concentrations.
This raises questions about the effect these chemicals may have on other organisms, says Dr. Gerald LeBlanc, professor of environmental and molecular toxicology at NC State and the corresponding author of the paper describing the results. He adds that additional research will be needed to explore those questions.
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.
"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."
The research was funded by the Environmental Protection Agency and the National Science Foundation.
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"
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.
Dr. Gerald LeBlanc | EurekAlert!
Multi-institutional collaboration uncovers how molecular machines assemble
02.12.2016 | Salk Institute
Fertilized egg cells trigger and monitor loss of sperm’s epigenetic memory
02.12.2016 | IMBA - Institut für Molekulare Biotechnologie der Österreichischen Akademie der Wissenschaften GmbH
A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.
Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...
In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.
“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...
The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.
The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...
Broadband rotational spectroscopy unravels structural reshaping of isolated molecules in the gas phase to accommodate water
In two recent publications in the Journal of Chemical Physics and in the Journal of Physical Chemistry Letters, researchers around Melanie Schnell from the Max...
The efficiency of power electronic systems is not solely dependent on electrical efficiency but also on weight, for example, in mobile systems. When the weight of relevant components and devices in airplanes, for instance, is reduced, fuel savings can be achieved and correspondingly greenhouse gas emissions decreased. New materials and components based on gallium nitride (GaN) can help to reduce weight and increase the efficiency. With these new materials, power electronic switches can be operated at higher switching frequency, resulting in higher power density and lower material costs.
Researchers at the Fraunhofer Institute for Solar Energy Systems ISE together with partners have investigated how these materials can be used to make power...
16.11.2016 | Event News
01.11.2016 | Event News
14.10.2016 | Event News
02.12.2016 | Medical Engineering
02.12.2016 | Agricultural and Forestry Science
02.12.2016 | Physics and Astronomy