| Phytoestrogen Signaling and Symbiotic Gene Activation Are Disrupted by Endocrine-Disrupting Chemicals Jennifer E. Fox,1,2 Marta Starcevic,1 Phillip E. Jones,1,3 Matthew E. Burow,1,4,5 and John A. McLachlan1,6 1Environmental Endocrinology Laboratory, Center for Bioenvironmental Research at Tulane and Xavier Universities, New Orleans, Louisiana, USA; 2Center for Ecology and Evolutionary Biology, University of Oregon, Eugene, Oregon, USA; 3Department of Biology, Xavier University, New Orleans, Louisiana, USA; 4Section of Hematology and Medical Oncology, Department of Medicine, and 5Department of Surgery, Tulane University Medical School, New Orleans, Louisiana, USA; 6Department of Pharmacology, Tulane University Medical School, New Orleans, Louisiana, USA Abstract
Some organochlorine pesticides and other synthetic chemicals mimic hormones in representatives of each vertebrate class, including mammals, reptiles, amphibians, birds, and fish. These compounds are called endocrine-disrupting chemicals (EDCs) . Similarly, hormonelike signaling has also been observed when vertebrates are exposed to plant chemicals called phytoestrogens. Previous research has shown the mechanism of action for EDCs and phytoestrogens is as unintended ligands for the estrogen receptor (ER) . Although pesticides have been synthesized to deter insects and weeds, plants produce phytoestrogens to deter herbivores, as attractant cues for insects, and as recruitment signals for symbiotic soil bacteria. Our data present the first evidence that some of the same organochlorine pesticides and EDCs known to disrupt endocrine signaling through ERs in exposed wildlife and humans also disrupt the phytoestrogen signaling that leguminous plants use to recruit Sinorhizobium meliloti soil bacteria for symbiotic nitrogen fixation. Here we report that a variety of EDCs and pesticides commonly found in agricultural soils interfere with the symbiotic signaling necessary for nitrogen fixation, suggesting that the principles underlying endocrine disruption may have more widespread biological and ecological importance than had once been thought. Key words: ecosystem, endocrine-disrupting chemicals, endocrine disruption, environmental signaling, estrogen receptor, nitrogen fixation, Rhizobium, symbiosis. Environ Health Perspect 112:672-677 (2004) . doi:10.1289/ehp.6456 available via http://dx.doi.org/ [Online 29 January 2004]
Address correspondence to J.E. Fox, University of Oregon, 335 Pacific Hall, Eugene, OR 97403 USA. Telephone: (541) 346-1537. Fax: (541) 346-2364. E-mail: jenfox@uoregon.edu We thank the members of our laboratory for their support. We also thank S.R. Long of Stanford University for the Rhizobium construct Sinorhizobium meliloti 1021pRmM57. J.E.F. was supported by a National Science Foundation graduate fellowship. This work was supported by Department of Energy grant 540841 and U.S. Department of Agriculture grant 586435-7019. The authors declare they have no competing financial interests. Received 14 May 2003 ; accepted 27 January 2004.
The full version of this article is available for free in HTML or PDF formats. |
