PROGRESS TOWARD IDENTIFYING CAUSES OF MALDEVELOPMENT INDUCED IN XENOPUS BY POND WATER AND SEDIMENT EXTRACTS FROM MINNESOTA, USA

Abstract

In previously conducted laboratory studies with the South African clawed frog (Xenopus laevis), pond water and sediment samples collected from various sites in Minnesota, USA, were demonstrated to have the potential to induce a variety of developmental abnormalities, including early embryo-larval maldevelopment, abnormal limb development, and disruption of metamorphosis. The results of exposure of X. laevis to suspect pond water and sediment samples supported the hypothesis that these samples were capable of inducing these abnormalities as the result of either the presence of developmental toxicants or the absence of essential micronutrients. Physicochemical characterization of the causes of abnormal frog embryo-larval and limb development were performed using the frog embryo teratogenesis assay-Xenopus (FETAX). Specific compounds were subsequently identified within the complex mixture fractions and tested by dilution in a control solution and native reference water using both the 4- and 30-d treatment protocols. Results from these studies suggested that a complex mixture of both naturally occurring and man-made compounds was primarily responsible for the effects observed in X. laevis. The potency of several compounds was also enhanced by the site water, thus indicating that the water matrix deserves consideration as a contributing factor for both laboratory and field studies.

<title>Biosensor, ELISA, and frog embryo teratogenesis assay: Xenopus (FETAX) analysis of water associated with frog malformations in Minnesota</title>

“…2,3,4 However, parasites may not be the sole cause of frog malformations in Minnesota. Filtration does not reduce the incidence of malformations in Xenopus and C-18 solid phase extraction was able to concentrate the biological activity 14 .…”

Enhancing the predictive validity of Frog Embryo Teratogenesis Assay—Xenopus (FETAX)

“…The FETAX model, or modifications thereof has been used to screen chemicals and prioritize discovery-level products, 1 evaluate modes of biotransformation, detoxification and mechanisms of action, 2 -14 serve as a model of limb development, 14,15 evaluate the impact of chemicals on thyroid function, 16,17 assess nutritional essentiality and toxicity of trace elements, 18 -23 evaluate environmental samples for potential effects on amphibian populations 24,25 and study mixture toxicity and structure-activity relationships. 26 -30 Thus, FETAX represents one of the most extensively validated alternative developmental toxicity test systems.…”

Wildlife Toxicity Assessment for Diphenylamine

“…Amphibian Toxicity: Other Fort et al [40] conducted 4-day Frog Embryo Teratogenesis Assay Xenopus (FETAX), and 30-day limb development tests using the South African clawed frog (Xenopus laevis). FETAX tests were conducted using both pond water and sediment extracts from a site with observed amphibian malformations and mortality.…”