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Identifying the adverse impacts of pesticide exposure is essential to guide regulations that are protective of wildlife and human health. Within rice ecosystems, amphibians are valuable indicators because pesticide applications coincide with sensitive reproductive and developmental life stages. We conducted two experiments using wild cane toads (Rhinella marina) to test 1) whether environmentally relevant exposure to a commercial formulation of butachlor, an acetanilide herbicide used extensively in rice, affects amphibian development and 2) whether cane toad tadpoles are capable of acclimatizing to sub-lethal exposure. First, we exposed wild cane toads to 0.002, 0.02, or 0.2 mg/L of butachlor (Machete EC), during distinct development stages (as eggs and hatchlings, as tadpoles, or continuously) for 12 days. Next, we exposed a subset of animals from the first experiment to a second, lethal concentration and examined survivorship. We found that cane toads exposed to butachlor developed slower and weighed less than controls, and that development of the thyroid gland was affected: exposed individuals had smaller thyroid glands and thyrocyte cells, and more individual follicles. Analyses of the transcriptome revealed that butachlor exposure resulted in downregulation of transcripts related to metabolic processes, anatomic structure development, immune system function, and response to stress. Last, we observed evidence of acclimatization, where animals exposed to butachlor early in life performed better than naïve animals during a second exposure. Our findings indicate that the commercial formulation of butachlor, Machete EC, causes thyroid endocrine disruption in vertebrates, and suggest that exposure in lowland irrigated rice fields presents a concern for wildlife and human health. Furthermore, we establish that developmental assays with cane toads can be used to screen for adverse effects of pesticides in rice fields.

اظهر المزيد [+]

thyroid gland human health amphibians transcriptome immune system wildlife rhinella marina endocrine disruption acclimation stress response thyroid survival rate ...

National Agricultural Library - United States of America

Evidence of sulfur-bound reduced copper in bamboo exposed to high silicon and copper concentrations النص الكامل

2014

الإصدارات الـ 2كلها [+]

Evidence of sulfur-bound reduced copper in bamboo exposed to high silicon and copper concentrations النص الكامل

2014

We examined copper (Cu) absorption, distribution and toxicity and the role of a silicon (Si) supplementation in the bamboo Phyllostachys fastuosa. Bamboos were maintained in hydroponics for 4 months and submitted to two different Cu (1.5 and 100 mm Cu2þ) and Si (0 and 1.1 mM) concentrations. Cu and Si partitioning and Cu speciation were investigated by chemical analysis, microscopic and spectroscopic techniques. Copper was present as Cu(I) and Cu(II) depending on plant parts. Bamboo mainly coped with high Cu exposure by: (i) high Cu sequestration in the root (ii) Cu(II) binding to amino and carboxyl ligands in roots, and (iii) Cu(I) complexation with both organic and inorganic sulfur ligands in stems and leaves. Silicon supplementation decreased the visible damage induced by high Cu exposure and modified Cu speciation in the leaves where a higher proportion of Cu was present as inorganic Cu(I)S compounds, which may be less toxic. (Résumé d'auteur)

اظهر المزيد [+]

france

Centre de coopération internationale en recherche agronomique pour le développement - France

Evidence of sulfur-bound reduced copper in bamboo exposed to high silicon and copper concentrations النص الكامل

2014

We examined copper (Cu) absorption, distribution and toxicity and the role of a silicon (Si) supplementation in the bamboo Phyllostachys fastuosa. Bamboos were maintained in hydroponics for 4 months and submitted to two different Cu (1.5 and 100 μm Cu2+) and Si (0 and 1.1 mM) concentrations. Cu and Si partitioning and Cu speciation were investigated by chemical analysis, microscopic and spectroscopic techniques. Copper was present as Cu(I) and Cu(II) depending on plant parts. Bamboo mainly coped with high Cu exposure by: (i) high Cu sequestration in the root (ii) Cu(II) binding to amino and carboxyl ligands in roots, and (iii) Cu(I) complexation with both organic and inorganic sulfur ligands in stems and leaves. Silicon supplementation decreased the visible damage induced by high Cu exposure and modified Cu speciation in the leaves where a higher proportion of Cu was present as inorganic Cu(I)S compounds, which may be less toxic.

اظهر المزيد [+]

poaceae bamboos toxicity toxicity chemical analysis roots x-ray absorption spectroscopy ...

National Agricultural Library - United States of America

Clean air: time for responsible reform [Air pollution].

1982

Hart G.

Wolters Kluwer - United States of America

أجريس - النظام الدولي للعلوم الزراعية والتكنولوجيا

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Developmental assays using invasive cane toads, Rhinella marina, reveal safety concerns of a common formulation of the rice herbicide, butachlor النص الكامل

Developmental assays using invasive cane toads, Rhinella marina, reveal safety concerns of a common formulation of the rice herbicide, butachlor النص الكامل

Developmental assays using invasive cane toads, Rhinella marina, reveal safety concerns of a common formulation of the rice herbicide, butachlor النص الكامل

Evidence of sulfur-bound reduced copper in bamboo exposed to high silicon and copper concentrations النص الكامل

Evidence of sulfur-bound reduced copper in bamboo exposed to high silicon and copper concentrations النص الكامل

Evidence of sulfur-bound reduced copper in bamboo exposed to high silicon and copper concentrations النص الكامل