Environmentally-relevant concentrations of atrazine induce non-monotonic acceleration of developmental rate and increased size at metamorphosis in Rhinella arenarum tadpoles

Brodeur, Jean‐Marc; Sassone, Alina Grisel; Hermida, Gladys N.; Codugnello, Nadia

doi:10.1016/j.ecoenv.2013.01.019

Cited by 59 publications

(26 citation statements)

References 69 publications

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“…Most studies of atrazine have found no effect on body size at concentrations similar to that used in the present study but a reduction in size at higher concentrations (reviewed in Rohr and McCoy ). However, Brodeur et al found an increase in body size of Rhinella [ Bufo ] arenarum tadpoles near metamorphosis at low atrazine concentrations (1 µg/L and 10 µg/L), which they associated with estrogenic effects of atrazine. Although we found no effect of 1.11 mg/L acid equivalent glyphosate in Roundup, previous laboratory studies have found reduced survival and growth in various anuran species at similar concentrations (e.g., Relyea and Howe et al ).…”

Section: Discussionmentioning

confidence: 99%

Assessment of interactive effects of elevated salinity and three pesticides on life history and behavior of southern toad (Anaxyrus terrestris) tadpoles

Wood

Welch

2015

Enviro Toxic and Chemistry

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Because habitats are increasingly exposed to multiple stressors simultaneously, assessing the interactive effects of stressors is crucial for understanding how populations respond to human-altered habitats. Salinization of freshwater habitats is increasing and has the potential to interact with other stressors. Chemical pollutants also contribute to habitat degradation in freshwater environments, and both salinity and various pesticides can harm amphibians. The present study used a factorial experiment to investigate the effect of elevated salinity alone and in combination with each of 3 pesticides-atrazine, carbaryl, and glyphosate-on life history and behavior of southern toad larvae (Anaxyrus terrestris). Tadpoles were negatively affected by elevated salinity and by exposure to the insecticide carbaryl, with the most deleterious outcomes associated with both stressors combined. Carbaryl exposure led to reduced survival as well as sublethal effects on growth, activity and feeding behavior, escape response swimming, and time to metamorphosis. Tadpoles reared at elevated salinity were also smaller and less active, and ultimately metamorphosed later and at smaller size. Together, carbaryl and elevated salinity had a synergistic effect, resulting in particularly poor growth, depressed activity and feeding, and sluggish escape swimming among tadpoles exposed to both stressors simultaneously. These results suggest that both elevated salinity and carbaryl represent threats for amphibian populations and that pesticide exposure in salinized habitats may pose a particularly high risk.

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Section: Discussionmentioning

confidence: 99%

Assessment of interactive effects of elevated salinity and three pesticides on life history and behavior of southern toad (Anaxyrus terrestris) tadpoles

Wood

Welch

2015

Enviro Toxic and Chemistry

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“…In that study, genes important for thyroid function, such as thyroid receptor β, deiodinase (conversion of T4 to T3) and corticotropin‐releasing hormone binding protein were also upregulated. One other study has reported stimulatory effects on the rate of metamorphosis in the absence of co‐exposure, for exposure to atrazine at 1–100 µg/l, but not at lower (0.1 µg/l) nor higher (1000 µg/l) concentrations in the common South American toad ( Rhinella arenarum ) (Brodeur et al ., ).…”

Section: Metamorphosismentioning

confidence: 97%

Do hormone‐modulating chemicals impact on reproduction and development of wild amphibians?

Orton

Tyler

2014

Biological Reviews

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Globally, amphibians are undergoing a precipitous decline. At the last estimate in 2004, 32% of the approximately 6000 species were threatened with extinction and 43% were experiencing significant declines. These declines have been linked with a wide range of environmental pressures from habitat loss to climate change, disease and pollution. This review evaluates the evidence that endocrine-disrupting contaminants (EDCs) -pollutants that affect hormone systems -are impacting on wild amphibians and contributing to population declines. The review is limited to anurans (frogs and toads) as data for effects of EDCs on wild urodeles (salamanders, newts) or caecilians (limbless amphibians) are extremely limited. Evidence from laboratory studies has shown that a wide range of chemicals have the ability to alter hormone systems and affect reproductive development and function in anurans, but for the most part only at concentrations exceeding those normally found in natural environments. Exceptions can be found for exposures to the herbicide atrazine and polychlorinated biphenyls in leopard frogs (Rana pipiens) and perchlorate in African clawed frogs (Xenopus laevis). These contaminants induce feminising effects on the male gonads (including 'intersex' -oocytes within testes) at concentrations measured in some aquatic environments. The most extensive data for effects of an EDC in wild amphibian populations are for feminising effects of atrazine on male gonad development in regions across the USA. Even where strong evidence has been provided for feminising effects of EDCs, however, the possible impact of these effects on fertility and breeding outcome has not been established, making inference for effects on populations difficult. Laboratory studies have shown that various chemicals, including perchlorate, polychlorinated biphenyls and bromodiphenylethers, also act as endocrine disrupters through interfering with thyroid-dependent processes that are fundamental for amphibian metamorphosis. Perchlorate has also been shown to induce these effects in wild anuran populations from perchlorate-contaminated environments. Overall, the published data available suggest that some health effects observed in wild anuran populations, most notably intersex, likely have a chemical aetiology; however they derive only from very few anuran species and for a few pesticides at field sites in the USA. To understand better the impacts of EDCs on wild anuran populations, as well as other amphibian groups, assessment of fertility in exposed animals are required. Development of non-destructive biomarkers that are indicative of specific EDC-effect mechanisms are also needed to allow the study of vulnerable populations. This will help to distinguish the effects of EDCs from other environmental and/or genetic influences on development and reproduction.

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“…It has been reported that low, environmentally relevant levels of AZ can affect metamorphosis of tadpoles in several frog species (LaFiandra et al, 2008;Langlois et al, 2010;Brodeur et al, 2013;Rohr and McCoy, 2010;Zaya et al, 2011). Meanwhile, other studies showed that AZ can alter gonadal differentiation in developing Rana pipiens (Langlois et al, 2010).…”

Section: Introductionmentioning

confidence: 92%

Gene expression profiles in testis of developing male Xenopus laevis damaged by chronic exposure of atrazine

Sai¹,

Dong

Li³

et al. 2016

Chemosphere

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As a widely used herbicide, atrazine (AZ) has been extensively studied for its adverse effects on the reproductive system, especially feminization in male animals. However, the relationship of gene expression changes and associated toxicological endpoints remains unclear. In this study, developing Xenopus laevis tadpoles were exposed to concentration of AZ at 0.1, 1, 10 or 100 μg/L continuously. Compared with froglets in the control group, there were no significant differences in body length, body weight, liver weight and hepatosomatic index (HSI) of males in groups treated with AZ for 90 d. At 100 μg/L AZ treatment caused a significant reduction of gonad weight and gonadosomatic index (GSI) of males (p < 0.01). In addition, AZ at all dose levels caused testicular degeneration, especially in froglets from the groups with 0.1 and 100 μg/L which exhibited U-shaped dose-response trend. We further investigated the gene expression changes associated with the testicular degeneration induced by AZ. We found that the expression of 1165 genes was significantly altered with 616 upregulated and 549 downregulated compared to the expression profile of the control animals. KEGG analysis showed that genes which were significantly affected by AZ are mainly involved in arginine and proline metabolism, cell cycle, riboflavin metabolism, spliceosome, base excision repair and progesterone-mediated oocyte maturation pathway. Our results show that AZ may affect reproductive and immune systems by interference with the related gene expression changes during the male X. laevis development. The findings may help to clarify the feminization mechanisms of AZ in male X. laevis.

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Environmentally-relevant concentrations of atrazine induce non-monotonic acceleration of developmental rate and increased size at metamorphosis in Rhinella arenarum tadpoles

Cited by 59 publications

References 69 publications

Assessment of interactive effects of elevated salinity and three pesticides on life history and behavior of southern toad (Anaxyrus terrestris) tadpoles

Assessment of interactive effects of elevated salinity and three pesticides on life history and behavior of southern toad (Anaxyrus terrestris) tadpoles

Do hormone‐modulating chemicals impact on reproduction and development of wild amphibians?

Gene expression profiles in testis of developing male Xenopus laevis damaged by chronic exposure of atrazine

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