Non-destructive methods to assess health of wild tropical frogs (túngara frogs: Engystomops pustulosus) in Trinidad reveal negative impacts of agricultural land.

Amphibians are threatened globally with at least 43% of species declining and the most important stressor being habitat loss or degradation. Amphibians inhabiting highly biodiverse tropical regions are disproportionately threatened; however, the effects of landscape alterations on amphibian health are virtually unknown. In this study, we utilised non-destructive techniques to compare size (weight, snout-vent length [SVL]), body condition, male secondary sexual features (forelimb width, nuptial pad length) and breeding success (egg number, fertility [percentage fertilised eggs], hatching success) in túngara frogs (Engystomops pustulosus) collected from reference (n = 5), suburban (n = 6) and agricultural (n = 4) sites in Trinidad; characterised by presence/absence of crops/houses.

Laboratory-Based Comparison for the Effects of Environmental Stressors Supports Field Evidence for the Relative Importance of Pollution on Life History and Behavior of the Pond Snail, .

Biodiversity is declining at an alarming rate globally, with freshwater ecosystems particularly threatened. Field-based correlational studies have "ranked" stressors according to their relative effects on freshwater biota, however, supporting cause-effect data from laboratory exposures are lacking. Here, we designed exposures to elicit chronic effects over equivalent exposure ranges for three ubiquitous stressors (temperature: 22-28 °C; pollution [14 component mixture]: 0.

A laboratory investigation into features of morphology and physiology for their potential to predict reproductive success in male frogs.

Amphibian populations are declining globally, however, the contribution of reduced reproduction to declines is unknown. We investigated associations between morphological (weight/snout-vent length, nuptial pad colour/size, forelimb width/size) and physiological (nuptial pad/testis histomorphology, plasma hormones, gene expression) features with reproductive success in males as measured by amplexus success and fertility rate (% eggs fertilised) in laboratory maintained Silurana/Xenopus tropicalis. We explored the robustness of these features to predict amplexus success/fertility rate by investigating these associations within a sub-set of frogs exposed to anti-androgens (flutamide (50 μg/L)/linuron (9 or 45 μg/L)).

Effects of Common Pesticides on Prostaglandin D2 (PGD2) Inhibition in SC5 Mouse Sertoli Cells, Evidence of Binding at the COX-2 Active Site, and Implications for Endocrine Disruption.

Background: There are concerns that diminished prostaglandin action in fetal life could increase the risk of congenital malformations. Many endocrine-disrupting chemicals have been found to suppress prostaglandin synthesis, but to our knowledge, pesticides have never been tested for these effects.

Objectives: We assessed the ability of pesticides that are commonly used in the European Union to suppress prostaglandin D2 (PGD2) synthesis.

Screening breeding sites of the common toad (Bufo bufo) in England and Wales for evidence of endocrine disrupting activity.

Anuran amphibians are often present in agricultural landscapes and may therefore be exposed to chemicals in surface waters used for breeding. We used passive accumulation devices (SPMD and POCIS) to sample contaminants from nine breeding sites of the Common toad (Bufo bufo) across England and Wales, measuring endocrine activity of the extracts in a recombinant yeast androgen screen (YAS) and yeast estrogen screen (YES) and an in vitro vitellogenin induction screen in primary culture of Xenopus laevis hepatocytes. We also assessed hatching, growth, survival, and development in caged larvae in situ, and sampled metamorphs for gonadal histopathology.

A novel biomarker for anti-androgenic activity in placenta reveals risks of urogenital malformations.

It has been hypothesized that the rise in male reproductive disorders over recent decades may at least be partially attributable to environmental factors, including chemical exposures, but observed associations with single chemicals were rather weak. The aim of this case-control study was to explore the relationship between exposure to mixtures of (anti-)androgenic chemicals during pregnancy and the risk of cryptorchidism and/or hypospadias in offspring, using the total effective xenobiotic burden of anti-androgens (TEXB-AA) as a biomarker. A subsample of 29 cases (16 of cryptorchidism, 12 of hypospadias, and one of both disorders) and 60 healthy controls was nested in a cohort of male newborns recruited between October 2000 and July 2002.

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

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.

Body size, nuptial pad size and hormone levels: potential non-destructive biomarkers of reproductive health in wild toads (Bufo bufo).

Amphibians are declining and fertility/fecundity are major drivers of population stability. The development of non-destructive methods to assess reproductive health are needed as destructive measures are fundamentally at odds with conservation goals for declining species. We investigated the utility of body size, nuptial pad size and forelimb width as non-destructive biomarkers of internal reproductive physiology, by analysing correlations with commonly used destructive methods in adult male toads (Bufo bufo) from a low human impact and a high human impact site.

Mixture effects at very low doses with combinations of anti-androgenic pesticides, antioxidants, industrial pollutant and chemicals used in personal care products.

Many xenobiotics have been identified as in vitro androgen receptor (AR) antagonists, but information about their ability to produce combined effects at low concentrations is missing. Such data can reveal whether joint effects at the receptor are induced at low levels and may support the prioritisation of in vivo evaluations and provide orientations for the grouping of anti-androgens in cumulative risk assessment. Combinations of 30 AR antagonists from a wide range of sources and exposure routes (pesticides, antioxidants, parabens, UV-filters, synthetic musks, bisphenol-A, benzo(a)pyrene, perfluorooctane sulfonate and pentabromodiphenyl ether) were tested using a reporter gene assay (MDA-kb2).

Batrachochytrium dendrobatidis infection and lethal chytridiomycosis in caecilian amphibians (Gymnophiona).

Batrachochytrium dendrobatidis (Bd) is commonly termed the 'amphibian chytrid fungus' but thus far has been documented to be a pathogen of only batrachian amphibians (anurans and caudatans). It is not proven to infect the limbless, generally poorly known, and mostly soil-dwelling caecilians (Gymnophiona). We conducted the largest qPCR survey of Bd in caecilians to date, for more than 200 field-swabbed specimens from five countries in Africa and South America, representing nearly 20 species, 12 genera, and 8 families.

Competitive androgen receptor antagonism as a factor determining the predictability of cumulative antiandrogenic effects of widely used pesticides.

Background: Many pesticides in current use have recently been revealed as in vitro androgen receptor (AR) antagonists, but information about their combined effects is lacking.

Objective: We investigated the combined effects and the competitive AR antagonism of pesticide mixtures.

Methods: We used the MDA-kb2 assay to test a combination of eight AR antagonists that did not also possess AR agonist properties ("pure" antagonists; 8 mix: fludioxonil, fenhexamid, ortho-phenylphenol, imazalil, tebuconazole, dimethomorph, methiocarb, pirimiphos-methyl), a combination of five AR antagonists that also showed agonist activity (5 mix: cyprodinil, pyrimethanil, vinclozolin, chlorpropham, linuron), and all pesticides combined (13 mix).

Agricultural intensity in ovo affects growth, metamorphic development and sexual differentiation in the common toad (Bufo bufo).

Pollution was cited by the Global Amphibian Assessment to be the second most important cause of amphibian decline worldwide, however, the effects of the agricultural environment on amphibians are not well understood. In this study, spawn from Bufo bufo was taken from four sites in England and Wales with varying intensities of arable agriculture. Spawn was either placed in tanks containing aged tap water (ex-situ, five replicates) or in cages at the native site (caged, five replicates).

Demasculinization and feminization of male gonads by atrazine: consistent effects across vertebrate classes.

Atrazine is the most commonly detected pesticide contaminant of ground water, surface water, and precipitation. Atrazine is also an endocrine disruptor that, among other effects, alters male reproductive tissues when animals are exposed during development. Here, we apply the nine so-called "Hill criteria" (Strength, Consistency, Specificity, Temporality, Biological Gradient, Plausibility, Coherence, Experiment, and Analogy) for establishing cause-effect relationships to examine the evidence for atrazine as an endocrine disruptor that demasculinizes and feminizes the gonads of male vertebrates.

Endocrine disrupting effects of herbicides and pentachlorophenol: in vitro and in vivo evidence.

The potential for agricultural chemicals to cause endocrine disruption (ED) in humans and wildlife is an increasing concern; however, the effects of commonly used pesticides at environmentally relevant concentrations are largely unknown. Therefore, 12 environmentally relevant pesticides (11 herbicides and pentachlorophenol (PCP)) were tested for their endocrine disrupting potential in two in vitro assays. A recombinant yeast screen was used to detect receptor mediated (anti-) estrogenic and (anti-) androgenic activity (concentration range: 0.

Effects of nitrate and atrazine on larval development and sexual differentiation in the northern leopard frog Rana pipiens.

Pollution from agrochemicals may be contributing to the global decline in amphibian populations. Environmentally relevant concentrations of nitrate and/or atrazine on anuran development and gonadal differentiation were tested. Four replicates of 20 tadpoles per tank (80/treatment) were exposed from Taylor-Kollros stage 2 to 3 to stage 23 to 34 to either 10 mg/L nitrate, 10 microg/L atrazine, a combined exposure of 10 mg/L nitrate plus 10 microg/L atrazine, or untreated controls.