Recent concern for the adverse effects from neonicotinoid insecticides has centered on risk for insect pollinators in general and bees specifically. However, natural resource managers are also concerned about the risk of neonicotinoids to conservation efforts for the monarch butterfly (Danaus plexippus) and need additional data to help estimate risk for wild monarch butterflies exposed to those insecticides. In the present study, monarch butterfly larvae were exposed in the laboratory to clothianidin via contaminated milkweed plants from hatch until pupation, and the effects upon larval survival, larval growth, pupation success, and adult size were measured. Soils dosed with a granular insecticide product led to mean clothianidin concentrations of 10.8–2,193 ng/g in milkweed leaves and 5.8–58.0 ng/g in larvae. Treatment of soils also led to clothianidin concentrations of 2.6–5.1 ng/g in adult butterflies indicating potential for transfer of systemic insecticides from the soil through plants and larvae to adult butterflies. Estimated LC50s for total mortality (combined mortality of larvae and pupae) and EC50 for larval growth were variable but higher than the majority of concentrations reported in the literature for clothianidin contamination of leaves.

The distributions of PCB 105, 156, 189, and endosulfan in incubating, maternally exposed, viable white leghorn chicken eggs (Gallus domesticus) were investigated. Hens were subcutaneously injected every 4 days with a mixture of the above chemicals. One group of five eggs was removed from the incubator at each of 9, 14, and 19 days of incubation; dissected into three compartments (embryo, chorioallantoic membrane, and yolk + albumin); weighed; frozen; and then later analyzed for the dosing chemicals. Through 19 days of development (90% of incubation), greater than 70% of the total chemical mass in the whole egg remained within the yolk + albumin, whereas, depending on the chemical, 17% to 30% was absorbed by the embryo and 0.2% to 9% was transported into the chorioallantoic membrane. As a percentage of total PCB mass within the respective compartment, PCB 105 composition in the embryo and chorioallantoic membrane decreased significantly throughout development while PCB 156 and 189 composition increased significantly throughout development. Though endosulfan composition within any of the compartments was highly variable, it did not change significantly during development. The results of this study indicate that the majority of avian chick exposure to contaminants occurs posthatch as the chick continues to utilize the residual yolk.

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BackgroundThe eastern mosquitofish (Gambusia holbrooki) has the potential to become a bioindicator organism of endocrine disrupting chemicals (EDCs) due to its androgen-driven secondary sexual characteristics. However, the lack of molecular information on G. holbrooki hinders its use as a bioindicator coupled with biomarker data. While traditional gene-by-gene approaches provide insight for biomarker development, a holistic analysis would provide more rapid and expansive determination of potential biomarkers. The objective of this study was to develop and utilize a mosquitofish microarray to determine potential biomarkers of subchronic androgen exposure. To achieve this objective, two specific aims were developed: 1) Sequence a G. holbrooki cDNA library, and 2) Use microarray analysis to determine genes that are differentially regulated by subchronic androgen exposure in hepatic tissues of 17β-trenbolone (TB) exposed adult female G. holbrooki.ResultsA normalized library of multiple organs of male and female G. holbrooki was prepared and sequenced by the Illumina GA IIx and Roche 454 XLR70. Over 30,000 genes with e-value ≤ 10-4 were annotated and 14,758 of these genes were selected for inclusion on the microarray. Hepatic microarray analysis of adult female G. holbrooki exposed to the vehicle control or 1 μg/L of TB (a potent anabolic androgen) revealed 229 genes upregulated and 279 downregulated by TB (one-way ANOVA, p < 0.05, FDR α = 0.05, fold change > 1.5 and < −1.5). Fifteen gene ontology biological processes were enriched by TB exposure (Fisher’s Exact Test, p < 0.05). The expression levels of 17β-hydroxysteroid dehydrogenase 3 and zona pellucida glycoprotein 2 were validated by quantitative polymerase chain reaction (qPCR) (Student’s t-test, p < 0.05).ConclusionsCoupling microarray data with phenotypic changes driven by androgen exposure in mosquitofish is key for developing this organism into a bioindicator for EDCs. Future studies using this array will enhance knowledge of the biology and toxicological response of this species. This work provides a foundation of molecular knowledge and tools that can be used to delve further into understanding the biology of G. holbrooki and how this organism can be used as a bioindicator organism for endocrine disrupting pollutants in the environment.