Relationship between DDE concentrations and laying sequence in eggs of two passerine species.

Passerine eggs make useful biomonitors of environmental pollutants. Among passerines, it is not known whether organochlorine contaminants in eggs within the same clutch are independent observations or follow a laying order effect. Intraclutch variation of DDE (1,1-dichloro-2,2-bis[(p-chlorophenyl)]ethylene) concentrations was studied in eggs collected from prothonotary warblers (Protonotaria citrea) and European starlings (Sturnus vulgaris) nesting on National Priority List sites in lower Alabama and central Colorado, respectively. All 209 eggs collected for this study contained detectable levels of DDE. Mean concentration of DDE across all prothonotary warbler eggs (mean 8.71 microg/g +/- 1.19, n = 20) was almost two orders of magnitude greater than mean concentrations of DDE in all starling eggs (mean 0.70 microg/g +/- 0.06, n = 189). In both species, there was a large amount of variability among individual eggs of the same clutch and no significant relationship between laying order and DDE concentration. Variation among eggs laid in the same sequential order was high and effectively masked any potential trends in laying order effect. We hypothesized that the variability was caused by the spatial heterogeneity of DDE on our study sites, the nature of egg development within a female passerine, or a combination of these factors. Investigators focusing on lipophilic contaminants should exercise caution when making inferences about contaminant concentrations in an entire clutch of passerine eggs after the collection and analysis of a single egg because our data show that DDE levels in a single egg collected for analysis do not consistently reflect DDE levels in the eggs remaining in the nest.

Effects of environmentally relevant concentrations of 2,3,7,8-TCDD on domestic chicken immune function and CYP450 activity: F1 generation and egg injection studies.

Domestic chickens (Gallus gallus) were used as a surrogate species for wild turkey to assess risk from environmental 2,3,7,8-TCDD exposure. Lymphocyte proliferation and CYP450 induction were assessed in adults exposed via i.m. injection, in F1 14-day old hatchlings, in F1 adults (30-weeks old), and in 14-day old hatchlings exposed via yolk sac injections. Hatchlings from injected eggs exhibited a dose-response in lymphocyte proliferation, IgM titers, EROD, and PROD endpoints. Exposed adults showed a significant dose-dependent increase in CYP450 induction. F1 14-day old chicks exhibited a significant dose-dependent suppression of B-cell proliferation and induction of CYP450 enzymes. F1 adult proliferative responses exhibited B-cell suppression, that was not statistically significant. Significant sex-dependent EROD and MROD induction was also observed in F1 adults, indicating mixed-function oxidase imprinting from maternal exposure.