Insecticide has asymmetric effects on two tadpole species despite priority effects.

Priority effects are defined as asymmetric responses of different species colonizing the same habitat in different sequences and are important in structuring communities, particularly for ephemeral systems that are colonized annually. Amphibians often use ephemeral ponds and have been shown to experience priority effects from interspecific competition. Pesticide exposure can impact amphibian species interactions like competition, and has been linked to declines.

Pesticide has asymmetric effects on two tadpole species across density gradient.

Northern leopard frogs (Rana pipiens) have been disappearing throughout their range. The causes for extirpations have been elusive, although habitat alteration appears to be a major factor. Pesticides have been implicated in declines in western amphibians, but no mechanism has been identified.

Carbaryl concentration gradients in realistic environments and their influence on our understanding of the tadpole food web.

Although exposure to pesticides has been correlated with amphibian declines, the mechanism of their role remains enigmatic. Declines have been associated with sublethal exposure, but few outdoor studies have evaluated impacts of low pesticide concentrations. Understanding the effects of a range of pesticide concentrations on amphibians in outdoor mesocosms provides a framework for both direct and indirect effects of exposure.

Effects of aquatic and terrestrial carbaryl exposure on feeding ability, growth, and survival of American toads.

The present study evaluates whether larval density and aquatic exposure to the insecticide carbaryl influenced susceptibility to terrestrial exposure of carbaryl through effects on juvenile feeding ability, growth, and survival with metamorphs of American toads (Bufo americanus). Tadpoles were reared in outdoor mesocosms, and individuals were brought into the lab at metamorphosis for terrestrial exposure studies. The present study indicated that feeding and survival of toads after metamorphosis was not affected by earlier aquatic or subsequent terrestrial exposure; therefore, the impacts of short-lived insecticides may be most significant to aquatic, larval stages.

Effects of aquatic exposure to the insecticide carbaryl and density on aquatic and terrestrial growth and survival in American toads.

No single mechanism has been explicitly linked to explain global amphibian declines, but pesticides have been implicated as potential drivers. In mesocosm experiments, we tested the hypotheses that American toads (Bufo americanus) would respond differently to the insecticide carbaryl at low or high density (i.e.

STAT3- and STAT5-dependent pathways competitively regulate the pan-differentiation of CD34pos cells into tumor-competent dendritic cells.

The clinical outcomes of dendritic cell (DC)-based immunotherapy remain disappointing, with DCs often displaying a tenuous capacity to complete maturation and DC1 polarization in the tumor host. Surprisingly, we observed that the capacity for successful DC1 polarization, including robust IL12p70 production, could be regulated by STAT-dependent events even prior to DC differentiation. Exposure of CD34(pos) cells to single-agent granulocyte-macrophage colony-stimulating factor (GMCSF) induced multilineage, STAT5-dependent differentiation, including DCs that failed to mature in the absence of further exogenous signals.