To monitor genotoxicity in small bodies of water (e.g., creeks, ponds, and drainage ditches) we examined tadpole erythrocytes of two species: Rana clamitans and Rana pipiens,using the alkaline single cell gel DNA electrophoresis (SCG) or "comet" assay. This approach involves detection, under alkaline conditions, of cell DNA fragments which on electrophoresis migrate from the nuclear core, resul...

Anti-parasite behaviour can reduce parasitic infections, but little is known about how such behaviours affect infection location within the host's body and whether parasite distribution ultimately affects tolerance of infection. To assess these questions, we exposed both anaesthetized (no behaviour) and non-anaesthetized Hyla femoralis tadpoles to plagiorchiid cercariae (larval trematodes), and...

Tadpoles of several amphibian species have been shown to accelerate metamorphosis when their ponds dry. To understand the proximate mechanisms that mediate the developmental response to pond drying, I analyzed changes in endocrine activity in tadpoles of the Western spadefoot toad (Scaphiopus hammondii) exposed to experimental water volume reduction in the laboratory. Tadpoles exposed to a decl...

Central CO(2) chemosensitivity is crucial for all air-breathing vertebrates and raises the question of its role in ventilatory rhythmogenesis. In this study, neurograms of ventilatory motor outputs recorded in facial nerve of premetamorphic and postmetamorphic tadpole isolated brainstems, under normo- and hypercapnia, are investigated using Continuous Wavelet Transform spectral analysis for buc...

Most studies of predator-induced plasticity have focused on documenting how prey species respond to predators by modifying phenotypic traits and how traits correlate with fitness. We have previously shown that Pleurodema thaul tadpoles exposed to the dragonfly Rhionaeschna variegata responded strongly by showing morphological changes, less activity, and better survival than non-exposed tadpoles...

The morphology and distribution of lateral line neuromasts vary between ecomorphological types of anuran tadpoles, but little is known about how this structural variability contributes to differences in lateral-line mediated behaviors. Previous research identified distinct differences in one such behavior, positive rheotaxis towards the source of a flow, in two tadpole species, the African claw...

In orbifold gauge theories localized tadpoles can be radiatively generated at the fixed points where U(1) subgroups are conserved. If the Standard Model Higgs fields are identified with internal components of the bulk gauge fields (Higgs-gauge unification) in the presence of these tadpoles the Higgs mass becomes sensitive to the UV cutoff and electroweak symmetry breaking is spoiled. We find th...

T H E accelerated transformation of frog tadpoles to adults by thyroid feeding and also iodine, demonstrated by many workers since Gudernatsch's original experiments, and further, the inability of thyroidless tadpoles to change unless given either thyroid or iodine (Swingle), has established the importance of both thyroid and iodine in amphibian metamorphosis. Various glands of internal secreti...

We examined indices of thyroid development in tadpoles from ammonium perchlorate (AP)-exposed sites. Bullfrog (Rana catesbeiana) tadpoles collected from a reference site exhibited normal developmental features, with many completing metamorphoses. In contrast, tadpoles collected from the AP contaminated site exhibited a 5-fold lower hindlimb/snout-vent length ratio than tadpoles from the referen...

1. While the antipredator behaviour of prey has been well studied, little is known about the rules governing the predation risk assessment of prey. In this study, I measured the activity levels of predator-naive green frog (Rana clamitans) tadpoles during and after exposures to the chemical cue of predatory larval dragonflies (Anax spp.). I then used the lengths of the time lags from the end of...