Estradiol uptake, toxicity, metabolism, and adverse effects on cadmium-treated amphibian embryos.

Abstract

The exposure of Bufo arenarum embryos to 25 µmol/L 17β-estradiol (E 2 ) resulted in 100% lethality within 48 hr, whereas 10 µmol//L E 2 was the no observed effect concentration value for shortterm chronic (7 days) exposure. The toxicity profile curves show that lethal effects were proportional to the E 2 concentration and the time of exposure. The E 2 uptake resulted in 20.1 ng E 2 /mg embryo at 8 hr posttreatment, but 67.3% of this value was achieved during the first 30 min of incubation with this estrogen. Regarding metabolism, the embryos synthesize estrone (E 1 ) from E 2 by means of 17β-hydroxysteroid dehydrogenase. Simultaneous treatments of Bufo arenarum embryos with 1 mg/L Cd 2+ and 0.1, 1, or 10 µmol/L E 2 enhanced the lethality exerted by cadmium in 76.7, 80, and 83.3% of embryos, respectively. The results indicate that estrogenic endocrine disruptors could have an adverse effect on amphibian embryos and enhance the toxic effect of Cd on amphibian embryos. This study points to the possibility of using the AMPHITOX test as a screening method for potential endocrine disruption as well as the combined effects of chemical mixtures.

Cadmium-Induced Toxicity on Larvae of the Common Asian Toad Duttaphrynus Melanostictus (Schneider 1799): Evidence from Empirical Trials

“…It is noteworthy that tadpoles exposed to 1.0 mg L -1 and above suffered 100 % mortality while no mortality occurred in the controls indicating high survival rates in uncontaminated water. Cd-induced mortality was also dose-dependent (Pearson correlation r = 0.92, p \ 0.001) which is consistent with results of Fridman et al (2004) observed in amphibians.…”

Metalloestrogens: an emerging class of inorganic xenoestrogens with potential to add to the oestrogenic burden of the human breast

“…In rainbow trout, cadmium can act as an endocrine disrupter through alterations to oestrogen-regulated gene expression (LeGuevel et al, 2000;Vetillard and Bailhache, 2005). In amphibian embryos, exposure to oestradiol can be lethal and this effect could also be found following exposure to cadmium, and furthermore, exposure to cadmium and oestradiol simultaneously produced an additive effect on lethality (Fridman et al, 2004). These reports justify further research into the endocrine disrupting properties of cadmium and in vivo studies on other metalloestrogens are now needed.…”

Effects of copper on the egg development and hatching of a freshwater pulmonate snail Lymnaea luteola L.

“…Tripathi and Singh [12] reported the effects of cypermethrin and alphamethrin insecticides on the reproduction, hatching, and embryogenesis of an Indian freshwater pulmonate snail Lymnaea acuminata. Furthermore, L. luteola egg assay can also serve as a model species for an invertebrate embryo test, as, e.g., the subtropical zebra fish, Danio rerio for fish and vertebrates [13,14]. There are proteins [21].…”