Induction of adaptive response in utero by ionizing radiation:A radiation quality dependent phenomenon

Investigation on possible induction of adaptive response(AR)by high-liner energy transfer(LET)particle radiation for protection against low-LET photon radiation-induced detrimental effects has not yet been performed in utero.This study verified if an AR could be induced by high-LET particle radiation from accelerated heavy ions against low-LET X-ray radiation-induced detrimental effects on fetal mice.Total body irradiation of pregnant C57BL/6J mice were performed by delivering a priming dose ranging from 10 mGy to 320 mGy of particle radiation on gestation day 11 followed one day later by a challenge dose at 3500 mGy from X-ray radiation.The monoenergetic beams of carbon,silicon and iron with the LET values of about 15,55,and 200 KeV/μm,respectively,were examined.Significant suppression by the priming radiation of the detrimental effects(fetal death,malformation,or low body weight)was used as the endpoints for judgment of a successful AR induction on gestation day 18.Existence of AR was not observed.On the other hand,the priming dose of high-LET particle radiation,in some cases,even increased the detrimental effects induced by the challenge dose from low-LET X-ray radiation.Although existence of AR induced by high-LET radiation in cultured mammalian cells in vitro and in certain tissues of laboratory mice in vivo was demonstrated,the present study did not suggest that low dose of high-LET particle radiation could induce an AR in fetal mice in utero under the setup of our experimental system.

The Effect of Aqueous Extract of Cecropia glazioui Snethlage (Embauba) in the Rat Fetal Development

The effect of aqueous extract of Cecropia glazioui Snethlage (Embauba) in the rat fetal development. This study was to complement previous assays on the physical and neurobehavioral development of rats resulted from oral administration of 1 g/kg/day Cecropia glazioui Snethlage (C. glazioui) aqueous extract (LD50 > 5 g·kg-1in pregnant rats (peri- and post-natal studies). In the present study, the effect of 2.5 g/kg/week C. glazioui aqueous extract, administered to pregnant rats during 15 days, was verified in the rat offspring development. No acute or chronic toxicity (no effects on mortality or weight average daily gain) were observed. In addition, no effects on reproductive parameters (offspring vitality, placenta and fetus weight, number of corpora lutea on each ovary, pre- and post-implantation loss) and on offspring external morphology were found. We concluded that C. glazioui aqueous extract administered during pregnancy did not cause abnormalities in rat offspring.

Low concentrations of atrazine,glyphosate,2,4-dichlorophenoxyacetic acid,and triadimefon exposures have diverse effects on Xenopus laevis organ morphogenesis

Many chemicals are released into the environment, and chemical contamination has been suggested as a contributing factor to amphibian declines. To add to a growing body of knowledge about the impact of individual chemicals on non-target organisms, we examined the specificity of deformities induced by exposure to four pesticides （atrazine, 2,4-dichloropheoxyacetic acid （2,4-D）, triadimefon, and glyphosate） in the model amphibian species, Xenopus laevis. We focused on the period of organ morphogenesis, as it is frequently found to be particularly sensitive to chemical exposure yet also commonly overlooked. We found similar levels of intestine malformations and edemas, as well as disruption of skeletal muscle, in atrazine and triadimefon exposed tadpoles. The effects of 2,4-D were only apparent at the highest concentrations we examined; glyphosate did not induce dramatic malformations at the concentrations tested. While researchers have shown that it is important to understand how chemical mixtures affect non-target organisms, our results suggest that it is first crucial to determine how these chemicals act independently in order to be able to identify consequences of individual pesticide exposure.