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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 e ects 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 a ect 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. 相似文献
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甲基汞暴露不同时期对大鼠胚胎致畸作用的研究 总被引:1,自引:0,他引:1
本文应用全胚胎培养模型探讨了致畸物甲基汞(04μG/ml)在器官形成早期暴露不同时期后,对大鼠胚胎生长发育的影响。结果显示早期暴露6h,畸胎发生率为333%;12h,绝大多数反映胚胎生长发育和器官形态分化的指标埴均明显降低且50%的胚胎出现多种畸形表现,例如,神经管未闭、心包积液及脑部形态异常等;暴露24h和48h,甲基汞对胚胎发育的抑制作用及诱发的畸胎率匀与12h的结果类似(p>005);但在晚期暴露12h,未见胚胎发育异常。结果提示体外培养胚胎对甲基汞的敏感时期约在1—12h这一期间 相似文献
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J.H.J. Copius Peereboom‐Stegeman 《毒物与环境化学》2013,95(4):273-292
Successful reproduction requires a well developed genital tract, including a good cooperation between hypothalamus, pituitary, ovaries and uterus on the female side and good sperm quality and motility on the male side. Heavy metals may interact with every single step of these processes, and after successful implantation the feto‐placental unit may be another target for heavy metal toxicity. In this review the reproduction process and the interaction of the heavy trace elements Cd (cadmium), Pb (lead) and Hg (mercury) are described. 相似文献
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Papis E Bernardini G Gornati R Prati M 《Environmental science and pollution research international》2006,13(4):251-255
- DOI: http://dx.doi.org/10.1065/espr2006.01.014
Background, Aims and Scope Triazole-derivatives are potent antifungal agents used as systemic agricultural fungicides and against fungal diseases in
humans and domestic animals. They act by inhibiting the cytochrome P-450 conversion of lanosterol to ergosterol, thus resulting
in faulty fungal cell wall synthesis. Some data have been published about the teratogenic activity of triazoles on rodent
embryos: Hypoplasias, abnormal shape, agenesis of the branchial arches, for example, were reported as typical induced malformations.
Unfortunately, no data are available on the embryotoxicity of these compounds in amphibians, despite the increasing concern
among the scientific community about the phenomenon of global amphibian population declines. The aim of the present work is
to evaluate the embryo-lethal and teratogenic potentials of Triadimefon (FON), a triazolederivative widely used as an antimycotic
in agriculture, by the test FETAX (Frog Embryos Teratogenic Assay, Xenopus) with particular attention being paid to the analysis
of branchial arch malformations.
Methods Xenopus laevis embryos were exposed continuously from stage 9 to increasing concentrations of FON and analyzed at stage 47
for mortality and teratogenicity (group I) to determine the median lethal (LC50) and teratogenic (TC50) concentrations. Another
two pools of larvae were exposed to FON for a 2 hour period at early gastrula (Group II) or neurula (Group III) stages to
verify which period of development is the most sensitive to FON. The malformations observed were further investigated by histological
section and cartilage staining with Alcian blue.
Results and Discussion The assay has estimated LC50 and TC50 values of 63.8 μM and 2.73 μM, respectively; the resulting TI (Teratogenic Index =
LC50/TC50) value of 23.4 has underlined the very high teratogenic risk associated with this compound. Neurulation was more
sensitive to FON exposure than gastrulation, since the TC50 estimated values for group III (neurula exposed) specimens was
7.6 times lower than those of group II (gastrula exposed). Interestingly, for each group analyzed, 100% of malformed embryos
showed alterations at branchial arch derived cartilages: Anterior cartilages were reduced, missing, fused or incorrectly positioned
while gill cartilages were altered only in the most severely affected specimens. In some cases these malformations were associated
with hyperpigmentation. Our results support the hypothesis that FON can interfere with Neural Crest Cell (NCC) migration,
since craniofacial components and melanophores are derived from neural crest material.
Conclusion In conclusion, our data show Triadimefon to be a potent teratogen able to induce specific craniofacial malformation in Xenopus
laevis embryos, probably interfering with the NCC migration into the branchial mesenchyme. These results are also interesting
for ecotoxicological reasons as FON, as well as other pesticides, are likely to be present in water systems near agricultural
or urban areas which may serve as habitats for developing amphibians and fishes.
Recommendation and Outlook Our results are in agreement with the data obtained on in vitro cultured rat embryos suggesting that the FON mechanism of
action involves strongly conserved molecules. The choice of Xenopus laevis as the model organism allows us to extend the toxicological
and teratological observations to a molecular level, in order to search for novel genes regulated by FON exposure. 相似文献
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