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Kamata R, Shiraishi F, Takahashi S, Shimizu A, Shiraishi H: Reproductive and developmental effects of transovarian exposure to o,p'-DDT in Japanese quails. Environ Toxicol Chem. 2008 Dec 31:1.
Avian species have the possible risk of embryonic exposure to persistent, lipophilic environmental contaminants, such as DDT, by transfer of chemicals accumulated in mother birds to eggs. To model developmental and reproductive disorders of wild birds living in contaminated areas we exposed Japanese quails in ovo to o,p'-DDT prior to incubation. o,p'-DDT (1 to 100 mug/g of egg) and a positive estrogenic substance, diethylstilbestrol (DES, 1 and 10 ng/g of egg), were injected into the yolk before incubation. Treatment with o,p'-DDT (10 or 100 mug/g), but not with DES, significantly reduced the hatchability of eggs. After sexual maturation, o,p'-DDT affected eggshell formation in female quails but had little influence on laying; high doses of o,p'-DDT significantly reduced eggshell strength, shell weight and shell thickness, and several females treated with 100 mug o,p'-DDT/g laid eggs lacking shells. DES decreased egg production itself but had little effect on the eggshell. Both o,p'-DDT and DES caused dose-dependent shortening of the left oviduct and abnormal development of the right oviduct in females, while testis asymmetry was observed in males treated with a high dose of DES. In the uterus of the oviduct, the mRNAs for calcium regulating factors osteopontin and calbindin D28K were dose-dependently reduced by both treatments, particularly that with o,p'-DDT. The results indicated that transovarian exposure to o,p'-DDT could bring about population declines in avian species through loss of fecundity caused by depression of hatchability and dysfunction of the reproductive tract. |
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