The female rabbit was used to study (i) accumulation of lipophilic chlorinated hydrocarbons in genital tract tissues and (ii) subsequent morphological and functional effects after long-term low-dose exposure. Polychlorinated biphenyl (PCB), 1,1-di(p-chlorophenyl)-2,2,2-trichloroethane (DDT) and gamma-hexachlorocyclohexane (gamma-HCH) (dosages: 4, 3 and 0.8 mg per kg body weight, respectively) and a combination of these three components (and dosages) were administered to sexually mature rabbits over a period of 12-15 weeks. The animals were killed shortly before and at various times after ovulation. Accumulation of chlorinated hydrocarbons was high in ovarian, oviductal and uterine tissues, in follicular fluid and clearly detectable in uterine secretions. In follicular fluid, the concentration and patterns of congeners and isomers of PCB and DDT were distinctly different from serum. DDT- and gamma-HCH-treated animals showed a significantly reduced ovulation rate (P < 0.002 and 0.05, respectively). During early pregnancy DDT decreased serum progesterone levels and changed the protein pattern of uterine secretion. Functional effects, however, were much less expressed compared with the highly significant accumulation of the persistent organochlorines in the genital tract.
The commercial polychlorinated biphenyl (PCB) formulation Aroclor 1260 (4 mg/kg body weight), technical grade dichlorodiphenyltrichloroethane (DDT; 3 mg) and Lindane (gamma-hexachlorocyclohexane; 0.8 mg) were administered orally, either separately or in combination, to sexually mature female rabbits three times per week for 12-15 weeks. Oviductal and uterine luminal fluid, cleavage stage embryos (day 1 post coitum), blastocysts (day 6), fetuses, exocoelic fluid and placentae (day 11) were analysed, firstly for chlorinated hydrocarbon residues, and secondly for embryonic and fetal development. The doses applied were well tolerated by the treated animals. PCB and DDT accumulated in uterine secretions (day 6) but not in oviductal luminal fluid (day 1). Both chlorinated hydrocarbons were found in preimplantation blastocysts. Residues in day 11 fetuses were 16- (DDT) or 18-fold (PCB) higher than in day 6 blastocysts. Significant amounts were also detected in placental tissue and in exocoelic fluid. A specific accumulation of the highly chlorinated biphenyl congener no. 180 was noted in fetuses, placentae and exocoelic fluid. The clear accumulation of the chlorinated hydrocarbon compounds in luminal fluid and embryonic tissue is contrasted by rather weak effects on fertility. No statistically significant differences between treated animals and controls were observed for fertilization rate and pre- and post-implantation (up to day 11 post coitum) losses. However, in females exposed to PCB, a 20% higher loss of blastocysts was noticed, as compared with controls (P > 0.05). This effect was shown on day 6 of embryonic development and may be due to the embryotoxic activities of PCB.
The optical properties of 3D metacrystals made of gold nanoparticles in protein nanocages are studied. These metacrystals have sizes of tens of micrometers and are of high structural and optical quality. Through microspectroscopy measurements and model calculations it is demonstrated that the metacrystals show plasmonic absorption in the green wavelength range and are largely transparent in the red and infrared ranges. By using empty nanocages as placeholders in the metacrystal lattice, it is possible to control how strongly the metamaterial absorbs. Measurements on a pyramidal metacrystal show that it deflects visible light. The deflection shows evidence for anomalous refraction at short wavelengths and normal refraction at long wavelengths. The refractive dispersion is ascribed to the optical dispersion relation of the plasmonic metamaterial.
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