Abstract
Sexual glands are key sites affected by nanotoxicity, but there is no sensitive assay for measuring reproductive toxicity in animals. The aim of this study was to investigate the toxic effects of cadmium telluride quantum dots (CdTe-QDs) on gonads in a model organism, Bombyx mori. After dorsal vein injection of 0.32 nmol of CdTe-QDs per individual, the QDs passed through the outer membranes of gonads via the generation of ROS in the membranes of spermatocysts and ovarioles, as well as internal germ cells, thereby inducing early germ cell death or malformations via complex mechanisms related to apoptosis and autophagy through mitochondrial and lysosomal pathways. Histological observations of the gonads and quantitative analyses of germ cell development showed that the reproductive toxicity was characterized by obvious male sensitivity. Exposure to QDs in the early stage of males had severe adverse effects on the quantity and quality of sperm, which was the main reason for the occurrence of unfertilized eggs. Ala- or Gly-conjugated QDs could reduce the nanotoxicity of CdTe-QDs during germ cell development and fertilization of their offspring. The results demonstrate that males are preferable models for evaluating the reproductive toxicity of QDs in combined in vivo/in vitro investigations.
Highlights
Sexual glands are key sites affected by nanotoxicity, but there is no sensitive assay for measuring reproductive toxicity in animals
We showed that quantum dots (QDs) can rapidly enter circulating blood cells in silkworms after dorsal vein injection of 0.08 or 0.32 nmol CdTe QDs per larva (10 μLat 8 μMor 32 μM per individual), thereby reducing the capacity for hematopoiesis[6]
We further investigated the effects of modifying the surfaces of QDs with amino acids on their transfer into the reproductive system
Summary
Sexual glands are key sites affected by nanotoxicity, but there is no sensitive assay for measuring reproductive toxicity in animals. The aim of this study was to investigate the toxic effects of cadmium telluride quantum dots (CdTe-QDs) on gonads in a model organism, Bombyx mori. Histological observations of the gonads and quantitative analyses of germ cell development showed that the reproductive toxicity was characterized by obvious male sensitivity. An in vivo animal experiment showed that CdTe/CdS QDs may be transferred from female mice to their fetuses across the placental barrier[23]. In vitro experiments have demonstrated that CdSe-core QDs induced apoptosis in incubated mouse blastocysts, as well as inhibiting cell proliferation, retarding early post-implantation blastocyst development, increasing early-stage blastocyst death[23], and reducing the rates of oocyte maturation and fertilization, whereas the same effects were not obtained with ZnS-coated CdSe QDs24. The reproductive toxicity of QDs is still a controversial issue and the possible mechanism involved remains unknown in mammals
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