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Reproductive toxicity and gender differences induced by cadmium telluride quantum dots in an invertebrate model organism

View Article: PubMed Central - PubMed

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.

No MeSH data available.


Effects of QDs on oviposition and fertilization.(A) Type of egg laid and remaining eggs in the ovaries. (B) Egg-laying habits and fertilization of eggs. Fifth instar larvae received vascular injection of 0.32 nmol CdTe QDs per individual (10 μL at 32 μM) at 48 h after molting, whereas the control organisms (CK) were injected with the same volume of pure water. The larvae were reared on fresh mulberry leaves at 25 °C with a photoperiod of 12 h light and 12 h dark until they became adult moths. The female adults were mated for 4 h with descriptive mates and then laid eggs 24 h. Next, the ovaries were removed from the female moths to determine the remaining eggs. The yellow unfertilized eggs and puce fertilized eggs were measured at 72 h after oviposition. n = 5 pairs.
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f2: Effects of QDs on oviposition and fertilization.(A) Type of egg laid and remaining eggs in the ovaries. (B) Egg-laying habits and fertilization of eggs. Fifth instar larvae received vascular injection of 0.32 nmol CdTe QDs per individual (10 μL at 32 μM) at 48 h after molting, whereas the control organisms (CK) were injected with the same volume of pure water. The larvae were reared on fresh mulberry leaves at 25 °C with a photoperiod of 12 h light and 12 h dark until they became adult moths. The female adults were mated for 4 h with descriptive mates and then laid eggs 24 h. Next, the ovaries were removed from the female moths to determine the remaining eggs. The yellow unfertilized eggs and puce fertilized eggs were measured at 72 h after oviposition. n = 5 pairs.

Mentions: In B. mori, the 5th larval stage, which lasts about 1 week, is the key stage for spermatogenesis in the testes and oogenesis in the ovaries37. In this study, 5th instar larvae in the early stage of the silkworm life cycle were exposed to 0.32 nmol CdTe QDs via a single dorsal vein injection. The results showed that QDs had a significant impact on oviposition by the adults during the later stage of the life cycle and fertilization of the offspring eggs. When a pair of male and female silkworms was exposed to QDs, almost all of the eggs laid by female moths were not capable of being fertilized and some eggs in their ovaries were not laid, thereby indicating that QDs can severely affect reproductive toxicity (Fig. 2A). It should be noted that if only one of the pair was exposed to QDs, the impact of QDs on oviposition and fertilization varied greatly. Exposing female larvae to QDs changed the oviposition behavior of the female moths, including increased eggs remaining in the body, but the fertilization of the laid eggs was almost normal. When a male larva was exposed to QDs, the male moth mated later with a normal female moth and the fertilization rate of the laid eggs was significantly reduced (Fig. 2A). This phenomenon was confirmed by quantitative comparisons using multiple duplicate individuals (Fig. 2B and Fig. S2).


Reproductive toxicity and gender differences induced by cadmium telluride quantum dots in an invertebrate model organism
Effects of QDs on oviposition and fertilization.(A) Type of egg laid and remaining eggs in the ovaries. (B) Egg-laying habits and fertilization of eggs. Fifth instar larvae received vascular injection of 0.32 nmol CdTe QDs per individual (10 μL at 32 μM) at 48 h after molting, whereas the control organisms (CK) were injected with the same volume of pure water. The larvae were reared on fresh mulberry leaves at 25 °C with a photoperiod of 12 h light and 12 h dark until they became adult moths. The female adults were mated for 4 h with descriptive mates and then laid eggs 24 h. Next, the ovaries were removed from the female moths to determine the remaining eggs. The yellow unfertilized eggs and puce fertilized eggs were measured at 72 h after oviposition. n = 5 pairs.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5037452&req=5

f2: Effects of QDs on oviposition and fertilization.(A) Type of egg laid and remaining eggs in the ovaries. (B) Egg-laying habits and fertilization of eggs. Fifth instar larvae received vascular injection of 0.32 nmol CdTe QDs per individual (10 μL at 32 μM) at 48 h after molting, whereas the control organisms (CK) were injected with the same volume of pure water. The larvae were reared on fresh mulberry leaves at 25 °C with a photoperiod of 12 h light and 12 h dark until they became adult moths. The female adults were mated for 4 h with descriptive mates and then laid eggs 24 h. Next, the ovaries were removed from the female moths to determine the remaining eggs. The yellow unfertilized eggs and puce fertilized eggs were measured at 72 h after oviposition. n = 5 pairs.
Mentions: In B. mori, the 5th larval stage, which lasts about 1 week, is the key stage for spermatogenesis in the testes and oogenesis in the ovaries37. In this study, 5th instar larvae in the early stage of the silkworm life cycle were exposed to 0.32 nmol CdTe QDs via a single dorsal vein injection. The results showed that QDs had a significant impact on oviposition by the adults during the later stage of the life cycle and fertilization of the offspring eggs. When a pair of male and female silkworms was exposed to QDs, almost all of the eggs laid by female moths were not capable of being fertilized and some eggs in their ovaries were not laid, thereby indicating that QDs can severely affect reproductive toxicity (Fig. 2A). It should be noted that if only one of the pair was exposed to QDs, the impact of QDs on oviposition and fertilization varied greatly. Exposing female larvae to QDs changed the oviposition behavior of the female moths, including increased eggs remaining in the body, but the fertilization of the laid eggs was almost normal. When a male larva was exposed to QDs, the male moth mated later with a normal female moth and the fertilization rate of the laid eggs was significantly reduced (Fig. 2A). This phenomenon was confirmed by quantitative comparisons using multiple duplicate individuals (Fig. 2B and Fig. S2).

View Article: PubMed Central - PubMed

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.

No MeSH data available.