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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.


Related in: MedlinePlus

Effects of the duration of exposure to CdTe QDs on the levels of reactive oxygen species (ROS) in testes (A) and ovaries (B). (C) Merged images showing the organizational orientation of ROS in gonads. Fifth instar larvae received vascular injection of 0.32 nmol CdTe QDs, QDs-Ala, or QDs-Gly per larva (10 μL at 32 μM per individual) at 48 h after molting, whereas the control organisms (CK) were injected with the same volume of pure water. ROS were stained at 12 h, 48 h, or 72 h after exposure. TOM, testis outer membrane. TIM, testis inner membrane. SCs, spermary cells. OOM, ovarian outer membrane. OM, ovariole membrane. Ov, ovarioles. Bars = 200 μm.
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f6: Effects of the duration of exposure to CdTe QDs on the levels of reactive oxygen species (ROS) in testes (A) and ovaries (B). (C) Merged images showing the organizational orientation of ROS in gonads. Fifth instar larvae received vascular injection of 0.32 nmol CdTe QDs, QDs-Ala, or QDs-Gly per larva (10 μL at 32 μM per individual) at 48 h after molting, whereas the control organisms (CK) were injected with the same volume of pure water. ROS were stained at 12 h, 48 h, or 72 h after exposure. TOM, testis outer membrane. TIM, testis inner membrane. SCs, spermary cells. OOM, ovarian outer membrane. OM, ovariole membrane. Ov, ovarioles. Bars = 200 μm.

Mentions: Figure 6 shows that at 12 h after exposure to QDs, the ROS levels in the testes were higher compared with the control group and they continued to increase until 72 h after exposure, while the ROS levels in the ovaries were also higher than those in the control group at 12 h to 72 h after exposure to QDs (Fig. 6A). In contrast to the testes, although the ROS levels increased in the ovaries at 12–48 h after exposure, the levels were lower at 72 h after exposure compared with those at 48 h after exposure (Fig. 6B). The merged images in Fig. 6C show the organizational orientation of ROS in the gonads after exposure to QDs. In the testes, when the ROS levels were low, ROS mainly occurred in the inner membranes of the testis, which comprise squamous cells. As the ROS levels increased, they gradually appeared in the spermary cells. Very low levels of ROS were detected in the outer membrane of the testis, which contains no cells. In the ovaries, ROS also occurred rarely in the ovarian outer membrane, but they appeared very rapidly in the ovariole membrane, and even in the ovarioles. These results indicate that exposure to QDs induced the generation of ROS in the internal gonadal tissues and even in the germ cells. The changes in the ROS levels varied in the male and female gonads, but the ROS levels induced by exposure to QDs decreased faster in the ovaries compared with the testes, thereby indicating that the ovaries have a stronger oxidative stress regulatory function than the testes.


Reproductive toxicity and gender differences induced by cadmium telluride quantum dots in an invertebrate model organism
Effects of the duration of exposure to CdTe QDs on the levels of reactive oxygen species (ROS) in testes (A) and ovaries (B). (C) Merged images showing the organizational orientation of ROS in gonads. Fifth instar larvae received vascular injection of 0.32 nmol CdTe QDs, QDs-Ala, or QDs-Gly per larva (10 μL at 32 μM per individual) at 48 h after molting, whereas the control organisms (CK) were injected with the same volume of pure water. ROS were stained at 12 h, 48 h, or 72 h after exposure. TOM, testis outer membrane. TIM, testis inner membrane. SCs, spermary cells. OOM, ovarian outer membrane. OM, ovariole membrane. Ov, ovarioles. Bars = 200 μm.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f6: Effects of the duration of exposure to CdTe QDs on the levels of reactive oxygen species (ROS) in testes (A) and ovaries (B). (C) Merged images showing the organizational orientation of ROS in gonads. Fifth instar larvae received vascular injection of 0.32 nmol CdTe QDs, QDs-Ala, or QDs-Gly per larva (10 μL at 32 μM per individual) at 48 h after molting, whereas the control organisms (CK) were injected with the same volume of pure water. ROS were stained at 12 h, 48 h, or 72 h after exposure. TOM, testis outer membrane. TIM, testis inner membrane. SCs, spermary cells. OOM, ovarian outer membrane. OM, ovariole membrane. Ov, ovarioles. Bars = 200 μm.
Mentions: Figure 6 shows that at 12 h after exposure to QDs, the ROS levels in the testes were higher compared with the control group and they continued to increase until 72 h after exposure, while the ROS levels in the ovaries were also higher than those in the control group at 12 h to 72 h after exposure to QDs (Fig. 6A). In contrast to the testes, although the ROS levels increased in the ovaries at 12–48 h after exposure, the levels were lower at 72 h after exposure compared with those at 48 h after exposure (Fig. 6B). The merged images in Fig. 6C show the organizational orientation of ROS in the gonads after exposure to QDs. In the testes, when the ROS levels were low, ROS mainly occurred in the inner membranes of the testis, which comprise squamous cells. As the ROS levels increased, they gradually appeared in the spermary cells. Very low levels of ROS were detected in the outer membrane of the testis, which contains no cells. In the ovaries, ROS also occurred rarely in the ovarian outer membrane, but they appeared very rapidly in the ovariole membrane, and even in the ovarioles. These results indicate that exposure to QDs induced the generation of ROS in the internal gonadal tissues and even in the germ cells. The changes in the ROS levels varied in the male and female gonads, but the ROS levels induced by exposure to QDs decreased faster in the ovaries compared with the testes, thereby indicating that the ovaries have a stronger oxidative stress regulatory function than the testes.

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.


Related in: MedlinePlus