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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

Mitochondrial staining in the gonads and the BmDronc gene expression levels under after exposure to CdTe QDs.Fifth instar larvae received vascular injection of CdTe QDs, QDs-Ala, or QDs-Gly per larva (10 μL at 32 μM per individual in Fig. 8A–F, and 10 μL at 64 μM in Fig. 8A–C per individual) at 48 h after molting, whereas the control organisms (CK) were injected with the same volume of pure water. (A) Fluorescence images showing the degree of mitochondrial damage in testes (♂) and ovaries (♀). (B) Merged images showing the organizational orientation of damaged mitochondria in the gonads. (C) Enlarged images showing the organizational orientation of damaged mitochondria in the gonads. a and b indicate enlarged images of the testes and ovaries within the box in Fig. 8A, respectively. b indicates an enlarged image of the ovary within the box in Fig. 8B. The gonads were collected and stained at 24 h after exposure to QDs. Mi, mitochondria. TOM, testis outer membrane. TIM, testis inner membrane. SCs, spermary cells. OOM, ovarian outer membrane. OM, ovariole membrane. Ov, ovarioles. Bars = 200 μm in (A,B), and 50 μm in (C). (D) Relative expression level (REL) of the BmDronc gene in gonads. The testes and ovaries were collected for qRT-PCR at 6 h, 24 h, and 48 h after exposure. The BmDronc gene transcript level was analyzed by qRT-PCR. The BmRP49 gene was selected as an internal control. *P < 0.05 and **P < 0.01 indicate significant differences (n = 3 technical repeats).
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f7: Mitochondrial staining in the gonads and the BmDronc gene expression levels under after exposure to CdTe QDs.Fifth instar larvae received vascular injection of CdTe QDs, QDs-Ala, or QDs-Gly per larva (10 μL at 32 μM per individual in Fig. 8A–F, and 10 μL at 64 μM in Fig. 8A–C per individual) at 48 h after molting, whereas the control organisms (CK) were injected with the same volume of pure water. (A) Fluorescence images showing the degree of mitochondrial damage in testes (♂) and ovaries (♀). (B) Merged images showing the organizational orientation of damaged mitochondria in the gonads. (C) Enlarged images showing the organizational orientation of damaged mitochondria in the gonads. a and b indicate enlarged images of the testes and ovaries within the box in Fig. 8A, respectively. b indicates an enlarged image of the ovary within the box in Fig. 8B. The gonads were collected and stained at 24 h after exposure to QDs. Mi, mitochondria. TOM, testis outer membrane. TIM, testis inner membrane. SCs, spermary cells. OOM, ovarian outer membrane. OM, ovariole membrane. Ov, ovarioles. Bars = 200 μm in (A,B), and 50 μm in (C). (D) Relative expression level (REL) of the BmDronc gene in gonads. The testes and ovaries were collected for qRT-PCR at 6 h, 24 h, and 48 h after exposure. The BmDronc gene transcript level was analyzed by qRT-PCR. The BmRP49 gene was selected as an internal control. *P < 0.05 and **P < 0.01 indicate significant differences (n = 3 technical repeats).

Mentions: The staining of mitochondria in the gonadal cells showed that mitochondrial debris, which was dyed green, was present in female gonadal cells at 24 h after the injection of 0.32 nmol CdTe QDs via the dorsal vein (Fig. 7A,B). Star-shaped swollen mitochondria were visible due to changes in membrane permeability, which are typical during apoptosis (Fig. 7C). When the concentration of QDs increased to 0.64 nmol, green mitochondrial debris was also found in the testis cells, where the green fluorescence in the testis inner membrane cells, particularly the four sperm chambers, was significantly greater than that in the germ cells inside the sperm chambers. In the female ovaries, the CdTe-QDs appeared to associate with the isolated mitochondria according to their inherent fluorescence (Fig. 7A,B).


Reproductive toxicity and gender differences induced by cadmium telluride quantum dots in an invertebrate model organism
Mitochondrial staining in the gonads and the BmDronc gene expression levels under after exposure to CdTe QDs.Fifth instar larvae received vascular injection of CdTe QDs, QDs-Ala, or QDs-Gly per larva (10 μL at 32 μM per individual in Fig. 8A–F, and 10 μL at 64 μM in Fig. 8A–C per individual) at 48 h after molting, whereas the control organisms (CK) were injected with the same volume of pure water. (A) Fluorescence images showing the degree of mitochondrial damage in testes (♂) and ovaries (♀). (B) Merged images showing the organizational orientation of damaged mitochondria in the gonads. (C) Enlarged images showing the organizational orientation of damaged mitochondria in the gonads. a and b indicate enlarged images of the testes and ovaries within the box in Fig. 8A, respectively. b indicates an enlarged image of the ovary within the box in Fig. 8B. The gonads were collected and stained at 24 h after exposure to QDs. Mi, mitochondria. TOM, testis outer membrane. TIM, testis inner membrane. SCs, spermary cells. OOM, ovarian outer membrane. OM, ovariole membrane. Ov, ovarioles. Bars = 200 μm in (A,B), and 50 μm in (C). (D) Relative expression level (REL) of the BmDronc gene in gonads. The testes and ovaries were collected for qRT-PCR at 6 h, 24 h, and 48 h after exposure. The BmDronc gene transcript level was analyzed by qRT-PCR. The BmRP49 gene was selected as an internal control. *P < 0.05 and **P < 0.01 indicate significant differences (n = 3 technical repeats).
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Related In: Results  -  Collection

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f7: Mitochondrial staining in the gonads and the BmDronc gene expression levels under after exposure to CdTe QDs.Fifth instar larvae received vascular injection of CdTe QDs, QDs-Ala, or QDs-Gly per larva (10 μL at 32 μM per individual in Fig. 8A–F, and 10 μL at 64 μM in Fig. 8A–C per individual) at 48 h after molting, whereas the control organisms (CK) were injected with the same volume of pure water. (A) Fluorescence images showing the degree of mitochondrial damage in testes (♂) and ovaries (♀). (B) Merged images showing the organizational orientation of damaged mitochondria in the gonads. (C) Enlarged images showing the organizational orientation of damaged mitochondria in the gonads. a and b indicate enlarged images of the testes and ovaries within the box in Fig. 8A, respectively. b indicates an enlarged image of the ovary within the box in Fig. 8B. The gonads were collected and stained at 24 h after exposure to QDs. Mi, mitochondria. TOM, testis outer membrane. TIM, testis inner membrane. SCs, spermary cells. OOM, ovarian outer membrane. OM, ovariole membrane. Ov, ovarioles. Bars = 200 μm in (A,B), and 50 μm in (C). (D) Relative expression level (REL) of the BmDronc gene in gonads. The testes and ovaries were collected for qRT-PCR at 6 h, 24 h, and 48 h after exposure. The BmDronc gene transcript level was analyzed by qRT-PCR. The BmRP49 gene was selected as an internal control. *P < 0.05 and **P < 0.01 indicate significant differences (n = 3 technical repeats).
Mentions: The staining of mitochondria in the gonadal cells showed that mitochondrial debris, which was dyed green, was present in female gonadal cells at 24 h after the injection of 0.32 nmol CdTe QDs via the dorsal vein (Fig. 7A,B). Star-shaped swollen mitochondria were visible due to changes in membrane permeability, which are typical during apoptosis (Fig. 7C). When the concentration of QDs increased to 0.64 nmol, green mitochondrial debris was also found in the testis cells, where the green fluorescence in the testis inner membrane cells, particularly the four sperm chambers, was significantly greater than that in the germ cells inside the sperm chambers. In the female ovaries, the CdTe-QDs appeared to associate with the isolated mitochondria according to their inherent fluorescence (Fig. 7A,B).

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&thinsp;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