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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

Staining of lysosomes in gonads and the BmAgt6/BmAtg8 gene expression levels 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 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 lysosome level in testes (♂) and ovaries (♀). (B) Merged images showing the organizational orientation of dyed lysosomes in gonads. (C) Enlarged images showing the organizational orientation of dyed lysosomes in gonads. a and c indicate the enlarged images of testes and ovaries within the box in Fig. 8A, respectively. b indicates the enlarged image of ovaries within the box in Fig. 8A. The gonads were collected and stained at 24 h after exposure to QDs. Ly, lysosome. SCs, spermary cells. Ov, ovarioles. Bars = 200 μm in (A) and (B), and 50 μm in (C). Relative expression levels (REL) of the BmAtg6 and BmAtg8 genes in testes (D) and ovaries (E) determined by qPCR. The gonads were collected for qRT-PCR at 6 h, 24 h, and 48 h after exposure to QDs. The BmAtg6 and BmAtg8 gene transcript levels were analyzed by qRT-PCR. The BmRP49 gene was selected as an internal control. Samples marked with the same letter do not differ significantly from each other, P < 0.05 (n = 3 technical repeats).
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f8: Staining of lysosomes in gonads and the BmAgt6/BmAtg8 gene expression levels 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 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 lysosome level in testes (♂) and ovaries (♀). (B) Merged images showing the organizational orientation of dyed lysosomes in gonads. (C) Enlarged images showing the organizational orientation of dyed lysosomes in gonads. a and c indicate the enlarged images of testes and ovaries within the box in Fig. 8A, respectively. b indicates the enlarged image of ovaries within the box in Fig. 8A. The gonads were collected and stained at 24 h after exposure to QDs. Ly, lysosome. SCs, spermary cells. Ov, ovarioles. Bars = 200 μm in (A) and (B), and 50 μm in (C). Relative expression levels (REL) of the BmAtg6 and BmAtg8 genes in testes (D) and ovaries (E) determined by qPCR. The gonads were collected for qRT-PCR at 6 h, 24 h, and 48 h after exposure to QDs. The BmAtg6 and BmAtg8 gene transcript levels were analyzed by qRT-PCR. The BmRP49 gene was selected as an internal control. Samples marked with the same letter do not differ significantly from each other, P < 0.05 (n = 3 technical repeats).

Mentions: The lysosomal staining results shown in Fig. 8A and B demonstrates that lysosomal-specific red fluorescence was present in the testis and ovarian cells at 24 h after exposure to 0.32 nmol CdTe QDs. When the concentration of QDs increased to 0.64 nmol, the red fluorescence in the testes and ovaries indicated that the abundance of lysosomes increased. In contrast to the mitochondrial staining results shown in Fig. 7, the increased levels of lysosomes in gonad cells caused by exposure to QDs did not exhibit obvious gender differences, thereby suggesting that after exposure to the low dose of QDs employed in the experiment, oxidative stress could induce the formation of lysosomes in both male and female gonadal cells. The enlarged image in Fig. 8C shows that the mitochondria generating positions were different from those in Fig. 7, where the red fluorescence from lysosomes occurred mainly in germ cells inside the gonadal tissues, with bright red scattered spermatocysts with various shapes visible through the outer membrane of the testes (Fig. 8C-a), and the red fluorescence in female ovarioles was arranged in the shape of spinal bone spurs or combined into a single piece when more lysosomes were generated (Fig. 8C-b,c).


Reproductive toxicity and gender differences induced by cadmium telluride quantum dots in an invertebrate model organism
Staining of lysosomes in gonads and the BmAgt6/BmAtg8 gene expression levels 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 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 lysosome level in testes (♂) and ovaries (♀). (B) Merged images showing the organizational orientation of dyed lysosomes in gonads. (C) Enlarged images showing the organizational orientation of dyed lysosomes in gonads. a and c indicate the enlarged images of testes and ovaries within the box in Fig. 8A, respectively. b indicates the enlarged image of ovaries within the box in Fig. 8A. The gonads were collected and stained at 24 h after exposure to QDs. Ly, lysosome. SCs, spermary cells. Ov, ovarioles. Bars = 200 μm in (A) and (B), and 50 μm in (C). Relative expression levels (REL) of the BmAtg6 and BmAtg8 genes in testes (D) and ovaries (E) determined by qPCR. The gonads were collected for qRT-PCR at 6 h, 24 h, and 48 h after exposure to QDs. The BmAtg6 and BmAtg8 gene transcript levels were analyzed by qRT-PCR. The BmRP49 gene was selected as an internal control. Samples marked with the same letter do not differ significantly from each other, P < 0.05 (n = 3 technical repeats).
© Copyright Policy - open-access
Related In: Results  -  Collection

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f8: Staining of lysosomes in gonads and the BmAgt6/BmAtg8 gene expression levels 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 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 lysosome level in testes (♂) and ovaries (♀). (B) Merged images showing the organizational orientation of dyed lysosomes in gonads. (C) Enlarged images showing the organizational orientation of dyed lysosomes in gonads. a and c indicate the enlarged images of testes and ovaries within the box in Fig. 8A, respectively. b indicates the enlarged image of ovaries within the box in Fig. 8A. The gonads were collected and stained at 24 h after exposure to QDs. Ly, lysosome. SCs, spermary cells. Ov, ovarioles. Bars = 200 μm in (A) and (B), and 50 μm in (C). Relative expression levels (REL) of the BmAtg6 and BmAtg8 genes in testes (D) and ovaries (E) determined by qPCR. The gonads were collected for qRT-PCR at 6 h, 24 h, and 48 h after exposure to QDs. The BmAtg6 and BmAtg8 gene transcript levels were analyzed by qRT-PCR. The BmRP49 gene was selected as an internal control. Samples marked with the same letter do not differ significantly from each other, P < 0.05 (n = 3 technical repeats).
Mentions: The lysosomal staining results shown in Fig. 8A and B demonstrates that lysosomal-specific red fluorescence was present in the testis and ovarian cells at 24 h after exposure to 0.32 nmol CdTe QDs. When the concentration of QDs increased to 0.64 nmol, the red fluorescence in the testes and ovaries indicated that the abundance of lysosomes increased. In contrast to the mitochondrial staining results shown in Fig. 7, the increased levels of lysosomes in gonad cells caused by exposure to QDs did not exhibit obvious gender differences, thereby suggesting that after exposure to the low dose of QDs employed in the experiment, oxidative stress could induce the formation of lysosomes in both male and female gonadal cells. The enlarged image in Fig. 8C shows that the mitochondria generating positions were different from those in Fig. 7, where the red fluorescence from lysosomes occurred mainly in germ cells inside the gonadal tissues, with bright red scattered spermatocysts with various shapes visible through the outer membrane of the testes (Fig. 8C-a), and the red fluorescence in female ovarioles was arranged in the shape of spinal bone spurs or combined into a single piece when more lysosomes were generated (Fig. 8C-b,c).

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