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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.

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Impact of QDs on the development of silkworm gonads and the nuclear morphometry of gametes.(A) The HE staining of testes or ovaries. A1 and A2 indicate the early and late anagen stages in the oogonia, respectively. During this stage, an oogonium differentiated into one primary oocyte and seven nurse cells. MS1 indicates the early stage of maturity; 1–3 indicate the stage of primary spermatocytes in spermatocysts, the spermatocysts during spermiogenesis, and the stage of spermatodesms, respectively. (B) The DAPI staining of histiocytes in testes or ovaries. 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 gonads were removed from older larvae at 120 h after exposure to QDs and used for HE or DAPI staining. For DAPI staining, the histiocytes were stained with DAPI after thoroughly splitting from the outer membrane of testes and ovaries with forceps.♀ indicates female and ♂ indicates male. Bar = 100 μm in (A) and 10 μm in (B).
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f3: Impact of QDs on the development of silkworm gonads and the nuclear morphometry of gametes.(A) The HE staining of testes or ovaries. A1 and A2 indicate the early and late anagen stages in the oogonia, respectively. During this stage, an oogonium differentiated into one primary oocyte and seven nurse cells. MS1 indicates the early stage of maturity; 1–3 indicate the stage of primary spermatocytes in spermatocysts, the spermatocysts during spermiogenesis, and the stage of spermatodesms, respectively. (B) The DAPI staining of histiocytes in testes or ovaries. 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 gonads were removed from older larvae at 120 h after exposure to QDs and used for HE or DAPI staining. For DAPI staining, the histiocytes were stained with DAPI after thoroughly splitting from the outer membrane of testes and ovaries with forceps.♀ indicates female and ♂ indicates male. Bar = 100 μm in (A) and 10 μm in (B).

Mentions: At 120 h after the 5th instar larvae were exposed to QDs, hematoxylin and eosin (HE) staining of the gonad slices (Fig. 3A) showed that the germ cells in the testes and ovaries developed at a significantly slower rate than those in the control water-treatment group. In the ovaries of the QDs treatment group, only oogonia in the anagen phase were present and there were no signs of mature eggs at the early stage, while only primary spermatocytes were observed in spermatocysts in the testes, and spermatocysts undergoing spermiogenesis and the spermatodesms that were found in large numbers in the control group were not observed, thereby indicating that exposure to QDs reduced the development rate of germ cells at the early and middle stages in the gonads.


Reproductive toxicity and gender differences induced by cadmium telluride quantum dots in an invertebrate model organism
Impact of QDs on the development of silkworm gonads and the nuclear morphometry of gametes.(A) The HE staining of testes or ovaries. A1 and A2 indicate the early and late anagen stages in the oogonia, respectively. During this stage, an oogonium differentiated into one primary oocyte and seven nurse cells. MS1 indicates the early stage of maturity; 1–3 indicate the stage of primary spermatocytes in spermatocysts, the spermatocysts during spermiogenesis, and the stage of spermatodesms, respectively. (B) The DAPI staining of histiocytes in testes or ovaries. 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 gonads were removed from older larvae at 120 h after exposure to QDs and used for HE or DAPI staining. For DAPI staining, the histiocytes were stained with DAPI after thoroughly splitting from the outer membrane of testes and ovaries with forceps.♀ indicates female and ♂ indicates male. Bar = 100 μm in (A) and 10 μm in (B).
© Copyright Policy - open-access
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC5037452&req=5

f3: Impact of QDs on the development of silkworm gonads and the nuclear morphometry of gametes.(A) The HE staining of testes or ovaries. A1 and A2 indicate the early and late anagen stages in the oogonia, respectively. During this stage, an oogonium differentiated into one primary oocyte and seven nurse cells. MS1 indicates the early stage of maturity; 1–3 indicate the stage of primary spermatocytes in spermatocysts, the spermatocysts during spermiogenesis, and the stage of spermatodesms, respectively. (B) The DAPI staining of histiocytes in testes or ovaries. 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 gonads were removed from older larvae at 120 h after exposure to QDs and used for HE or DAPI staining. For DAPI staining, the histiocytes were stained with DAPI after thoroughly splitting from the outer membrane of testes and ovaries with forceps.♀ indicates female and ♂ indicates male. Bar = 100 μm in (A) and 10 μm in (B).
Mentions: At 120 h after the 5th instar larvae were exposed to QDs, hematoxylin and eosin (HE) staining of the gonad slices (Fig. 3A) showed that the germ cells in the testes and ovaries developed at a significantly slower rate than those in the control water-treatment group. In the ovaries of the QDs treatment group, only oogonia in the anagen phase were present and there were no signs of mature eggs at the early stage, while only primary spermatocytes were observed in spermatocysts in the testes, and spermatocysts undergoing spermiogenesis and the spermatodesms that were found in large numbers in the control group were not observed, thereby indicating that exposure to QDs reduced the development rate of germ cells at the early and middle stages in the gonads.

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