DNA damage in BV-2 cells: An important supplement to the neurotoxicity of CdTe quantum dots.

Microglial cells are resident immune cells in the central nervous system. Activation of microglia as induced by CdTe quantum dots (QDs) can trigger damage to neurons. To quantify the intracellular QDs, we monitored the intracellular Cd concentration in the QD-exposed mouse microglial cells (BV-2 cell line). The extent of cell injury at different times correlated with the Cd concentration in cells at that time. In addition to Cd ion detection, we also monitored the intracellular fluorescence of the QDs. More QDs accumulated in the nucleus than in the cytoplasm. Comet assays confirmed that QDs induce DNA damage. However, DNA cannot interact with QDs, so the DNA damage was not caused by CdTe QDs adducts to DNA but by the increase of the Cd ion concentration and the secondary oxidative damage. In addition to DNA damage, biofilm injury and endogenous reduced glutathione depletion were also apparent in QD-exposed BV-2 cells. These changes can be prevented or even reversed by exogenous reduced glutathione administration.

A metabolomics study: CdTe/ZnS quantum dots induce polarization in mice microglia.

In this study, a metabolomic analysis was used to reveal the neurotoxicity of the CdTe/ZnS QDs via microglia polarization. A gas chromatography-mass spectrometer (GC-MS) was applied to uncover the metabonomic changes in microglia (BV-2 cell line) after exposure to 1.25 µM CdTe/ZnS QDs. 11 annotated metabolic pathways (KEGG database) were significantly changed in all exposed groups (3 h, 6 h, 12 h), 3 of them were related to glucose metabolism. The results of the Seahorse XFe96 Analyzer indicated that the CdTe/ZnS QDs increased the glycolysis level of microglia by 86% and inhibited the aerobic respiration level by 54% in a non-hypoxic environment. In vivo study, 3 h after the injection of CdTe/ZnS QDs (2.5 mM) through the tail vein in mice, the concentration of the CdTe/ZnS QDs in hippocampus reached the peak (1.25 µM). The polarization level of microglia (Iba-1 immunofluorescence) increased 2.7 times. In vitro study, the levels of the extracellular TNF-α, IL-1ß and NO of BV-2 cells were all increased significantly after a 6 h or 12 h exposure. According to the results of the Cell Counting Kit-8, after a 6 h or 12 h exposure to the CdTe/ZnS QDs, the exposed microglia could significantly decrease the number of neurons (HT-22 cell line). This study proved that CdTe/ZnS QDs could polarize microglia in the brain and cause secondary inflammatory damage to neurons. There are potential risks in the application of the CdTe/ZnS QDs in brain tissue imaging.

[Mixed infection of Echinococcus granulosus and Echinococcus multilocularis in dog].

OBJECTIVE: To identify mixed infection of Echinococcus granulosus and E. multilocularis in a dog from Xinjiang. METHODS: Thirty dogs from the pasture area were dissected and over 10,000 Echinococcus adult worms were found from one dog. Morphological observation revealed possible mixed infection of the two Echinococcus species. Further identification was made by amplification of the target gene DNA fragment (mitochondrial 12S rRNA gene). RESULTS: The adult worms of E. granulosus showed a relatively longer and larger gravid proglottid, its genital pore situated near or below the middle-side of the segment. The uterus was in a sacculate shape with irregular branches and approximately over 200 - 800 eggs in it. Morphology of the adult worms of E. multilocularis was similar to E. granulosus, slightly smaller, consisting of 4 to 5 proglottids. The uterus was not sacculate and with no branch. Its lateral genital pore often situated in the anterior part of the segment. Sequence analysis of mitochondrial 12S rRNA gene showed that amplification with the Eg1f/r primers shared complete identity with E. granulosus G1 genotype (GenBank accession no. AY462129), while that witht the EmH15/17 primers shared complete identity with E. multilocularis (GenBank accession no. AB031351). The presence of both E. granulosus and E. multilocularis was confirmed by microscopy and gene identification. CONCLUSION: Mixed infection of the two species of Echinococcus has been confirmed in the dog by morphological observation and PCR technique.