title: From the Cover: ZnO Nanoparticles Enhanced Germ Cell Apoptosis in Caenorhabditis elegans, in Comparison with ZnCl2.
abstract: Effects of ZnO NPs and ionic Zn on germline apoptosis and the regulation of genes in the apoptosis pathway were investigated in vivo using the model organism Caenorhabditis elegans.Age synchronized Bristol N2 worms were exposed to ZnO NPs and ZnCl2 at concentrations of 6.14 × 10-1, 61.4, and 614 μM form larval stage 1 (L1) to early adulthood. Possible ZnO nanoparticles were observed under the worm cuticle and also in the gonadal region by transmission electron microscopy (TEM). ZnO NPs and ZnCl2 both significantly increased the number of apoptotic cells as compared with controls in the 61.4 and 614 μM treatment groups (P < .05). However, ZnO NPs induced more apoptotic cells in the 61.4 μM treatment than ZnCl2 (P <  .05), suggesting ZnO NP is more potent in inducing apoptosis at specific exposure concentration. Findings using the MD701 (bcIs39 [(lim-7)ced-1p::GFP + lin-15(+)]) strain further confirmed the observations in N2 strain. Genes involved in the apoptosis pathway (ced-13, ced-3, ced-4, ced-9, cep-1, dpl-1, efl-1, efl-2, egl-1, egl-38, lin-35, pax-2, and sir-2.1) were in general upregulated in response to ZnO NP exposure. The cep-1/p53 gene was up-regulated in gene expression assay. In the cep-1 loss of function mutant, no significant increase in apoptosis was observed. Therefore, the increased apoptosis resulting from ZnO NPs exposure is likely cep-1/p53 dependent. This study provides evidence that ZnO nanoparticles affect germ cell apoptotic machinery as a potential mechanism of reproductive toxicity.
authors.affiliation: Department of Biology, East Carolina University, Greenville, North Carolina.|West Pharmaceutical Services, Inc. Kinston, North Carolina 28504.
authors.forename: Brittany
authors.initials: B
authors.lastname: O'Donnell
authors.affiliation: Junius H Rose High School, Greenville, North Carolina 27858.
authors.forename: Lily
authors.initials: L
authors.lastname: Huo
authors.affiliation: Department of Pharmaceutical Sciences, SUNY-Buffalo, New York, 14260.
authors.forename: Joseph R
authors.initials: JR
authors.lastname: Polli
authors.affiliation: College of Veterinary Medicine, Northwest Agriculture and Forestry University, Yangling 712100, China.
authors.forename: Li
authors.initials: L
authors.lastname: Qiu
authors.affiliation: Department of Pediatrics, East Carolina University, Greenville, North Carolina 27858.
authors.forename: David N
authors.initials: DN
authors.lastname: Collier
authors.affiliation: Department of Biology, East Carolina University, Greenville, North Carolina.
authors.forename: Baohong
authors.initials: B
authors.lastname: Zhang
authors.affiliation: Department of Biology, East Carolina University, Greenville, North Carolina.
authors.forename: Xiaoping
authors.initials: X
authors.lastname: Pan
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects* / Q000235:genetics; D017173:Caenorhabditis elegans / Q000187:drug effects* / Q000235:genetics; D029742:Caenorhabditis elegans Proteins / Q000235:genetics; D002712:Chlorides / Q000494:pharmacology*; D005854:Germ Cells / Q000187:drug effects*; D053768:Metal Nanoparticles; D017967:Zinc Compounds / Q000494:pharmacology*; D015034:Zinc Oxide / Q000494:pharmacology*
chemical_list: D029742:Caenorhabditis elegans Proteins; D002712:Chlorides; D017967:Zinc Compounds; C016837:zinc chloride; D015034:Zinc Oxide
keywords: C. elegans; ZnO; apoptosis; cep-1/p53 pathway.; gene expression; nanoparticles