title: Cellular internalization and stress response of ingested amorphous silica nanoparticles in the midgut of Drosophila melanogaster.
abstract: BACKGROUND
  Amorphous silica nanoparticles (aSNPs) are used for various applications including food industry. However, limited in vivo studies are available on absorption/internalization of ingested aSNPs in the midgut cells of an organism. The study aims to examine cellular uptake of aSNPs (<30nm) in the midgut of Drosophila melanogaster (Oregon R(+)) owing to similarities between the midgut tissue of this organism and human and subsequently cellular stress response generated by these nanoparticles.
  
  
  METHODS
  Third instar larvae of D. melanogaster were exposed orally to 1-100μg/mL of aSNPs for 12-36h and oxidative stress (OS), heat shock genes (hsgs), membrane destabilization (Acridine orange/Ethidium Bromide staining), cellular internalization (TEM) and apoptosis endpoints.
  
  
  RESULTS
  A significant increase was observed in OS endpoints in the midgut cells of exposed Drosophila in a concentration- and time-dependent manner. Significantly increased expression of hsp70 and hsp22 along with caspases activation, membrane destabilization and mitochondrial membrane potential loss was also observed. TEM analysis showed aSNPs-uptake in the midgut cells of exposed Drosophila via endocytic vesicles and by direct membrane penetration.
  
  
  CONCLUSIONS
  aSNPs after their internalization in the midgut cells of exposed Drosophila larvae show membrane destabilization along with increased cellular stress and cell death.
  
  
  CONCLUSIONS
  Ingested aSNPs show adverse effects on the cells of GI tract of the exposed organism thus their industrial use as a food-additive may raise concern to human health.
authors.affiliation: CSIR-Indian Institute of Toxicology Research, Uttar Pradesh, India.
authors.forename: Ashutosh
authors.initials: A
authors.lastname: Pandey
authors.forename: Swati
authors.initials: S
authors.lastname: Chandra
authors.forename: Lalit Kumar Singh
authors.initials: LK
authors.lastname: Chauhan
authors.forename: Gopeshwar
authors.initials: G
authors.lastname: Narayan
authors.forename: Debapratim Kar
authors.initials: DK
authors.lastname: Chowdhuri
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D002462:Cell Membrane / Q000378:metabolism* / Q000473:pathology; D004331:Drosophila melanogaster; D004705:Endocytosis / Q000187:drug effects; D007413:Intestinal Mucosa / Q000378:metabolism*; D007422:Intestines / Q000473:pathology; D007814:Larva; D053758:Nanoparticles / Q000009:adverse effects*; D012822:Silicon Dioxide / Q000009:adverse effects* / Q000494:pharmacology; D013312:Stress, Physiological / Q000187:drug effects*
chemical_list: D012822:Silicon Dioxide