title: The effect of paraoxon on spermatogenesis in Dugesia gonocephala from the Chilean Altiplano: proliferation and apoptosis.
abstract: OBJECTIVE
  The Chilean Altiplano ecosystem is conserved free from contaminants and pollutants because of the absence of major local human activities such as agriculture or other industries. We studied the effects of paraoxon on proliferation and apoptosis of testicular cells during active spermatogenesis in Dugesia gonocephala collected from a pristine river (Guacollo) in the Altiplano region nearby Visviri town, Chile.
  
  
  METHODS
  Adult planarians were incubated in varying concentrations of paraoxon (0.8, 0.4, 0.04, 0.004, and 0.0004 mM) for 4 h. After 3 h of incubation, bromodeoxyuridine (BrdU) was added. Effects on cell proliferation (BrdU) and apoptosis (Apaf-1) were determined by immunohistochemistry.
  
  
  RESULTS
  Paraoxon concentrations of 0.4 and 0.8 mM caused 100% mortality in the respective treatment groups. The lowest tested concentration (0.0004 mM) caused a significant increase on cell proliferation in the seminiferous tubules, as well as an increase in the number of apoptotic cells. All other tested concentrations significantly inhibited cell proliferation and induced apoptosis.
  
  
  CONCLUSIONS
  Paraoxon inhibits DNA synthesis and induces apoptosis during spermatogenesis in adult planarians from a high-altitude, pollution-free environment. This could suggest its use as a biosensor or biomarker for contamination with agro pesticides.
authors.affiliation: Unidad de Histoembriología, ICBM, Faculty of Medicine, University of Chile, Avenida Independencia 1027, 8389100, Santiago, Chile. hrodrigu@med.uchile.cl
authors.forename: Hector Hernan
authors.initials: HH
authors.lastname: Rodríguez
authors.forename: Omar
authors.initials: O
authors.lastname: Espinoza-Navarro
authors.forename: Ivan
authors.initials: I
authors.lastname: Silva
authors.forename: Douglas
authors.initials: D
authors.lastname: Needham
authors.forename: María Eugenia
authors.initials: ME
authors.lastname: Castro
authors.forename: Luis
authors.initials: L
authors.lastname: Sarabia
authors.forename: Juan
authors.initials: J
authors.lastname: Inostroza
authors.forename: Leonella
authors.initials: L
authors.lastname: Jimenez
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D053477:Apoptotic Protease-Activating Factor 1 / Q000378:metabolism; D001973:Bromodeoxyuridine / Q000378:metabolism; D049109:Cell Proliferation / Q000187:drug effects; D002677:Chile; D005618:Fresh Water / Q000737:chemistry; D007306:Insecticides / Q000032:analysis / Q000633:toxicity*; D010261:Paraoxon / Q000032:analysis / Q000633:toxicity*; D010932:Planarians / Q000187:drug effects* / Q000378:metabolism; D013091:Spermatogenesis / Q000187:drug effects*; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000633:toxicity*
chemical_list: D053477:Apoptotic Protease-Activating Factor 1; D007306:Insecticides; D014874:Water Pollutants, Chemical; D001973:Bromodeoxyuridine; D010261:Paraoxon