title: Metamorphosis delay in Xenopus laevis (Daudin) tadpoles exposed to a 50 Hz weak magnetic field.
abstract: OBJECTIVE
  The experiment was performed to prove that exposure to a relatively weak extremely low frequency (ELF) magnetic field retards tadpoles' development.
  
  
  METHODS
  Two cohorts of Xenopus laevis laevis (Daudin) tadpoles were exposed during their immature period ( approximately 60 days) to a 50 Hz magnetic field of 63.9 < or = B < or = 76.4 microT rms (root mean square, average values) magnetic flux density in a solenoid. At the same time, as controls, two comparable cohorts were reared in two aquariums remote from the solenoid. Cohorts' degree of development was quantified by daily inspections of animal limbs and attributing them to a stage of the Nieuwkoop and Faber ( 1956 ) classification. The experiment was replicated three times.
  
  
  RESULTS
  (a) Mean developmental rate of exposed cohorts was reduced with respect to controls (0.43 vs. 0.48 stages/day, p < 0.001) starting from early larval stages; (b) Exposure increased the mean metamorphosis period of tadpoles by 2.4 days compared with the controls (p < 0.001); (c) Maturation rates of exposed and control tadpoles changed during maturation period; and (d) Important mortality, malformations or teratogenic effects were not observed in exposed matured tadpoles.
  
  
  CONCLUSIONS
  A long-term exposure of X. laevis tadpoles to a relatively weak 50 Hz magnetic field causes a sub-lethal effect that slows down their larval developmental rate and delays their metamorphosis.
authors.affiliation: Department of Ecology and Economical Sustainable Development, Tuscia University, Viterbo, Italy. m.severini@unitus.it
authors.forename: Maurizio
authors.initials: M
authors.lastname: Severini
authors.forename: Luigi
authors.initials: L
authors.lastname: Bosco
authors.forename: Roberta
authors.initials: R
authors.lastname: Alilla
authors.forename: Massimo
authors.initials: M
authors.lastname: Loy
authors.forename: Maurizio
authors.initials: M
authors.lastname: Bonori
authors.forename: Livio
authors.initials: L
authors.lastname: Giuliani
authors.forename: Angelico
authors.initials: A
authors.lastname: Bedini
authors.forename: Claudia
authors.initials: C
authors.lastname: Giliberti
authors.forename: Raffaele
authors.initials: R
authors.lastname: Palomba
authors.forename: Simone
authors.initials: S
authors.lastname: Pesolillo
authors.forename: Emanuele
authors.initials: E
authors.lastname: Giacomozzi
authors.forename: Agostina Congiu
authors.initials: AC
authors.lastname: Castellano
mesh_terms: D000818:Animals; D004574:Electromagnetic Fields; D007814:Larva / Q000254:growth & development / Q000528:radiation effects*; D008280:Magnetics; D008675:Metamorphosis, Biological / Q000528:radiation effects*; D013997:Time Factors; D014982:Xenopus laevis / Q000254:growth & development*