title: Control of Maintenance and Regeneration of Planarian Eyes by ovo.
abstract: OBJECTIVE
  Following decapitation, the planarian Schmidtea mediterranea regenerates its head and eyes. The gene ovo is required for eye maintenance and regeneration in response to wounding. In this study, we investigated whether eye regeneration in S. mediterranea could occur absent a wound healing response.
  
  
  METHODS
  One hundred twenty S. mediterranea were treated with ovo RNA interference (RNAi) or control (unc-22) RNAi by feeding double-stranded RNA (dsRNA). Following eye loss, ovo RNAi treatment was halted and replaced with control RNAi treatment. Quantitative real-time PCR (qPCR) was used to monitor ovo expression. Eye functionality was monitored via a phototaxis assay. Photoreceptor neurons were visualized via immunofluorescence staining of arrestin.
  
  
  RESULTS
  Treatment with ovo RNAi caused eyes to gradually shrink until they were completely absent. One hundred percent of ovo RNAi-treated planarians lost both eyes within 137 days of treatment onset. ovo RNAi-treated planarians were unable to regenerate eyes in response to decapitation. Upon removal of ovo RNAi, eyes became visible as small pigmented spots in the head within 28 days. The eyes slowly developed, appearing to gain pigmented cells first and then nonpigmented photoreceptors. Phototaxis assays demonstrated functional eye loss and eye restoration. ovo mRNA was significantly decreased following treatment with ovo RNAi and significantly increased following removal of ovo RNAi. Arrestin staining was present in the eyes, optic nerves, and optic chiasm of worms with regenerated eyes but not in eyeless worms.
  
  
  CONCLUSIONS
  S. mediterranea have the ability to generate functional eyes in the absence of a wound healing response. This ability requires the expression of ovo.
authors.affiliation: Department of Ophthalmology Mayo Clinic, Rochester, Minnesota, United States.
authors.forename: Samuel D
authors.initials: SD
authors.lastname: Cross
authors.affiliation: Department of Ophthalmology Mayo Clinic, Rochester, Minnesota, United States.
authors.forename: Adiv A
authors.initials: AA
authors.lastname: Johnson
authors.affiliation: Department of Ophthalmology Mayo Clinic, Rochester, Minnesota, United States.
authors.forename: Benjamin J
authors.initials: BJ
authors.lastname: Gilles
authors.affiliation: Department of Ophthalmology Mayo Clinic, Rochester, Minnesota, United States.
authors.forename: Lori A
authors.initials: LA
authors.lastname: Bachman
authors.affiliation: Department of Biophysics, Graduate School of Science, Kyoto University, Kyoto, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Inoue
authors.affiliation: Department of Biophysics, Graduate School of Science, Kyoto University, Kyoto, Japan.
authors.forename: Kiyokazu
authors.initials: K
authors.lastname: Agata
authors.affiliation: Department of Ophthalmology Mayo Clinic, Rochester, Minnesota, United States.
authors.forename: Lihua Y
authors.initials: LY
authors.lastname: Marmorstein
authors.affiliation: Department of Ophthalmology Mayo Clinic, Rochester, Minnesota, United States.
authors.forename: Alan D
authors.initials: AD
authors.lastname: Marmorstein
mesh_terms: D000818:Animals; D009416:Nerve Regeneration / Q000502:physiology*; D009474:Neurons / Q000166:cytology / Q000378:metabolism*; D010786:Photoreceptor Cells / Q000166:cytology / Q000378:metabolism*; D010932:Planarians / Q000235:genetics / Q000378:metabolism; D060888:Real-Time Polymerase Chain Reaction; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism; D059467:Transcriptome / Q000502:physiology*
chemical_list: D014157:Transcription Factors