title: Intravital imaging of fluorescent markers and FRET probes by DNA tattooing.
abstract: BACKGROUND
  Advances in fluorescence microscopy and mouse transgenesis have made it possible to image molecular events in living animals. However, the generation of transgenic mice is a lengthy process and intravital imaging requires specialized knowledge and equipment. Here, we report a rapid and undemanding intravital imaging method using generally available equipment.
  
  
  RESULTS
  By DNA tattooing we transfect keratinocytes of living mice with DNA encoding fluorescent biosensors. Subsequently, the behavior of individual cells expressing these biosensors can be visualized within hours and using conventional microscopy equipment. Using this "instant transgenic" model in combination with a corrected coordinate system, we followed the in vivo behavior of individual cells expressing either FRET- or location-based biosensors for several days. The utility of this approach was demonstrated by assessment of in vivo caspase-3 activation upon induction of apoptosis.
  
  
  CONCLUSIONS
  This "instant skin transgenic" model can be used to follow the in vivo behavior of individual cells expressing either FRET- or location-based probes for several days after tattooing and provides a rapid and inexpensive method for intravital imaging in murine skin.
authors.affiliation: Department of Immunology, The Netherlands Cancer Institute, Plesmanlaan 121, 1066 CX Amsterdam, The Netherlands. a.bins@nki.nl <a.bins@nki.nl>
authors.forename: Adriaan D
authors.initials: AD
authors.lastname: Bins
authors.forename: Jacco
authors.initials: J
authors.lastname: van Rheenen
authors.forename: Kees
authors.initials: K
authors.lastname: Jalink
authors.forename: Jonathan R
authors.initials: JR
authors.lastname: Halstead
authors.forename: Nullin
authors.initials: N
authors.lastname: Divecha
authors.forename: David M
authors.initials: DM
authors.lastname: Spencer
authors.forename: John B A G
authors.initials: JB
authors.lastname: Haanen
authors.forename: Ton N M
authors.initials: TN
authors.lastname: Schumacher
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000502:physiology; D053148:Caspase 3 / Q000378:metabolism*; D002478:Cells, Cultured; D015342:DNA Probes; D031541:Fluorescence Resonance Energy Transfer / Q000379:methods*; D005456:Fluorescent Dyes; D015603:Keratinocytes / Q000166:cytology / Q000201:enzymology*; D051379:Mice; D008856:Microscopy, Fluorescence / Q000379:methods; D015336:Molecular Probe Techniques; D014162:Transfection / Q000379:methods*
chemical_list: D015342:DNA Probes; D005456:Fluorescent Dyes; D053148:Caspase 3