title: Gene inactivation by multiphoton-targeted photochemistry.
abstract: Multiphoton-targeted photochemistry was used to selectively inactivate the expression of genes in vertebrate cells. A membrane permeable DNA-associating vital dye, ethidium bromide monoacetate (visible wavelength single photon absorption peak at 530 nm) was used to photosensitize chromosomes in dividing cells. A 100-ps infrared laser beam operating at 1.06 microns was focused onto a selected region of a mitotic chromosome corresponding to the sites of the nucleolar (ribosomal) genes. Individual cells followed through mitosis demonstrated a reduction in the number of nucleoli formed in daughter cells that corresponded to the number of nucleolar genes sites irradiated. These results demonstrate the ability to selectively manipulate genes by using the focal point specificity characteristic of multiphoton microscopy. This technique should have wide biotechnology applications both in vitro and in vivo.
authors.affiliation: Beckman Laser Institute and Medical Clinic and Center for Biomedical Engineering, University of California, Irvine 92612-1475, USA. mberns@bli.uci.edu
authors.forename: M W
authors.initials: MW
authors.lastname: Berns
authors.forename: Z
authors.initials: Z
authors.lastname: Wang
authors.forename: A
authors.initials: A
authors.lastname: Dunn
authors.forename: V
authors.initials: V
authors.lastname: Wallace
authors.forename: V
authors.initials: V
authors.lastname: Venugopalan
mesh_terms: D000818:Animals; D001386:Azides / Q000378:metabolism / Q000494:pharmacology; D001709:Biotechnology / Q000379:methods*; D002460:Cell Line; D002463:Cell Membrane Permeability; D002466:Cell Nucleolus / Q000187:drug effects / Q000235:genetics / Q000528:radiation effects; D002470:Cell Survival / Q000187:drug effects / Q000528:radiation effects; D002875:Chromosomes / Q000187:drug effects / Q000235:genetics / Q000528:radiation effects; D004275:DNA, Ribosomal / Q000235:genetics / Q000528:radiation effects; D020868:Gene Silencing / Q000187:drug effects / Q000528:radiation effects*; D005796:Genes / Q000235:genetics* / Q000528:radiation effects*; D020459:Genes, rRNA / Q000235:genetics / Q000528:radiation effects; D007259:Infrared Rays; D007834:Lasers; D007614:Macropodidae; D008677:Metaphase / Q000187:drug effects / Q000235:genetics / Q000528:radiation effects; D008856:Microscopy, Fluorescence; D008938:Mitosis / Q000187:drug effects / Q000235:genetics / Q000528:radiation effects; D010777:Photochemistry; D017785:Photons
chemical_list: D001386:Azides; D004275:DNA, Ribosomal; C014535:8-azidoethidium