title: Molecular organization of crystalline β-carotene in carrots determined with polarization-dependent second and third harmonic generation microscopy.
abstract: Polarization-in, polarization-out (PIPO) second harmonic generation (SHG) and third harmonic generation (THG) microscopy was used to study the crystalline organization of β-carotene molecules within individual aggregates contained in the chromoplasts of orange carrots in vivo. Multimodal PIPO SHG and PIPO THG studies of the aggregates revealed one dominant SHG and THG dipole signifying that β-carotene molecules are oriented along a single axis. Three-dimensional visualization of the orientation of β-carotene molecules with respect to the aggregate axis was also performed with both microscopy modalities and revealed organization of the aggregates as ribbon-like structures consisting of twists and folds. Therefore, PIPO SHG and PIPO THG microscopy provides information on the crystalline organization and the orientation of ordered biological structures in vivo where multimodal polarization dependent SHG and THG investigations are particularly advantageous as both noncentrosymmetric and centrosymmetric crystalline organizations can be probed.
authors.affiliation: Department of Chemical and Physical Sciences, University of Toronto Mississauga , 3359 Mississauga Road North, Mississauga, Ontario, Canada L5L 1C6.
authors.forename: Danielle
authors.initials: D
authors.lastname: Tokarz
authors.forename: Richard
authors.initials: R
authors.lastname: Cisek
authors.forename: Serguei
authors.initials: S
authors.lastname: Krouglov
authors.forename: Lukas
authors.initials: L
authors.lastname: Kontenis
authors.forename: Ulrich
authors.initials: U
authors.lastname: Fekl
authors.forename: Virginijus
authors.initials: V
authors.lastname: Barzda
mesh_terms: D003460:Crystallization; D018552:Daucus carota / Q000737:chemistry* / Q000378:metabolism; D008853:Microscopy; D008962:Models, Theoretical; D019207:beta Carotene / Q000737:chemistry*
chemical_list: D019207:beta Carotene