title: Intermyofilament dynamics of myocytes revealed by second harmonic generation microscopy.
abstract: Drosophila melanogaster larva myocytes are imaged with second harmonic generation (SHG) microscopy undergoing forced stretching and rhythmic contractions to determine the nature of the SHG signal. During stretching, double peaked SHG profiles of the anisotropic (A-) bands evolve into single peaks with a higher SHG intensity. The dip in the intensity profile at the center of the A-band is attributed to destructive interference from out-of-phase second harmonic radiating myosin molecules that, in the central region of myofilaments, are arranged antiparallel. An intensity increase at the center of the A-band appears during forced stretching due to a small, less than 100 nm, intermyofilament separation of the antiparallel myosin molecules leading to constructive interference of the SHG radiation. In addition, the same phenomenon occurs during periodic contractions of the myocyte, where an SHG intensity increase with the lengthening of sarcomeres is observed. The SHG intensity dependence on sarcomere length can be used for imaging myocyte contractions with low resolution microscopy, and can be applied for the development of diagnostic tools where monitoring of muscle contraction dynamics is required.
authors.affiliation: University of Toronto, Department of Physics, Institute for Optical Sciences, 3359 Mississauga Road North, Mississauga, Ontario L5L 1C6, Canada.
authors.forename: Nicole
authors.initials: N
authors.lastname: Prent
authors.forename: Chantal
authors.initials: C
authors.lastname: Green
authors.forename: Catherine
authors.initials: C
authors.lastname: Greenhalgh
authors.forename: Richard
authors.initials: R
authors.lastname: Cisek
authors.forename: Arkady
authors.initials: A
authors.lastname: Major
authors.forename: Bryan
authors.initials: B
authors.lastname: Stewart
authors.forename: Virginijus
authors.initials: V
authors.lastname: Barzda
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D004331:Drosophila melanogaster / Q000166:cytology* / Q000502:physiology*; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008853:Microscopy / Q000379:methods*; D009119:Muscle Contraction / Q000502:physiology*; D018485:Muscle Fibers, Skeletal / Q000166:cytology* / Q000502:physiology*