title: Myofibrillar misalignment correlated to triad disappearance of mdx mouse gastrocnemius muscle probed by SHG microscopy.
abstract: We show that the canonical single frequency sarcomeric SHG intensity pattern (SHG-IP) of control muscles is converted to double frequency sarcomeric SHG-IP in preserved mdx mouse gastrocnemius muscles in the vicinity of necrotic fibers. These double frequency sarcomeric SHG-IPs are often spatially correlated to double frequency sarcomeric two-photon excitation fluorescence (TPEF) emitted from Z-line and I-bands and to one centered spot SHG angular intensity pattern (SHG-AIP) suggesting that these patterns are signature of myofibrillar misalignement. This latter is confirmed with transmission electron microscopy (TEM). Moreover, a good spatial correlation between SHG signature of myofibrillar misalignment and triad reduction is established. Theoretical simulation of sarcomeric SHG-IP is used to demonstrate the correlation between change of SHG-IP and -AIP and myofibrillar misalignment. The extreme sensitivity of SHG microscopy to reveal the submicrometric organization of A-band thick filaments is highlighted. This report is a first step toward future studies aimed at establishing live SHG signature of myofibrillar misalignment involving excitation contraction defects due to muscle damage and disease.
authors.affiliation: IPR, CNRS, UMR-CNRS UR1- 6251, Université de Rennes1, Campus de Beaulieu, Rennes, F-35000, France.
authors.forename: Denis
authors.initials: D
authors.lastname: Rouède
authors.affiliation: IRSET, INSERM, U1085, Université de Rennes1, Campus de Beaulieu, Rennes, F-35000, France.
authors.forename: Pascal
authors.initials: P
authors.lastname: Coumailleau
authors.affiliation: IPR, CNRS, UMR-CNRS UR1- 6251, Université de Rennes1, Campus de Beaulieu, Rennes, F-35000, France.
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Schaub
authors.affiliation: LTSI, INSERM, U1099, Université de Rennes1, Rennes, F-35000, France.
authors.forename: Jean-Jacques
authors.initials: JJ
authors.lastname: Bellanger
authors.affiliation: ISM, CNRS, UMR-CNRS 5255, Université de Bordeaux 1, Talence, F-33405, France.
authors.forename: Mireille
authors.initials: M
authors.lastname: Blanchard-Desce
authors.affiliation: IRSET, INSERM, U1085, Université de Rennes1, Campus de Beaulieu, Rennes, F-35000, France.
authors.forename: François
authors.initials: F
authors.lastname: Tiaho
keywords: (170.3880) Medical and biological imaging; (180.4315) Nonlinear microscopy; (190.4160) Multiharmonic generation