title: Structural origin of the drastic modification of second harmonic generation intensity pattern occurring in tail muscles of climax stages xenopus tadpoles.
abstract: Second harmonic generation (SHG) microscopy is a powerful tool for studying submicron architecture of muscles tissues. Using this technique, we show that the canonical single frequency sarcomeric SHG intensity pattern (SHG-IP) of premetamorphic xenopus tadpole tail muscles is converted to double frequency (2f) sarcomeric SHG-IP in metamorphic climax stages due to massive physiological muscle proteolysis. This conversion was found to rise from 7% in premetamorphic muscles to about 97% in fragmented muscular apoptotic bodies. Moreover a 66% conversion was also found in non-fragmented metamorphic tail muscles. Also, a strong correlation between predominant 2f sarcomeric SHG-IPs and myofibrillar misalignment is established with electron microscopy. Experimental and theoretical results demonstrate the higher sensitivity and the supra resolution power of SHG microscopy over TPEF to reveal 3D myofibrillar misalignment. From this study, we suggest that 2f sarcomeric SHG-IP could be used as signature of triad defect and disruption of excitation-contraction coupling. As the mechanism of muscle proteolysis is similar to that found in mdx mouse muscles, we further suggest that xenopus tadpole tail resorption at climax stages could be used as an alternative or complementary model of Duchene muscular dystrophy.
authors.affiliation: UMR CNRS 6026, Université de Rennes1, Campus de Beaulieu, Rennes F-35000, France; Department of Physiology, Development and Neuroscience, University of Cambridge, Downing Street, Cambridge CB2 3DY, UK.
authors.forename: Gaëlle
authors.initials: G
authors.lastname: Recher
authors.affiliation: UMR CNRS 6026, Université de Rennes1, Campus de Beaulieu, Rennes F-35000, France; 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: Denis
authors.initials: D
authors.lastname: Rouède
authors.affiliation: UMR CNRS 6026, Université de Rennes1, Campus de Beaulieu, Rennes F-35000, France; IRSET, INSERM, U1085, Université de Rennes1, Campus de Beaulieu, Rennes F-35000, France. Electronic address: francois.tiaho@univ-rennes1.fr.
authors.forename: François
authors.initials: F
authors.lastname: Tiaho
mesh_terms: D000818:Animals; D007814:Larva / Q000254:growth & development / Q000648:ultrastructure; D018482:Muscle, Skeletal / Q000254:growth & development / Q000648:ultrastructure*; D013623:Tail / Q000254:growth & development / Q000648:ultrastructure; D029867:Xenopus Proteins / Q000648:ultrastructure; D014982:Xenopus laevis / Q000033:anatomy & histology* / Q000254:growth & development
chemical_list: D029867:Xenopus Proteins
keywords: Apoptosis; Electron microscopy; Second harmonic generation microscopy; Skeletal muscle; Two photon excitation fluorescence; Xenopus