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Superelongation in helical muscles of leeches


The fine structure of leech body wall muscles, has been analysed under great length variations. All the measurable parameters of the fibre (distance between thick filaments, sarcomere and A band width, percentage of actin crowns around myosin filaments, fibre radius) at different elongations were tested with equations describing the geometrical model of helical fibres.

Anaesthetized and nonanaesthetized worms behave in different ways and can be utilized to verify the ‘changing partner hypothesis’. The fit between theoretical and experimental data suggests that a double change of partner actually takes place in extremely stretched fibres.

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  1. APRIL, E. W., BRANDT, P. W. & ELLIOTT, G. E. (1971) The myofilament lattice: studies on isolated fibers. I. The constancy of the unit-cell volume with variation in sarcomere length in a lattice in which the thin to thick myofilament ratio is 6:1.J. Cell Biol. 51, 72–82.

  2. CANDIA CARNEVALI, M. D., de EGUILEOR, M. & VALVASSORI, R. (1980) Z-line morphology of functionally diverse insect skeletal muscles.J. Submicrosc. Cytol. 12, 427–46.

  3. ELDER, H. Y. (1975) Muscle structure. InInsect Muscle (edited by USHERWOOD, P. N. R.) pp. 1–57. New York, London: Academic Press.

  4. HOYLE, G., MCALEAR, J. H. & SELVERSTON, A. (1965) Mechanism of supercontraction in a striated muscle.J. Cell Biol. 26, 621–40.

  5. INGLIS, W. G. (1983) The structure and operation of the obliquely striated supercontractile somatic muscles in Nematodes.Aust. J. Zool. 31, 677–93.

  6. LANZAVECCHIA, G. (1977) Morphological modulations in helical muscles (Aschelminthes and Annelida).Int. Rev. Cytol. 51, 133–86.

  7. LANZAVECCHIA, G. (1981a) Morphofunctional and phylogenetic relations in helical muscles.Boll. Zool. 48, 29–40.

  8. LANZAVECCHIA, G. (1981b) Evolution of muscle fibers in lower Metazoa. InOrigine dei Grandi Phyla dei Metazoi. Atti Convegni Lincei 49, 11–22.

  9. LANZAVECCHIA, G. & de EGUILEOR, M. (1976) Studies on the helical and paramyosinic muscles. V. Ultrastructural morphology and contraction speed of muscular fibers ofHerpobdella octoculata andHerpobdella testacea (Annelida, Hirudinea).J. Submicrosc. Cytol. 8, 69–88.

  10. LANZAVECCHIA, G. & ARCIDIACONO, G. (1981) Contraction mechanism of helical muscles: experimental and theoretical analysis.J. Submicrosc. Cytol. 13, 253–66.

  11. MCALEAR, J. H. & HOYLE, G. (1963) The mechanism of super contraction in a striated muscle fiber of the barnacleBalanus nubilus. J. Cell Biol. 19, 49A.

  12. MILLER, J. B. (1975) The length tension relationship of the dorsal longitudinal muscle of a leech.J. expl Biol. 62, 43–53.

  13. ROME, E. (1967) Light and X-ray diffraction studies of the filament lattice of glycerol-extracted rabbit psoas muscle.J. molec. Biol. 27, 591–602.

  14. ROME, E. (1968) X-ray diffraction studies of the filament lattice of striated muscle in various bathing media.J. molec. Biol. 37, 331–44.

  15. ROSENBLUTH, J. (1965) Ultrastructural organization of obliquely striated muscle fibers inAscaris lumbricoides.J. Cell Biol. 25, 495–515.

  16. ROSENBLUTH, J. (1972) Obliquely striated muscle. InThe Structure and Function of Muscle (edited by BOURNE, G. H.), Vol. 1, 2nd edn, pp. 389–420. New York: London: Academic Press.

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Lanzavecchia, G., De Eguileor, M. & Valvassori, R. Superelongation in helical muscles of leeches. J Muscle Res Cell Motil 6, 569–584 (1985).

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  • Experimental Data
  • Fine Structure
  • Band Width
  • Length Variation
  • Geometrical Model