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Studies on the nature of the Z‐discs in skeletal muscle fibres of sharks, Etmopterus spinax L. and Galeus melastomus Rafinesque‐Schmaltz
Author(s) -
Slinde E.,
Kryvi H.
Publication year - 1980
Publication title -
journal of fish biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.672
H-Index - 115
eISSN - 1095-8649
pISSN - 0022-1112
DOI - 10.1111/j.1095-8649.1980.tb03707.x
Subject(s) - myosin , anatomy , biology , actin , ultrastructure , white (mutation) , skeletal muscle , denaturation (fissile materials) , differential scanning calorimetry , biophysics , crystallography , chemistry , biochemistry , physics , nuclear chemistry , gene , thermodynamics
The ultrastructural details of Z‐discs from red, intermediate, and white axial muscle fibres from the sharks Etmopterus spinax and Galeus melastomus are described. Red fibre Z‐discs contain the most amorphous matrix material, and are thicker (100–115 nm) than intermediate (85–88 nm) and white Z‐discs (75–80 nm). Four sets of oblique bars extend tangentially from each thin filament. In each set two bars are present, those of white fibres are close together (approximately 5 nm), while those of red fibres are separated by a distance of 15 nm. A model of shark Z‐disc structure is proposed. The denaturation (heat transition) temperatures of the muscle proteins were studied by differential scanning calorimetry (DSC). The heat transitions of collagen, actin, and myosin were identified; the actin heat transition temperature increased in the sequence red, intermediate, and white. The total protein pattern of red and white muscle were studied by SDS electrophoresis. A protein with a molecular weight of about 55000 may represent a Z‐disc protein.