[Expression of several domains of twitchin and myorod in the ontogenesis of mussel Mytilus trossulus].

The expression of MLCK- and PEVK-domains of twitchin, as well as the unique N-terminal domain of myorod in early development of the mussel Mytilus trossulus has been studied. The MLCK-domain of twitchin and the unique N-terminal domain of myorod appear at the early stages of development, whereas the PEVK-domain of twitchin is present only in muscles of adult mussel. The sizes of genes of the N-terminal domain of myorod, obtained at the blastula stage and from the adult animal are similar, but the proteins have significant differences in the amino acid sequences.

[Development of the muscle system and contractile activity in the mussel Mytilus trossulus (Mollusca, Bivalvia)].

The development of contractile apparatus was subjected to comparative analysis during ontogenesis of the mussel Mytilus trossulus. Indirect immunofluorescence with the polyclonal antibody against mussel twitchin, a protein of thick filaments, and florescent phalloidin as a marker of filamentous cell actin were used to monitor changes in the developing muscle system at different larval stages. The first definitive muscle structures were found at the late trochophore stage (36 h after fertilization) and starting from the midveliger stage (96 h), striated muscles, which are never present in adult mussels, were distinctly seen.