Expression of thick filament proteins during ontogenesis of the mussel Mytilus trossulus (Mollusca: Bivalvia)

The appearance of thick filament proteins organized into supramolecular complexes was studied by SDS-PAGE and Western-blot analysis at different developmental stages of the mussel Mytilus trossulus. Paramyosin appeared at the egg stage, while twitchin and myorod appeared at the blastula stage (12 h after fertilization). In addition, RT-PCR analysis showed that the twitchin genes were expressed starting from the blastula stage. Thus, the proteins forming thick filaments of the contractile apparatus of mussel muscles are expressed long before the formation of the first well-organized muscle system of the veliger larvae (55 h). Further, the ratios actin/myosin heavy chain (MHC) and paramyosin/MHC at the veliger stage (96 h) distinctly differed from those in the adult mussel.

Cryopreservation of primary cell cultures of marine invertebrates

Primary cell cultures obtained from somatic and larval tissues of bivalve molluscs and from embryos of sea urchins were frozen to -196 degrees C by two-step freezing using 10% dimethyl sulfoxide (DMSO) or/and trehalose (3-30 mg/ml) as cryoprotectants. We estimated both cell viability and the RNA synthetic activity after freeze-thaw. Total lipid extracts from the tissues of echinoderms examined as possible cryoprotective agents demonstrated a weak cryoprotective capacity. Mussel lipid extract was found to possess a considerable cryoprotective activity. Cryoprotective capacity of tested lipids correlated with their thermotropic behaviour. DMSO + trehalose combination was shown to be a favourable cryoprotectant and sea urchin blastula cells the most freezing-tolerant cells.