Degradation of micro-nano-sized polytetrafluoroethylene and acrylic fluorinated copolymer particles in the periwinkle digestive tract.

The aim of the work was to investigate the possible biodegradation of such stable plastics as fluorated acrylic copolymer Protacryl-M and polytetrafluoroethylene-teflon (PTFE)-that are widely applied in medicine for prosthetics in dentistry and orthopedics. Our tasks were as follows: 1. To select a suitable marine biological object (multicellular invertebrate) 2. To develop a method for delivering microplastic particles (MP) of selected plastics to the gastrointestinal tract (GIT) of an experimental animal 3. To develop a technique for separating MP particles from animal feces 4. To develop a technology for multiple passages of MP particles through the gastrointestinal tract of an animal 5. To select methods and techniques for determining the degradation of the surface of MP particles after passing through the gastrointestinal tract of the animal The effect of a biological agent on the types of plastic above is considered using marine gastropods of the genus Littorina (in particular, the periwinkle L. brevicula) as a model organism widely distributed in the marine intertidal zone.

A massive bloom of Karenia species (Dinophyceae) off the Kamchatka coast, Russia, in the fall of 2020.

In the fall of 2020, a long-lasting and massive harmful algal bloom (HAB) with extensive fields of yellow sea foam was observed in relatively cold waters (7-13 °C) off the coasts of the Kamchatka Peninsula, Russia. According to the estimates based on bio-optical parameters in satellite imagery, the Kamchatka bloom 2020 lasted for two months and covered a vast area of more than 300 × 100 km. An abundance of dead fish and invertebrates, including sea urchins, sea anemones, chitons, cephalopods, bivalves were found on shore during the bloom. Animals suffered almost 100% mortality within a depth range between 5 and 20 m. To identify the causative microalgal species, light and scanning electron microscopy, Raman spectroscopy, and molecular phylogenetic approaches were used. The HAB area was estimated by the spectral analysis of satellite-derived imagery. The causative organisms were unarmored dinoflagellates of Karenia species. Their density and biomass reached 100-620 cells·mL-1 and 1300-7700 mg·m-3, respectively, which accounted for 31-99% of the total cell density and 82-99% of the total phytoplankton biomass in late September to mid-October. The dominant species was Karenia selliformis, and the other co-occurring kareniacean species were K. cf. cristata, K. mikimotoi, K. papilionacea, K. longicanalis, and two unidentified morphotypes of Karenia spp. The molecular phylogeny inferred from LSU rDNA and ITS region showed that K. selliformis from Kamchatka in 2020 belonged to the cold-water group I and was identical to K. selliformis strains from Hokkaido, Japan, identified in 2021. This is the first HAB event caused by K. selliformis recorded from Russian coastal waters.

Micro-nano-sized polytetrafluoroethylene (teflon) particles as a model of plastic pollution detection in living organisms.

Micro- and nano-sized particles of polytetrafluoroethylene (PTFE) were used as model (reference) particles to study the biological effects of plastic pollution. Since the PTFE molecule contains fluorine, considered as an "atomic marker" sharply distinguishing it from other common plastics, micro- and nano-particles of PTFE have a specific crystalline structure and are, therefore, well identified by the methods of polarized light microscopy (POL), Raman microspectroscopy (micro-Raman), and energy-dispersive spectroscopy (EDS). Examples of PTFE particles detection in hemolimph of the cockroach Blatella germanica, in hemolimph of the larva and in faecal pellets of imago of a fly Lucilia sp., in the stomach and hingat of brine shrimp Artemia salina, and in association with cell wall of green unicellular alga Chlorococcus sp. are provided. The presented results strongly suggest that PTFE particles can be detected and identified in the biological medium using the method of "atomic markers", polarization microscopy and Raman spectroscopy.

Comparative characteristic of Mytilus muscle cells developed in vitro and in vivo.

The mussel cells from premyogenic larval stages are capable of differentiation into smooth muscle cells in vitro. However, the behavior and protein composition of these cells are not completely identical to those of smooth muscle cells of adult mussels. In this study we compared some properties of mussel muscle cells forming from cells of trochophore (premyogenic larval stage) in vitro with those of muscle cells of veliger and adult mussel. We found a substantial difference between the contractile apparatus protein composition of veliger muscle and cultivated cells. Myorod, one of the molecular markers of the phenotype of mollusc smooth muscle cells (Shelud'ko et al., 1999, Comp Biochem Physiol 122:277-285), is not a constituent of the contractile apparatus of veliger muscle. At the same time the protein composition of contractile apparatus in cultivated cells was similar to that of adult Mytilus muscles. There were only few quantitative differences between them. The contractile activity of cultivated cells was changing in time. The kinetic parameters of first spontaneous contractions were similar to those of phasic contractions, while their period was close to that of tonic contractions. After 50-55 hrs cultivation the cells produced both phasic and tonic contractions, but the character of contractile activity of cultivated cells was regulated after six days of cultivation only. However, there were no muscle cells in vitro, whose contractile activity was similar to that of veliger muscle cells. So, we concluded that properties of muscle cells forming from premyogenic larval mussel cells in culture are similar to those of muscle cells of the adult mussel, but not of veliger.