SIZE STRUCTURE IN SETTLEMENTS OF MUSSEL CRENOMYTILUS GRAYANUS AT THE COAST OF PRIMORSKY KRAI (JAPAN SEA)

Current size structure of mussel Crenomytilus grayanus in the coastal waters at Primorye (Japan Sea) is considered on results of diving surveys conducted in 2003–2018. In total, 3635 mussel specimens were weighed and measured. Size structure of the mussel settlements is determined for each surveyed area using the data on shell length. The following parameters are evaluated: i) index of settling — ratio of mollusks number with shell < 30 mm (spat, yearlings) and > 50 mm (adults); ii) index of maturation — ratio of mollusks number with shell 35–50 mm (pre-reproductive) and > 50 mm (adult); iii) index of commercial recruitment — ratio of mollusks number with shell 90–100 mm (recruits) and >100 mm (commercial stock). The portion of mussels with non-commercial size exceeds 50 % in most settlements that indicates their active natural reproduction. The index of settling varied from 0.03 to 1.80, by areas; the index of maturation — from 0.04 to 0.58; the index of commercial recruitment — from 0.03 to 0.53.The indices variations are not proportional and depend on presence of the pelagic larvae in plankton and on survival of the juveniles. Low settling of spat in some years could be leveled by its good survival in favorable environments. Potential annual recruitment to commercial stock of C. grayanus in the coastal waters of Primorye is estimated as 5 . 103 t. State of the C. grayanus settlements beyond the areas of anthropogenic impact and active fishing is evaluated as stable.

Mutagenesis Studies and Structure-function Relationships for GalNAc/Gal-Specific Lectin from the Sea Mussel Crenomytilus grayanus

The GalNAc/Gal-specific lectin from the sea mussel Crenomytilus grayanus (CGL) with anticancer activity represents а novel lectin family with β-trefoil fold. Earlier, the crystal structures of CGL complexes with globotriose, galactose and galactosamine, and mutagenesis studies have revealed that the lectin contained three carbohydrate-binding sites. The ability of CGL to recognize globotriose (Gb3) on the surface of breast cancer cells and bind mucin-type glycoproteins, which are often associated with oncogenic transformation, makes this compound to be perspective as a biosensor for cancer diagnostics. In this study, we describe results on in silico analysis of binding mechanisms of CGL to ligands (galactose, globotriose and mucin) and evaluate the individual contribution of the amino acid residues from carbohydrate-binding sites to CGL activity by site-directed mutagenesis. The alanine substitutions of His37, His129, Glu75, Asp127, His85, Asn27 and Asn119 affect the CGL mucin-binding activity, indicating their importance in the manifestation of lectin activity. It has been found that CGL affinity to ligands depends on their structure, which is determined by the number of hydrogen bonds in the CGL-ligand complexes. The obtained results should be helpful for understanding molecular machinery of CGL functioning and designing a synthetic analog of CGL with enhanced carbohydrate-binding properties.