[Features of lysozyme content in cods (order Gadiformes) and flatfish (order Pleuronectiformes)].

The content of lysozyme as an indicator of nonspecific immunity in kidney, liver, spleen, and blood serum in 8 fish species of the order Gadiformes and the order Pleuronectiformes was analyzed. The Gadiformes are characterized by a very low level of enzyme or the absence of its activity in individual organs and serum, regardless of the fish habitat location. The Pleuronectiformes demonstrated diversity in content and distribution of lysozyme in the body of various fish species. Two plaice species with the unique distribution inhabiting the Sea of Okhotsk were found. This feature is due, first, to the highest lysozyme content in serum of the previously studied fish; second, to the 2-3-fold excess of the enzyme content in serum as compared with the studied immunocompetent organs. The obtained results confirm the opinion about the existence of various related groups among fishes which essentially differ in the lysozyme role in nonspecific immunity.

[Variability of some blood serum beta-globulins in the life cycle of the true sturgeons (Acipenseridae)].

Blood proteins of true sturgeons of three genera Acipenser, Huso, and Pseudocaphirhynchus preserving unidirectional variability in ontogenesis regardless of peculiarities of the fish ecology can indicate unity of origin of the current species. Age-related protein transformations have heterochronous character. The slowest ontogenetic development lasting 4-6 years is peculiar to one of antigens of beta-globulins. Analysis of variability of beta-globulins in the age diapason beginning from the 4-month-old fry and including adult spawned individuals indicates different functional significance of their individual components. The beta A-globulin absent at early postembryonic stages becomes the second, after albumin, quantitatively predominant antigen in the adult fish blood. The amount of beta B-globulin, like antigens of alpha 1- and alpha 2-globulins preserving relative ontogenetic stability, can decrease significantly in freshwater sturgeons due to their preparation for spawning.

[Age-related variability of serum protein antigens in sturgeons (Acipenseridae, Acipenseriformes)]. / Vozrastnaia izmenchivost' antigennykh svoistv belkov osetrov (Acipenseridae, Acipenseriformes).

We studied the variability of antigenic properties of proteins in two sturgeon species at different stages of postembryonic development. The deepest changes occurred in individual components of albumins and beta-globulins (transferrins) and were mostly related to an increased proportion of the protein accounting for these antigens. Transformation of the main component of albumins A1 into adult antigens was completed in 5-month old fry. The main component of beta-globulins A (component of transferrins) appeared in the blood flow much later than other proteins and could retain the fry features until the age of 3-4 years. Other antigens belonging to alpha1- and alpha2-globulins and the second component of transferrins were more stable and did not undergo substantial changes. The direction of ontogenetic variability of serum antigens in sturgeon fry did not depend on the habitat of adult fish in fresh or sea water.