SOME INDICES OF NON-SPECIFIC IMMUNITY OF BREAM OF THE SARATOV RESERVOIR

Abstract

The study of some parameters of nonspecific humoral and cellular immunity in sexually mature bream of the Saratov Reservoir was carried out. The fish were caught by bottom trawl in September 2019 during a complex hydrobiological expedition aboard the R/V “Akademik Topchiev” organized by the Papanin Institute for Biology of Inland Waters, Russian Academy of Sciences. Trawling operations were performedt at three standard stations: 1 – Shiroky Buerak, 2 – Khvalynsk, 3 – Kashpir Rudnik. The first two stations were located in the lower reaches of the reservoir and the third one was in the central part. Fish blood was sampled from the tail vein to obtain serum and prepare smears for phagocytic activity of neutrophils. After autopsy, pieces of immunocompetent organs (kidney, spleen and liver) were also taken from the fish in dry sterile tubes. The level of antimicrobial properties and C-reactive protein of blood serum, nonspecific immune complexes in kidney, spleen and liver tissues were studied, the proportion of immunodeficient individuals and phagocytic activity of neutrophils were determined. The study established quantitative indicators of humoral and cellular immunity of bream of the Saratov Reservoir. The comparative analysis showed significant differences in antimicrobial properties of blood serum and the content of non-enzymatic cationic protein in lysosomes of neutrophils of peripheral blood in bream from the central part and the lower reaches of the reservoir. Fish caught in the central part of the reservoir were characterized by high level of bactericidal activity of blood serum and low level of phagocytic activity of neutrophils. The majority of the studied individuals had a positive level of C-reactive protein and unreliable differences in the content of IR in tissues and organs. The revealed differences are probably caused by the impact of different environmental factors on the bream organism.