Characteristics of Leukocytes and Thrombocytes of Selected Sturgeon Species from Intensive Breeding

Palíková M., J. Mare‰ , J. J i rásek : Characteristics of Leukocytes and Thrombocytes of Selected Sturgeon Species from Intensive Breeding. Acta Vet. Brno, 1999, 68: 259–264. Analysis of leukocyte and thrombocyte characteristics in Acipenser baerii, Acipenser stellatus and Huso huso sturgeons at the age of about 200 days kept under intensive breeding conditions is presented. The differential leukocyte count of studied fish species was of lymphocytic character (68.0-73.5% of lymphocytes), and the neutrophilic and eosinophilic granulocytes amounted to 21.8-25.1% and 3.0-4.6%, respectively. Statistically significant (p< 0.05) differences were found between individual sturgeon species in morphometric characteristics of studied cells (i.e. thrombocytes, lymphocytes, neutrophilic and eosinophilic granulocytes). The highest values were found in Acipenser baerii. These results are in good agreement with data on the ploidy in sturgeon species under study. Acipenser baerii, Acipenser stellatus, Huso huso, differential leukocyte count, thrombocytes, lymphocytes, neutrophilic granulocytes, eosinophilic granulocytes The family Acipenseridae may be divided into two groups with respect to the number of chromosomes and the amount of nuclear DNA. The first group comprises species having a large number of chromosomes (2n = 250). The species A. baerii and A. gueldenstaedti belong to this group. The second group includes, for example, H. huso, A. ruthenus, A. stellatus with lower numbers of chromosomes in their genomes (2n = 118-120) (Vasi lyev et al. 1980; Gorshkova et al. 1996; Arefjev and Nikolaev 1991). Several studies have shown correlation between the ploidy in various fish species and the red blood cell size (Aref jev and Nikolaev 1991; Flaj‰hans 1997; Svobodová et al. 1998). The aim of our study was to evaluate interspecies differences in morphological characteristics of leukocytes and thrombocytes in selected sturgeon species (i.e. A. baerii, H. huso and A. stellatus) known for different numbers of chromosomes. Materials and Methods A total of 10 Acipenser baerii, 10 Huso huso and 5 Acipenser stellatus sturgeons originating from the Fishery Hluboká, Mydlovary farm were sampled (A. baerii in September, A. stellatus a H. huso early in December). All the fish used in the study were clinically healthy without any signs of disease. The fish were kept under intensive breeding conditions in flow-through troughs with controlled environment (water temperature of 20 oC, water oxygen saturation over 80%). Other hydrochemical indicator values assessed in discharge water characterise the environmental conditions suitable for intensive sturgeon culture. The fish were fed complete feeding mixtures. Basic haematological and biochemical parameters have been already published (Jirásek and Mare‰ 1998). Proke‰ et al. (1995ab;1996) studied morphometric characteristics of these sturgeon species with respect to plastic and meristematic signs. Using morphometric characteristics these authors determined the studied species to be pure species. Blood from the fish was sampled by cardiac puncture into a heparinised syringe (Jirásek et al. 1980) and further processed employing standard methods (Svobodová et al. 1986). Blood smears were stained according to Pappenheim and the leukocyte differential count, the longitudinal and transverse axis of leukocytes (eosinophilic granulocytes, neutrophilic granulocytes and lymphocytes) and thrombocytes were determined. No basophilic ACTA VET. BRNO 1999, 68: 259–264 Address for correspondence: MVDr. M. Palíková Department of Game, Fish and Bee Diseases University of Veterinary and Pharmaceutical Sciences, Palackého 1-3 612 42 Brno, Czech Republic Phone: +420 5 4156 2821 E-mail: [email protected] http://www.vfu.cz/acta-vet/actavet.htm granulocytes were found. The above mentioned values were also measured for the cell nuclei of thrombocytes and were used for computing the surface area of individual cells. In all, we measured 100 thrombocytes with their nuclei, 100 eosinophilic granulocytes, 200 neutrophilic granulocytes and 200 lymphocytes in every sturgeon species. The data were statistically evaluated. For the assessment of the significance of differences, ANOVA with subsequent testing by Scheffe’s method was utilized. Results are presented in tables as mean and standard deviation ( SD), and variation coefficient (V). Results and Discussion Length and weight characteristics of the fish analysed are given in Table 1, i. e. the total body length (TL) and the body weight (W). Figs 1 to 3 present differential leukocyte counts and relative counts of subpopulations of eosinophilic and neutrophilic granulocytes. The differential leukocyte counts of all three fish species were similar and of lymphocytic character (68.0 73.5%), neutrophilic and eosinophilic granulocytes amounted to 21.8 25.1 % and 3.0 4.6 %, respectively. Other cell types (monocytes and developmental stages of younger granulocytes and lymphocytes – blasts, prolymphocytes and promyelocytes) occurred only sporadically (0.7 2.0 %). Compared with bony fishes, in sturgeons there was a smaller number of myelocytes and metamyelocytes and a larger number of eosinophilic and neutrophilic granulocytes with band or segmented nuclei. Table 2 presents interspecies comparisons of cell sizes of the fish species studied. Comparison of individual cell types proved in some cases differences. Greatest differences 260 Table 1 Length and weight characteristics of sturgeon species studied Species TL [mm] W [g] Age Mean ± SD Mean ± SD [day] Acipenser baerii 426.30 ± 8.30 274.30 ± 23.15 206 Acipenser stellatus 276.83 ± 12.25 46.59 ± 7.17 184 Huso huso 347.40 ± 26.25 130.56 ± 59.31 208