Nucleolar variations during the ontogenesis of diploid and tetraploid cyprinid species

Studying the quantitative characteristics of nucleoli in cells of several cyprinid species (Cyprinus carpio, Carassius alontus gibelio, Carassius auratus auratus, Aristichthys nobilis, Ctenopharyngodon idella, Hypophthalmichthys molitrix) has shown a definite programme that controls genetically changes in the nucleolar characteristics during fish ontogenesis. In embryogenesis, the nucleolar activity, which has been estimated from the number and size of nucleoli, decreased; this process was realized dissimilarly in diploid and tetraploid cells. A correlation between the nucleolar characteristics and the body mass of juvenile fish was found. Parameters of the nucleolar activity were closely related to the physiological state of mature organisms and featured tissue specificity, rhythmicity, and high level of heritability. (C) 1999 The Fisheries Society of the British Isles.