POLYTENE CHROMOSOMES OF GLYPTOTENDIPES GLAUCUS MG. (DIPTERA, CHIRONOMIDAE) AS TEST – OBJEKT TO STUDY TOXIC EFFECTS OF LEAD IONS

Abstract

Results of the analysis of cytogenetic effects of lead ions on polytene chromosomes of Glyptotendipes glaucus Mg are reported. The functional state of polytene chromosomes was determined via computation: chromosome compactness index (CR); coefficient of genetic activity of the nucleolar organizer (NOR) and coefficient of genetic activity of the Balbiani ring (BR). With increase of the lead nitrate solution concentration, the compactness index increases, that is, the chromosomes compactness decreases: medians of CR values (when measuring shoulder E) in the control are 6.05, for the maximum concentration studied they are 7.3. As a result of the of lead ions action, the activity of the nucleolar organizer genes decreases: medians of the NOR values decrease from 2.3 in the control to 2.0 for the highest concentrations used in the experiment. The activity of the Balbiani ring genes increases with the growing concentration of the lead nitrate solution: medians of the BR values in the control are 1.45, for the maximum studied concentration they are 1.95. The G. glaucus genome responds ambiguously to the change in the lead ions concentration in the medium: the coefficient of the nucleolar organizer’s genetic activity decreases, while the genetic activity of the Balbiani ring, on the contrary, increases.