Effect of Contaminants on the Genome of Some Species of Genus Chironomus (Chironomidae, Diptera) Live in Sediments of Dunajec River and Czorsztyn Reservoir

The effect of contaminants on the genomes of Chironomus plumosus L. and Chironomus bernensis Wülker, Klötzli species was studied in the Dunajec River (station 1) and in the littoral of Czorsztyn Reservoir (stations 2 and 3). According to the index of geoaccumulation, the sediments were polluted by cadmium (Cd) and chromium (Cr). Cd concentrations at stations 1, 2, and 3 were 0.71, 0.56, and 1.27 μg g, while Cr concentrations were 841.5, 186.9, and 40.7 μg g, respectively. The pH of sediments ranged from 6.7 to 7.1. Genome instability of C. bernensis and C. plumosus L. was evaluated at the stations and was determined by structural and functional chromosome alterations. Living in sediment containing higher concentrations of Cr and elevated concentrations of Cd (station 1), C. bernensis was found to possess a high spectrum of somatic chromosome rearrangements with a somatic index of 0.92. C. plumosus collected from stations 2 and 3 was found to have somatic indices of 0.77 and 0.5, respectively. Both species mobilized their genome by changes in their functional activity: the appearance of novel puffs and the participation of chromosomes in an ectopic pairing (more common in C. bernensis than in C. plumosus). The observed chromosome alterations were interpreted as a response of the genome to stressful conditions in the environment. The study indicates that the salivary gland chromosomes of the observed species provide a sensitive system for the easy tracking of genome changes induced by stressful conditions.