The genome response, realized by structure chromosome rearrangements in the polytene chromosomes of two sibling species Prodiamesa bureshi Michailova and Prodiamesa olivacea Mg., was studied. The larvae of the species were collected in May and September, 2016, from Biała Przemsza River, a metal-mine-affected site in southern Poland, where Zn, Cd, and Pb concentrations in the sediment exceeded many times the reference data and those from unpolluted sites. The water had high contents of different major ions and nutrients. A high spectrum of somatic chromosome aberrations was detected in the salivary gland chromosomes of both species, which defined a high somatic index (from 1.2 to 7), indicating the sensitivity of both genomes to anthropogenic stress. The cells with somatic rearrangements of both species were significantly higher (P. bureshi: G = 25.636, P < 0.001 May, G = 32.722, P < 0.001 September; P. olivacea: G = 47.863, P < 0.001 May, G = 38.742, P < 0.001 September) than the control. Both species from polluted and unpolluted sites showed a high frequency of ectopic conjugations, as between arms B, CD (centromere regions), and E (NOR). Some deformities of mentum and mandibles of P. bureshi (20%) and P. olivacea (35%) were detected. We postulate that the appearances of somatic chromosome aberrations are more sensitive indicators of genotoxicity in the studied species than changes in external morphology. The sensitivity of the P. olivacea and P. bureshi genomes shows that these species are good candidates for detecting the presence of genotoxic compounds in aquatic basins and evaluating their genotoxic effects.
Keywords: Genome instability; Metal-mine-contaminated river; Polytene chromosomes; Prodiamesa species; Somatic aberrations.