The effect of long-term heavy metals contamination on genome alterations of Chironomidae (Diptera) in rivers of southern Poland
Воздействие длительного загрязнения тяжелыми металлами на изменение генома хирономид в водоемах южной Польши
The long period of river contamination with heavy metals can have genotoxic effect and damage either the DNA or chromosome structures. The aim of this study is to examine the effect of trace metals on the genome instability of the Chironomids, inhabited two rivers in southern Poland: Chechło and BiałaPrzemsza strongly polluted by Cd, Pb and Zn. The metals concentrations in both rivers exceed the threshold effect concentration of SEL (severe effect level) above which adverse effects on the majority of sediment dwelling organisms are expected.The salivary gland chromosomes of four species (Chironomus riparius Meigen, Chironomus annularius Meigen, Prodiamesa olivacea Meigen and Prodiamesa bureshi Michailova) are analyzed using their standard chromosome maps. Inherited and somatic chromosome rearrangements were established. As a valuable tool to detect genotoxicity in the sedimentsomatic index(S) was calculated as a ratio of number of different aberrations of each site relative to the number of individuals at that locality. C. annularius has the highest value (S=2), while P. olivacea has the lowest S index (S=0.69). The observed high frequency of ectopic pairing between different chromosomes in Prodiamesa species may be reflected on the changes of the genome function under stress conditions.Our results show that the species of the phylogenetically younger genus Chironomus are more sensitive to stress agents than these in genus Prodiamesa. However, the Prodiamesa species are also sufficiently sensitive. We can conclude that the Chironomids are a good model system for genotoxicity testing within a biomonitoring programme. The changes in the Chironomid genome indicate continuing pollution from past actions plus an early warning of recent environmental changes.
Acknowledgements: The research was funded by National Science Center, Poland, grant no. 2014/15/B/ST10/03862