Petrova N.A.1, Michailova P.V.2 2021. [The use of salivary gland chromosomes of Chironomids (Diptera, Chironomidae) for assessing the pollution of aquatic ecosystems] // Euroasian Entomological Journal. Vol.20. No.1: 38–48 [in Russian, with English summary].
1 Zoological Institute RAS, Universitetskaya Nab. 1, Saint-Peterburg 199034 Russia. E-mail: chironom@zin.ru
2 Institute of Biodiversity and Ecosystem Research, BAS, Sofia 1000 Bulgaria. E-mail: pmichailova@yahoo.com
doi: 10.15298/euroasentj.20.1.06
ABSTRACT. The role of chironomid larvae in assessing the degree of pollution of various aquatic ecosystems is discussed. It was shown that chironomids are sensitive to different forms of environmental pollution, including heavy metals and radionuclides. Various structural rearrangements appear in the polytene chromosomes of chironomid larvae collected from polluted water bodies, namely different inherited chromosomal aberrations and many somatic aberrations. The sensitivity of the small G chromosome is especially high, which turns into a “pompom-like” chromosome, a good biomarker for heavy metal contamination. The use of two indices for environmental assessment are proposed: the somatic index to assess the genome response and the cytogenetic index to assess the degree of pollution of the reservoir. As a rule, aberrations are localized in regions of chromosomes rich in mobile elements or highly repetitive DNA sequences. Together with structural aberrations, heavy metals cause changes in the transcriptional activity of important regions of chromosomes: the nucleolus (NOR) and Balbiani rings (BRs). Under stressful conditions, functional activity in these regions is reduced or completely suppressed. A wide range of structural and functional changes in the genome of chironomids is also demonstrated in experimental conditions after exposure to chromium (Cr), lead (Pb), aluminum (Al) and other metals. The influence of the radiation in a number of chironomid species in the Chernobyl zone is considered. Many new chromosome aberrations were discovered (inversions, duplications, additional chromosomes, contacts between telomeres of different chromosomes). The transcriptional activity of the nucleolus (NOR) and BRs decreased. The results presented in the review demonstrate the significance of the cytogenetic approach for analyzing the influence of factors of anthropogenic environmental pollution. Somatic aberrations and changes in the transcriptional activity of important chromosome regions can be successfully used as biomarkers to assess the state of aquatic ecosystems.
KEY WORDS: Chironomidae, polytene chromosomes, chromosome aberrations, structural and functional alterations, heavy metals, radiation.